Clinical Ophthalmology (Dec 2023)

Scheimpflug-Derived Keratometric, Pachymetric and Pachymetric Progression Indices in the Diagnosis of Keratoconus: A Systematic Review and Meta-Analysis

  • Owusu S,
  • Zaabaar E,
  • Kwarteng MA,
  • Ankamah S,
  • Abowine JBV,
  • Kyei S

Journal volume & issue
Vol. Volume 17
pp. 3941 – 3964

Abstract

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Sandra Owusu,1 Ebenezer Zaabaar,1,2 Michael Agyemang Kwarteng,3,4 Samuel Ankamah,5 John Baptist Vianney Abowine,6 Samuel Kyei1,7 1Department of Optometry and Vision Science, University of Cape Coast, Cape Coast, Ghana; 2Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong; 3Department of Optometry, Bindura University of Science Education, Bindura, Zimbabwe; 4Discipline of Optometry, University of Kwazulu-Natal, Durban, South Africa; 5University of Ghana Library System, University of Ghana, Accra, Ghana; 6Dr. Rose Mompi Eye Hospital, Hohoe, Ghana; 7Biomedical and Clinical Research Center, University of Cape Coast, Cape Coast, GhanaCorrespondence: Samuel Kyei, Email [email protected]: Scheimpflug Pentacam Tomography is becoming crucial in the diagnosis and monitoring of keratoconus, as well as in pre- and post-corneal refractive care, but there are still some inconsistencies surrounding its evidence base diagnostic outcome. Therefore, this study aimed at employing meta-analysis to systematically evaluate the keratometric, pachymetric, and pachymetric progression indices used in the diagnosis of Keratoconus. The review protocol was registered with PROSPERO (Identifier: CRD4202310058) and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. PubMed, MEDLINE, Web of Science, and EMBASE were used for data search, followed by a quality appraisal of the included studies using the revised tool for the quality assessment of diagnostic accuracy studies (QUADAS-2). Meta-analysis was conducted using the meta (6.5.0) and metafor (4.2.0) packages in R version 4.3.0, as well as Stata. A total of 32 studies were included in the analysis. All keratometry (K) readings (flattest meridian, K1; steepest meridian, K2, maximum, Kmax) were significantly steeper in keratoconic compared to normal eyes: [MD (95% CI)], K1 [2.67 (1.81; 3.52)], K1-back [− 0.71 (− 1.03; − 0.39)], K1-front [4.06 (2.48; 5.63)], K2 [4.32 (2.89; 5.75)], K2-back [− 1.25 (− 1.68; − 0.82)], K2-front [4.82 (1.88; 7.76)], Kmax [7.57 (4.80; 10.34)], and Kmean [2.80 (1.13; 4.47)]. Additionally, corneal thickness at the center, CCT [− 61.19 (− 73.79; − 48.60)] and apex, pachy-apex [− 41.86 (− 72.64; − 11.08)] were significantly thinner in keratoconic eyes compared to normal eyes. The pooled estimates for pachymetric progression index (PPI): PPImin [0.66 (0.43; 0.90)], PPImax [1.26 (0.87; 1.64)], PPIavg [0.90 (0.68; 1.12)], and Ambrosio relational thickness (ART): ARTmax [− 242.77 (− 288.86; − 196.69)], and ARTavg [− 251.08 (− 308.76; − 195.39)] revealed significantly more rapid pachymetric progression in keratoconic eyes than in normal eyes. The Pentacam Scheimpflug-derived keratometric, pachymetric, and pachymetric progression indices are good predictors in discriminating KC from normal eyes.Keywords: corneal topography, keratometric readings, central corneal thickness, keratoconus, pachymetric progression

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