Related Experiment Video
Updated: Jul 16, 2026
06:12
Recording Horizontal Saccade Performances Accurately in Neurological Patients Using Electro-oculogram
Published on: March 13, 2018
Electrophysiological findings in persons with nyctalopia
1Singapore National Eye Centre.
Annals of the Academy of Medicine, Singapore
|January 16, 2007
Summary
Electrophysiological testing is valuable for investigating night blindness (nyctalopia) even with normal eye exams. While many patients show normal electroretinogram (ERG) results, 26% reveal underlying rod photoreceptor dysfunction.
Area of Science:
- Ophthalmology
- Visual Electrophysiology
- Retinal Physiology
Background:
- Nyctalopia, or difficulty seeing at night, can present without visible fundus abnormalities.
- Visual electrophysiology offers objective assessment of rod photoreceptor function when fundus examination is normal.
Purpose of the Study:
- To evaluate the utility of electrophysiological testing in patients with nyctalopia and normal fundi.
- To identify the prevalence and types of retinal dysfunction in such cases.
Main Methods:
- Retrospective study of 50 patients under 40 with nyctalopia and normal fundi.
- Assessment included subjective scotopic threshold sensitivity (STS) and objective full-field electroretinogram (ERG).
Main Results:
- 74% of subjects exhibited normal ERG scotopic responses.
- Abnormal ERG findings were observed in 26%, including nonspecific rod dysfunction, rod-cone dystrophies, and congenital stationary night blindness (CSNB).
- No significant differences in age, refraction, or STS were found between normal and abnormal ERG groups.
Conclusions:
- Normal ERG results in nyctalopia patients suggest non-rod pathway causes like optical or psychological factors.
- Electrophysiological testing is recommended for nyctalopia evaluation, even with normal fundus appearance, due to the 26% detection rate of abnormalities.
More Related Videos
Related Concept Videos
01:20Anatomy of the Eyeball
The eye is a spherical, hollow structure composed of three tissue layers. The outer layer — the fibrous tunic, comprises the sclera — a white structure — and the cornea, which is transparent. The sclera encompasses some of the ocular surface, most of which is not visible. However, the 'white of the eye' is distinctively visible in humans compared to other species. The cornea, a clear covering at the front of the eye, enables light penetration. The eye's middle layer, the vascular tunic,...
01:22Photoreceptors and Visual Pathways
At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category, whereas...