COMPARISON OF SINGLE DRUSEN SIZE ON COLOR FUNDUS PHOTOGRAPHY AND SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY.

PURPOSE

To determine the relationship of drusen size as determined by spectral-domain optical coherence tomography (SD-OCT) with that measured on registered color fundus photography (CFP) images and to derive an OCT-based classification system that was comparable with that determined by CFP.

METHODS

Custom software was developed to register CFP images to the scanning laser ophthalmoscopy fundus images obtained simultaneously with the corresponding SD-OCT images, so that individual drusen observed on CFP could be matched with those seen on SD-OCT. Single druse size (diameter, area, volume, and height) on CFP and SD-OCT images from a phase two clinical trial was determined with the Duke OCT Retinal Analysis Program.

RESULTS

The sizes of 213 individual drusen were measured on CFP and SD-OCT. The drusen diameter measured on CFP was significantly correlated with those determined on SD-OCT (R: 0.879, P < 0.001). Based on the corresponding formula: drusen diameter on SD-OCT = 0.77 × (drusen diameter on CFP) + 50.67 µm, large drusen defined as ≥125 µm on CFP had a diameter ≥145 µm on OCT, medium drusen defined as 63 µm to 124 µm on CFP had diameters 100 µm to 144 µm on OCT, and small drusen defined as <63 µm on CFP had diameters <100 µm on OCT.

CONCLUSION

With our registration software and imaging processing algorithms, we were able to correlate individual druse sizes measured on CFP with those determined on SD-OCT. These data can be used to develop an SD-OCT-based grading scale, analogous to the CFP Age-Related Eye Disease Study drusen scale that may be useful in the clinic and in clinical trials.