Lateral meniscal cyst. Retrospective study of 105 cysts treated with arthroscopy with 5 year follow-up

PURPOSE: To investigate possible functional correlates of an apparent ON-pathway defect observed in the cone electroretinogram of a patient with acquired unilateral night blindness. METHOD: Visual evoked potentials were recorded to the onset of a grid pattern consisting of either incremental or decremental squares. Saccadic eye movements were measured to luminance increments and decrements presented 5 degrees from fixation. The patient's results were compared with normative data. RESULTS: Visual evoked potential latencies were prolonged to incremental stimulation of the patient's affected left eye but were within normal limits for the other three conditions (increments and decrements, right eye; decrements, left eye). A similar pattern of asymmetry between latencies to incremental and decremental stimulation of the affected eye was observed for saccadic eye movements. CONCLUSIONS: The observed predominant delay in response to luminance increments supports the hypothesis of an ON-pathway dysfunction in this patient with acquired unilateral night blindness.