# Discrepancies Between Autofluorescence Imaging Modalities in CNGB3-Associated Achromatopsia and Correlation With Ellipsoid Zone Continuity

## TL;DR

This study compares two autofluorescence imaging methods in a rare eye condition and finds differences in results that correlate with age and retinal structure.

## Contribution

The study reveals discrepancies between blue and green FAF imaging in CNGB3-associated achromatopsia and links these to ellipsoid zone continuity and patient age.

## Key findings

- Discordance between blue and green FAF occurred in 27% of patients, all younger individuals.
- Patients with continuous ellipsoid zones showed FAF discordance, while those with interrupted zones did not.
- FAF platforms are not interchangeable, which has implications for study design in this condition.

## Abstract

To explore discrepancies on fundus autofluorescence (FAF) obtained with two widely used devices in patients with CNGB3-associated achromatopsia, with respect to the central foveal signal. Secondly, to explore continuity of the foveal ellipsoid zone (EZ) in these patients.

Patients who had undergone blue (488 nm; Heidelberg Spectralis) and green (532 nm; Optos) FAF imaging during the same visit were included. The central foveal signal was graded qualitatively as brighter or darker compared to the wider foveal/parafoveal region. Optical coherence tomography images from the same visit were also graded (masked to FAF grading) with respect to foveal EZ continuity.

Forty-one patients (24 females; mean age, 32 ± 19 years) were included. For blue FAF, the central foveal signal was graded darker in all cases. For green FAF, the central fovea was brighter in 11 patients (27%), indicating discordance with blue FAF. The discordant group were significantly younger (P = 0.022). The EZ line was gradable in 40 patients: 22 (55%) had continuous foveal EZ in both eyes; these were younger than those with an interrupted EZ in one or both eyes (P < 0.0001). All patients discordant for FAF images had continuous foveal EZ.

Discordance occurred between the FAF modalities in more than one-quarter of patients; these patients were significantly younger, and all had a continuous EZ line. Investigating mechanisms of discordance could yield pathophysiological insights.

FAF platforms are not interchangeable; these findings could inform the design of natural history studies and therapeutic trials for this condition.