Design: Multicentre retrospective natural history cohort
Population: 126 Korean patients with biallelic EYS variants
Primary outcome: Annual change in ellipsoid zone width and area, and visual acuity
Effect: Ellipsoid zone width -124.1 µm/year (106.4-141.8); acuity -0.043 logMAR/year

A multicentre retrospective cohort from eight Korean centres (American Journal of Ophthalmology, 23 September 2026) followed 126 patients with biallelic EYS variants, a common cause of autosomal recessive retinitis pigmentosa in East Asia, for a median of 5.2 years.

Ellipsoid zone width on OCT shrank by 124 µm a year (95% CI 106-142), about 4.6% a year, and visual acuity worsened by 0.043 logMAR a year. Decline was close to linear. Sixty-six variants were found, 20 of them new, and progression did not differ between loss-of-function and missense genotypes.

These figures give families a realistic expectation of pace and give gene therapy trials a benchmark. The lack of genotype-phenotype correlation means genotype alone cannot predict an individual's course.

Use serial OCT ellipsoid zone measurement to track EYS-associated retinal degeneration
Counsel that structural loss is typically steady rather than sudden
Do not predict an individual's pace from genotype alone
Refer suitable patients for genetic diagnosis to enable trial eligibility

Why it matters

It provides a measurable benchmark for counselling and for future gene therapy trials.

The statistics, in plain English

A median R² of 0.90 for a straight-line fit means progression in each eye followed a line closely. The genotype comparison (P = .923) found no difference, which with 126 patients makes a large genotype effect unlikely.