The Neuro-Ophthalmology Clinic evaluates nerve disorders involving the eye and brain, including:
- Patients who suddenly lose part of their side vision
- Patients who get double vision
- Patients with unequal pupils
- Patients whose vision goes suddenly out of focus
- Patients with strokes
- Patients with brain tumors
- Patients with unusual visual problems that are hard to sort out
If you have a disease or injury in the eyeball itself, an ophthalmologist can look at the cornea and the lens, or into the eye at the retina and see an abnormality in the eye, but if the problem is behind your eye in the optic nerve or in some of the visual pathways in the brain, it is harder to be sure what is going on and that is when neurologists become involved.
In that case, you are sent to the neuro-ophthalmologists for special tests, which may include:
- Kinetic (Goldmann) perimetry ('perimetry' is the quantitative testing of the side vision). These 'visual fields' are done manually by experienced perimetrists. We often use this kind of perimetry at the first visit when we really need to understand the nature of the problem.
- Automated (computerized) perimetry is also done by experienced perimetrists--especially when we are looking to see if anything has changed since the last visit. In this test, spots of light are automatically projected into predetermined areas of the visual field. The test continues until the dimmest light is found that can be seen in each area of the side vision.
- Frequency-Doubling Perimetry is a new visual field test that is performed to screen patients for visual loss. It only takes about five minutes per eye.
- Critical Flicker Fusion Frequency. (CFF) Patients view a flickering light to test the ability of the optic nerve to conduct impulses with uniform speed. This test has proven to be very useful in identifying visual loss due to optic nerve damage.
- Infra-red video pupillography. This is a way of seeing the pupils clearly in the dark so that a more certain diagnosis can be made. We also use it to transilluminate the iris to identify local iris causes for pupillary abnormalities.
- Electroretinography. A regular ERG (eletroretinogram) records the electrical activity of the whole retina in response to light and helps to tell us if the rods and cones of the retina are firing in the way they are supposed to.
- The Multi-focal ERG (MERG) does about a hundred ERGs at once by illuminating various little bits of the retina sequentially. It uses a computer to sort out the information and then it presents us with a map of the sensitivity of various parts of the retina, based on the electrical activity (in response to light) of all those different regions. If this map matches the map we got from perimetry then the problem is in the retina and not in the optic nerve or brain.
- Multi-focal Visual-Evoked Potentials (MVEP). Using a MERG stimulus, information can be picked up from the scalp that tells us if the visual pathways in the brain are damaged.
- Computer controlled infra-red sensitive pupillography is used to monitor pupillary movements in response to different types of light in order to quantify how much damage there might be in the visual system.
- Computer controlled "Pupil" Perimetry uses the pupil movement in response to small lights presented in the field of vision as an objective indicator of how well the eye sees the light.
- Computer recording of eye movements. This instrument can be used for monitoring pupil movements, plus it has the capacity to record the small movements of both eyes at the same time to see if they are tracking together and have normal movements in different directions of gaze.
- Optical Coherence Tomography (OCT). This is a new device that looks at the retina at the back of the eye and measures the thickness of the layer of nerves coming from all quadrants of the retina and leading into the optic nerve. This nerve fiber layer may be thickened, thinned or normal, depending on the nature of the disease affecting the optic nerve. Optical Coherence Tomography has become a very important test to help us understand the extent and the reversibility of optic nerve damage.
- Ishihara Color Vision Test Cards are used for color vision evaluation. A test chart of color dots will appear as identifiable numbers or patterns to individuals who have various types of color vision defects.