عینک eyewear

Allergic conjunctivitis is inflammation of the conjunctiva (the membrane covering the white part of the eye) due to allergy. Although allergens differ between patients, the most common cause is hay fever. Symptoms consist of redness (mainly due to vasodilation of the peripheral small blood vessels), oedema (swelling) of the conjunctiva, itching and increased lacrimation (production of tears). If this is combined with rhinitis, the condition is termed allergic rhinoconjunctivitis.

Allergic conjunctivitis occurs when the conjunctiva becomes swollen or inflamed due to a reaction to pollen, dust mites, pet dander, mold, or other allergy-causing substances.

The symptoms are due to release of histamine and other active substances by mast cells, which stimulate dilation of blood vessels, irritate nerve endings and increase secretion of tears.

Treatment of allergic conjunctivitis is by avoiding the allergen (e.g. avoiding grass in bloom during the "hay fever season") and treatment with antihistamines, either topical (in the form of eye drops), or systemic (in the form of tablets). Antihistamines, medication that stabilizes mast cells, and non-steroidal anti-inflammatory drugs (NSAIDs) are safe and usually effective.

Causes eResearch by Navid Ajamin -- winter 2013

The cause of allergic conjunctivitis is an allergic reaction of the body's immune system to an allergen. Allergic conjunctivitis is common in people who have other signs of allergic disease such as hay fever, asthma and eczema.

Among the most common allergens that cause conjunctivitis are:

• Pollen from trees, grass and ragweed

• Animal skin and secretions such as saliva

• Perfumes

• Cosmetics

• Skin medicines

• Air pollution

• Smoke

• Dust mites

• Eye drops

Most cases of seasonal conjunctivitis are due to pollen and occur in the hay fever season, grass pollens in early summer and various other pollens and moulds may cause symptoms later in the summer.

Perennial conjunctivitis is commonly due to an allergy to house dust mite (a tiny insect-like creature that lives in every home).

Giant papillary conjunctivitis is a very rare condition that is mainly caused by an allergic reaction to "debris". Surgery may also cause this type of allergic conjunctivitis.

Contact dermatoconjunctivitis is caused by the rest of the allergens that conjunctiva may come into contact with: cosmetics, medications and so on.

Symptoms

Symptoms may be seasonal and can include:

• Intense itching or burning eyes
• Puffy eyelids, most often in the morning
• Red eyes
• Stringy eye discharge
• Tearing (watery eyes)
• Widened blood vessels in the clear tissue covering the white of the eye

Exams and Tests

Your health care provider may look for the following:

• Small, raised bumps on the inside of the eyelids (papillary conjunctivitis)
• Positive skin test for suspected allergens on allergy tests

Allergy testing may reveal the pollen or other substances that trigger your symptoms.

• Skin testing is the most common method of allergy testing.
• Skin testing is more likely to be done if symptoms do not respond to treatment.

Treatment

The best treatment is to avoid what causes your allergy symptoms as much as possible. Common triggers to avoid include dust, mold and pollen.

Some things you can do to ease symptoms are:

• Use lubricating eye drops.
• Apply cool compresses to the eyes.
• Do not smoke and avoid secondhand smoke.
• Take over-the-counter oral antihistamines or antihistamine or decongestant eye drops. These medicines can offer more relief, but they can sometimes make your eyes dry. (Do not use the eye drops if you have contact lenses in place. Also, do not use the eye drops for more than 5 days, as rebound congestion can occur).

If home-care does not help, you may need to see a provider for treatments such as eye drops that contain antihistamines or eye drops that reduce swelling.

Mild eye steroid drops can be prescribed for more severe reactions. You may also use eye drops that prevent a type of white blood cell called mast cells from causing swelling. These drops are given along with antihistamines. These medicines work best if you take them before you come in contact with the allergen. Referral to an ophthalmologist before using steroid eye drops should be done since intraocular pressure measurements and a more thorough eye exam (using a slit lamp) is needed.

