ABSTRACT
Objective To compare the dry-eye features of normal cornea and keratoconus at different stages using non-invasive dry-eye integrated analyzer (Keratograph) and it clinical significance.Methods A case-control study was conducted in 35 patients (44 eyes) with keratoconus who were treated in our hospital from May 2015 to December 2016 as keratoconus group and 45 patients (45 eyes) who received laser corneal refractive surgery as normal cornea group;and subjects in the keratoconus group were subgrouped into mild group (19 eyes),moderate group (15 eyes) and severe group (10 eyes) according to Amsler-Krumeich grading method.The first tear break-up time (first BUT),mean BUT,tear meniscus height (TMH) and conjunctival hyperemia scoring (CHS) of the both eyes in all groups were measured by Keratograph,and the diagnostic values of these variables for keratoconus at different stages were analyzed by ROC curve.Results The levels of horizontal central curvature,vertical center curvature,surface variation index,keratoconus index,posterior corneal surface height and CHS of the keratoconus group were higher than those of the normal cornea,and the difference were statistically significant (all P ＜ 0.05).The non-invasive first BUT,mean BUT and TMH in the keratoconus group were significantly lower than those of the normal cornea group,approaching significant difference (all P ＜ 0.05).The differences in horizontal central curvature,vertical center curvature,surface variation index,keratoconus index,posterior corneal surface height,first BUT and mean BUT among subgroups of keratoconus patients had statistically significance (all P ＜ 0.05).The first BUT and mean BUT in the moderate and severe group were lower than those in the mild group,the difference was statistically significant (all P ＜ 0.05),but there was no significant difference between the moderate and severe group (all P ＞ 0.05).In addition,the mean BUT was negatively correlated with horizontal central curvature,vertical center curvature,surface variation index,keratoconus index and posterior corneal surface height,but had no significant correlation with TMH and CHS (all P ＞ 0.05).ROC curve analysis showed that keratoconus index had the highest diagnostic value for keratoconus than other variables (AUC =0.790,95％ CI:0.689-0.892;P ＜ 0.001).Conclusion The Keratograph dry-eye analyzer can effectively measure the dry-eye parameters of the cornea and the mean BUT in the measurement parameters is the most valuable for the diagnosis of keratoconus,and it is more meaningful for the diagnosis of mild keratoconus.