Calculation error of local radius of anterior surface curvature of the cornea by optical cuts as independent diagnostic characteristic of keratokonus (preliminary report)

Gridin V. N.
Doctor of Technology, Professor¹

Novikov I. A.
Senior Researcher¹; Senior Researcher, Laboratory for Fundamental Studies in Ophtalmology²

Solodovnikov V. I.
PhD, CTechSci, Laboratory Head¹

Trufanov M. I.
Associate Professor, Laboratory Head¹

Lebedev A. S.
Junior Researcher¹

Bubnova I. A.
Doctor of Medicine, Leading Researcher¹; Senior Researcher, Department for Refractive Disorders²

Borisenko T. E.
Consultant on Medical Statistics²

1 - Russian Academy of Sciences, Design Information Technologies Сenter, Odintsovo, Russia
2 - Research Institute of Eye Diseases of the Russian Academy of Sciences, Moscow, Russia

Corresponding Author: Bubnova Irina Alekseevna e-mail: bubnovai@mail.ru. Funding: Research has been supported by grant of Russian Foundation for Basic Research “Theoretical bases development for the diagnosis of keratoconus at early stage” № 18-29-02049 mk. Conflict of interest: None declared.

Purpose: to evaluate significance of calculation errors of recognition and reconstruction of the cornea shape by analyzing of optical cuts images as independent diagnostic characteristic of keratokonus. Material and methods: In research series images of transverse optical cuts of the cornea of patients with I-IV stage keratokonus (24 patients, 24 eyes – 6 cases of each stage) and patients with regular corneal astigmatism as a control group (6 patients, 6 eyes) were included. In floating window for each image local curvature of corneal surface was calculated and its error numerically characterized. For evaluation of correlation between average error of calculation the radius of curvature of the anterior corneal surface with different stages of keratokonus each optical cut of the cornea was divided into 5 broad areas. In each area pairwise comparison of the calculation error of curvature radius for I and II stage of keratokonus as well as for control group using criteria of Mann-Whitney was done. Results: It was revealed that in control group average calculation error of the radius of curvature of the anterior corneal surface significantly differs (p<0,001) from such in groups with I and II stages of keratokonus. In control group average calculation error was near to 0,5 mm while in groups with I and II stages of keratokonus it was in 0,33-0,38 mm interval. Conclusion: evaluation of calculation error of the curvature radius of the anterior corneal surface can se used for creation of highly sensitive detectors of early keratokonus as independent diagnostic characteristic.

keratokonus, keratotopography, image recognition

10.29234/2308-9113-2019-7-1-42-54

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