Patients with choroideremia experience disparate rate of decline before and after the age of ~30 to ~40 years, with an earlier age of rapid best-corrected visual acuities (BCVA) decline onset in the worse-seeing eye (WSE) compared with the best-seeing eye (BSE). Additionally, results show increasing BCVA interocular asymmetry before the age of 40, according to a large meta-analysis into the rare retinal condition published in BMC Ophthalmology

Better recognition of the natural progression of choroideremia will facilitate improved diagnosis, note facilitators of this pooled, cross-sectional meta-analysis using the largest choroideremia data set to date. Data from 1602 eyes of 1037 patients (all men, mean age of 41.8 years) across 23 studies, were included. Researchers evaluated VAs of patients before and after a cut-off age of 33.8 years, and before and after 39.1 years of age to determine the rates of VA deterioration between the patients’ BSE and WSE. 

The study found that patients younger than 33.8 years experienced a VA loss of 0.0086 logMAR per year in the WSE, which rose to 0.0219 logMAR per year after age 33.8 years. Before and after 39.1 years, BCVA decline rates for the BSE were 0.00001 and 0.0203 logMAR per year, respectively. 


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Underdiagnosis of choroideremia because of overlapping conditions with other retinal diseases points to the need for more recognition of the natural progression of this rare inherited retinal disease, according to the report. Accurate descriptions of the natural deterioration of bilateral VA to potentially assess treatment effects that new therapies — such as investigational gene therapies now in phase 3 clinical trials (ClinicalTrials.gov Identifier: NCT03496012)— may change the course of this disease.

Investigators conclude that disparate interocular progression rates can be observed before the transition age, while similar progression rates were observed after the transition age. Results show that, before and after an age cutoff of 33.8 years, decline rates for the WSE were 0.0086 and 0.0219 logMAR per year. Before and after an age cutoff of 39.1 years, BCVA decline rates for the BSE were 0.00001 and 0.0203 logMAR per year, respectively. 

Differences in absolute BCVA and decline rates decrease between the 2 eyes until approximately age 40. Differences in absolute BCVA and decline rates were similar between eyes. While previous studies suggest an accelerated BCVA decline between the ages of 30 to 60 years, meta-analysis maintains a 2-phase linear model of BCVA decline with a transition age of 39 years.  

“Understanding the natural progression of BCVA decline in choroideremia can inform the interpretation of clinical studies and the design of future clinical studies. Furthermore, an understanding of vision decline based on age data may support ideal management strategies for future therapies,” researchers explain. 

The study was limited by its single-sex particpant cohort and incomplete patient data.

Clear understanding of the differential BCVA decline between eyes should help physicians determine when and if to treat one or both eyes — vital information for clinical studies and future therapies for choroideremia. 

Reference

Bozkaya D, Zou H, Lu C, Tsao N, Lam B. Bilateral visual acuity decline in males with choroideremia: a pooled, cross-sectional meta-analysis. BMC Ophthalmol. Published online January 16, 2022. doi:10.1186/s12886-022-02250-z