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Rohit Shetty, Rajesh Sasikumar, Harsha Nagaraju, Koushik R. Sargod, Bhujang K. Shetty; Agreement in Measuring Depth of Demarcation Line after Corneal Collagen Cross-Linking using Invivo Confocal Microscopy and Anterior Segment Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4207.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the depth of the stromal demarcation line in vivo after corneal collagen cross-linking (CXL) in Asian Indian eyes with kertatoconus using in vivo confocal microscopy (IVCM) and anterior segment optical coherence tomography (ASOCT).
In this prospective observational study, consecutive patients with keratoconus who underwent CXL were examined with a slit lamp and imaged using IVCM (Heidelberg Retina Tomograph II; Heidelberg, Germany) and ASOCT (Source swept Fourier domain OCT; Tomey, Japan) at one week and 3 months after the procecure. Demarcation line was defined on IVCM as increased density of hyper-refractile extracelluar matrix and on ASOCT as a hyper-reflective stromal line. Bland Altman (BA) plots were used to determine agreement in measurements between the two devices.
Twenty-three eyes (15 subjects) with keratoconus were evaluated; the demaraction line was seen in all eyes using IVCM and ASOCT at week 1 after CXL, but only in 18/23 (78.3%) eyes on slit lamp. At 3 months follow-up, the line was seen in 69.5% using IVCM, 65.3% eyes using ASOCT, and in only 30.4% eyes on slit lamp. The mean depth of the line measured using IVCM was 320.3 µ (95% C.I, 301.8-338.8) and 294.7 µ ( 95% C.I, 277.8-311.5) and with ASOCT at 3 months follow-up. The BA plots demonstrated a systematic difference between the two devices, with the ASOCT underestimating the depth of the line when compared to IVCM (95% limits of agreement, -90.5 to 39.2).
Although both IVCM and ASOCT appear adept at demonstrating the demarcation line following CXL, differences in depth measurement obtained from the devices indicate that these measurements cannot be used interchangeably.
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