Abstract
Purpose :
To describe the rate of progression of vision and retinal parameters in PDE6B-associated rod cone retinal dystrophy, in a cohort of Māori patients, over a 9 year period, in New Zealand/Aotearoa. All carried at least one copy of the same pathogenic variant, (c.2197G > C, p.(Ala 733Pro)).
Methods :
Retrospective review of patients identified from the the New Zealand Database of Inherited Retinal Disease with the PDE6B founder variant. Clinical notes were reviewed to determine best corrected visual acuity at each visit. Sequential Spectralis OCT scans through the fovea and shortwave autofluorescence (SW-AF) were reviewed, with the ellipsoid line identified and measured. The hyperautofluorescent ring was marked and measured in the horizontal and vertical meridian. Progression rates for width of the EZ, AF ring diameters and area, and BCVA were estimated using linear mixed models.
Results :
19 patients were identified (53% female) with an average age at first visit of 47 years (range 21-68 years) and average follow-up of 3.2 years ( range 1-9 years), and 16 were homozygous for the p.(Ala 733Pro) allele. Almost all patients in this study had an initial baseline measurement of <3000μm for EZ line width and SW-AF ring diameters, EZ-line widths decreased by 350μm per year, area of SW-AF ring diameters decreased by 2.2mm2 per year and average horizontal and vertical hyper SW-AF ring diameters decreased by 320μm and 430μm per year, respectively.
Estimated mean rate of LogMAR visual acuity decline, based on the slope of each patient was 0.0529 increments per year.
Conclusions :
This study characterises the rate of progression of a cohort of patients with the same unique PDE6B founder mutation. Consistent with previous studies, disease progression rate was observed to be a function of initial baseline measurement. This study also provides information on the rate of progression for patients with more advanced stages of the disease (<3000μm for EZ line). Documenting the natural history is a prerequisite for preparedness for any gene-directed treatment.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.