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Confrontation visual field testing is a test used in ophthalmology for rapid and gross detection of large-scale visual field problems. It is done by asking the patient to look directly at the examiner's eye or nose and compare the patient's visual field with the examiner's field. It can be used to test the binocular visual field (with both eyes open) and or the visual field of each eye separately (with one eye closed).

What test is used to test peripheral vision?

The visual field test is a subjective measure of central and peripheral vision, or “side vision,” and is used by your doctor to diagnose, determine the severity of, and monitor your glaucoma. The most common visual field test uses a light spot that is repeatedly presented in different areas of your peripheral vision.

A common way for your doctor to screen for any problems in your visual field is with a confrontation visual field test. You will be asked to look directly at an object in front of you, (such as the doctor’s nose) while one of your eyes is covered. Your doctor may hold up different numbers of fingers in areas of your side vision field and ask how many you see as you look at the target in front of you.

What is a confrontation test used for?

Confrontation visual field testing is a test used in ophthalmology for rapid and gross detection of large-scale visual field problems. It is done by asking the patient to look directly at the examiner's eye or nose and compare the patient's visual field with the examiner's field.

What is the difference between confrontation and gross perimetry?

Though the terms confrontation and gross perimetry are often used as synonyms, strictly speaking confrontation describes one of several 'comparison' tests whereas gross perimetry is the use of a target to measure the extent of the visual field and to map any large scotomas within the field.

What is a gross visual field test?

A visual field test measures your peripheral vision, or how well you can see above, below and to the sides of something you're looking at. It's also called a perimetry test. Visual field testing is important for many conditions, including glaucoma.

What is the gross measurement of peripheral vision?

Peripheral vision is also sometimes referred to as “side vision” or “indirect vision.” The peripheral is the edge of your visual field, or the full range you can see at a given moment. The typical visual field for humans is 170 degrees: 70 degrees for central vision and 100 degrees for peripheral vision.

Confrontation visual field testing does not need a clinical setting to perform. It can be done in any well-illuminated room. Since the visual fields of both eyes overlap in the nasal area, each eye is tested separately. Patient is asked to sit in front of the examiner, at a distance between 66 and 100 cm, maintaining the eye level same as examiner's. Patient is asked to remove his/her spectacles before starting the test. For testing the right eye field, the patient is asked to close his left eye, and look straight at the examiner's left eye (preferably) or nose. Examiner should also close his/her right eye. Move a finger or bead-on-a-stick inwards from an area outside the usual 180º visual field, and ask the patient when they first see the targets. Alternatively, the patient may be asked to count the number of fingers the examiner shows or identify wiggling fingers. For an accurate assessment of the patient's visual field, it is essential that the distance of all test objects from the patient is the same as the distance from the examiner. The Examiner should compare the point at which the patient sees the target with his own visual field. Repeat the procedure for all eight meridians.

Recording confrontation visual field results. (A) Normal result: the patient counts fingers in all quadrants of both eyes. (B) Bitemporal hemianopia: the patient fails to count fingers in the temporal quadrants of each eye. (C) Homonymous hemianopia: the patient fails to count fingers in the temporal quadrants of one eye and the nasal quadrants of the other eye. CF = Counts Fingers.

Record the type of target used and whether there are any significant abnormalities in the patient's visual field. Colored targets such as red are more sensitive than a white test target. The test reliability may improve when techniques like finger counting, finger wiggling, identifying a target etc. are combined. Confrontation testing can be done with both eyes open also. It is done for testing the binocular visual field.

What does a false positive mean in a visual field test?

Fixation losses occur when the patient reports seeing a stimulus that is presented in the predicted area of the physiologic blind spot. False positives occur when a patient presses the button when no stimulus is presented.

Can a visual field test be wrong?

Unfortunately, visual fields are highly nonspecific. According to Dr. Eisengart, there are many false-positive results, and any visual field can be inaccurate. “If I see something on a visual field that looks worse, I need to either have that test repeated, or I need to have something corroborating it.

See also:

• Why Is My Peripheral Vision Blurry?
• How to Test Peripheral Vision at Home
• The four-meter confrontation visual field test

Reference:

• en.wikipedia.org/wiki/Confrontation_visual_field_testing
• aao.org/education/image/recording-confrontation-visual-fields

Epithelial Cells:

Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial (mesothelial) tissues line the outer surfaces of many internal organs, the corresponding inner surfaces of body cavities, and the inner surfaces of blood vessels.

Vitamin A (VitA) is a micronutrient that is crucial for maintaining vision, promoting growth and development, and protecting epithelium and mucus integrity in the body.

Epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues lack blood or lymph supply, but are supplied by nerves.

There are several different types of epithelial cells based on their shape and arrangement.

There are three principal shapes of epithelial cell: squamous (scaly), columnar, and cuboidal.

These can be arranged in a singular layer of cells as simple epithelium, either simple squamous, simple columnar, or simple cuboidal, or in layers of two or more cells deep as stratified (layered), or compound, either squamous, columnar or cuboidal. In some tissues, a layer of columnar cells may appear to be stratified due to the placement of the nuclei. This sort of tissue is called pseudostratified. All glands are made up of epithelial cells. Functions of epithelial cells include diffusion, filtration, secretion, selective absorption, germination, and transcellular transport. Compound epithelium has protective functions.

Epithelial tissue has several important functions that are essential to life. Since epithelial cells are found throughout your body, their function and purpose change based on their location. eResearch by Navid Ajamin -- summer 2026

Epithelial tissue can have one or a combination of the following several functions:

• Protection: Epithelial tissue protects several aspects of your body. For example, your skin is made up of epithelial tissue and protects the tissues deeper in your body, such as blood vessels, muscle and internal organs. The cilia on the epithelial cells that line your intestines protect the rest of your body from intestinal bacteria.
• Secretion: Epithelial tissue in your glands (glandular epithelium) can secrete (release) enzymes, hormones and fluids.
• Absorption: The epithelial lining of your internal organs, such as your liver and lungs, can allow the absorption of certain substances. For example, the internal epithelial lining of your intestines absorbs nutrients from the food you eat.
• Excretion: Excretion is the removal of waste from your body. The epithelial tissue in your kidneys excrete waste, and the epithelial tissue in your sweat glands excrete sweat.
• Filtration: The epithelium of your respiratory tract filters out dirt and particles and cleans the air that you breathe in. Epithelial tissue in your kidneys filters your blood.
• Diffusion: In biology, diffusion is the passive movement of molecules or particles from regions of higher concentrations to regions of lower concentration. Simple squamous epithelial cells form a membrane that allows selective diffusion of materials to pass through. Diffusion helps with filtration, absorption and secretion functions.
• Sensory reception: Sensory nerve endings that are embedded in epithelial tissue allow your body to receive outside sensory stimuli. As an example, the stereocilia on the surface of the epithelial tissue in your ear are essential for hearing and balance. In addition, your taste buds are embedded in the stratified squamous epithelium of your tongue.

