Abstract
Purpose: :
To investigate the influence of choroidal thickness on rod-mediated dark adaptation in healthy subjects.
Methods: :
Cross-sectional observational study of 42 eyes of 42 healthy university students who underwent dark adaptometry and assessment of choroidal thickness using enhanced-depth imaging optical coherence tomography. The speed of rod dark adaptation was expressed as the time taken to reach a pre-defined rod threshold named the rod intercept.
Results: :
The mean subfoveal choroidal thickness was 351 μm (SD 106 µm, range 115-568 µm). The mean time to rod intercept was 7.34 min (SD 1.0 min, range 5.02-10.34 min). Regression analysis showed a non-significant decrease in the speed of dark adaptation with increasing choroidal thickness 0.0019 (-0.0012 to 0.0050) min/µm, p=0.21, adjusted for age and sex. Further adjusting for axial length or refraction error did not alter the results. There was no signifcant association between axial length (p=0.18) or refraction (p=0.64) on speed of dark adaptation.
Conclusions: :
Rod-mediated dark adaptation was not associated with subfoveal choroidal thickness although the study population presented a large variation the in thickness of the subfoveal choroidea. Choroidal thickness does not appear to influence rod photoreceptor performance in healthy young adults.
Keywords: choroid • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • adaptation: chromatic