Case Report: Occult Macular Dystrophy.

Significance: This case report discusses a case of suspected occult macular dystrophy, which is an underrecognized but not rare subtype of cone dystrophy. Increasing clinician recognition of occult macular dystrophy will lead to increased accurate diagnosis of affected patients.

Purpose: A clinical presentation and diagnosis of a case of suspected occult macular dystrophy, as well as background information and management, are reported.

Case Report: A 44-year-old White man reported long-standing decreased vision and photophobia in both eyes. Examination revealed a bilateral reduction in best-corrected visual acuity, abnormal color vision, central visual field defects, and subtle disruption of subfoveal photoreceptor integrity on optical coherence tomography with a normal fundus appearance. The multifocal electroretinogram showed decreased perifoveal responses, whereas both the photopic and scotopic full-field electroretinograms were normal. This distinctive electroretinogram response pattern was critical in the diagnosis of occult macular dystrophy.

Conclusions: Reduced visual acuity with a normal clinical examination result is commonly encountered in patients with occult macular dystrophy. Therefore, clinicians must be aware of occult macular dystrophy and order appropriate testing to accurately identify cases of occult macular dystrophy. Without thorough evaluation, patients may be easily misdiagnosed with other etiologies of vision loss.