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Anatomy- versus sensitivity-based loci preselection in detecting USH2A-retinopathy microperimetric progression
Journal article   Open access   Peer reviewed

Anatomy- versus sensitivity-based loci preselection in detecting USH2A-retinopathy microperimetric progression

Jason Charng, David Alonso-Caneiro, Tina M. Lamey, Jennifer A. Thompson, Jeremiah K.H. Lim, Elaine Ong, Terri L. McLaren and Fred K. Chen
Ophthalmology Science, Vol.6(2), pp.1-11
2026
DOI: https://doi.org/10.1016/j.xops.2025.101018
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Published Version Open Access CC BY V4.0

Abstract

autofluorescence imaging microperimetry progression Retinitis pigmentosa Robson-Holder ring trial end point USH2A Usher syndrome
PURPOSE To compare microperimetry progression rate in USH2A-retinopathy using pre-specified points based on fundus autofluorescence co-registration with loci pre-selected based on retinal sensitivity profile. DESIGN Cohort longitudinal study SUBJECTS Seventeen eyes from seventeen patients with biallelic pathogenic variants in USH2A gene. METHODS Microperimetry was recorded using 10-2 grid. The grid was partitioned into 68 2°×2° non-overlapping squares, representing the retinal coverage of each locus. Four metrics were defined at baseline: (1) mean macular sensitivity (MMS): average sensitivity of all loci, (2) edge of scotoma sensitivity (ESS): average sensitivity of all loci adjacent to a scotomatous loci at baseline, (3) a modified RUSH2A study-defined functional transitional point (mFTP): selection based on ranking of the proportion peripheral adjacent loci that showed ≥7 dB decrease and (4) hyperautofluorescent ring sensitivity (HRS): average sensitivity of stimulus squares which the HAR boundary transects into. Trend-based progression rates (gradient from linear regression) were compared between these metrics and event-based analysis of the US Food and Drug Administration definition of clinically significant change in visual field (mean change of ≥ 7 dB across ≥ 5 prespecified loci). MAIN OUTCOME MEASURE Trend- and event-based measures in MMS, ESS, mFTP and HRS. RESULTS Seventeen patients (median age 37.0) had mean baseline values of 9.7 dB, 9.2 dB, 17.9 dB and 13.1 dB for MMS, ESS, mFTP and HRS, respectively. Using all longitudinal data (mean follow-up 4.0 yr), trend analysis showed mFTP progression rate (-1.53 ± 1.37 dB/yr) was significantly faster than MMS (-0.51 ± 0.63 dB/yr) and ESS (-1.11 ± 1.23 dB/yr) but similar to HRS (-1.29 ± 1.41 dB/yr). ESS was more prone to floor effect and had lower baseline sensitivity than mFTP and HRS. In event-based analysis, the proportion of eyes that demonstrated clinically significant mean change was similar between ESS (2-year 36.4%, overall 45.5%), mFTP (2-year 33.3%, overall 43.8%) and HRS (2-year 28.5%, overall 42.9%) but noticeable less in MMS (2-year 13.3%, overall 12.5%). CONCLUSIONS HRS and mFTP showed comparable performance in both trend- and event-based analyses, superior to that of MMS and ESS. mFTP offers additional advantage of including patients without the autofluorescent ring.

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