THE PARAOPTOMETRIC: DISORDERS OF THE CONJUNCTIVA AND SCLERA

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Pink eye is the most common conjunctiva disorder.
(ISTOCKPHOTO: dtimiraos)

Offering relief from red eyes can sometimes be tricky due to the root of the problem often being a mystery. The conjunctiva and sclera are often overlooked as culprits, but some common disorders could be coming into play.

CONJUNCTIVA BASICS
The conjunctiva is a transparent membrane that lines the back of the eyelids and covers the surface of the sclera. It’s made up of non-keratinized, stratified squamous epithelium with goblet cells, small blood vessels, and tiny mucus secretory glands that all assist in maintaining the tear film. The tear film mucus layer acts as the anchor for tear film adherence to the eye. When the conjunctiva is inflamed, the blood vessels dilate and the eye looks red.
The conjunctiva is divided into three parts. Each assists in providing moisture to the eyes and allowing for a smooth surface for the eyelid to open and close.
•Palpebral: This part lines the inside of the eyelid and contains the openings for the lacrimal ducts that assist in providing moisture to the eye.
•Bulbar: This thin transparent portion is mobile and covers the white sclera. Since it’s clear, the underlying blood vessels can be seen. The bulbar conjunctiva contains “goblet cells,” which secrete the mucinous layer of the tear film.
•Fornix: It forms the junction between the palpebral and bulbar conjunctiva and allows free movement of the lids and eyeball.

CONJUNCTIVA DISORDERS
Conjunctivitis: Known as “pink eye,” this inflammation can range from a mild allergic reaction to quite severe. It’s the most common cause of red eyes. Most conjunctivitis cases result from infection (bacteria, virus), allergy, or inflammation (caused by dust, debris, or chemicals).

Bacterial infection: The two biggest causes of bacterial conjunctivitis are Staphylococcus and Streptococcus. These bacteria cause yellow-green sticky pus to be discharged along with a gritty feeling. These infections are highly contagious.

Virus infection: Viral conjunctivitis is also easily transmissible. It presents as watery, red, uncomfortable eyes, and it’s often associated with symptoms such as sore throat, runny nose, and/or tender lymph nodes. The irritation may last for a few weeks.

Allergic conjunctivitis: This is caused by an abnormal hypersensitive reaction to a normal environmental substance. Typical allergic reactions cause the eye to become red and itchy, producing a discharge.

Inflammatory conjunctivitis: Occurring when the eye has a hypersensitive reaction to environmental factors such as chemicals, a foreign object, dust, or debris, inflammatory conjunctivitis causes eyes to become red, watery, and uncomfortable. Once the irritant’s cleared out, the eye will clear easily.

Subconjunctival hemorrhage: This presents as a bright-red patch that obscures visualization of the underlying sclera. The bright color results from bleeding of the conjunctival or the episcleral blood vessels into the subconjunctival space. The cause is usually unknown but may be the result of a trauma, straining, systemic illness, or drugs (blood thinners). The patch will gradually disappear within two weeks and doesn’t require treatment unless the hemorrhage becomes recurrent, which may signal an underlying disorder.

Pinguecula: This benign non-cancerous, elevated yellow growth is caused by the thickening of the conjunctiva. It’s more common in older individuals who spend a lot of time outdoors with continued exposure to ultra-violet (UV) light, or in those who live in sunny, windy equatorial climates. The affected eye might also itch or become red and inflamed. No treatment is necessary unless there is increased discomfort. Artificial lubricating tear supplements are recommended.

Pterygia: These are elevated, triangular, non-cancerous growths that form on the conjunctiva, usually on the nasal side. With continued exposure to UV light, they can grow and invade the cornea, causing distortion to its shape and producing astigmatism. For mild irritation, treatment includes artificial tear lubrication and/or mild steroid drops. Surgical intervention is recommended for severe irritation or compromised vision.

ALL ABOUT THE SCLERA
The sclera is the fibrous covering of the eye that presents as a dense white layer. It’s located under the transparent layer of the conjunctiva and is made up of a disorganized network of transverse, oblique collagen fibers that gives it its nontransparent white coloring.

The sclera is protected by the episclera, a matrix of blood vessels that provide nutrition. Since it’s made up of collagen, the sclera is susceptible to destructive conditions that affect joints and collagenous tissue. Diseases that affect the sclera are usually painful and collagen destructive, with an inflammatory response provided by the episclera.

The sclera provides a firm protective coat for the eye’s intraocular contents and its flexibility allows for intraocular pressure variations. It’s also always fully hydrated: If its water content is reduced to 40%, the sclera becomes translucent.

SCLERA DISORDERS
Episcleritis: A relatively common inflammation usually seen in younger patients, episcleritis can be related to allergy, infection, or collagen vascular disease. It sometimes occurs in the superficial layers just above the sclera. Redness and pain that’s localized to a section of the eye is present in acute onset. Nodular episcleritis is localized swelling underneath the sclera.

Scleritis: This chronic disease occurs more frequently in older individuals and may be associated with other underlying disorders such as rheumatoid arthritis and tuberculosis. It can be a result of an infectious process caused by bacteria, or from trauma, chemical exposure, or past surgical inflammation. Scleritis is more prevalent in females and a risk factor is the presence of an autoimmune disease or connective tissue disease. OO

Janet Hunter, president of Eye Source, LLC, specializes in ophthalmic technician training.

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