Epithelial layers contain no blood vessels (avascular), so they must receive nourishment via diffusion of substances from the underlying connective tissue, through the basement membrane.  Cell junctions are especially abundant in epithelial tissues.

The endothelium (pl.: endothelia) is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vessel wall.

Corneal epithelium.

The corneal epithelium is a stratified (possessing five or six layers) squamous non-keratinized epithelium (the superficial cells are flattened, nucleated and non-keratinized). It is 50–60 µm in thickness and adjacent cells are held together by numerous desmosomes and to the underlying basal lamina by hemidesmosomes and anchoring filaments.

Endothelial cells in direct contact with blood are called vascular endothelial cells whereas those in direct contact with lymph are known as lymphatic endothelial cells. Vascular endothelial cells line the entire circulatory system, from the heart to the smallest capillaries.

These cells have unique functions that include fluid filtration, such as in the glomerulus of the kidney, blood vessel tone, hemostasis, neutrophil recruitment, and hormone trafficking. Endothelium of the interior surfaces of the heart chambers is called endocardium. An impaired function can lead to serious health issues throughout the body.

The corneal epithelium (epithelium corneae anterior layer) is made up of epithelial tissue and covers the front of the cornea. It acts as a barrier to protect the cornea, resisting the free flow of fluids from the tears, and prevents bacteria from entering the epithelium and corneal stroma.

The inner layer of cells that make up the cornea. These cells remove extra fluid from the cornea.

What happens if the corneal epithelium is damaged?

Disruptions in the protective epithelial and stromal layers of the cornea can render the eye susceptible to infection, stromal ulceration, perforation, scarring, and significant vision loss.

Can a damaged cornea heal?

Small abrasions (scratches) on the cornea usually heal on their own. Deeper scratches or other injuries can cause corneal scarring and vision problems.

What type of epithelium is found in the retina?

Retinal pigment epithelium (RPE) is formed from a single layer of regular polygonal cells arranged at the outermost layer of the retina. The outer side of the RPE is connected to Bruch's membrane and the choroid, while the inner side is connected to the outer segment of photoreceptor cells.

Reference:

• en.wikipedia.org/wiki/Epithelium
• en.wikipedia.org/wiki/Endothelium
• aao.org/eye-health/anatomy/endothelium
• en.wikipedia.org/wiki/Corneal_epithelium
• pmc.ncbi.nlm.nih.gov/articles/PMC6778469
• pmc.ncbi.nlm.nih.gov/articles/PMC8355697
• pmc.ncbi.nlm.nih.gov/articles/PMC6162863
• my.clevelandclinic.org/health/articles/22062-epithelium
• sciencedirect.com/topics/neuroscience/corneal-epithelium
• nei.nih.gov/eye-health-information/eye-conditions-and-diseases/corneal-conditions
• geeksforgeeks.org/biology/epithelial-tissue-introduction-characteristics-types-importance

Nevus is the medical term for a birthmark. Just as freckles, moles, and birthmarks can occur on your skin, a nevus can also be found inside your eye. They are most often seen in the pigmented layer beneath the retina called the choroid.

A choroidal nevus can only be seen by an eye care specialist using specialized tools to see inside your eye.

Is a choroidal nevus serious?

Most choroidal nevi remain benign (non-cancerous) and have no symptoms. However, occasionally, a nevus can transform into uveal melanoma. The rate of choroidal nevi transforming into melanoma is estimated at approximately 1 in 9000 per year.

Can eye nevuses affect vision?

Almost always, a nevus causes no visual symptoms. Rarely, a nevus can cause a blind spot in the vision of one eye, but this rarely affects a patient's day to day vision. Sometimes visual changes are a sign of other problems or that a nevus has begun to change into a malignant choroidal melanoma.

Is it normal for a choroidal nevus to grow?

Whereas choroidal melanomas tend to grow relatively rapidly, choroidal nevi may enlarge slowly over a period of several years. In younger patients, this slow, non-malignant growth is more common and does tend to stabilize with age.

What is the treatment for choroidal nevus?

Benign choroidal nevi that remain stable usually require no treatment—just regular monitoring. Our doctors recommend annual screenings for nevi that pose no clinical risk. However, those with more risk require close monitoring every 4-6 months.

What is the difference between a choroidal nevus and a melanoma?

Key Points on Choroidal Melanoma

Melanomas are larger than benign lesions of nevus and are usually greater than 3 millimeters in size. Unlike fixed nevi, melanomas increase in size and number over time. They also look elevated and thick, with a dome shape that bulges into the eye.

Reference:

• retinalmd.com/retina-conditions/choroidal-nevus
• newportretina.com/retinal-diseases/what-is-a-choroidal-nevus

Scintillating scotoma is a visual aura that was first described by 19th-century physician Hubert Airy (1838–1903). Originating from the brain, it may precede a migraine headache, but can also occur without headache (also known as visual migraine). It is often confused with retinal migraine, which originates in the eyeball or socket.

Hubert Airy (June 14, 1838 – June 1, 1903) was an English physician who was the pioneer in the study of a migraine. He was the son of Sir George Airy, Astronomer Royal. He has two portraits in the National Portrait Gallery. Airy was one of the first to describe the common visual aura, which is the second stage in an outbreak of a migraine attack and precede a headache, and also coined the term scintillating scotoma for it.

As the scotoma area expands, some people perceive only a bright flickering area that obstructs normal vision, while others describe seeing various patterns. Some describe seeing one or more shimmering arcs of white or colored flashing lights. An arc of light may gradually enlarge, become more obvious, and may take the form of a definite zigzag pattern, sometimes called a fortification spectrum (i.e. teichopsia, from Greek τεῖχος, town wall), because of its resemblance to the fortifications of a castle or fort seen from above. It also can resemble the dazzle camouflage patterns used on ships in World War I. Others describe patterns within the arc as resembling herringbone or Widmanstätten patterns.

