Abstract
Purpose :
Alterations in scotopic sensitivity have been associated with abnormalities in Bruch’s membrane that are known to precede age related macular degeneration (AMD) development. The purpose of this study is to evaluate suitability of the Purkinje shift based rapid dark adaption test (RDAT) for patient home use and examine RDAT metrics based on age and visual acuity correlates.
Methods :
This was a cross-sectional, observational exploratory study using non-probability subject sampling. Enrolled subjects performed the RDAT test based on previously developed protocol. In brief, subjects were shown 15 colored “poker” matte finish discs 5 each of red, white and blue and instructed to separate them by color into 3 piles; red on the left, blue on the right, white in center. Prior to sorting, the subject was asked to look at a blank computer screen a distance of 1 meter for 1 minute after which lights were dimmed. Each eye was tested separately, right preceding left. The time required to sort the discs to 100% accuracy was measured, and is considered a surrogate measure of the Purkinje shift.
Results :
We enrolled 30 subjects age range 24-83, mean 58.33. Mean logmar vision of the right eye was 0.1330, range 0.0 to 0.6021 (20/20 to 20/80 Snellen equivalent). Mean logmar vision of the left eye was 0.1932, range 0.0 to 1.0 (20/20 to 20/200 Snellen equivalent). Time to complete the RDAT was directly correlated to subject age for both right and left eyes (Pearson correlation; r = 0.5612, p = 0.0013; r = 0.5260, p = 0.0024 right and left eyes respectively). There was a statistically significant difference in the time required to complete the RDAT between the right and left eyes with the second eye tested being significantly faster (p = 0.0024). The time to complete the RDAT test was found to be unrelated to visual acuity for either the right or left eyes. The study protocol was completed by all study subjects without need for prompting or repeated testing.
Conclusions :
Diminished scotopic sensitivity as measured by RDAT testing appears to be directly related to patient age. Visual acuity appears unrelated to scotopic sensitivity assessment by RDAT measurement. A significant learning effect is observed as noted by the marked improvement in test time with second, left eye testing. Further study is required to fully assess the relevance of home deployment of the RDAT for use in AMD diagnosis and management.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.