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Tracey Topacio, Ava K Bittner; Dark Adaptation Testing in Retinitis Pigmentosa Patients using the AdaptDx. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3245.
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© ARVO (1962-2015); The Authors (2016-present)
We report our experience with testing RP patients who have a wide range of vision loss using an instrument that has received FDA 510(k) clearance for measurement of dark-adaptation function, the AdaptDx (Maculogix).
The AdaptDx was used for dark adaptation testing at 5 degrees from fixation using a 76% initial bleach to assess the most sensitive location (i.e., temporal, nasal, inferior or superior) determined by photopic Humphrey 10-2 static perimetry in 23 RP subjects. Testing was stopped after 5-6 minutes if there was no evidence of dark adaptation (i.e., consistent cone-mediated sensitivity only). Testing was completed twice at two visits within a month for 16 of the subjects. At the same visits, subjects completed the following central visual function tests with and without a NoIR U23 4% transmission filter to simulate low luminance: ETDRS visual acuity (VA), Pelli-Robson contrast sensitivity (CS), and quick contrast sensitivity function (qCSF).
Mean VA across subjects was 0.45 logMAR (SD 0.46; range -0.07 to 1.56). About a quarter to a fifth of the subjects (n=5; 22%) had a measurable rod intercept at 3 log units. Two subjects had a cone plateau at 2 log units and the majority (n=16; 70%) had only a minimal cone response <1 log unit. The test-retest 95% coefficient of repeatability was 0.5 log units for mean sensitivity across subjects with cone-only AdaptDx responses (i.e., no measurable rod intercept). A Bland-Altman graph analysis revealed there was no tendency across subjects with cone-only AdaptDx responses to perform better at either the first or second visit. Reduced mean sensitivity for cone-only AdaptDx responses was significantly associated with reduced central vision with the 4% transmission filter: VA (-0.76; 95%CI:-1.29,-0.23; p=0.005), CS (0.74; 95%CI:0.35,1.12; p<0.001) and qCSF (0.97; 95%CI: 0.51,1.42; p<0.001). Subjects who had >0.2 logMAR reduction in VA with the 4% filter compared to without the filter had significantly reduced AdaptDx cone sensitivity on average (-0.65; 95%CI:-1.12,-0.18; p=0.007).
The AdaptDx may be helpful to characterize RP patients who have rod versus cone-mediated dark adaptation at perifoveal locations and monitor for longitudinal changes.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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