The visual anomaly results from abnormal functioning of portions of the occipital cortex at the back of the brain, not in the eyes nor any component thereof, such as the retinas. This is a different disease from retinal migraine, which is monocular (only one eye).

It may be difficult to read and dangerous to drive a vehicle while the scotoma is present. Normal central vision may return several minutes before the scotoma disappears from peripheral vision.

Sufferers can keep a diary of dates on which the episodes occur to show to their physician, plus a small sketch of the anomaly, which may vary between episodes.

Scintillating Scotoma

Scintillating scotomas are usually visual auras associated with migraines. These temporary blind spots are often characterized by flickering lights or geometric patterns and can precede or accompany a migraine headache.

Paracentral Scotoma

Paracentral scotomas occur near the center of one’s vision and are often linked to glaucoma, which damages the optic nerve due to increased pressure in the eye. Early detection and treatment are crucial to prevent significant vision loss.

Junctional Scotoma

Junctional scotomas involve a combination of a central scotoma in one eye and a superior or inferior nasal step defect in the other. This type is typically associated with lesions at the junction of the optic nerve and chiasm, such as in cases of tumors or aneurysms.

What causes a scintillating scotoma in only one eye?

A scintillating scotoma may affect one or both of your eyes. It's a blind spot that flickers and wavers between light and dark. They're typically not permanent but could indicate an underlying health condition. A scotoma is an aura or blind spot that obstructs part of your vision.

How to get rid of a visual migraine aura?

The visual aura is often resolved by the time the headache occurs, does not cause any permanent vision damage and is typically not the target of treatment. The treatment options vary from over-the-counter analgesics (pain medication) to migraine-specific prescribed medications such as the triptan class of medications.

Scotomas, or blind spots in the eye, can result from a variety of conditions affecting the retina or optic nerve. The causes vary depending on the type of scotoma. Here’s a breakdown of common causes for different types of scotomas:

Causes of Central Scotomas

• Macular Degeneration: Deterioration of the central portion of the retina, leading to a loss of central vision. Learn more about macular degeneration.
• Diabetic Retinopathy: Damage to the blood vessels in the retina due to diabetes. More on diabetic retinopathy.

Causes of Junctional Scotomas

• Optic Nerve Disorders: Issues at the junction of the optic nerve and chiasm, possibly due to tumors or aneurysms.
• Trauma or Inflammation: Injury or swelling in the area can affect the optic nerve function.

Causes of Paracentral Scotomas

• Glaucoma: Increased pressure in the eye leading to optic nerve damage. Glaucoma details.
• Diabetic Eye Conditions: Diabetes can cause various eye problems, including scotomas. Diabetic eye care information.

Causes of Scintillating Scotomas

• Migraines: Visual auras associated with migraines often manifest as scintillating scotomas.
• Vascular Issues: Blood flow problems to the brain or retina can cause temporary scotoma.

The treatment of scotomas varies based on their underlying cause. While some types are treatable, others may only be manageable. Common treatment methods include:

• Corrective Lenses: For scotomas caused by refractive errors, prescription eyeglasses or contact lenses can help.
• Medication: Certain drugs can treat underlying conditions like migraines or autoimmune diseases that cause scotomas.
• Laser Therapy: Used in cases like diabetic retinopathy to reduce the risk of vision loss.
• Surgery: In some cases, surgical intervention might be necessary, especially for scotomas caused by eye injuries or tumors.
• Vision Therapy: Helps in adapting to the scotoma and improving visual function.

Reference:

• discovervision.com/blog/scotoma-blind-spot-in-eye
• en.wikipedia.org/wiki/Scintillating_scotoma

Transient Light Sensitivity Syndrome (TLSS) Incidence Following Femtosecond LASIK for Myopic and Hyperopic Eyes and Femtosecond SMILE for Myopic Eyes

Short- and Long-Term Light Sensitivity after LASIK surgery

Why are my eyes sensitive to artificial light?

Your eyes can be sensitive to light due to photophobia, a condition often caused by migraines, eye issues, or neurological problems. To improve it, use tinted glasses, prescribed eye drops, and visit an eye doctor to address the underlying cause.

What causes unilateral photophobia?

Photophobia is defined as pain with normal or dim light. Unilateral photophobia suggests an inflammatory process in the affected eye, but may be seen with the trigeminal autonomic cephalalgias.

What are the symptoms of light sensitivity?

People with it can also experience pain or discomfort, eye fatigue, tears or dry eyes, difficulty reading, excessive squinting and seeing bright spots no matter the lighting condition. Outdoor light is just one kind of light that can be irritating.

This complication, termed transient light-sensitivity syndrome (TLSS), is characterized by moderate-to-severe photophobia bilaterally that appears two to eight weeks after ocular procedures and is associated with inflammation of peripheral structures, such as the ciliary body, and possibly the trabecular meshwork and ...

Astigmatism can be corneal, lenticular, or retinal. Based on the meridian, it can be with the rule, against the rule, oblique and bi-oblique astigmatism. Astigmatism can also be subdivided as simple, compound, and mixed.

What is the rarest type of astigmatism?

This defect in the eye is categorized as:

• myopic astigmatism (or with the rule, WTR)
• hyperopic astigmatism (or against the rule)
• mixed astigmatism: the rarest.

What level of astigmatism needs glasses?

What Level of Astigmatism Requires Glasses? You'll likely need glasses if your astigmatism has a strength of 1.0 or more. But even if your astigmatism needs less than 1.0 diopters of correction, it doesn't mean you won't need glasses.

but What does residual astigmatism mean?

The portion of astigmatism that remains uncorrected or is newly induced after a surgical procedure (such as cataract surgery or LASIK) or after the fitting of a contact lens. It must be accounted for in the final prescription.

Residual astigmatism can be caused by incorrect placement of the IOL, incorrect marking of the cornea, inaccurate preoperative measurements, unanticipated surgically induced astigmatism, posterior corneal curvature, or rotation of the IOL itself.

incorrect placement of the IOL:

Most times, a primary malposition occurs because of surgeon error. In these instances, part of the lens may be sitting in the capsular bag and part in the sulcus. Alternately, the lens haptic may break during insertion, and rather than centering properly within the bag, the IOL sits lopsided.

How to find residual astigmatism?

Calculated residual astigmatism (CRA) was determined by subtracting, in minus cylinder form, the corneal toricity (difference between the keratometer readings of the two principal meridians), from the spectacle astigmatism.

Which lens is preferred for correcting residual astigmatism?

