In the past we hardly heard the term “Dry eyes”. Today we hear this term so often that it has almost everyone seems to suffer from this condition. To get more insight into this annoying condition affecting eyes, we turn to Dr. Vivek Kadambi, a renowned eye Surgeon in Bengaluru city.
So Dr. Kadambi, what do you mean by the term dry eyes?
As the name suggests “Dry Eyes” means that the eyes are dry. This could be because the tear producing gland does not produce enough tears, or more commonly the tears are adequate in quantity but poor in quality. The main function of tears is to lubricate the surface of the eye, particularly the cornea, to keep well hydrated, moist and provide nutrition to the surface all of which keeps it transparent and shiny. If there is any deficiency in the quality of tears then the optical properties of the corneas gets affected and vision becomes poor. Even before the vision is affected, the patient suffers from classical symptoms such as itching, burning sensation, redness and watering of eyes.
Doctor, what exactly do you mean by “quality” of tears?
The surface of cornea has tear film which has 3 layers. The outer layer is the “oily” layer, which prevents the tears from evaporating. The middle layer is the watery layer that provides the electrolyes, nutrition and antibodies. The layer that is in touch with cornea is the mucus layer. The mucus layer provides lubrication, ensures even spreading of the tears with each blink and literally hold the tears on to the surface of the cornea. So, the quantity of tears depends upon the secretion of the middle watery layer of the tears from the lacrimal gland but the quality of tears depends upon the oily and the mucus layer. Deficiencies in either of these gives rise to the typical symptoms of dry eyes. Sometimes, all the three layers may be perfect but the surface of the cornea is scarred, making it difficult for tears to stay uniformly on the surface. Here again you have a situation that presents as dry eyes.
Now that you have explained the three layers of the tear film, can you tell us what conditions can affect the oily, watery and mucus layers?
Deficiency of the watery layer occurs in certain autoimmune conditions like Rheumatoid arthritis, Lupus and Sjogren’s syndrome. The oily layer is secreted by multiple glands that are present along the margins of the eyelids. When these glands are inflamed, a condition known as “Blepharitis”, the nature of the oily secretions becomes thicker and paste-like and hence unable to form a uniform layer in front of the eye. This condition has to be treated with anti-inflammatory medicines along with topical Antibiotics. More commonly the mucus producing glands in the eye is affected. Such cases actually come with dry eyes symptoms with paradoxical overflow of tears. Most tear substitutes mimic the mucus layer and provide relief from symptoms. Sometimes, liquid tear substitutes are not enough and one needs to use gels and ointments at bedtime.
Ok, so why has dry eyes become so common in recent times?
There are multiple reasons for this. There has been an exponential increase in the quantum of ambient radiation the eyes are being exposed to from smartphones, Laptops, computers and Television. Air pollution, toxins in food and water and nutritional deficiencies have made matters worse. One more important reason for this is the increase in the incidence of hormonal imbalance. Hypothyroidism, Autoimmunue thyroiditis, insulin resistance, Menopause, Andropause can present with dry eyes.
Can dry eyes be caused by medicines?
Long term use of certain medicines taken for Hypertension, autoimmune diseases, allergic conditions and mood disorders also leads to dry eyes in the long run. Contact lens wearers also can suffer from dry eyes which ultimately may force a person to give up contact lens. Many patients suffer from dry eyes for a few months after LASIK procedure.
That is interesting. Now, how does one diagnose Dry eyes?
Firstly the clinical history with classical symptoms should alert the ophthalmologist to the possibility of dry-eyes. Any experienced ophthalmologist can diagnose dry eyes with just one look under the slit lamp microscope. However there are some tests that can help document dry-eyes. One such test is the schirmer’s test. Basically, we use a strip of filter paper with markings in millimetres (show sample). Put one bent end into the fornix of the lower lid under standard conditions and remove after 5 minutes. If less the 10mm is wet, the one can diagnose insufficiency of tear production. Another test performed with a dye instillation in the eye is the tear film break-up time. A very small quantity of Fluoresceine in used to stain the tears. The patient is positioned in front of the slit lamp with blue light thrown on the eye. The patient is asked to blink and then hold the blink. The time from the last blink to the first appearance of first distinct patch of tear film breakup is noted. If this is less than 5 seconds, Dry eye is diagnosed.
Lastly, how do you treat Dry eyes?
For a start one needs to use lubricating drops or artificial tears that basically contain polymers that absorb moisture and retains the same for a longer time. Sometimes liquid drops are not enough and one has to use gels. In cases of Blepharitis, the patient need to be treated with hot foamentation, massage of lid margin, Antibiotic and anti-inflammatory medicines given topically and even systemically. Medicated eye drops containing diluted cyclosporine helps to improve the function of the mucus producing gland. In addition to this I advice my patients on healthy eating habits and often prescribe Vitamins and Omega-3 supplements in appropriate doses. Management of Insulin resistance, optimizing Thyroids and sex hormones also should be integral to medical management. Ofcourse, one should not forget the preventive aspect like avoidance of dust, protection of eyes particularly when driving a two wheeler, use of glasses with anti-reflective coating when working on computers, getting adequate sleep and blinking adequately throughout the day.