INTRODUCTIONOphthalmologists are occasionally confronted with an individual presenting with nyctalopia (i.e., a relatively greater difficulty seeing at night). When there is no accompanying abnormality seen in the fundus, visual electrophysiology becomes useful as an objective means of assessing rod (scotopic) photoreceptor function or pathway defects.

MATERIALS AND METHODSA retrospective study was performed on 50 consecutive patients, aged less than 40 years, with seemingly normal fundi and good vision [visual acuity (VA) >6/12] presenting to the Visual Electrodiagnostic Unit, Singapore National Eye Centre, for the investigation of nyctalopia over a 2-year period. Subjective scotopic threshold sensitivity (STS) and objective full-field electroretinogram (ERG) were performed. Persons with abnormal test results were identified.

RESULTSNormal ERG scotopic responses were obtained in 74% of subjects. There was no significant difference in age, refraction and STS levels between subjects with abnormal and normal ERG. In the group with abnormal scotopic ERG responses, 9 were identified to have nonspecific rod dysfunction, 2 had rod-cone dystrophies and 2 had ERG changes suggestive of congenital stationary night blindness (CSNB).

CONCLUSIONA large number of subjects presenting with nyctalopia had normal ERG findings. We can only assume that in these patients, no significant rod pathway dysfunction exists and that optical (e.g., night or instrument myopia) and psychological aetiologies should be considered. The fact that an abnormal result occurs in 26%, however, suggests that ncytalopia should be evaluated with electrophysiolgoical testing even when the fundi appear normal.

Adult ; Comorbidity ; Electroretinography ; Female ; Humans ; Male ; Night Blindness ; epidemiology ; physiopathology ; Refraction, Ocular ; Retinal Diseases ; epidemiology ; etiology ; physiopathology ; Retrospective Studies

Choroideremia is a rare hereditary disease with characteristic fundus that causes night blindness and peripheral visual field loss. The authors encounter choroideremia accompanied by recurrent uveitis. This paper is designed to give a description of the condition, along with an investigation of the literature. Ophthalmological tests and treatments were performed. Characteristic fundus, night blindness, peripheral visual field loss, electroretinography and other manifestations led us to a diagnosis of choroideremia. The anterior uveitis was managed with medication.
Adult ; Choroideremia/*complications/diagnosis ; Electroretinography ; Fluorescein Angiography ; Fundus Oculi ; Human ; Male ; Night Blindness/etiology ; Recurrence ; Uveitis, Anterior/*complications ; Vision Disorders/etiology ; Visual Fields

OBJECTIVE: To detect potential variants in a family affected with Usher syndrome type I, and analyze its genotype-phenotype correlation. METHODS: Clinical data of the family was collected. Potential variants in the proband were detected by high-throughput sequencing. Suspected variants were verified by Sanger sequencing. RESULTS: The proband developed night blindness at 10 year old, in addition with bilateral cataract and retinal degeneration. Hearing loss occurred along with increase of age. High-throughput sequencing and Sanger sequencing revealed that she has carried compound heterozygous variants of the MYO7A gene, namely c.2694+2T>G and c.6028G>A. Her sister carried the same variants with similar clinical phenotypes. Her daughter was heterozygous for the c.6028G>A variant but was phenotypically normal. CONCLUSION The clinical features and genetic variants were delineated in this family with Usher syndrome type I. The results have enriched the phenotype and genotype data of the disease and provided a basis for genetic counseling.
Child ; Female ; Genetic Variation ; Genotype ; Heterozygote ; High-Throughput Nucleotide Sequencing ; Humans ; Mutation ; Myosin VIIa ; genetics ; Night Blindness ; etiology ; Pedigree ; Phenotype ; Usher Syndromes ; genetics ; pathology