For patients with higher amounts of astigmatism, a toric lens and limbal relaxing incisions can be used in combination. The toric lens handles the majority of the correction, while the incisions address any remaining irregularity. This pairing can reduce astigmatism that would be too high for either technique alone.

Limbal relaxing incision is an effective method in reducing corneal astigmatism during implantable collamer lens surgery.

If a patient presents with residual astigmatism after the implantation of any IOL, surgeons should first examine his preoperative and postoperative keratometry values to determine whether the astigmatism is naturally occurring or surgically induced.
If the amount of astigmatism present after surgery is different from the preoperative amount, it may be surgically induced astigmatism. In these cases, we would look at the preoperative and postoperative keratometry readings and evaluate for any astigmatism induced by the incision. This can be determined just by looking at the keratometry readings.

After LASIK, irregular astigmatism can be schematized into three categories: preoperative (preexisting), intraoperative (induced), and postoperative.

Corneal warping is one of the prominent causes of preoperative astigmatism. Therefore, patients must discontinue the use of contact lenses for at least 1 to 3 weeks prior to treatment. Intraoperative causes of astigmatism include poor laser optics; irregular hydration of the stromal bed; central islands; decentered ablations; flap-related complications, including flap decentration and poor flap alignment causing a buttonhole, lost flap; and hinge ablation. Postoperative irregular astigmatism may result from corneal ectasia or as a result of flaps and wrinkles from flap displacement.

After PRK, residual astigmatism may occur based on the individual's surface healing; some may end up with a small amount of irregular astigmatism secondary to the adjustment of epithelial cells and keratocytes.

How to correct residual astigmatism?

There are four primary options for correcting residual astigmatism: spectacles or contact lenses, laser vision correction, corneal relaxing incisions, and rotation of the IOL.

Reference:

• lens.com/what-is/residual-astigmatism
• crstodayeurope.com/crste-issues/2008-oct/1008_21-php/46052
• reviewofophthalmology.com/article/residual-astigmatism--after-iol-implantation
• crstoday.com/topics/general/correcting-residual-astigmatism-after-the-implantation-of-a-toric-iol-2/42259
• lensmartonline.com/blog/glasses-lifestyle-guides/details/residual-astigmatism-after-surgery-need-glasses?

See also:

• How Much Residual Astigmatism is Acceptable?
• How long does astigmatism take to heal after LASIK?
• Residual Astigmatism After Corneal Ablation
• Residual Astigmatism: Dr Ben LaHood and Dr Nick Andrew

Blind spot test

To see or not to see.

The eye’s retina receives and reacts to incoming light and sends signals to the brain, allowing you to see. One part of the retina, however, doesn't give you visual information—this is your eye’s “blind spot.”

At the back of your eye is the retina. Your retina is made up of light-sensitive cells which send messages to your brain about what you see. Everyone has a spot in their retina where the optic nerve connects. In this area there are no light-sensitive cells so this part of your retina can’t see. We call this the blind spot.

Most of the time you don’t notice your blind spot because the spot in one eye doesn’t match the spot in the other eye. Each eye supplies information to the brain, filling in what’s missing. Also, sometimes the brain will fill in the missing information with what it thinks should be there. That causes one kind of optical illusion. eResearch by Navid Ajamin -- Autumn 2025

Instructions:

R ... L

Place your eye a distance from the screen approximately equal to three times the distance between the R and the L. Move your eye towards or away from the screen until you notice the other letter disappear. For example, close your right eye, look at the "L" with your left eye, and the "R" will disappear.

(Upper row) A cross section of the eye showing the blind spot and retinal veins, as well as the fact that light goes through all the retinal layers before hitting the photoreceptors. (Lower row) Top-down view of the retina, showing how big the blind spot and retinal veins are relative to the fovea, which is the high-resolution region of the retina. (Images adapted with permission from Webvision-University of Utah).

Night blind spot

It is estimated that once fully adapted to darkness, the rods are 10,000 times more sensitive to light than the cones, making them the primary receptors for night vision. Since the cones are concentrated near the fovea, the rods are also responsible for much of the peripheral vision. The concentration of cones in the fovea can make a night blind spot in the center of the field of vision.

Description: Students will make a simple prop and use it to find their blind spot

Purpose: To locate and identify the blind spot

Length of Activity: 20 minutes

Materials:

• One 3 x 5 inch card (or other stiff paper) per student.
• Black markers.
• 1 ruler per student.

Steps:

1. Students should be instructed to make a dot and an X on the white side of the index card as pictured.

2. They should then hold the card so the X is on the right side and raise it to eye level about an arm's length away.

3. Have students close their right eye.

4. Student should look directly at the X with their left eye only. They should note that they can also see the dot, but should not focus on it.

5. While looking at the X, and keeping an awareness of the dot, have students bring the cards slowly towards their faces. At some point they should be aware that the dot has disappeared and then reappeared.

6. Now have students repeat but this time close their left eyes. They should use their right eyes to look at the dot while keeping aware of (but not looking directly at) the X. This time the X will disappear and then reappear as the card is slowly brought towards their faces.

7. Now have students take their markers and ruler to draw a straight line through the center of both the dot and the X.

8. Repeat the activity. Note that this time the line seems to be continuous, with no gap, even as the X or dot disappears.

What’s Going On?

At the back of your eye is the retina. Your retina is made up of light-sensitive cells which send messages to your brain about what you see. Everyone has a spot in their retina where the optic nerve connects. In this area there are no light-sensitive cells so this part of your retina can’t see. We call this the blind spot. The point at which the mark on the card disappears is where your blind spot is.

When you draw a line through the dot and X you set up an optical illusion. The brain knows that a line is there and fills in the gap, even as it loses sight of the dot or X.

Reference:

• researchgate.net/figure/Upper-row-A-cross-section-of-the-eye-showing-the-blind-spot-and-retinal-veins
• aao.org/museum-eye-openers/experiment-blind-spot
• en.wikipedia.org/wiki/Blind_spot_(vision)
• exploratorium.edu/snacks/blind-spot

Pars plana refers to a region of the eye that is characterized by clear, smooth, cystoid cavities known as pars plana cysts, which exist between the pigmented and nonpigmented epithelial layers.

The pars plana (also known as orbicularis ciliaris) (Latin: flat portion) is part of the ciliary body in the uvea (or vascular tunic, the middle layer of the three layers that comprise the eye). It is about 4 mm long, located near the junction of the iris and sclera, and is scalloped in appearance.

