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Observational Study
. 2017 Apr;65(4):305-310.
doi: 10.4103/ijo.IJO_690_16.

Effect of post crosslinking haze on the repeatability of Scheimpflug-based and slit-scanning imaging devices

Rohit Shetty  1 , Aarti Agrawal  1 , Rashmi Deshmukh  1 , Luci Kaweri  1 , Harsha L Rao  1 , Harsha Nagaraja  1 , Chaitra Jayadev  1
Affiliations
Observational Study

Effect of post crosslinking haze on the repeatability of Scheimpflug-based and slit-scanning imaging devices

Rohit Shetty et al. Indian J Ophthalmol. 2017 Apr.

Abstract

Purpose: The aim of this study was to analyze the effect of postcollagen crosslinking (CXL) haze on the measurement and repeatability of pachymetry and mean keratometry (Km) of four corneal topographers.

Materials and methods: Sixty eyes of sixty patients with progressive keratoconus who had undergone accelerated CXL (ACXL) underwent imaging with a scanning slit imaging device (Orbscan II) and three Scheimpflug imaging devices (Pentacam HR, Sirius, and Galilei). Post-ACXL haze was measured using the densitometry software on the Pentacam HR. Readings of the thinnest corneal thickness (TCT) and Km from three scans of each device were analyzed. Effect of haze on the repeatability of TCT and Km measurements was evaluated using regression models. Repeatability was assessed by coefficient of variation.

Results: Corneal densitometry in different zones affected the repeatability of TCT measurement of Orbscan (P < 0.05) significantly but not the repeatability of TCT with Pentacam HR and Sirius (P = 0.03 and 0.05, respectively). Km values were affected by haze when measured with the Pentacam HR (P < 0.05). The repeatability of Km readings for all devices was unaffected by haze. In the anterior 0-2 mm and 2-6 mm zone, TCT (P = 0.43 and 0.45, respectively), Km values (P = 0.4 and 0.6, respectively), repeatability of TCT (P = 0.1 in both zones), and Km (P = 0.5 and 0.1, respectively) with Galilei were found to be the most reliable.

Conclusion: Galilei measurements appear to be least affected by post-ACXL haze when compared with other devices. Hence, topography measurements in the presence of haze need to be interpreted with caution.

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Conflict of interest statement

There are no conflicts of interest.

Figures

Figure 1
Figure 1
(a) Cornea divided into four zones from center to periphery. (b) Cornea divided into 3 zones from anterior to posterior
Figure 2
Figure 2
Measurement of haze using the corneal densitometry software on Pentacam
See this image and copyright information in PMC

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