Correlation of Manually Determined Optic Cup and Disc Borders in Fundus Photographs With Anatomical Optic Nerve Head Structures in SDOCT Images

Abstract

 

Purpose:

 

To correlate the optic cup and disc determined from fundus photos with the anatomical structures visualized by spectral domain optical coherence tomography (SDOCT).

 

Methods:

 

The fundus photos of eleven eyes were correlated with the cross-sectional structures collected by our clinical video-rate SDOCT instrument by registering the fundus photos to the corresponding integrated reflectance (en-face) SDOCT maps. The optic cup and disc borders were drawn by two ophthalmologists on the fundus photos using a tablet PC. The location of the drawn borders in the cross-sectional SDOCT images were determined by axial projection.

 

Results:

 

Three eyes showed good agreement between subjective determinations of optic disc borders and the edges of the retinal pigment epithelium (RPE) (Fig. 1, top row), four showed moderate and four showed poor agreement (Fig. 1, bottom row). Fig. 1. Left column: fundus photos, black circles: manual drawings of the cup (inner circle) and disc (outer circle), green rectangle: OCT scan area. Middle column: SDOCT en-face images, blue circles: manual drawings superposed onto the SDOCT en-face images, red vertical line: position of the vertical cross-sectional SDOCT frame on the right. Right column: vertical cross-sectional SDOCT frames through the optic nerve head, red vertical lines: projections of the manual drawings (i.e. inner pair: estimated optic cup; outer pair: estimated optic disc).  

 

Conclusions:

 

The optic disc determined based on the color contrast in fundus photos does not necessarily correspond to the edges of the RPE; the optic cup correspondence remains unclear. A method based on anatomical retinal structures as clearly visualized by SDOCT might improve objectivity of cup and disc assessment.

 

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • optic disc • image processing