In vivo confocal microscopy indicates an inverse relationship between the sub- basal corneal plexus and the conjunctivalisation in patients with limbal stem cell deficiency

Background/ aims Limbal stem cell deficiency (LSCD) is characterised by a marked decrease in limbal stem cells. It is classified primarily using subjective slit- lamp observations. In vivo confocal microscopy (IVCM) can non- invasively provide objective information on the condition of the limbal niche, the corneal epithelial basal cell density and the corneal sub- basal nerve plexus density (SND). We here used IVCM to evaluate changes in SND to improve LSCD classification. Methods We evaluated and classified 38 patients (76 eyes, 44 with LSC and 32 control eyes) using the Rama, Lopez- Garcia and Deng (clinical and confocal) classifications and evaluated the concordance of the confocal and clinical classifications. We constructed a logistic regression model using multivariate analysis to correlate different degrees of conjunctivalisation with IVCM parameters and used receiver operating characteristic (ROC) curve analysis to establish the SND cut- off value with maximum diagnostic sensitivity and specificity. Results The classification systems correlated moderately at best (kappa, 0.449). The corneal SND of cases (6469 +/- 6295 mu m/ mm2) was less (p< 0.001) than in controls (20911 +/- 4142 mu m/ mm2). The SND, but not basal cell density, played a protective role against conjunctivalisation (OR, 0.069; 95% CI 0.008- 0.619; p= 0.01). An SND cut- off value of 17 215 mu m/ mm2 yielded a sensitivity and specificity of 95.5% and 90.6%, respectively, for LSCD diagnosis. Conclusion The density of the corneal sub- basal nerve plexus was inversely related to conjunctivalisation in LSCD. Further studies are needed to verify this and to elucidate the directionality between these factors.