Pointwise Structure-Function Analysis of the Ellipsoid Zone in Retinitis Pigmentosa Using an Artificial...

Area of Science:

• Ophthalmology
• Medical Imaging
• Artificial Intelligence

Background:

• Retinitis pigmentosa (RP) is a group of inherited retinal diseases that cause progressive vision loss.
• The ellipsoid zone (EZ) is a key indicator of photoreceptor health, often assessed using spectral-domain optical coherence tomography (SD-OCT).
• Understanding the structure-function relationship of the EZ is crucial for monitoring RP progression and evaluating potential therapies.

Purpose of the Study:

• To conduct a pointwise structure-function analysis of the ellipsoid zone (EZ) in retinitis pigmentosa (RP).
• To utilize an artificial intelligence (AI)-based overlay of SD-OCT and microperimetry images to investigate EZ structure-function relationships.
• To identify potential discrepancies between EZ integrity and visual function at a localized level.

Main Methods:

• A retrospective study involving patients with clinically confirmed RP.
• Overlaying same-day SD-OCT and microperimetry near-infrared images using an AI model for coarse alignment.
• Grading EZ structure at 68 microperimetry grid loci (0=not visible, 1=attenuated, 2=normal) and correlating grades with microperimetry sensitivity (dB).

Main Results:

• Analysis of 51 eyes (31 patients) revealed significant correlations between EZ grade and microperimetry sensitivity (r=0.65, P < 0.001).
• Mean sensitivity differed significantly across EZ grades (Grade 0: 6.02 dB, Grade 1: 18.36 dB, Grade 2: 20.90 dB).
• Notably, 57.5% of loci with grade 0 EZ showed some visual function (>0 dB), with 4% even having sensitivity ≥20 dB.

Conclusions:

• Pointwise analysis using AI overlay identified local EZ structure-function incongruencies in RP.
• These localized discrepancies may be missed in analyses averaging across the visual field.
• Preserved photoreceptor function in the absence of a visibly intact EZ warrants further investigation for understanding RP pathophysiology and treatment strategies.