The pars plana constitutes the two-thirds of the ciliary body as the posterior portion. It is a 4 mm wide, smooth surface structure. The pars plana is positioned between the retina and pars plicata and is avascular. Avascular pertains to having little or no blood vessels.

The pars plicata is 2 mm wide and consists of 70 ciliary processes, each approximately 0.5–0.8 mm high and 0.5 mm wide.

The pars plicata (also known as corona ciliaris) (Latin: folded portion) is the folded and most anterior portion of the ciliary body of an eye. The ciliary body is a part of the uvea, one of the three layers that comprise the eye. eResearch by Navid Ajamin -- autumn 2025

What is the difference between pars plana and plicata?

The pars plicata gives rise to the ciliary processes to which the zonules of the lens attach and it surrounds the periphery of the iris. The pars plana has a scalloped posterior border that fits into the scalloped edge of the retina at the ora serrata.

What is the difference between vitrectomy and pars plana?

A vitrectomy performed for diseases of the posterior segment is called a posterior or pars plana vitrectomy. This kind of vitrectomy is performed by a retina specialist. Anterior Vitrectomy: In rare cases, the vitreous gel comes through the pupil into the anterior (front) chamber of the eye.

What are the symptoms of Pars Planitis?

Patients with Pars Planitis usually do not have frank eye pain. What they do notice though is floaters or “stuff” in their vision. In some cases patients with Pars Planitis may go on to develop cataracts and resultant blurry vision.

At pars plana vitrectomy (PPV), changes in ciliary body dimensions with age may affect how sclerotomies are placed so as to avoid iatrogenic damage to the crystalline lens and peripheral retina.

Pars plana vitrectomy is defined as a surgical procedure used to address complicated proliferative diabetic retinopathy and other retinal conditions such as non-clearing vitreous hemorrhage and retinal detachment.

Patients with pars planitis present with minimal symptoms, for example, floaters or blurry vision. In most cases, there is the absence of photophobia and pain. Occasionally patients may present with sudden loss of vision due to retinal detachment or acute vitreous hemorrhage.

Pars plicata refers to the area of the ciliary body that is located between the pars plana and the iris, measuring 2 mm wide. It gives rise to the ciliary processes, which are responsible for attaching the zonules of the lens, and surrounds the periphery of the iris. The non-pigmented epithelium of pars plicata plays a crucial role in the production of aqueous humor, and damage to this area can lead to hypotony.

Reference:

• en.wikipedia.org/wiki/Pars_plicata
• pmc.ncbi.nlm.nih.gov/articles/PMC11130848
• eyesurgeonsnyc.com/contents/education/uveitis-2/pars-planitis
• sciencedirect.com/topics/immunology-and-microbiology/ciliary-body
• entokey.com/the-ciliary-body-and-aqueous-fluid-formation-and-drainage
• taylorandfrancis.com/knowledge/Medicine_and_healthcare/Anatomy/Pars_plicata

What are the properties of the color green?

Researchers have shown that the green color has the ability to soothe our nervous system. Indeed, since it is the easiest color to perceive for our eyes, our whole body can then relax when this color surrounds us. That's why green is so prevalent in hospitals, schools or offices.

THE COLOUR GREEN

• Soothing, and restful on the eye.
• Relaxing mentally as well as physically.
• Helps alleviate depression, nervousness and anxiety.
• Offers a deep sense of renewal, self-control and harmony.

What are green lenses good for?

• Sunglasses with green lenses provide better contrast than gray lenses.
• transmit color accuracy better than brown lenses, and are ideal for both sunny and low-light environments.
• Perfect for water or field sports such as cycling or skiing, green lenses protect and comfort your eyes on foggy, cloudy, or bright days.

What are green lenses used for?

Another reason why green tinted glasses can be a good choice is that they help reduce the temperature as well as the glare that is eliminated by excessive lights. This reduction in the glare can create a soothing ambience and help you focus and work for longer hours without any strain or headaches.

What are the benefits of green cut lenses?

Green lens sunglasses can reduce the high and low-energy light that reaches the eyes while emphasizing the middle of the visible light spectrum. They result in a more comfortable experience, enhance contrast, and make colors look more natural compared to other tinted lenses.

Are Green Lens Sunglasses Right For You?

Green lens sunglasses can reduce the high and low-energy light that reaches the eyes while emphasizing the middle of the visible light spectrum. They result in a more comfortable experience, enhance contrast, and make colors look more natural compared to other tinted lenses.

Green sunglasses are suitable for a wide range of activities, including driving, hiking, fishing, golf, and more. They’re also ideal for protecting sensitive eyes from glare and eye fatigue.

There are a few factors to consider when shopping around for green sunglasses, including anti-glare and UV protection coatings, and a comfortable fit.

Green Coating

To set them apart from uncoated lenses, the original coated lenses were produced in green colour. The reflection gives a 2 percent enhancement at 515 nm, which makes the contrast visible, and the reflection appears as a green film.

The common reflection reduction film, which is currently excellent and old, makes up this layer of film. In terms of UV protection and alleviation of eye fatigue, the green film layer performs somewhat better, and the light green colour, which is currently the common colour of the lens coating layer, is harder to find on the lens.

Advantages

• When viewed from specific angles, green coatings exhibit a greenish-teal hue.
• In the green and yellow regions of the visible light spectrum, they are effective at reducing reflections. In bright outdoor environments, green coatings can improve visual clarity and contrast.
• For sunglasses and outdoor activities, they are a popular choice.

Which lens is better, green or black?

Green lenses provide good contrast in low-light conditions and enhance your vision in shaded areas. They make a trendy everyday alternative to classic dark-tinted sunglasses.

See also:

• Why Green Lens Sunglasses Are a Great Choice?
• How to Spot Fake Designer Sunglasses: 5 Red Flags
• What Are Green Tinted Sunglasses Best For?
• How Green Sunglass Lenses Work?

Corneal densitometry (CD) uses the biological properties of the cornea to visualize the morphology of the cornea and determine the degree of corneal transparency. At present, it is an emerging metric that has shown promise in various clinical diagnosis and evaluation of eye diseases and surgeries. We introduce the different methodologies used to measure CD.

Corneal topography is a painless test that produces color-coded maps of your cornea. Your cornea is the clear, outer surface of your eye. It has a slightly curved shape that refracts (bends) light as it enters your eye, allowing you to see the world around you.

Expected topography: Progressive flattening from center to the periphery by 2-4D, with the nasal area flattening more than the temporal area. Q-val: Describes the corneal shape factor, or eccentricity of the cornea. The ideal value is -0.26.

