Rod and Cone function and its relationship to OCT sub structural changes in Age-related Macular degeneration

Abstract

 

Purpose

 

To better understand structure and functional relationships in early AMD. In this abstract, we analyze the optical coherence tomography (OCT) features of early AMD and correlate these findings with cone and rod function as measured by microperimetry.

 

Methods

 

Clinical and imaging data were collected from patients with dry AMD undergoing Spectral domain OCT and dark adapted microperimetry ( cone and rod function on Nidek MP1-s) and scotopic microperimetry (cone function MAIA microperimeter) . Custom image analysis software (OCTOR) was used for quantitative analysis segmentation of the retinal substructure . Retinal spaces quantified included retina, photoreceptor outer segments, RPE to choriocapillaris (i.e. drusen/PED). Segmented enface images were overlaid onto the microperimetry maps and descriptive data generated.

 

Results

 

12 patients underwent MPIS, MAIA and high density spectralis OCT. A subset of these patients underwent segmentation of the retinal layers and overlay of retinal sensitivity maps. The following regions were found to have relationship between functional deficit on testing and structural abnormalities. Ellipsoid zone and RPE to choriocapillaris thickness (drusen height). Area of normal values of RPE to choriocapillaris thickness (ie no confluent drusen or drusenoid PED) was associated with a median retinal sensitivity of 12.7dB (quartiles : 11dB, 14dB). The median retinal sensitivities were 7.4dB (quartiles: 7dB, 9dB) for sub RPE drusen.

 

Conclusions

 

Sub retinal drusen deposits is associated with reduced retinal sensitivities. Understanding structural markers that relate to rod and cone functional defecits amy help to better understand subtypes of early AMD and help develop novel clinical trial endpoints

 

 

Microperimetry (MP1S) functional map overlaid onto segmented OCT enface map illustrating RPE to choriocapillaris thickness (i.e. drusen/PED) . Pseudocolor map within the ETDRS zone represents thickness values. This shows reduced sensitivity in areas of significant drusen deposition.

 

Keywords: 412 age-related macular degeneration • 550 imaging/image analysis: clinical • 585 macula/fovea