Congenital stationary night blindness with hypoplastic discs, negative electroretinogram and thinning of the inner nuclear layer

Abstract

Purpose: To describe congenital stationary night blindness (CSNB) with a negative electroretinogram, hypoplastic discs, nystagmus and thinning of the inner nuclear layer (INL). Methods:Retinal structure was analyzed qualitatively with spectral domain optical coherence tomography and wide field imaging. Retinal function was evaluated with full-field electroretinography (ffERG). Molecular genetic testing included next-generation sequencing (NGS) of the known genes involved in CSNB.Results: Patients presented with CSNB presented with nystagmus, high myopia, hypoplastic discs and negative ffERG with no measurable rod response. The retinas appeared normal and automated segmentation of retinal layers demonstrated a relative reduction of thickness of the INL. There was no significant change in the ffERG after prolonged 2 hour dark adaptation compared to standard 30 minute dark adaptation. Affec ted family members harboured the homozygous 1-bp deletion c.2394delC in exon 18 of the TRPM1 gene, whereas their unaffected parents were heterozygous carriers. Conclusions:This data expands the genotype and phenotype spectrum of CSNB. The lack of improvement of rod responses after prolonged dark adaptation, together with thinning of the INL, is compatible with postreceptoral transmission dysfunction in the bipolar cells. Such knowledge may prove useful in future development of treatment for outer retinal dystrophies, using opsin genes to restore light responses in survivor neurons in the inner retina.

Clinical Features and Spectral-Domain Optical Coherence Tomography Findings of Complete Congenital Stationary Night Blindness Patients

“…1,9 Al Oreany et al were analyzed SD-OCT findings of two affected twin brothers diagnosed with complete CSNB with TRPM1 mutations and compared them with five myopic control eyes. 7 They did not find significant thinning in total retinal thickness compared to control group; however, they observed relative thinning of INL compared to other retinal layers.…”

“…4 Both complete CSNB and incomplete CSNB demonstrate the classic negative ERG pattern, or Schubert Bornschein type, in which the b-wave is smaller than the a-wave during maximal response. 5,6 Previously, optical coherence tomography findings in incomplete CSBN has been defined by Chen et al 1 and recently Al Oreany et al 7 reported relative thinning in inner nuclear layer (INL) compared to other retinal layers in affected twin brothers of a family diagnosed with autosomal recessive complete CSNB.…”

Multimodal imaging in CABP4-related retinopathy

“…[11] Here, we found thinning of foveal retinal thickness by optical coherence tomography, and in addition, our results strongly suggest macular retinal thinning also outside the fovea in all 9 ETDRS sectors. It is to be noted that the control group used for this study consisted of healthy myopic subjects (range 6-9, median 7.5 diopters of myopia) designed to match myopic patients from a previous study, [8] and would thus be expected to have thinner-than normal retinas of emmetropic subjects. This further supports a generalized macular retinal thinning in CABP4-related retinopathy.…”

“…This enabled automated software algorithm to display with numeric averages of the macular thickness measurements for each of the 9 map sectors as defined by the Early Treatment Diabetic Retinopathy Study (ETDRS). [7] Retinal thickness in patients was compared to that of controls from a previously published paper by us, [8] using identical protocols (caliper measurement and ETDRS map) in patients and controls. (Fig.…”

“…Four of the patients (all except Patient 2) had macular autofluorescence imaging with a fundus camera (Topcon TRC-50DX, Topcon Medical Systems, Inc., NJ, US).Retinal function was evaluated with full-field electroretinography (ffERG, NicoletBiomedical Instruments, Madison, Wisconsin, USA), in dark adapted and light adapted state according to ISCEV standards,[9] with a few modifications as follows. Retinal function was evaluated with full-field electroretinography (ffERG, Nicolet Biomedical Instruments, Madison, Wisconsin, USA), in dark adapted and light adapted state according to ISCEV standards, with a few modifications as follows [8]. Full-field electroretinograms were recorded in a Nicolet analysis system (Nicolet Biomedical Instruments, Madison, Wisconsin, USA), after dark adaptation of subjects for 40 min, dilatation of the pupils with topical cyclopentolate 1% and metaoxedrine 2,5% and topical anaesthesia, with a Burian Allen bipolar contact lens and a ground electrode applied to the forehead.…”