If you read only one chapter in this book, read this one. It covers the most common and most serious mistakes made by ophthalmologists and ophthalmic trainees when dealing with neuro-ophthalmic patients.
Twenty neuro “rules” to keep you out of trouble
The following 20 practice guidelines have a good chance of keeping your patients (and you) safe. Naturally, as with all “rules”, there are rare exceptions to all of these, but they are still useful to keep in the back of your mind in the clinic or ophthalmic emergency department.
Beware the “silent” neuro-ophthalmic patient!
patients with optic nerve or brain tumors will sometimes be referred to you as “cataract”, “glaucoma”, “optic neuritis”, “ischemic sixth nerve palsy”, “senile ptosis” or other benign-sounding diagnoses ( Fig. 1.1 )
Every new eye patient complaining of blurred vision should have:
confrontation field testing (peripheral and central)
a “swinging torch test” for a relative afferent pupillary defect (RAPD) before dilation
perimetry if either of these is abnormal, the patient describes a field defect, or the degree of visual loss is not consistent with the ocular examination ( Fig. 1.2 )
Blurred vision or field loss
You can never diagnose the cause of optic nerve dysfunction just by looking at the disc ( Fig. 1.3 ).
All patients with non-traumatic ACUTE optic nerve dysfunction who do not meet all the clinical diagnostic criteria for either:
anterior ischemic optic neuropathy (AION) ( p. 36 )
require urgent referral to a neuro-ophthalmologist (or, if this is not possible, urgent investigation as suggested on p. 38 ) ( Fig. 1.4 ).
All patients with CHRONIC optic nerve dysfunction who do not meet all the clinical diagnostic criteria for glaucomatous optic neuropathy ( p. 37 ) require referral to a neuro-ophthalmologist (or, if this is not possible, investigation as suggested on p. 38 ) ( Fig. 1.5 ).
Amblyopia is a specific diagnosis, with specific diagnostic features; never use a history of “lazy eye” as the explanation for worsening vision. Features of optic nerve disease should be absent and a demonstrable cause for the amblyopia should be present ( Fig. 1.6 ).
Whenever you look in an eye, think: is the level of vision explained by visible intraocular disease? If not, there could be disease behind the eye. Unexplained poor vision, optic atrophy, disc cupping or field loss always requires investigation ( Fig. 1.7 ).