Classification criteria for keratoconus evaluation using data from anterior and posterior corneal surfaces: local index

Abstract

Purpose: Propose a complementary classification method, named LOTH criteria, that includes datafrom the posterior corneal surface reported by an Orbscan II, which, in conjunction with the experience of the ophthalmologist, allows for the classification of normal, suspected KC, and KC eyes, with better discernment that allows reducing the number of erroneous diagnoses, that is, reducing the number of false negatives and false positives obtained from the KISA% Index.

Methods: We performed a prospective, comparative, cross-sectional study of a group of 102 eyes from 51 volunteers; all volunteers were born in the central region of Mexico. Topographic data were used in our proposal to classify them based on descriptors supported by the experience of an ophthalmologist, a member of our team. Additionally, to compare the classifications, an external optometrist, with expertise in corneal ectasia, reviewed our database and diagnosed the 102 eyes: 51 with confirmed KC, 12 with suspected KC, and 39 with normal eyes.

Results: When comparing the results of our proposed LOTH criteria with the KISA% Index and with clinical diagnosis in our sample population, we found that the LOTH criteria contributed to the classification of the KISA% Index, reducing the detection of false positives in 2.9% and the detection of false negatives in 7.8%.

Conclusion: The LOTH criteria based on clinical experiences provide a new approach to classify suspected, healthy, and KC eyes. This means that including the posterior surface of the cornea provides further information that should be considered to reduce false positive and false negative records of the KISA% Index, which would impact health systems.