Ultra-widefield OCT-A Identifies Quantitative Biomarker and Four-Stage Grading System for Retinitis Pigmentosa Severity
核心洞察
A multicenter study of 544 eyes from 272 retinitis pigmentosa (搜索) patients identified two distinct peripheral retinal vascular phenotypes using ultra-widefield OCT angiography (搜索).
The capillary non-remodeled zone (CNZ) strongly tracked visual function and served as the basis for a validated four-stage severity grading system.
Type 1 "Terminal Remodeling" eyes (56.2%) showed worse visual acuity and more constricted visual fields than Type 2 "Simple Atrophy" eyes.
A new multicenter study suggests that ultra-widefield OCT angiography (搜索) (UWF OCT-A) may offer eyecare clinicians a more objective way to gauge disease severity in retinitis pigmentosa (搜索) (RP), a condition that often progresses unpredictably and is difficult to stage with conventional tests. Published in Retina, the study analyzed 544 eyes from 272 patients with primary RP enrolled at three tertiary hospitals in China.
Researchers found two distinct peripheral retinal vascular phenotypes in RP and showed that the capillary non-remodeled zone (CNZ) strongly tracked visual function. They then used CNZ measurements to build and validate a four-stage severity grading system that stratified patients by functional loss.
Two Peripheral Vascular Phenotypes
Investigators used UWF OCT-A to characterize peripheral retinal vasculature, classifying eyes into two phenotypes: Type 1, termed "Terminal Remodeling," and Type 2, termed "Simple Atrophy." Type 1 was the more common pattern, seen in 56.2% of eyes, while Type 2 was found in 43.8%. Patients also underwent multimodal visual testing.
The researchers found that Type 1 eyes generally represented a more severe form of disease than Type 2 eyes. In the function dataset, Type 1 eyes had smaller CNZ areas than Type 2 eyes: 182.4mm² vs. 222.9mm². They also had worse best-corrected visual acuity (BCVA) (20/73 vs. 20/50) and more constricted visual fields, including smaller III4e and V4e areas.
CNZ as a Structural Biomarker
The CNZ emerged as the strongest structural biomarker. In the combined analysis, CNZ area correlated significantly with all visual function measures and explained a large proportion of variance in kinetic visual fields. The authors were able to create the following four-stage grading system based on CNZ size, which explained substantial functional variation and discriminated BCVA in both internal and external validation cohorts:
- Stage I: ≥260mm²
- Stage II: 200mm² to 260mm²
- Stage III: 150mm² to 200mm²
- Stage IV: <150mm²
"While the underlying mechanisms warrant further investigation," the authors explained in their paper, "the identification of these phenotypes has immediate clinical relevance." For example, they noted that "the age-at-observation analysis linked Type 1 remodeling to a clinically unfavorable phenotype with severe visual impairment at younger observed ages."
Implications for Emerging Therapies
The researchers concluded that "CNZ area may serve as a quantitative structural surrogate for peripheral neurovascular status in RP." While conventional endpoints such as BCVA can't capture peripheral progression, they argued that "the CNZ area emerges as a promising, objective candidate for patient stratification and efficacy assessment in upcoming gene- and cell-based therapies."