When evaluating patients with unexplained visual loss, I believe it's essential to maintain the assumption of an underlying organic process. Even in patients with a demonstrable non-organic component to their presentation, the possibility of coexistent real disease must be considered. That said, when a patient presents with clinical features that appear to be inconsistent or contradictory, a functional etiology (e.g. psychogenic, malingering, etc.) must also be kept in mind.
This 44-year-old man presented with bilateral HM vision, yet the clinical information provided to the group includes no objective evidence of an organic etiology. Subsequent visual fields demonstrated bilateral symmetrical constriction. And more recently, the patient presents with convergence spasm that's reportedly relieved by sunglasses. Some degree of suspicion would appear to be warranted in this case.
I would suggest beginning the analysis by reviewing the original history, the examination findings, and the neuroimaging results.
HISTORY
Did the patient report pain on eye movement prior to or coincident with the onset of visual loss?
Did the patient give a history of other neurological symptoms?
Did the patient drive himself to his appointment?
Has the patient asked for documentation of disability?
EXAMINATION
On initial examination, when acuity was measured as HM in both eyes, how brisk were the DIRECT pupillary responses? (Although the absence of an APD could have been explained by bilateral, symmetrical involvement, both pupils should have been very sluggish to direct stimulation).
What were the fundus findings? In particular, was there any disc swelling at onset? If not, did optic atrophy and loss of the nerve fiber layer develop bilaterally after four to six weeks?
Was color vision tested? (Any color perception using standard testing methods would be inconsistent with HM vision from optic nerve disease).
What was the response to testing with the OKN drum? (With acuities below CF at 2 feet, the OKN response should have been absent).
Did the patient ambulate independently in the exam room and waiting area?
NEURO-IMAGING
What did the MRI show prior to treatment with IV steroids? In particular, was there optic nerve enhancement unilaterally or bilaterally? Also, were there any white matter lesions in the brain?
Sharing the above data will greatly facilitate the diagnostic process.
Steve
Stephen C. Pollock, M.D.