Abstract
Purpose :
To characterize the status of cone photoreceptor inner segments and retinal pigment epithelial (RPE) cells in vitelliform macular dystrophy.
Methods :
Four eyes from four patients with vitelliform macular lesions and molecularly confirmed diagnoses (IMPG1, IMPG2, BEST1, and RDS) were imaged using adaptive optics (AO) along with high resolution clinical imaging. The custom-built high resolution AO multimodal imager has the capability to assess photoreceptors (IOVS 55:4244-4251, 2014) and RPE cells labeled by indocyanine green (ICG) dye (IOVS 57:4376-4384, 2016). Cone inner segments and RPE cell-to-cell spacing were quantified in areas overlying the vitelliform lesion, at the margin, and at non-lesion areas ~1o from the margin. Published normative data was used for comparison (IOVS 54:7498–7509, 2013; BOE 8:4348-4360, 2017).
Results :
Intact cone inner segments, anteriorly-displaced by vitelliform lesions, were visible in 3 of 4 eyes with increased spacing compared to normal values (p<0.05). In general, RPE cells could not be successfully imaged beneath vitelliform lesions due to blocking of the late phase AO-ICG signal. Although RPE cells exhibited the characteristic heterogeneous AO-ICG pattern outside of the lesion in all eyes, there was an increase in spacing at lesion margins. In each eye, RPE cell spacing was increased by an average of 16% (ranging from 10% to 22%) at lesion margins when compared to non-lesion areas from the same eye (p<0.05, paired t-test). Prior to expansion of a vitelliform lesion in one eye, intact cones (within or near normal spacing) were noted with enlarged RPE cells relative to the non-lesion areas (increased by 20%). Following resorption of the vitelliform material in a different eye, both cone and RPE spacing were increased (p<0.05 for both; cones, 36%, RPE, 103%).
Conclusions :
Remodeling of RPE cells occurs in the proximity of vitelliform lesions with relative preservation of cone inner segments, while vitelliform material is present. Monitoring RPE cell spacing may be an important parameter for evaluating eyes with vitelliform macular dystrophies, regardless of the genetic etiology.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.