Abstract
BackgroundDark adaptation is an energy-requiring process in the outer retina nourished by the profusely perfused choroid. We hypothesized that variations in choroidal thickness might affect the rate of dark adaptation.MethodCross-sectional, observational study of 42 healthy university students (mean age 25 ± 2.0 years, 29 % men) who were examined using an abbreviated automated dark adaptometry protocol with a 2° diameter stimulus centered 5° above the point of fixation. The early, linear part of the rod-mediated dark adaptation curve was analyzed to extract the time required to reach a sensitivity of 5.0 × 10−3 cd/m2 (time to rod intercept) and the slope (rod adaptation rate). The choroid was imaged using enhanced-depth imaging spectral-domain optical coherence tomography (EDI-OCT).ResultsThe time to the rod intercept was 7.3 ± 0.94 (range 5.1 - 10.2) min. Choroidal thickness 2.5° above the fovea was 348 ± 104 (range 153–534) μm. There was no significant correlation between any of the two measures of rod-mediated dark adaptation and choroidal thickness (time to rod intercept versus choroidal thickness 0.072 (CI95 -0.23 to 0.38) min/100 μm, P = 0.64, adjusted for age and sex). There was no association between the time-to–rod-intercept or the dark adaptation rate and axial length, refraction, gender or age.ConclusionChoroidal thickness, refraction and ocular axial length had no detectable effect on rod-mediated dark adaptation in healthy young subjects. Our results do not support that variations in dark adaptation can be attributed to variations in choroidal thickness.Electronic supplementary materialThe online version of this article (doi:10.1186/s12886-016-0273-6) contains supplementary material, which is available to authorized users.
Highlights
Dark adaptation is an energy-requiring process in the outer retina nourished by the profusely perfused choroid
Choroidal thickness, refraction and ocular axial length had no detectable effect on rod-mediated dark adaptation in healthy young subjects
We have examined the effect of choroidal thickness on retinal function using such an abbreviated dark adaptometry protocol to measure the rate of rod dark adaptation in healthy young adults
Summary
Dark adaptation is an energy-requiring process in the outer retina nourished by the profusely perfused choroid. The reference method of measuring dark adaptation is Goldmann-Weekers dark adaptometry, that records full adaptation, including the phase of maximum rod sensitivity, which is reached in healthy subjects after approximately 40 min in darkness [11]. This method is relatively time-consuming for a clinical procedure and can be biased by patient fatigue [12]. An abbreviated method has been developed [12] It measures the rate of dark adaptation from bleaching to a standard sensitivity threshold rather than following dark adaptation to the final rod threshold. If the patient has impairment of cone adaptation, a full exponential recovery may be observed [14]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
