Neuro-ophthalmology

By May 13, 2020Focus

WHAT IS A NEURO-OPHTHALMOLOGIST?

Technically, in South Africa, such a person does not exist. After first becoming a general practitioner or medical officer and then going on to specialize as an ophthalmologist (also called an eye specialist or ophthalmic surgeon), a doctor can go on to specialize even further in a subspeciality (sometimes called super-specialization). This is normally through a very intensive type of residency program called a fellowship and in ophthalmology this is almost always done at an overseas centre. Subspecialities include corneal surgery, glaucoma, neuro-ophthalmology, ocular oncology, oculoplastics, orbital surgery, paediatric ophthalmology, refractive surgery, uveitis, vitreoretinal surgery and medical retina. However, in South Africa not all subspecialities are formally recognized and registered, and these include those that fall under ophthalmology. Eye specialists still indicate their expertise and practice scope by saying that they have a fellowship / extensive experience / special interest in a specific subspeciality. There are also large areas of overlap between the different subspecialities, including neuro-ophthalmology. In short, all ophthalmologists in South Africa have been trained in neuro-ophthalmology, but it is not a separate field of sub-specialist practice recognized by the HPCSA.

Neuro-ophthalmology deals with disorders related to the nerves that travel between the brain and the eye as well as the brain itself with its various visual interpretation, control and integration areas. The nerve tissue of the visual system starts in the eye as the neuroretina. (Most people have at least heard about a condition called retinal detachment. This is a separation of the neuroretina from the rest of the tissue inside the eye. More about this in future.)

Groups of ophthalmic conditions that typically fall within the scope of neuro-ophthalmology are the following:
• Persistent vision loss such as that caused by damage to the optic nerve, strokes or brain tumours.
• Temporary vision loss like the aura some people see before the get a migraine or the curtain-like obscuration caused by a very small stroke in the eye.
• Visual illusions, hallucinations and other so-called higher cortical (located in the brain) visual disorders. This is a very complex group of conditions, including for instance, an inability to recognize familiar faces, an inability to read what one has just written, or being unaware that one is missing half of one’s visual field. Although relatively common in patients with previous strokes, they are easily missed or misinterpreted and it is important to help these patients get proper evaluation for neuro-rehabilitation.
• Double vision and eye movement disorders. Controlling the completely harmonious voluntary and involuntary movement of our eyes is another complex function of the brain and brainstem. When this control breaks down and specifically, when one or more of the three nerves that supply our eye muscles are damaged, we can no longer focus on two identical images for the brain to fuse together, but instead see two different images at the same time, causing tremendous discomfort.
• Other abnormal eye movements including the involuntary, jerky back-and-forth movements called nystagmus.
• Abnormal pupillary reactions, for instance an asymmetry in the sizes or reactivity of one’s pupils.
• Eyelid and/or facial abnormalities like twitching, uncontrollable blinking, eyelid retraction (abnormal staring gaze) and Bell palsy.
• Pain of the eye, the face (“around the eye”) or headache (pain “behind the eye”).
• Non-physiologic or nonorganic eye disorders, in which a patient has visual complaints even though there is nothing wrong with a person’s visual system.
• Systemic (“whole body”) conditions associated with neurological problems. A few big ones are infections (HIV, tuberculosis, syphilis and herpes virus), cardiovascular (diabetic vasculopathy, hypertension, high cholesterol) and auto-immune (including multiple sclerosis, thyroid dysfunction, systemic lupus, sarcoidosis and myasthenia gravis).

Do you know someone who needs neuro-ophthalmic evaluation?

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