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Giovanni Gregori, Carlos Alexandre Garcia Filho, Zohar Yehoshua, Renata Portella Nunes, William Feuer, Srinivas Sadda, Philip Rosenfeld; Measuring drusen over time: OCT vs. Fundus Photography. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5839.
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© ARVO (1962-2015); The Authors (2016-present)
To compare measurements of drusen area from digital color fundus photography and optical coherence tomography (SDOCT) prospectively in a population of patients with non-exudative age-related macular degeneration (AMD).
Patients with drusen with an SDOCT volume of at least 0.03 mm3 in the absence of geographic atrophy were recruited into a prospective study. Digital color fundus images (CFIs) and SDOCT images (CirrusTM HD-OCT, Carl Zeiss Meditec Inc., Dublin, CA), were obtained at baseline and at follow-up visits at months 3, 6, 9, and 12. CFIs were registered to the corresponding OCT datasets using the OCT Fundus Images and an automated registration algorithm. Matched circles centered on the fovea with diameters of 3 mm and 5 mm were identified on both the CFIs and the SDOCT images. SDOCT drusen measurements within the circles were obtained using a proprietary algorithm. Experienced graders at the Doheny Image Reading Center (DIRC) manually traced drusen boundaries on color fundus images. Based on our previous work showing that the square root of drusen area is a better parameter for statistical analysis than the actual drusen area, results are reported in terms of the square root of the drusen area (SQDA).
Thirty patients were enrolled and 42 eyes met inclusion criteria. The SDOCT mean SQDA in the central 3 mm was 1.451 mm at baseline and 1.464 mm at 26 weeks. The CFIs mean SQDA in the central 3 mm was 1.555 mm at baseline and 1.583 mm at 26 weeks. The differences between SDOCT and CFI measurements are statistically significant (p=0.004 at baseline, p=0.003 at 26 weeks). Excluding two eyes with very pronounced drusen loss, both modalities showed a statistically significant mean growth in SQDA over 26 weeks. The difference between the changes in SQDA over 26 weeks measured with SDOCT and CFI was not significantly different from 0 (mean 0.014 mm, p=0.5).
The SDOCT drusen area measurements are more reproducible and systematically smaller than the ones obtained from digital fundus photography. However, when considering the changes in drusen area over time, we found no bias between the two modalities. While SDOCT measurements differ somewhat from the classical interpretation of drusen area, our results support the conclusion that the results are similar and both approaches are very useful for studying drusen dynamics.
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