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Manjot Kaur Grewal, Alan C Bird, Glen Jeffery, Sobha Sivaprasad; Deep phenotyping of intermediate age-related macular degeneration (AMD) using rod function tests. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1191.
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© ARVO (1962-2015); The Authors (2016-present)
Dark adaptation is reported to be a sensitive test to distinguish between healthy eyes and those with intermediate AMD. In this study, we phenotyped intermediate AMD patients with and without reticular pseudodrusen (RPD) to investigate the integrity of rod function in intermediate AMD
In a prospective cross-sectional study, participants with varying severity of AMD and age-matched controls with best corrected visual acuity (BCVA) better than 6/19 were categorised into four groups based on their study eye: 1) normal and early AMD (n=14) 2) intermediate AMD without RPD (n= 16), 3) intermediate AMD with RPD (n=10) and 4) non-centre involving geographic atrophy with no RPD (n= 11). The participants underwent BCVA in ETDRS letters, low luminance visual acuity (LLVA), scotopic microperimetry to assess absolute rod thresholds using the Medmont dark-adapted chromatic (DAC) perimeter and dark adaptometry (DA) using AdaptDx to assess rod intercept time. Low luminance questionnaire (LLQ) provided patient reported outcomes in dim illumination. Imaging including fundus colour photography, spectral-domain optical coherence tomography (SD-OCT) and fundus autofluorescence to confirm the participant category.Eyes with neovascular AMD were excluded.
The BCVA was not significant between groups. Rod intercept time was significantly reduced in group 3 compared to group 1 (p<0.0001) and group 2 (p<0.0001), however, scotopic microperimetry and LLVA tests were not significantly associated between these groups. There was no difference in scotopic microperimetry thresholds, dark-adaptometry and LLVA assessments between Group 3 and group 4 (p = 0.06, p= 0.94 and p=0.1110 respectively). The LLQ score was statistically decreased in Group 4 compared to Group 1, 2 and 3.
Dark adaptometry was the most reliable functional biomarker that can further stratify the intermediate AMD group into those with RPD and without RPD. Eyes with intermediate AMD without RPD behaved similarly to those with normal or early AMD. However, eyes with RPD were significantly associated with decreased rod function similar to that observed with non-central geographic atrophy. We cannot rule out whether the eyes with non-central geographic atrophy had previous RPD that had disappeared before the study period.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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