Abstract
Purpose :
To assess the correlation between macular function and morphology in patients with ABCA4-related retinal degenerations (ABCA4-RD).
Methods :
Thirty-three patients with ABCA4-RD were enrolled in this retrospective case series. The diagnosis of ABCA4-RD was clinically established and confirmed, in all cases, by genetic testing. Examination protocol included visual acuity (BCVA) measurement, indirect ophthalmoscopy, optical coherence tomography (OCT) and focal electroretinogram (FERG) from the central 18 degrees according to a published protocol (Falsini et al., IOVS, 2000). Photoreceptors loss was estimated by measuring the linear extension of the interruption of photoreceptors inner/outer segments (IS/OS) junction. Macular thickness (MT) and foveal thickness (FT) were calculated by OCT software as the mean retinal thickness in two circular areas, centered at the fovea, of 6 and 1 mm of diameter respectively. Twenty age-matched healthy patients were also enrolled and served as controls for FERG.
Results :
FERG amplitude was significantly reduced in patients with ABCA4-RD compared with controls (p<0.0001). FERG amplitude alterations had a diagnostic accuracy of 100% to detect ABCA4-RD as showed by ROC analysis (area under the curve 1.0). FERG was reduced in all patients with ABCA4-RD while four patients (12%), due to foveal sparing, had a good visual acuity despite an extensive interruption of IS/OS junction. A significant correlation was found between FERG amplitude and IS/OS interruption (R2=0.41,p=0.0009) and MT (R2=0.16,p=0.02) but not with FT (R2=0.003, p=0.76). BCVA showed only a weak negative relationship with FT (R2=0.12, p=0.04).
Conclusions :
FERG amplitude is significantly reduced in patients with ABCA4-RD and FERG alterations may be helpful in the diagnosis of ABCA4-RD. Morphology/FERG relationship may be useful to estimate the degree of either foveal or peri-foveal photoreceptor dysfunction/loss. VA alterations weakly reflect the anatomical impairment of foveal photoreceptors.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.