Optical Coherence Tomography Combined With Videokeratography to Differentiate Mild Keratoconus Subtypes

PURPOSE: To develop parameters using a combination of optical coherence tomography (OCT) and videokeratography to detect early keratoconus.METHODS: Videokeratography, wavefront analysis, and measured OCT indices were performed on 180 normal eyes, 46 eyes with moderate keratoconus, 54 eyes with early keratoconus, 7 eyes with forme fruste keratoconus, and 16 eyes with keratoconus suspect to determine the most sensitive parameters for separating these groups.RESULTS: A combination of videokeratography and OCT indices (inferior-superior [I-S] value and minimum pachymetry) was statistically the most significant in separating the keratoconus groups from normal eyes (P < .001). Using a newly derived index, the minimum pachymetry divided by the I-S value (pachymetry/asymmetry [PA]/I-S index) with a cut-off of 100, 100% of early and forme fruste keratoconus could be identified as being abnormal with 7 normals misclassified (misclassification rate 2.7%). By adding keratoconus suspect to the analysis and an I-S value of 1.2 as a cut-off point, 5 suspects were classified as normal and 11 normals as abnormal (misclassification rate 7.8%). the PA/I-S index, with a cut-off point of 100, reduced this misclassification rate to 4.4%.CONCLUSIONS: These results suggest that OCT combined with videokeratography may be more useful for differentiating mild forms of keratoconus than videokeratography alone.National Eye Institutes of HealthSkirball Foundation for Molecular Ophthalmology, Los Angeles, CaliforniaEye Defects Research Foundation Inc., Beverly Hills, CaliforniaCornea Genet Eye Inst, Beverly Hills, CA USACedars Sinai Med Ctr, Regenerat Med Inst, Los Angeles, CA 90048 USAHarbor UCLA Med Ctr, Los Angeles BioMed Res Inst, Inst Translat Genom & Populat Sci, Torrance, CA 90509 USAUniv Calif Los Angeles, Jules Stein Eye Inst, Los Angeles, CA 90024 USAInst Olhos Renato Ambrosio, Rio de Janeiro, BrazilUniv São Paulo, UNIFESP, São Paulo, BrazilUniv São Paulo, UNIFESP, São Paulo, BrazilNational Eye Institutes of Health: NEI-RO1-09052Web of Scienc