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SYMPTOMS
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Nyctalopia, Vision loss, Visual field defects, Color vision defects
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RPE pigment clumping with subsequent chorioretinal atrophy that starts in the mid-periphery and spreads into the far periphery and posterior pole (the macula is affected last), Exposure of sclera, Exposure of large choroidal vessels, Posterior subcapsular cataracts (associated in 31% of patients)
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Typically, the retinal vessels and optic nerve remain normal
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WORK-UP
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Pupils, Color vision (abnormal), Full eye exam with dilation, Visual field, OCT of the macula, OCT-Angiography (presence of choriocapillaris loss), Fundus Autofluorescence, Fluorescein Angiography (presence of choriocapillaris loss), Indocyanine Green Angiography (presence of choriocapillaris loss), Fundus photos, Infrared photos, Electrodiagnostic testing (ERG: Abnormal / EOG), Dark adaptation (abnormal), Watzke-Allen test, Macular photostress test, Amsler grid
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TREATMENT
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Give take home Amsler grid in order to monitor for macula involvement
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Monitor. No treatment is effective
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Recommend genetic counseling for other family members
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If the patient develops poor vision, refer to low vision
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If the patient presents with a visual significant posterior subcapsular cataract, refer for cataract surgery
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FOLLOW-UP
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Patient should be seen back every 6-12 months
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ETIOLOGY
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X-linked recessive progressive hereditary retinal dystrophy that occurs due to a mutation in the CHM gene which plays a key role in producing REP-1. This leads to damage of the photoreceptors, RPE, and choriocapillaris
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DIFFERENTIAL DX
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Retinitis pigmentosa, Gyrate atrophy, “Salt and pepper" fundus, Ocular albinism
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NOTES
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Symptoms are typically first noted during adolescence. Central vision loss typically occurs during the fourth or fifth decade of life
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Female carriers may show mild RPE changes in the mid-peripheral retina that is not progressive
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