Comparison of Javal-Schiøtz keratometer, Orbscan IIz and Pentacam topographers in evaluating anterior corneal topography

Turner, Jennifer, Purslow, Christine and Murphy, Paul J 2023. Comparison of Javal-Schiøtz keratometer, Orbscan IIz and Pentacam topographers in evaluating anterior corneal topography. Clinical and Experimental Optometry 106 (5) , pp. 476-483. 10.1080/08164622.2022.2067470

Full text not available from this repository.

Abstract

ABSTRACT Clinical relevance: Inter-instrument variation in anterior corneal shape (ACS) measurement has a consequence for ocular clinical practice. Background: To consider inter-instrument variability in keratometry measurements across the ACS and to explore instrument protocols for determining ACS keratometric analogues (KAs). Methods: Mean keratometry/KAs of the right eye were recorded using Javal-Schiøtz keratometer (J- S), Orbscan IIz and Pentacam from 124 subjects (78 females; mean ± SD age: 24.71 ± 6.61 years). Mean radii of curvature were obtained for 1-mm wide annular zones extending up to 6 mm (horizontally) and 4 mm (vertically) from the apex for Orbscan and Pentacam. Zonal mean radius of curvature was calculated by averaging keratometry values for all measured points within the zone. Results: KA (mean ± SD): Horizontal: Orbscan (7.80 ± 0.31 mm) and J-S (7.82 ± 0.29 mm) were not significantly different (p = 0.072). Pentacam (7.86 ± 0.29 mm) was significantly flatter than J-S (p < 0.001) and Orbscan (p < 0.001). Vertical: Orbscan (7.64 ± 0.31 mm) was significantly steeper than J-S (7.67 ± 0.29 mm, p < 0.005) and Pentacam (7.70 ± 0.29 mm, p < 0.001). Pentacam was significantly flatter than J-S (p < 0.001) and significant flatter than Orbscan across the entire profile (1-4 mm zones horizontal and vertical, p < 0.001). LoAs (CI): J-S/Orbscan: ±0.75 mm (0.05–0.18); J-S/Pentacam: ±0.72 mm (0.01–0.12); Pentacam/ Orbscan: ±0.16 mm (0.04–0.08). There was a +0.03 mm positive bias for Orbscan compared to J-S, +0.06 mm positive bias for Orbscan compared to Pentacam and −0.03 mm negative bias for Pentacam compared to J-S. Conclusions: Algorithms used by Orbscan and Pentacam to solve the peripheral paraxial ray problem produce significantly different KAs. Instrument-specific KAs cannot be used inter-changeably between instruments. Differences in KA between instruments are not significant for ocular surgery, but may influence rigid contact lens fitting. Pentacam measures flatter than Orbscan and J-S

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Optometry and Vision Sciences
Subjects:	R Medicine > RE Ophthalmology
Publisher:	Taylor and Francis Group
ISSN:	0816-4622
Date of First Compliant Deposit:	29 July 2025
Date of Acceptance:	8 April 2022
Last Modified:	01 Aug 2025 08:45
URI:	https://orca.cardiff.ac.uk/id/eprint/180127

Actions (repository staff only)

Edit Item