Dry Eye

Introduction

Dry eye (keratoconjunctivitis sicca) is a common problem, particularly in elderly.

  • It causes varying degrees of discomfort.



Pathophysiology

Eye Anatomy

The tear film is needed to maintain a healthy eye surface and for enabling clear vision. Tears are made up of a complex mixture of water, salts, lipids, proteins and mucus.

  • The lipids, or oily component, surround the tear film and help to prevent evaporation of the water.
  • The mucous component helps spread the tear film evenly over the surface of the eye.
Historically, dry eye disease (DED) has been classified into 2 general groups:
  • Aqueous deficient DED
    • Decreased tear production due to Sjogren's syndrome, older age and diabetes mellitus.
  • Evaporative DED
    • Increased evaporative loss from the ocular surface due to meibomian gland dysfunction, structural abnormalities of eyelid position, decreased blink function, topical medicated or preserved eye drop use, chronic contact lens wear and ocular allergy syndrome.

However, it is now believed that both mechanisms are present in most patients, although one may be predominant.

NOTE: Tear production diminishes with age and is affected by female hormones, so the problem is most common in older women.



Clinical Features

Both eyes are usually affected.

Symptoms reported are eyes that burn, feel tired, itchy, irritated or gritty, with symptoms worsening throughout the day.

  • The conjunctiva is not red unless irritated (e.g. eye rubbing or allergy).

Typically, symptoms fluctuate in intensity.

  • Exacerbating causes include medications, windy conditions, cold weather, low-humidity environment, extend time spent looking at screens, and time of day.



Important Questions to Ask

Environment

  • Windy, dry climates increase tear evaporation.
  • Long periods of time spent working at a computer screen are associated with dry eye because blinking tends to be less frequent.

Medical conditions

  • Patients with rheumatoid arthritis, diabetes or thyroid problems are more likely to experience dry eyes.
  • Also, it is common to develop dry eye after eye surgery such as cataract or refractive surgery.

Medications

  • Antihistamines, beta-blockers, chemotherapy, diuretics, HRT, oral contraceptives, SSRIs and TCAs may affect the quantity and composition of tears.

Symptoms

  • Patients with dry eyes may report irritated, gritty, scratchy or burning eyes, a feeling of something in their eyes, excess watering and blurred vision.
  • Initial referral to an ophthalmologist if the diagnosis is in question or if the patient has severe pain or associated visual loss, or abnormal blinking or inability to close their eyes completely.

Contact lenses

  • Individuals who wear contact lenses are more likely to experience dry eyes.



Over-the-counter Medication

Management and Treatment of Dry Eye

Apart from lifestyle and environmental treatment (e.g. frequent blinking during computer use and minimize exposure to air conditioning), dry eyes are managed by the instillation of artificial tears and lubricating ointments.

  • For people with mild or moderate symptoms, artificial tears alone are usually sufficient.
  • For people with severe symptoms, consider adding an ocular ointment to use at night.

Evidence of superior efficacy among any of the ophthalmic lubricants is lacking.

  • Choice is based on patient acceptability and adherence as well as sensitivity/allergy to preservatives contained in the product.

The dosage of all products marketed for dry eye is largely dependent on the patient's need for lubrication, and is therefore given on an as-needed basis.

May consider using a preservative free product

  • if a product causes irritation,
  • if tear substitutes are used frequently and chronically
  • if soft contact lenses are worn

NOTE: You may refer to this post on method of administration of ophthalmic preparations and storage.



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