Visiting the Neuro-Opthomologist

Written by on October 21st, 2014 – No Comments

eyeMany of us living with Multiple Sclerosis and Neuromyelitis Optic (NMO) are likely to experience optic neuritis at some point, making it necessary for us to see a neuro-opthomologist. I thought I would take this opportunity to share what happens during a neuro-opthomology appointment.

Ophthalmology is the branch of medicine that focuses on the anatomy, physiology and diseases of the eye. Most people with visual issues see an opthomologist on a yearly basis. Generally speaking, an opthomologist is an expert in medical and surgical eye problems and will perform standard tests to evaluate the health of your eyes and if needed, prescribe glasses or contact lenses to correct your vision.

Neuro-ophthalmology is the sub-specialty of both neurology and ophthalmology focusing on visual problems that are related to the nervous system, so those of us living with MS or NMO are usually referred to a neuro-opthomologist through our clinic when we develop optic neuritis. A neuro-opthomologist’s skill set is very specific and they have a number of specialized tests allowing them to recognize even subtle changes to the optic nerve so they are better able to diagnose optic neuritis and other neurological conditions that can affect vision.

My neuro-ophthalmology exam begins with a careful history of any problems I am having with my vision and a review of any neurological or medical problems that could be relevant. Then I undergo a series of tests. These tests evaluate my vision, optic nerve function, eye movements, and gaze-holding abilities. Because the tests document  my neurological visual function at the time of the exam, the results serve as a basis for comparison during future exams-especially when there is a concern that my vision may be worsening due to NMO.

My vision is checked using several different vision charts. I wear glasses, so some of the tests require that I have them on and some that I take them off. My color vision is evaluated using the Ishihara Color Vision Test. The test is done by looking of a number of pictures of colored plates. Each one contains a circle of dots appearing randomized in color and size. Within the pattern are dots which form a number which is clearly visible to those with normal color vision, and is invisible, or difficult to see, to those with a red-green color vision defect. (If you look at the photo example in this post, there is a “6” in the centre of the circle.)

My peripheral and central vision is checked on a visual field testing machine. I sit looking into a white space and a machine displays dots of light at various points in my visual field. I press a button to acknowledge each light when I see it. This test will show any patterns of visual field loss that might exist.

The health of my optic nerves is evaluated using optical coherence tomography. (OCT) For this test, I look into camera with a very bright light while it takes photos of my eye. The camera allows the doctor to look at the retina at the back of my eye and measures the thickness of the layer of nerves coming from all quadrants of the retina and leading into the optic nerve. The nerve fiber layer may be thickened, thinned or normal, depending on the damage affecting the optic nerve. I get dilating drops in my eyes to allow easy viewing. I always think the picture this test creates is like one you would see of the layers of the earth’s crust. It’s pretty interesting! I’ve even been able to see what my eyeball looks like on screen-it reminds me of Mars-it looks like the angry red planet.

All of these tests are safe and painless. When we are done, the neuro-opthomologist goes over my results and if needed, outlines what treatment options we should pursue and what follow up care I might need.

Sometimes I need to come back to have additional testing, which is usually a visual evoke potential. (VEP) The person administering the tests places some electrodes on the back of my head and then I simply sit and focus my gaze on the centre of a computer screen while an alternating checkerboard pattern plays on a computer screen. The electrodes capture the responses from the area of the brain involved in receiving and interpreting visual signals and are observed as a reading on an electroencephalogram (EEG). This is to see how quickly the messages involved in the process of vision are being received in the brain and will show whether the nerve pathways are abnormal in any way. This test is also quick and painless.

So there you have it! I see my opthomologist yearly and my neuro-opthomologist whenever I am having vision issues related to NMO.

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