Comparison of en-face Optical Coherence Tomography and Fundus Autofluorescence for assessment of macular lesion area in Stargardt disease

Abstract

Purpose : This study compared the macular lesion area in Retinal Pigmented Epithelium (RPE), computed by an automatic algorithm (sub-RPE slab) from en-face Spectral Domain Optical Coherence Tomography (SD-OCT), with the fundus lesion area, assessed by Fundus Autofluorescence (FAF) imaging, in Stargardt disease (STGD1). Moreover, the progression of RPE lesion area was estimated over a multi-year follow-up in a large STGD1 patient cohort.

Methods : We reviewed the medical records of STGD1 patients with mutations in ABCA4 gene, who underwent best-corrected visual acuity (BCVA), fundus photography, FAF, SD-OCT, and full-field electroretinography. Linear models based on GEE were fitted in order to evaluate the disease progression over a multi-year follow-up. BCVA values were converted in LogMAR for statistical analysis. The data are presented as mean ± standard error of mean. The study adhered to the tenets of the Declaration of Helsinki and received approval by the Local Ethics Committee. Moreover, each patient gave written informed consent.

Results : We analyzed a subgroup of 25 patients (13 females; aged: 37.1 ± 2.8 years), undergoing both OCT and FAF imaging, to evaluate the correlation between the two parameters. The linear regression model showed a significant correlations between the two parameters (β=0.843; p-value <0.001; R²=0.947).
To assess the annual rate of disease progression, a cohort of 101 patients (aged: 30.0 ± 1.4 years), followed up for a mean time of 3.1 ± 0.1 years, was analyzed. Mean BCVA was 20/100 ± 20/1000 for both eyes. The mean RPE lesion area, measured by OCT, was 2.97 ± 0.39 mm², in right eyes, and 3.16 ± 0.42 mm², in left eyes. Furthermore, RPE lesion area was significantly correlated with BCVA (β=0.61, p=0.045). The longitudinal analysis revealed a significant enlargement of RPE lesion area at a mean linear rate of 0.146 mm²/year (p=0.021). Finally, the BCVA significantly worsened at a mean rate of 0.065 logMar (≈3 ETDRS letters) / year (p<0.001).

Conclusions : The current study describes, for the first time in literature, a longitudinal analysis of the macular lesion area assessed by SD-OCT in a STGD1 disease cohort, showing a significant progression over the follow-up. Our findings suggest that the evaluation of lesion area by SD-OCT could be a useful measurement of disease progression, in particular to design future clinical trials.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.