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Wanda L Pfeifer, Richard J Olson, Susannah Q Longmuir, Arlene V Drack; Is TRPM1 associated Congenital Stationary Night Blindness stationary?. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3287.
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© ARVO (1962-2015); The Authors (2016-present)
To describe the clinical characteristics and electroretinogram (ERG) of TRPM1 associated Congenital Stationary Night Blindness (CSNB) in children over time.
Retrospective chart review of children diagnosed with CSNB in the Pediatric Genetic Eye Clinic from 2008-2013. Inclusion criteria were TRPM1 mutations and 2 or more complete eye examinations at least 1 year apart.
7 different TRPM1 mutations were identified in 6 patients: 2 males, 4 females. 4 mutations were novel. Age at presentation averaged 8.8 months (range 7-12) with average follow-up 9 5/12 years (5 10/12 to 13 5/12). Presenting complaints included strabismus, nystagmus and failed vision screen. 2/6 had nystagmus at presentation; both resolved by age 2 years. Earliest cycloplegic refraction averaged -5.25 diopters (+1.00 to -12.00) at average age 14 months (7-36). Cycloplegic refraction at most recent visit (MRV) averaged -8.75 diopters (-4.25 to -14.75) at average age 10.5 years (7-15). Myopic shift averaged 0.4 diopters/year. Visual acuity at MRV averaged 20/40 (20/20-20/70). Average age at diagnosis of CSNB by ERG was 7.6 years; at molecular diagnosis, 9.8 years. Preceding diagnoses included pathologic myopia, motor nystagmus, strabismus, spasmus nutans, retinitis pigmentosa, Stickler’s syndrome, Ehlers Danlos Syndrome, keratoconus, and ametropic amblyopia. 6/6 patients demonstrated low amplitude scotopic and electronegative standard combined response waveforms, biphasic oscillatory potentials and square wave photopic ERG waveforms. 5/6 patients had 2 or more ERGs. 2/5 patients demonstrated ≥ 20% decline in both rod and cone amplitudes over an average of 3.5 years (range 3 to 4). 3/5 remained stable over an average 1.5 years (range 1 to 3). Three patients reported night blindness.
CSNB is believed to be stationary with diagnostic features of myopia, nystagmus and night blindness. This may not always be the case. 2/5 TRPM1 patients (40%) with serial ERGs demonstrated a decline in amplitudes over time. Only 2/6 had nystagmus and only 3/6 reported night blindness. All patients were myopic at an early age. TRPM1 CSNB should be suspected in young children with high myopia, even without other features of CSNB. Serial ERG’s are needed to evaluate stability.
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