Reference:

• en.wikipedia.org/wiki/Allergic_conjunctivitis
• Causes of eye allergies | drkashishgupta.com/- Bathinda India
• Allergic conjunctivitis Information | mountsinai.org/ Mount Sinai - New York

See Also:

• What Is Allergic Conjunctivitis? What Causes Allergic Conjunctivitis? medicalnewstoday.com

• How to cope with the spring conjunctivitis? eyejournal.net

• Vernal keratoconjunctivitis wikipedia.org

Exotropia (from Greek εξοτρὀπια, εξο "exo" meaning "to exit" or "move out of" and τρὀπειν "tropein" meaning "to turn") is a form of strabismus where the eyes are deviated outward. It is the opposite of esotropia. People with exotropia often experience crossed diplopia. Intermittent exotropia is a fairly common condition. "Sensory exotropia" occurs in the presence of poor vision. Infantile exotropia (sometimes called "congenital exotropia") is seen during the first year of life, and is less common than "essential exotropia" which usually becomes apparent several years later.

The brain's ability to see three-dimensional objects depends on proper alignment of the eyes. When both eyes are properly aligned and aimed at the same target, the visual portion of the brain fuses the forms into a single image. When one eye turns inward, outward, upward, or downward, two different pictures are sent to the brain. This causes loss of depth perception and binocular vision.[1]

Are there different forms of Exotropia?

Yes. The most common form affects children as young as 2 years of age and is intermittent, at least in the early stages. This is usually called intermittent exotropia or intermittent distance exotropia or intermittent divergent squint.

Infantile Exotropia is rare and affects children in the first 6 months of life. It is usually
constant and usually requires surgical correction.

Consecutive Exotropia occurs in the situation where surgery has been performed already for an esotropia (eye turning in towards the nose) and the eye has now overcorrected and turned outward.

Sensory Exotropia occurs as a result of a poorly sighted eye. This can happen at any age but the exotropia commonly occurs in adulthood. Treatment is surgery usually.

How common is Intermittent Exotropia

Squint or Strabismus affects up to 4% of the population. However, exotropia contributes only 10% of all cases of strabismus in childhood. Therefore it affects approximately one child in 200 in the UK. eResearch by Navid Ajamin -- winter 2013

The Good News
Most children with intermittent exotropia do well. Most do not need glasses. Most children do not need surgery and they do not seem to be all that bothered by the eye turning outward. [2]

Types of strabismus

• Esotropia (ET)
• Exotropia (XT)
• Hypertropia (HT)
• Hypotropia (HPO)

What causes Exotropia
The cause of exotropia is not known. Most experts believe that the brain has trouble controlling the position of they eye. This problem may run in families.

The age of onset varies but is often between 6 months and 4 years. As long as the eyes are straight some of the time, the brain will develop some normal functioning of the eyes (stereoscopic depth perception). Since the brain and eyes work properly some of the time, time is on your side.

Causes of Exotropia [7]

Exotropia, especially the intermittent type, often has no known cause. The condition might be associated with:

• Very poor vision in one eye
• Third cranial nerve palsy, which can paralyze or weaken eye muscles

Risk factors for exotropia include:

• Family history of amblyopia (“lazy eye”), childhood cataract, glaucoma, or any type of strabismus
• Certain genetic disorders that affect the eye

Sometimes when a child's eyes are not aligned on the same target, the brain ignores the image from one eye. That eye works less, and vision stops developing. This problem (called amblyopia) occurs rarely with exotropia. It is more common with other forms of strabismus.

Exotropia may result from:

• nerve problems
• deformities
• eye injuries
• head injuries

These problems, as well as diabetes,myasthenia gravis, multiple sclerosis, brainstem aneurysms, stroke, circulation problems, and thyroid disease can cause exotropia in adults. [3]

Classification of childhood exotropia:

It is broadly classified as:

• Intermittent exotropia
• Constant exotropia

Constant exotropia may be of following types:

• Congenital exotropia
• Decompensated intermittent exotropia
• Sensory deprivation exotropia
• Consecutive exotropia

According to distance-near relationships, exodeviations may be further subdivided as (Duane classification):-

Convergence insufficiency exotropia: Due to convergence insufficiency, exotropia is worse for near vision.