Furthermore, we systematically categorize the diagnostic value of CD into high, medium, and low levels based on its clinical significance.

By analyzing a wide range of conditions, including keratoconus, postrefractive surgery changes, and other corneal pathologies, we assess the utility of CD in each context. We also discuss the potential implications of these classifications for disease monitoring and prognosis evaluation. Our review underscores the importance of integrating CD assessments into routine clinical practice to enhance the accuracy and effectiveness of diagnostic processes for corneal disorders.

Spectral-domain optical coherence tomography scanning of the cornea before (a) and after (b) performing suture lysis using an argon laser. Note that the diffuse and thin fluid pocket in the corneal interface region (arrowheads) resolved when the intraocular pressure was lowered from 14 to 9 mmHg

Keratoconus (ker-uh-toe-KOH-nus) is an eye condition in which the clear, dome-shaped front of the eye, called the cornea, gets thinner, steeper and bulges outward into a cone shape. A cone-shaped cornea causes blurred vision and may cause sensitivity to light and glare. Keratoconus usually affects both eyes.

Symptoms of abnormal cornea include blurry vision, light sensitivity, and visible changes such as haziness or spots. Some of the most common causes of corneal issues include injuries, infections, inherited or genetic disorders, autoimmune disease, and age.

Optical density is a complex characteristic of materials that can slow down the propagation speed of light and produce refraction effect, which is a characterization of the shading ability of materials. It is expressed as a common logarithmic value of the ratio of incident light intensity to transmitted light intensity. The greater its value, the worse the light transmittance of the material.

What is corneal densitometry?

Corneal densitometry (CD) uses the biological properties of the cornea to visualize the morphology of the cornea and determine the degree of corneal transparency.

The transparent cornea forms the anterior portion of the outer casing of the eye and has the dual functions of protecting the inner contents of the eye as well as providing about two thirds of the eye's refractive power. The human cornea is composed of five layers, an overlying epithelium beneath which is a fibrous meshwork called Bowman's layer. The bulk of the tissue is constituted by the stroma, a collagen-rich central layer that comprises nearly 90% of the thickness of the cornea, and beneath this lies Descemet's membrane which supports the single layer of endothelial cells lining the posterior cornea. Other species have been reported to have certain differences in this construction, particularly with respect Bowman's layer and Descemet's membrane (Hayashi et al., 2002) but nevertheless, all these corneal layers need to be transparent. In normal corneas most of these are so thin that light scattering is minimal. For example, in humans, Bowman's layer and Descemet's membrane, both collagenous tissues like the stroma, together contribute less than 4% to the total corneal thickness. The corneal epithelium, on the other hand, is about 53 μm deep (Reinstein et al., 2008) and thus constitutes about 10% of the corneal thickness. Its transparency is a result of the homogeneity of the refractive index of all its constituent cells (Dohlman, 1971). In this review, we will concentrate on the structure and transparency of the corneal stroma. However, it should be noted that in a number of corneal pathologies, changes in one or more of the other layers can lead to increased light scattering and consequent loss of corneal transparency.

Reference:

• pubmed.ncbi.nlm.nih.gov/39326741
• pmc.ncbi.nlm.nih.gov/articles/PMC4655862
• oscb-berlin.org/deeper-insight-into-the-cornea
• sciencedirect.com/science/article/abs/pii/S003962572400122X

We suggest a theory to frozen light, which was first registered in 2000 by Lene Hau.

Lene Vestergaard Hau is a Danish physicist and educator. She is the Mallinckrodt Professor of Physics and of Applied Physics at Harvard University.She was also awarded tenure in 1999 and is now Mallinckrodt Professor of Physics and Applied Physics at Harvard. In 2001 she became the first person to stop light completely, using a Bose–Einstein condensate to achieve this. For her doctoral studies in quantum theory, Hau worked on ideas similar to those involved in fibre optic cables carrying light, but her work involved strings of atoms in a silicon crystal carrying electrons. While working towards her doctorate, Hau spent seven months at CERN, the European Laboratory for Particle Physics near Geneva. She received her doctorate from the University of Aarhus in 1991 at the age of 32, but by this time her research interests had changed direction.

Frozen light is explained here as a new state of matter. The explanation is given through space-time terms of the General Theory of Relativity. We consider a fully degenerate region of space (space-time), which is the ultimate case of the isotropic region (home of photons), where the metric is particularly degenerate. Both the space-time interval, the observable time interval, and the observable three-dimensional interval are zero in a fully degenerate region.-- Harvard University

فوتون (به انگلیسی: Photon) که معمولاً با نماد γ نمایش داده می‌شود، یک ذره بنیادی است. فوتون یک کوانتوم یا به‌عبارتی کم‌ترین مقدار قابل اندازه‌گیری در یک میدان الکترومغناطیسی مانند تابش الکترومغناطیسی (نور و امواج رادیویی) محسوب می‌شود و همچنین در نقش حامل نیرو برای نیروی الکترومغناطیس نیز عمل می‌کند. فوتون جرم ندارند. (جرم ذاتی یا سکون ندارند) اگرچه سرعت فوتون به محیط بستگی دارد اما در محیط خلأ، همواره با سرعتی برابر با سرعت نور، معادل ۲۹۹٬۷۹۲٬۴۵۸ متر بر ثانیه حرکت می‌کنند.

فوتون تفاوت‌هایی اساسی نسبت به ذراتی همچون «کوارک» (quarkquark) یا الکترون دارد. جرم ساکن این ذره برابر با صفر بوده، از این رو سرعت این ذره در خلاء دقیقا برابر با سرعت نور است. شاید مهم‌ترین تاثیری که فوتون در زندگی یک فرد عادی دارد، تاثیر آن در دیدن محیط اطراف است. در حقیقت بدون وجود فوتون قادر نخواهیم بود محیط اطرافمان را مشاهده کنیم.

فوتون هم خواص موج و هم خواص ذره را دارد. برای نمونه یک فوتون می‌تواند منعکس شده یا تداخل ویرانگر ایجاد کند. تداخل ویرانگر به حالتی گفته می‌شود که دو موج برخوردی یکدیگر را خنثی می‌کنند. بنابراین این ویژگی‌ها نشان‌گر موجی بودن فوتون است. از طرفی به عنوان یک ذره، فوتون تنها می‌تواند با انتقال مقدار مشخصی از انرژی، با دیگر مواد کنش داشته باشد.

What is the different nature of light?

