WILL GLAUCOMA SURGERY RESORE MY VISION TO NORMAL?

Ophthalmologist Carolina Valdivia, MD explains why glaucoma surgery does not restore vision to normal to a young man from India.

A 23 year-old man from India writes:

Hi Dr. Valdivia. I have glaucoma. When I was diagnosed, the doctor told me that my eye pressure was very high. Since then, I have had four surgeries in New Delhi, India. But my vision still is not good. I cannot see clearly without glasses. Is there any procedure that will return my vision to normal?

Carolina Valdivia, MD Thank you for your question and for your interest in glaucoma-eye-info.com.

Given the age at which you were diagnosed with glaucoma (prior to 23 years of age), and the fact that you do not report other health problems that might have caused it, such as previous eye trauma or severe inflammation, it is likely that you have a type of glaucoma known as Developmental Glaucoma (also known as Pediatric Glaucoma). However, you should confirm this with your ophthalmologist. You have had several surgeries to help with your glaucoma, but would like to know why these surgeries have not returned your vision to normal.

Developmental glaucoma can be congenital (present at birth), infantile, or juvenile depending on the age that it presents. Congenital glaucoma occurs in the first three months of life; infantile glaucoma presents between the ages of 3 months and 3 years, and juvenile glaucoma from 3 to 35 years. These types of glaucoma typically are associated with developmental abnormalities in the angle formed by the iris and the cornea in the front part of the eye known as the iridocorneal angle. However, developmental glaucoma also can have a secondary cause, meaning that injury or another disease process causes the glaucoma.

In either case, the following things should be considered when evaluating claims by practitioners that they can return your vision to normal.

There are certain conditions in the eye that even if a person has the best possible corrective lenses – meaning that under regular circumstances, they would restore vision to normal – either significant improvement in vision does not occur or vision with the corrective lenses improves somewhat but remains below normal. Developmental glaucoma, as well as other types of glaucoma, can be one of these conditions.
There are several reasons for the above to occur. With respect to glaucoma, the most common reason is damage to the optic nerve. This damage is irreversible. Neither corrective lens nor glaucoma surgery can compensate for the loss optic nerve fibers.
It is important to understand that corrective lenses function to improve refractive errors in the eye. Refraction refers to the ability of the cornea and the lens in the front part of the eye to properly bend light so that it is focused onto the retina. Thus, corrective lenses assist our eyes in image capture. On the other hand, the optic nerve serves to transmit captured images in the form of electrical signals to the visual cortex in the brain for image processing. For this reason, it is possible that the corrective lenses that you are using are doing a great job in helping to bend light onto the retina for improved image capture, but, due to damage, your optic nerve lacks the capacity to adequately transmit all of the electrical signals associated with an image to the brain. This would result in some, but not all, of the details associated with an image being processed by the visual cortex.
Another common cause may be the existence of amblyopia. Commonly known as "lazy eye", amblyopia is an eye condition that is marked by reduced vision that is not corrected by glasses or contact lenses and is not due to any eye disease. Although the exact mechanism is not well understood, for some reason the brain does not fully process images captured by the affected eye. Amblyopia almost always affects only one eye, but may manifest with reduction of vision in both eyes. A common cause of amblyopia is the existence of very different refractive errors. This means that one eye has a measure of more than 2 diopters over the opposite eye. (Diopter is a measurement of optical focusing power.)

Glaucoma can, and often does, occur in eyes with refractive errors, such as farsightedness, nearsightedness, or astigmatism. The goal of glaucoma surgery is to reduce intraocular pressure and thus prevent damage to the optic nerve, so that images are processed properly. But glaucoma surgery is not intended to correct refractive errors associated with image capture. This is not its purpose.

The fact that your vision is improved, even if only slightly, with corrective lenses is a good sign. It means that refractive errors in your eyes are being corrected. However, four surgeries suggests that there has been damage to your optic nerve. Depending on its severity, it may not be realistic to expect to achieve 20/20 vision with corrective lenses.

I mentioned two common causes of low vision above. However, there are many more. I recommend that you check with your ophthalmologist about the degree of damage to your optic nerve and if it is realistic for you to expect that any surgery or treatment could return your vision to normal, either with or without the assistance of corrective lenses. She or he also can help you with strategies for adapting to your current vision status.

In summary, as it stands, medical science has not yet reached a point where damage to the optic nerve can be repaired in a glaucoma patient. This is the only development that potentially could restore vision to normal.

Carolina Valdivia, MD

REFERENCE:

Shaarawy TM, Sherwood MB, Hitchings RA, and Crowston JG. Glaucoma Volume 1: Medical Diagnosis and Therapy. New York: Elsevier, 2009.

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My goal in answering your questions is to provide you with information, clear up misconceptions, and to explain options so that you can have an informed conversation with your doctor. However, under no circumstances should my response to your question be considered a substitute for ongoing consultation and examination with your doctor. Since I have not examined you, I only can speak in terms of generalities, whereas your doctor has sufficient clinical details to evaluate your case specifically.

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