Purchase this article with an account.
Rose Setiawan Tan, Robyn H Guymer, Emily Caruso, Chi D Luu; The reliability of rod and cone sensitivity measurements using a novel dark-adapted chromatic perimeter. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3700.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The dark-adapted chromatic perimeter (DACP) was designed to allow measurement of rod- and cone-mediated function at the same retinal location. This study investigated the intra-session reproducibility of dark-adapted rod and cone sensitivities using a DACP in non-neovascular age-related macular degeneration (AMD) and normal subjects.
Rod and cone sensitivities were measured in one eye of 31 AMD and 16 control subjects. The stimulus grid consisted of 28 test points spaced within the central 24° of the retina. Goldmann V size stimulus was used and threshold was determined using a 4-2 staircase threshold strategy. The rod and cone sensitivity was determined using a blue-green (505nm) and red (620nm) stimulus, respectively. Rod sensitivity was obtained 20 minutes after dark adaptation (DA) followed by cone sensitivity, and the tests were repeated at 30 minutes after DA. A subset of participants (6 cases and 14 controls) attended a second visit and measurements of rod and cone sensitivity were repeated. The intra-session coefficient of repeatability (CoR) was determined and compared between the control and AMD group.
The differences in mean sensitivity between the first and second test for both visits were significant for rod (p ≤ 0.01) but not for cone (p ≥ 0.07) sensitivity in both cases and controls. Thus the intra-session reproducibility of the DACP was determined only for the cone test. The CoR for 28 cone test points of the first visit ranged from 2.82 - 6.35 dB for controls and 4.10 - 12.13 dB for AMD subjects. The CoR of the second visit ranged from 2.41 – 12.35 dB for controls and from 2.02 – 10.42 dB for AMD cases. Outliers were detected in 1.2% of the data points. When these outliers were excluded, the CoR of the first visit ranged from 2.82 – 6.35 dB for controls and from 3.60 – 6.86 dB for AMD cases, and the CoR of the second visit ranged from 2.41 – 5.43 dB for controls and 2.02 - 7.01 dB for AMD cases.
The intra-session CoR for dark-adapted cone sensitivity of the control and AMD group appeared to be in a similar range after the outliers were excluded. When testing rod sensitivity, it was apparent that there was still adaptation occurring after 20 minutes of DA, even in control subjects. This is an important finding when one is considering using rod sensitivity as a marker of disease severity in clinical trials.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
This PDF is available to Subscribers Only