Ask the Doc...
Dr. N.R. Rangaraj, Consultant Ophthalmologist, Premier Eye Care and Surgical Centre, Chennai, answers this week's questions.
I AM 22 and wear spectacles from 2000. My last check up was in October 2005 since I had to constantly strain to see properly. The discomfort was obvious while watching a movie. The doctor said I needed to change my glasses. Initially the difference was quite obvious so I thought the problem was due to the old glasses. But now, I'm again facing the same discomfort. What is this problem? Harish
Answer: Strain can be caused by minor variations in power with time and insufficient convergence of eyes due to weakness in the eye muscles. Common causes of insufficient convergence are computer usage, reading in low light and long hours of watching TV. The age group 10-to-29 is the most affected by this condition. The power is determined with eye drops that paralyse the eye muscles that control the focusing ability. The true refractive error is then determined. This is verified after the effect of the drops wears off and the final prescription for spectacles is prescribed. Convergence insufficiency is measured with an instrument called Synaptophore. Eye exercises called orthoptic exercises are administered under supervision with the synaptophore for seven to 10 days. Home exercises are continued for three months to reinforce the orthoptic exercises. Remember, eye exercises only help improve the strength of the eye muscles and in no way affect the power.
I HAVE two sons. The elder one had myopia (-8). Laser surgery was done in October 2005. Sometimes he feels the vision is blurred and complains of frequent floaters and flashes. He wants bright light to read. Are these temporary difficulties? My second son is 23. His power is -11. Because of lesser microns, doctors have not advised laser, as full correction may be difficult. He is into computers. Will his studies make his condition worse? I had -3 at the age of 20. Now at 56 it is 0.75. Can it be a hereditary problem? Name withheld
Answer: Myopia, otherwise known as short sight, is a common refractory error. Myopia has both components of influence, genetic as well as environmental. The debate on the exact cause still continues.
Common forms of correction are spectacles, contact lens and LASIK. The results depend on the retina or the light sensitive layer being normal.
High degrees of myopia may have less than perfect vision for both near and distance. High myopia is also associated with changes in the retina and the vitreous humor or the jelly-like portion in front of the retina. There is no known treatment for such retinal degeneration. Abnormal blood vessels sometimes grow and are treated with laser sensitive dyes.
LASIK corrects only the power component, by sculpting the cornea to get the best possible focus. Despite precautions, contrast in vision that causes a blur may make vision less than perfect. Customised LASIK with wavefront correction helps minimise this blur.
Floaters are common in myopia. They are actually condensations in the vitreous humor casting a shadow on the retina and are harmless. In contrast, flashes often occur due to the vitreous humor pulling away from the retina. This needs a dilated fundus examination to rule out weak spots, tugging of retina or a frank detachment of the retina. As long as a person has good vision with proper correction for the refractive error, he or she can work with computers. LASIK is usually not performed when the cornea is very thin. The cornea that is left behind after treatment should be more than 250 microns. This number is only a guideline and needs to be taken in proper clinical perspective before any treatment in undertaken.
I AM 37. I have been suffering from floaters in both eyes for three years. I experience difficulties when looking at white paper, blue sky, light-coloured ceiling and particularly when working on a computer. My eye movements make floaters more visible. Some say this is due to retinal detachment. But this has been ruled out. My blood pressure and sugar are normal; so is pressure in the eye. But I feel the problem is gradually increasing. Will this affect my vision? M. Malaiarasan
Answer: Floaters are harmless. They are more obvious when the background is bright. What we perceive on the retina is the shadow of the particles. When flashes accompany floaters they herald irritation of the retina and are symptoms of retinal detachment. A dilated fundus examination with that of the peripheral retina is necessary to rule out retinal problems. Scleral depression — pressing the eye just away from the black of the eye to view the peripheral or the outer most part of the retina — is painless and completed with minimum discomfort. This dilated fundus with scleral depression may have to be repeated after a week as a precaution. Once they rule out retinal detachment, the symptoms are harmless. However if the frequency of the flashes and number of floaters increase, another dilated fundus examination may be necessary. Floaters in general do not affect vision and nor is there any known cure.
I AM 77. I am on medication after an angio five years ago. I take Lodoz 5 in the morning, Ecospirin 150 in the afternoon and Tonact 10 in the night. This May I underwent laser surgery for cataract. Foldable lens were put in and glasses prescribed and I have good vision. Now both eyes water occasionally. I have stopped cleaning my eyes with water. But still my eyes continue to water. But the vision is clear. Why does this happen? S. Visvanathan
Answer: Most eyelid conditions do not affect vision. Eyelids are important in maintaining good health of the surface of the cornea or the black portion of the eye. They protect and cover the eye and aid in the distribution and draining of tears. This delicate balance keeps the cornea moist with a tear film. An infection or condition that disturbs this balance causes tearing. The most common problem is blepharitis. The eyelid is reddish and there is accumulation of debris along the margin. Sometimes the glands that contribute to one of the components of the tear film may be infected. These glands called the mebomian glands, of which we have a dozen or more in each lid, lie within hard part (tarsal plate) of the lids. Infection of these glands, called meibomitis, commonly causes disruption of the tear film and causing watering of the eyes. Proper lid cleaning with baby shampoo and cotton bud applicator and/or warm compress along with/without antibiotics eye ointment may be the only treatment required. Other lid conditions that may require minor surgical procedures need a proper eye examination and assessment by an eye doctor.
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