Abstract
Blue cone monochromatism (BCM) is a rare X-linked congenital vision disorder that
is characterized by a cone dysfunction. We present a case of a 3-year-old boy referred
to our department with abnormal eye movements since birth, impaired vision, and difficulties
in distinguishing colors. A tendency to stare at the sun was noted. Examination revealed
severe loss of visual acuity, high myopia, and opsoclonus. A mutation screening of
OPN1LW/OPN1MW gene cluster was performed showing a nucleotide substitution encoding a Cys203Arg
(C203R) missense mutation. The diagnosis of BCM in this case was clear and the patient
harbored the most frequent genetic alteration. Opsoclonus and continued voluntary
light exposure are novel features that have not been previously reported in BCM.
Keywords
monochromatism - opsoclonus - cones
