ISCHEMIC OPTIC NEUROPATHYOphthalmologist Carolina Valdivia, MD answers a question about ischemic optic neuropathy and glaucoma from a reader in India.  A 62 year-old male from India writes:Hello Dr. Valdivia. Your website is very informative and useful. My ophthalmologist recently checked my intraocular pressure and found it to be high. The right eye is 24 and the left eye is 20. He suspected that I have ischemic optic neuropathy and ordered an MRI angiogram test. Results show that the appearance of ACA (anterior cerebral artery), MCA (middle cerebral artery), basilar artery, and both PCA's (posterior cerebral artery) were normal. The ophthalmic artery is not visualized on either side. The report says that the intra-orbital part of the ophthalmic artery is probably filling through collateral circulation. My ESR (erythrocyte sedimentation rate) is 7 mm/hr. My age is 62 years and I have been under treatment for hypertension for last five years. My blood pressure ranges from 120-80 to 170-90. I am strictly vegetarian. My ophthalmologist has prescribed vitamin B12 supplements, medicines to reduce the viscosity of my blood (clopidogrel and aspirin), and rosuvastatin to lower cholesterol – all taken at bed time. Could you help me to understand this diagnosis so I can prevent further loss of sight. Thank you.
Non-arteritic ischemic optic neuropathy is the most common form of the disease. It typically occurs in persons 45 years of age or older. You are 62 and therefore are within the parameters for age-related risk. The disease begins with diminished visual acuity that happens suddenly, without pain, and often is irreversible but non-progressive (does not worsen over time). One of the things that I look for as an ophthalmologist is a disturbance in the reflex of the pupil, in which it fails to contract (get smaller) in a normal manner upon exposure to light. Additionally, the optic disc is swollen or edematous (swelling caused by excess fluid trapped in your body's tissues) in nearly all cases. In addition to age, risk factors non-arteritic ischemic optic neuropathy include high blood pressure, high cholesterol, and elevated homocysteine levels. Homocysteine is an amino acid; amino acids are the building blocks of proteins. Elevated homocysteine levels are usually caused by deficiencies of folic acid (vitamin B9), vitamin B6 and vitamin B12. This is why your doctor has prescribed vitamin B12 as a supplement. Deficiencies in these three B vitamins often are common in vegetarians. Unfortunately, the only reliable food sources for these vitamins are meat and dairy products. Although some plant-based sources exist, the human digestive system is unable to release them in a form that is usable by the body. For this reason, it important that you continue to take the supplements that your ophthalmologist prescribed. It also would be advisable to see a nutritionist and review your diet to ensure that it is balanced and provides you with adequate amounts of vitamins and minerals. A vegetarian diet, like any other, must be managed properly. As you can see, you have several risk factors that together appear to have combined to cause your non-arteritic ischemic optic neuropathy. I am concerned that intraocular pressure in your right eye is 24 mmHg and is 20 mmHg in the left eye. I raise this issue because you did not mention if you are taking medications (eye drops) to lower your intraocular pressure. Damage to optic nerve fibers from your ischemic optic neuropathy makes them more prone to further damage from elevated intraocular pressure, in some cases even if the pressure is within the upper limits of the normal range. Remember, the true definition of normal intraocular pressure is one that does not cause damage to YOUR optic nerve. I suggest that you return to your ophthalmologist and inquire if you should take eye drops to lower your intraocular pressure. It also would be advisable to have regular monitoring of your interocular pressure and your optic disc to ensure that damage to optic nerve fibers does not continue. Carolina Valdivia, MD
REFERENCE:Tsai JC, Denniston AKO, Murray PI, Huang JJ and Aldad TS. Oxford American Handbook of Ophthalmology. New York: Oxford University Press, 2011:524-527.
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Return from Ischemic Optic Neuropathy to Answer My Health Question
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Ischemic optic neuropathy is an infarction (obstruction) of the blood supply to the optic disc. It often is referred to as a stroke of the