Optic disc imaging with spectral-domain optical coherence tomography: Variability and agreement study with heidelberg retinal tomograph

Abstract

Objective: To evaluate the agreement of optic disc measurements obtained with the Cirrus high-density optical coherence tomography (HD-OCT) and the Heidelberg retina tomograph (HRT) and compare the intervisit, test-retest variability between the instruments. Design: Prospective, cross-sectional study. Participants: Two hundred seven subjects (109 glaucoma and 98 normal subjects). Methods: One eye from each individual was selected randomly for optic disc imaging by the Cirrus HD-OCT and the HRT. Areas of the optic disc and the cup, cup volume, vertical cup-to-disc ratio and cup-to-disc area ratio were compared between the instruments. The OCT measurements were corrected for ocular magnification using the Littman's formula. The measurement agreement was evaluated with the Bland-Altman plots. The intervisit test-retest variability was examined in 17 randomly selected glaucoma patients who underwent optic disc imaging weekly for 8 consecutive weeks. The intraclass correlation coefficients (ICC) and the reproducibility coefficients of the optic disc parameters were computed. Main Outcome Measures: Measurement agreement, reproducibility coefficients, and ICCs of optic disc parameters. Results: The OCT measured smaller optic disc and rim areas and greater cup volume, vertical cup-to-disc ratio and cup-to-disc area ratio than the HRT did (all with P<0.001). There were proportional biases in the Bland-Altman plots between OCT and HRT optic disc measurements except for rim area and cup-to-disc area ratio. The 95% limits of agreement of rim area ranged between -0.28 and 0.88 mm before, and between -0.22 and 0.92 mm after correction for ocular magnification. Both OCT and HRT showed high test-retest reproducibility with ICCs <0.921. Although the reproducibility coefficient of OCT rim area (0.093 mm ; 95% confidence interval [CI], 0.081-0.105 mm ) was significantly smaller than that of the HRT (0.186 mm ; 95% CI, 0.163-0.210 mm ; P =.018), there were no differences in the ICCs between the instruments. Conclusions: Optic disc assessment by spectral-domain OCT and confocal scanning laser ophthalmoscopy demonstrates poor agreement but similarly low test-retest variability. The source of their disagreement and its effects on the detection of progression require further study. Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references. © 2012 American Academy of Ophthalmology. 2 2 2 2 2 2