Dry Eyes

Dry eye is due to either excessive evaporation of tears or insufficient production of tears. Currently, 32% of the Indian urban population suffers from Dry eye disease in the age group of 21-40 years1and it is expected that by 2030, it will increase to 45%.

How does tear work?

Tears keep your eyes wet and smooth and help focus light so you can see clearly. They also protect your eyes from infections and irritating things, like dirt and dust. Every time you blink, a thin layer of tears called a “tear film” spreads across the surface of your cornea (the clear outer layer of the eye). Tears come from glands above your eyes, then drain into your tear ducts (small holes in the inner corners of your eyes) and down through your nose.

When your eyes don’t make enough tears or your tears don’t work the right way, you can get dry eyes.

What are tears made of?

Tear film has 3 different layers

Oily outer layer keeps tears from drying up too quickly and makes the surface of the eyes smooth
Watery middle layer keeps the eyes wet and nourishes the eye tissue
Inner mucus layer helps the tear film stick to the surface of the eyes

Layers of Tear Film

Dry eye is one of the most common complaints in people who use digital devices extensively. People using digital devices for more than 6 hours a day can develop symptoms like dry itchy eyes, red eyes, and watering.

Symptoms of Computer Vision Syndrome such as irritated/burning eyes, tearing and dryness, tired eyes, and eye discomfort are closely linked to dry eye. The use of digital devices is associated with a reduced rate of blinking and an increased rate of tear evaporation, each of which contributes to dry eyes.

We normally blink about 16 to 18 times per minute, automatically. This blink rate decreases by half when our attention is focused on a computer monitor or smartphone. Blinking spreads tears across the front surface of the eye and this lubricates and nourishes the eyes, keeping them healthy and comfortable.

A study showed that the use of digital devices for more than 6 hours had symptoms of watering, red-eye, and dry eyes3 When the blink rate goes down by 50%, the tears evaporate and the eye becomes dry and irritated. Spending long hours staring at a digital screen can aggravate the symptoms if you are already suffering from an existing eye condition like blepharitis or dry eye. Also, if you are sitting in an air-conditioned room, that can evaporate the tears and aggravate symptoms further.

CAUSES OF DRY EYE

A leading cause of dry eye is Meibomian gland dysfunction (MGD), where the glands don’t function properly either due to blockage or oil deficiency. These glands in the eyelids contribute to oily secretion which helps in slowing down the evaporation of the tear film.

It occurs as a part of the natural ageing process, as a side effect of dry, dusty, or windy climates or medications. Air conditioning or a dry heating system in enclosed spaces can dry out your eyes.

Another cause is insufficient blinking, such as when staring at a computer screen or TV monitor all day.

Dry eyes may also be a symptom of systemic diseases such as rheumatoid arthritis, Lupus, and Sjogren’s syndrome (a triad of dry eyes, dry mouth, and rheumatoid arthritis).

Other causes are incomplete closure of the eyelids, eyelid disease, and a deficiency of the tear-producing glands

Besides causing eye problems, severe dry eye patients may have associated systemic autoimmune diseases that could potentially be life-threatening. These patients may experience role limitation, pain, and poor general health impacting their quality of life (QoL) comparable to QoL for serious illnesses like chronic kidney disease.

ASSESSMENT OF DRY EYE

Tear Film Break-Up time (TBUT)

Standard Patient Evaluation of Eye Dryness Questionnaire (SPEED) is filled up by the patient to understand the severity of their eye condition. Then we proceed with the following scheme of tests:

We assess the tear film using Schirmer’s test, Tear breakup time, Meibomian gland assessment, Dynamic assessment of Tear Secretion (DATS), and fluorescein stain photography.

After an elaborate evaluation, you can discuss with the doctor the best course of action for your visual needs.

PREVENTION OF DRY EYES

You can take the following steps to reduce symptoms of dry eyes:

Remember to blink regularly when reading or staring at a computer screen for long
Increase the humidity in the air at work and home
Wear sunglasses outdoors, particularly those with wraparound frames, to reduce exposure to drying winds and the sun
Nutritional supplements containing essential fatty acids may help decrease dry eye symptoms in some people
Avoid air getting blown in your eyes by directing air-conditioners or fan away from your face

TREATMENT FOR DRY EYES

In most cases, lifestyle changes and the use of eye drops can solve the problem. In severe cases, the use of steroids, immunomodulator drugs, and/or surgery may be considered.

On examination, your ophthalmologist will advise you whether you have any ocular or systemic diseases. They will also elaborate on drugs that can aggravate dry eyes and what to do in those circumstances.

Severe dry eye can be treated using more sophisticated methods such as steroids, punctal occlusion, or surgery to close the lids.

References:

Titiyal JS, Falera RC, Kaur M, Sharma V, Sharma N. Prevalence and risk factors of dry eye disease in North India: Ocular surface disease index-based cross-sectional hospital study. Indian J Ophthalmol. 2018 Feb;66(2):207-211.
http://www.censusindia.gov.in/2011Common/Sample_Registration_System.html
Usgaonkar U, Shet Parkar SR, Shetty A. Impact of the use of digital devices on eyes during the lockdown period of COVID-19 pandemic. Indian J Ophthalmol. 2021 Jul;69(7):1901-1906