Answer: Light has a dual nature, implying that it is made up of both waves and particles. Although Einstein believed that light is a particle (photon), quantum physics has revealed that light may operate as both a particle and a wave at the same time.

Light behaves in many different ways when it comes in contact with something.

What are the 7 natural sources of light?

Natural sources of light include the sun, stars, fire, and electricity in storms. There are even some animals and plants that can create their own light, such as fireflies, jellyfish, and mushrooms. This is called bioluminescence.

Light is a transverse, electromagnetic wave that can be seen by the typical human. The wave nature of light was first illustrated through experiments on diffraction and interference. Like all electromagnetic waves, light can travel through a vacuum. The transverse nature of light can be demonstrated through polarization. eResearch by Navid Ajamin -- autumn 2025

ماهیت‌های متفاوت نور

ماهیت ذره‌ای: ایزاک نیوتن در کتاب خود در رساله‌ای دربارهٔ نور نوشت: پرتوهای نور ذرات کوچکی هستند که

از یک جسم نورانی نشر می‌شوند. احتمالاً نیوتن نور را به این دلیل به صورت ذره در نظر گرفت که در محیط‌های همگن به نظر می‌رسد در امتداد خط مستقیم منتشر می‌شوند، این امر را قانون می‌نامند و یکی از مانندهای خوب برای توضیح آن، به وجود آمدن سایه است. برخی دیگر از دانشمندان نیز اظهار داشته‌اند که نور از ذرات در ارتعاش شدید تشکیل یافته است. نیوتن معتقد بود نور از درون واسطه‌ای به نام اتر گذر می‌کند که غیر مادّی است و دیده نمی‌شود. بر اساس نظریه اتر، فضا آکنده از این واسطه است. هم‌اکنون این نظریه باطل شده است و معتبر نیست.

ماهیت موجی: هم‌زمان با نیوتن، کریستیان هویگنس (۱۶۹۵–۱۶۲۹ میلادی) طرفدار توضیح دیگری بود که در آن حرکت نور به صورت موجی است و از چشمه‌های نوری به تمام جهات پخش می‌شود. هویگنس با به کار بردن امواج اصلی و موجک‌های ثانوی، قوانین بازتاب و شکست را تشریح کرد. حقایق دیگری که با تصور موجی بودن نور توجیه می‌شوند پدیده‌های تداخلی‌اند، مانند به وجود آمدن فریزهای روشن و تاریک در اثر بازتاب نور از لایه‌های نازک یا پراش نور در اطراف مانع، مانند آزمایش دوشکاف.

ماهیت الکترومغناطیس: بیشتر به خاطر نبوغ جیمز کلارک ماکسول (۱۸۷۹–۱۸۳۱) است که ما امروزه می‌دانیم نور نوعی انرژی الکترومغناطیسی است که معمولاً به عنوان امواج الکترومغناطیسی توصیف می‌شود. گستره کامل امواج الکترومغناطیسی شامل: موج رادیویی، تابش فروسرخ، نور مرئی از قرمز تا بنفش، تابش فرابنفش، پرتو ایکس و پرتو گاما می‌باشد.

ماهیت کوانتومی نور: طبق نظریه مکانیک کوانتومیِ نور، که در دو دهه اول سده بیستم به وسیله ماکس پلانک، آلبرت انیشتین و نیلز بور برای اولین بار پیشنهاد شد. انرژی الکترو مغناطیسی کوانتیده است، یعنی جذب یا نشر انرژی میدان الکترو مغناطیسی به مقدارهای گسسته‌ای به نام فوتون انجام می‌گیرد. انرژی است.

نظریه مکملی

نظریه جدید نور شامل اصولی از تعاریف نیوتن و کریستیان هویگنس است. بنابرین گفته می‌شود که نور رفتار دوگانه‌ای دارد برخی از پدیده‌ها مثل تداخل و پراش رفتار موجی آن را نشان می‌دهد و برخی دیگر مانند پدیده فتوالکتریک و پدیده کامپتون با رفتار ذره‌ای نور قابل توضیح هستند.

Therefore, we refer to such a region and particles which inhabit it as zero-space and zero-particles.

Moving to the coordinate quantities inside zero-space shows that real speed therein is that of light, depending on the gravitational potential and the rotation of space. It is shown that the eikonal equation for zero-particles is a standing wave equation: zero-particles are standing light waves, while zero-space is filled with a system of standing light waves (light-like hologram). With these, zero-particles appear to a regular (external) observer as mere stopped light. This paper has been submitted to The Abraham Zelmanov Journal. The Abraham Zelmanov Journal

This journal is named after Abraham Zelmanov (1913-1987), a prominent scientist working in the General Theory of Relativity and cosmology, whose main goal was the mathematical apparatus for calculation of the physical observable quantities in the General Theory of Relativity (it is also known as the theory of chronometric invariants).

Which country recently freezes light?

Generally, light exists only as a particle or wave. But recently, a team of researchers from Italy's University of Pavia and CNR Nanotec reported successfully 'freezing' light by manipulating photons in a meticulously arranged ultra-cold environment.

How long was light frozen?

A newly designed trap freezes a beam of light for 1 second. Researchers have frozen a pulse of light in place for a full second, a thousand times longer than the previous record.

Did scientists freeze light fact check?

“Freezing light” means slowing it down or stopping it for a short time. Scientists do this by making light interact with super-cold atoms or special materials, causing it to pause and then continue moving. It's not actually frozen like ice. As for “light being the source of all matter,” that's not true.

Is it possible to solidify light?

It has been theorized that solid light could exist. Some experiments claim to have created solid photonic matter or molecules by inducing strong interaction between photons. Potential applications of solid light could include logic gates for quantum computers and room-temperature superconductor development.

But Is it possible to freeze lighting?

Reference:

• researchgate.net/publication/253604073_A_Theory_of_Frozen_Light_According_to_the_General_Theory_of_Relativity
• study.com/academy/lesson/light-energy-sources-lesson-for-kids.html
• newatlas.com/scientists-freeze-light-like-kylo-ren/45621
• photonterrace.net/en/photon/behavior
• en.wikipedia.org/wiki/Solid_light
• en.wikipedia.org/wiki/Lene_Hau
• physics.info/light

A retinal tear or break happens when the gel-like vitreous in your eye pulls on your retina and causes a split. Your retina is a thin layer of tissue that’s sensitive to light found at the back of your eye.

A retinal tear isn’t the same as a retinal detachment. A retinal tear could lead to a retinal detachment if the tear isn’t treated. A retinal detachment happens when the retina pulls away from the tissues that support it.

