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Subclinical keratoconus detection with three‐dimensional (3‐D) morphogeometric and volumetric analysis
Author(s) -
Toprak Ibrahim,
Cavas Francisco,
Velázquez José S.,
Alio del Barrio Jorge L.,
Alio Jorge L.
Publication year - 2020
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/aos.14433
Subject(s) - keratoconus , subclinical infection , ophthalmology , medicine , sagittal plane , cornea , corneal topography , mathematics , nuclear medicine , anatomy
Purpose To assess the efficacy of morphogeometric and volumetric characterization of the cornea based on three‐dimensional (3‐D) modelling in diagnosis of subclinical keratoconus (KC). Methods Cross‐sectional study. Ninety‐three eyes with subclinical KC with a best spectacle‐corrected distance visual acuity ≥20/20 (grade zero KC according to the RETICS classification) and 109 control eyes were included. Computer‐based 3‐D corneal morphogeometric model was generated using raw topographic data. Distance‐, area‐ and volume‐based parameters were used for statistical analysis. Distance parameters included deviation of anterior (D apexant )/posterior (D apexpost ) apices and minimum thickness points (D mctant , D mctpost ) from corneal vertex, and D apexant ‐D apexpost difference. Areal variables were derived from anterior (A ant ) and posterior (A post ) corneal surfaces, sagittal plane passing through corneal apices (A apexant , A apexpost ) and thinnest point (A mctant , A mctpost ). Total corneal volume (V total ) and volumetric distribution (with 0.1mm steps) centred to thinnest corneal point (VOL mct ) and anterior (VOL aap )/posterior (VOL pap ) apices comprised the volume‐based parameters. Results In the subclinical KC group , all D values, D apexant ‐D apexpost difference, A ant , A post and A apexant values were higher (p < 0.001), while A apexpost , A mctpost , V total , VOL mct , VOL aap and VOL pap values were lower when compared to the control group (p < 0.001). Regression analysis‐based formula correctly classified 96.8% of the eyes with subclinical KC and 94.5% of the normal ones (p < 0.0001). Conclusions Eyes with subclinical KC seem to represent asymmetrically displaced anterior and posterior corneal apex, corneal thinning and volume loss. 3‐D morphogeometric and volumetric parameters and differentiation formula can be incorporated into topography software to detect subclinical KC with high sensitivity and specificity in clinical practice.