NIGHT study: natural progression of choroideremia

Abstract

Purpose : This ongoing, 2-year, prospective, multicenter, observational study (NIGHT: NSR-CHM-OS1, NCT03359551) investigates the natural progression of choroideremia.

Methods : Enrollment is completed and includes 322 adult males with genetically confirmed choroideremia and active disease visible within the macula. Eyes were classified at baseline into 3 cohorts by best-corrected visual acuity (BCVA): ≥74 Early Treatment of Diabetic Retinopathy Study (ETDRS) letters (201 eyes), 34-73 ETDRS letters (382 eyes), and <34 ETDRS letters (61 eyes). The analyses were conducted on participants who completed the 20-month study (186 participants [368 eyes]). Visits occurred at 4-month intervals; BCVA, preserved area of ellipsoid zone (EZ), preserved area of autofluorescence (PAF), microperimetry, contrast sensitivity, color vision, and reading-speed tests were assessed periodically. Endpoints other than BCVA were assessed only through 12 months (237 participants [468 eyes]).

Results : Change from baseline in most assessments demonstrated a consistent but modest decline. The mean (95% CI) change in BCVA from baseline to Month 12 was 0.9 (0.3, 1.5) and from baseline to Month 20 was -0.5 (-1.2, 0.2). Linear regression suggests BCVA decreases slowly, at approximately 0.5 letters annually, although loss is higher and progresses slightly faster in older individuals. When assessing effects of age on BCVA change over a 20-month period (adjusting for baseline BCVA), participants in their seventies lost ~1.9 letters. All other assessments decreased consistently from 4 to 12 months in all 3 BCVA cohorts. Mean (95% CI) change from baseline was -14.65% (-15.58, -13.72) in PAF and -15.07% (-16.39, -13.75) in preserved EZ area; mean (95% CI) change from baseline in microperimetry was -0.56 dB
(-0.77, -0.35). Changes from baseline in contrast sensitivity and color vision were minimal. Reading speed was highly variable.

Conclusions : Participants with choroideremia slowly lose vision. Older patients with a more advanced disease may experience greater decline over a 20-month interval. PAF and preserved EZ area decreased at each visit. Contrast sensitivity, color vision, and reading speed were not reliable measures of disease progression. This study reinforces the importance of BCVA, preserved EZ area, and PAF as measures of natural choroideremia progression.

This is a 2021 ARVO Annual Meeting abstract.