You can also develop a hole in your retina when your retina gets thinner. Retinal holes are less likely to lead to retinal detachment.

Retinal tears and any injury that damages your retina threatens your eyesight and is a medical emergency. Contact your eye care provider as soon as you have retinal tear symptoms or any type of eye injury.

How common is a retinal tear?

Retinal tears are common, with nearly one in ten people developing one at some point during their lifetime. Retinal detachments, on the other hand, are less common, occurring in approximately one in 300 people.

Can stress cause a retina tear?

Even though stress can't cause retinal detachment, it can be harmful to your eye health in other ways. In addition to cortisol during times of stress, the body also produces epinephrine or adrenaline. This causes the pupils to dilate so you are able to see the world more clearly and be protected from danger.

A retinal tear is less severe than a retinal detachment, but you still may need treatment. You probably won’t feel pain, but you may have blurry vision and a lot of eye floaters and light flashes. Your provider can repair a tear before it leads to a detached retina.

What are the symptoms of a retinal tear?

Symptoms of a retinal tear may include:

• Flashes of light (photopsia).
• Suddenly seeing more black spots or floaters than usual.
• Darkening vision.
• Blurred vision.

You might have a retinal tear and have no symptoms.

What causes a retinal tear?

Retinal tear causes include:

• Posterior vitreous detachment.
• Eye injuries.
• Eye surgeries.

What are the risk factors for retinal tears?

Risk factors for retinal tears include:

• Getting older.
• Being nearsighted (having myopia).
• Having a retina that’s thinning.
• A family history of retinal detachment or tears.

Reference:

• my.clevelandclinic.org/health/diseases/25107-retinal-tear

Does a concussion affect your eyesight?

A concussion can affect vision by damaging the eyes themselves, muscles that surround the eyes or parts of the brain involved in vision. Even small vision changes can affect your daily life by making it difficult to read, drive, exercise, and carry out work or school activities.

As an athlete, experiencing a concussion can be a scary and unsettling experience. The road to recovery can sometimes feel daunting, especially if you’re worried about returning to your pre-injury level. One aspect that many athletes may be concerned about is the effect of a concussion on their vision, particularly their vision stamina.

The good news is that with proper treatment and monitoring, vision stamina can be restored as part of your concussion recovery plan. So, if you’re grappling with a concussion and worry about your vision, know that there are steps you can take to regain your visual strength. With patience, support, and the right professional guidance, like the expert care you’ll receive at Parker Performance Institute, you’ll be back in the game in no time.

The Impact of Concussions on Vision Stamina

When determining the best concussion recovery plan, each athlete’s vision stamina, or their ability to sustain visual focus and clarity over time, should be thoroughly examined. Understanding post-concussion visual stamina is crucial for a successful recovery.

Signs Your Vision Stamina May Be Affected by a Concussion

After you’ve received a concussion, you may find that your eyes tire more quickly, and this is negatively affecting your overall quality of life. Other signs that your vision stamina has been compromised include:

• Frequent headaches
• Blurred or double vision
• Difficulty focusing on objects (close up or far away)
• Eye strain and fatigue
• Sensitivity to light

If you notice any of these signs, it’s essential to address them proactively.

Reference:

• sjvisiontherapy.com/success-stories/concussion-management
• parkerperformanceinstitute.com/blog/how-to-increase-vision-stamina-after-a-concussion
• completeconcussions.com/concussion-management/a-look-at-the-eyes-assessing-vision-in-concussion-patients

Phantom Eye Syndrome is NOT a multi-million dollar summer blockbuster movie. It is a real medical condition that many patients report after one eye has been surgically removed.

What is a phantom vision?

Phantom vision was manifest by the transient belief that visual sensations were present in the absent eye. This phenomenon was never spontaneously divulged; in all instances the visual sensations had to be specifically elicited.

Can watching TV cause glaucoma?

Impact on Eye Pressure

While screen time alone isn't likely to cause glaucoma, it can contribute to increased IOP, which can worsen the condition in glaucoma patients. It's a good idea to be mindful of your screen habits and ensure you're giving your eyes enough rest to avoid unnecessary pressure.

What is phantom glasses syndrome?

This eerie phenomenon is called Phantom Glasses Syndrome, and it's a spooky trick our brains play—especially when we go without glasses after years of wearing them. 👓🎃 Phantom Glasses Syndrome can make you feel like your frames are still resting on your nose or even that there's a “ghostly” lens smudge to clear away!

What causes phantom glasses syndrome?

The longer you've worn glasses, the more likely your brain has gotten used to them as part of you, creating this spooky sensation even when they're not there!

Much like Phantom Limb Syndrome, in which a person might still feel like they have their arm or leg following an amputation, a person whose eye has been removed might still get sensations of pain or visual perceptions. A recent study at the University of Liverpool involved 239 patients who had undergone eye removal due to cancer. Sixty percent of respondents reporting symptoms such as pain, visual sensations like colors or shapes, or the impression of actually seeing with the missing eye. Some even reported seeing objects or people that were not actually present. People who suffer severe vision loss but without eye removal can experience similar visual hallucinations. This is called Charles Bonnet Syndrome.

How do you treat phantom eye syndrome?

Treatment. Treatment on painful phantom eye syndrome is limited and does not point out a standard treatment protocol but possible treatment pathways include resting techniques, pharmacologic, non-pharmacologic, surgery, drug therapy, and psychological.

Can glaucoma cause you to hallucinate?

About one in five people with retinal conditions such as macular degeneration experiences hallucinations, which can also occur in people with other macular diseases and ocular conditions such as glaucoma, as well as stroke. CBS is more common in people aged 80 years and above, but can occur at any age.

Glaucoma” is Greek in origin and describes a “blue-grey” or a “blue-green” colour. How does a word describing colours come to be used in naming of an eye condition?

Well, one of the prominent features of glaucoma is a build up of pressure in the eye. As the pressure increases, the clear window at the front of the eye, the cornea, starts to have trouble in keeping itself transparent.

The inner surface of the cornea then “fractures” and fluid starts to accumulate in its substance. So that when light reflects off this damaged surface, the onlooker starts to see a bluish-green or bluish-grey colour instead of being able to look straight into the eye.

Reference:

• kidseyes.co.za/paediatric-eye-care/glaucoma
• glaucoma.org.au/news-details/news/phantom-vision-common-but-neglected

See also: Phantom Vision: Common But Neglected