The absent-minded professor: an unusual complication of melanoma

Dr. Alan Kimura: Patients with MAR often provide a history of photopsias and shimmering patches of color, and in this case shimmering yellow lights, the reappearance of which is a marker for too long an interval between IVIg treatments. Visual acuity is typically fairly well preserved. The largest review of patients with MAR documented a visual acuity of better then 20/60 in greater than 80% of patients. [ 1 ] Visual fields, however, are typically affected. Our patient showed constriction in visual fields with central scotomas. Though this type of presentation is common, there are many reports of patients with MAR that have normal visual fields. Thus, there are no specific visual field findings in MAR. The most important clinical diagnostic test is the electroretinogram (ERG). ERG is a measure of the electrical response of the retina to varying stimuli of light, under dark-adapted, then light-adapted states. The a-wave represents photoreceptor function, and the b-wave represents inner retinal function, reflecting either Müller cell or bipolar cell function. The classic finding of MAR, as demonstrated by our patient (Figure 5), is the socalled "negative ERG" featuring a low b/a-wave ratio in the "maximal, combined rod and cone response." This is seen with a markedly reduced b-wave and a normal dark-adapted a-wave, which in the right clinical scenario is pathognomonic for MAR. The loss of the b-wave is due to an autoimmune response involving antigens located within the bipolar layer. Selective b-wave loss on ERG is also seen in congenital stationary night blindness, and a number of other inherited and noninherited toxic states (Table 1 ). Approved therapies for melanoma include immune therapies such as interleukin-2 (Proleukin) and interferon. The fact that melanoma responds to immune therapy is further evidence that autoimmunity may be a favorable prognostic factor. Gogas et al evaluated melanoma patients treated with interferon alfa-2b (Intron A) and found that the appearance of autoantibodies or clinical manifestations of autoimmunity were associated with a statistically significant improvement in survival.! 14] Overall, though, there is not enough evidence to prove MAR as a favorable prognostic factor in melanoma patients. Dr. [Ragini Kudchadkar]: Melanoma-associated retinopathy is a rare but distinct clinical entity that must be considered in any melanoma patient with visual symptoms, especially a flashing lights phenomenon. Visual fields are often affe