Divergence excess: Due to divergence excess, exotropia is worse for distance vision.

Basic exotropia: Exotropia is equal for both near and distance vision.

Intermittent exotropia:

Intermittent exotropia frequently begins around the age of two years. A child with intermittent exotropia does not develop diplopia (double vision) due to bitemporal suppression, unlike acquired manifest exotropia in adults. With progressive suppression, constant exotropia may develop. Development of amblyopia (functional suppression of retina) is very rare. Manifest exotropia may be precipitated by factors such as fatigue, light glare, ill-health or visual distraction.

Congenital exotropia:

Congenital exotropia is rare and present at birth and may be associated with neurological abnormalities like cerebral palsy, midline defects or craniofacial syndromes. Infantile exotropia manifests during the first year of life.

Decompensated intermittent exotropia:

Manifest intermittent exotropia may increase with time and become constant exotropia.

Sensory deprivation exotropia:

Sensory deprivation exotropia is due to disruption of binocular reflexes by acquired conditions like opaque media due to a disease or cataract. It begins in children over five years of age or in adults.

Consecutive exotropia:

Consecutive exotropia may develop following surgical overcorrection of esotropia (inward deviation of eyes), especially in an eye which is amblyopic. Occasionally, a deeply amblyopic convergent eye may become divergent (acquire resting position of eye).

Secondary exotropia results from a primary sensory deficit (sensory deprivation exotropia) or occurs as a result of treatment for esotropia (consecutive exotropia).[4]

The pediatric ophthalmologist will perform all of the necessary tests to confirm that your child has an exotropia. This includes a comprehensive ocular motility exam and an evaluation of the internal ocular structures achieved with eye drops that dilate the pupils.

Treatment

Eye muscle surgery to improve ocular alignment is generally recommended if one or more of the following criteria are present:

• If the exotropia is present for more than 50% of each day.
• If the frequency of the exotropia is definitely increasing over time although it is not yet apparent for 50% of each day.
• If there is a significant exotropia when your child intently views objects at near.
• If there is evidence that your child is losing “binocular vision.” This refers to the brain’s ability to use both eyes together as a single unit. Among other benefits, binocular vision affords optimal depth perception.

If none of these criteria are met, surgical intervention is generally not recommended and simple observation with or without some form of eyeglass and/or patching therapy is then warranted.

What About Eye Patches And Glasses?

It is not uncommon that children with any form of strabismus (including exotropia) will have decreased vision in one eye. This is known as “amblyopia”. If there is a significant amblyopia present, the pediatric ophthalmologist will prescribe the appropriate eye patch to be worn over the stronger eye to force your child to use and strengthen the eye with amblyopia. If your child has a need for eyeglasses, they will be prescribed as well.

The eye muscle surgery is generally not recommended until the vision in each eye is maximized with either patching therapy and/or eyeglasses when appropriate. In some children, the exotropia can improve with only these measures and an operation may become unnecessary.

What About Eye Muscle Exercises?

There is an unusual type of exotropia known as “convergence insufficiency” that responds best to eye muscle exercises. This disorder is characterized by an inability of the eyes to work in unison when the child attempts to use the eyes at near only (e.g. reading). Instead of the eyes converging together on the near object, one of the eyes deviates outward.

Aside from treating convergence insufficiency, eye muscle exercises have proved to be an ineffective form of strabismus therapy.[5]

How to stop exotropia? [6]

Treatment for Exotropia

1. Glasses, sometimes with bifocal or prism lenses, as needed.
2. Eye patch on the stronger eye to strengthen the vision of the weaker eye in people with amblyopia.
3. Surgery to align the eye muscles.

Reference:

1. en.wikipedia.org/wiki/Exotropia
2. lazyeyesite.org/Exotropia.pdf
3. eyerobics.com.au/exotropia.html
4. aimu.us/2016/11/05/childhood-exotropia-symptoms-causes-and-management
5. pedseye.com/treatment/exotropia
6. utswmed.org/conditions-treatments/exotropia
7. aapos.org/glossary/exotropia

See Also:

• exotropia exercises for adults
• exotropia in infants