Subclinical keratoconus detection with three-dimensional (3-D) morphogeometric and volumetric analysis

Ibrahim Toprak; Francisco Cavas; José S Velázquez; Jorge L Alio Del Barrio; Jorge L Alio

doi:10.1111/aos.14433

Subclinical keratoconus detection with three-dimensional (3-D) morphogeometric and volumetric analysis

Acta Ophthalmol. 2020 Dec;98(8):e933-e942. doi: 10.1111/aos.14433. Epub 2020 May 15.

Authors

Ibrahim Toprak^{1

2}, Francisco Cavas³, José S Velázquez³, Jorge L Alio Del Barrio^{1

4

5}, Jorge L Alio^{1

4

5}

Affiliations

¹ Department of Research and Development, VISSUM, Alicante, Spain.
² Department of Ophthalmology, Faculty of Medicine, Pamukkale University, Denizli, Turkey.
³ Department of Structures, Construction and Graphical Expression, Technical University of Cartagena, Cartagena, Spain.
⁴ Cornea, Cataract and Refractive Surgery Department, VISSUM, Alicante, Spain.
⁵ Division of Ophthalmology, Department of Pathology and Surgery, Faculty of Medicine, Miguel Hernández University, Alicante, Spain.

PMID: 32410342
DOI: 10.1111/aos.14433

Abstract

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.

Keywords: corneal dystrophy; corneal model; corneal volume; keratoconus; keratoconus diagnosis; subclinical keratoconus; topography.

MeSH terms

Adult
Cornea / diagnostic imaging*
Corneal Pachymetry / methods*
Corneal Topography / methods*
Cross-Sectional Studies
Female
Humans
Imaging, Three-Dimensional / methods*
Keratoconus / diagnosis*
Male
Organ Size
ROC Curve

Grants and funding

RD16/0008/0012/Instituto de Salud Carlos III