In Vivo Confocal Microscopy Demonstrates Increased Immune Cell Densities in the Endothelial and Subbasal Layers During Corneal Graft Rejection that Correlate with Clinical Signs and Symptoms of Rejection

Abstract

Purpose : Corneal allograft rejection remains the leading cause of penetrating keratoplasty (PK) failure. Diagnosis of graft rejection is based on patient symptoms and on clinical signs by the slit-lamp biomicroscopy. The purpose of this study is to investigate whether laser in vivo confocal microscopy (IVCM) can aid in the diagnosis of corneal graft rejection by detecting cellular corneal changes that take place after transplantation.

Methods : A prospective, cross-sectional study was performed in 38 eyes of 38 patients with PK (15 eyes with corneal rejection and 23 without rejection) and 11 age-matched normal controls. Laser IVCM with the Heidelberg Retinal Tomograph 3/Rostock Cornea Module was performed in the corneal grafts centrally. The density of immune cells (IC) was assessed by ImageJ software for the epithelial, subepithelial, stromal and endothelial layers by two masked observers. Comparison of IC distribution among different groups was performed using Student’s t-test and analysis of variance (ANOVA).

Results : The IC density was significantly different between rejected and non-rejected grafts (P=0.004) as well as compared to normal controls (p=0.001). Among corneal sublayers, the IC density was significantly higher in rejected grafts compared to non-rejected grafts in only subbasal (611.54±573.74 vs. 340.61±268.60 cells/mm2;p=0.049) and endothelial layers (250.62±267.13 vs. 103.47±81.91; p=0.001). Patients with decreased BCVA, Khodadoust line and anterior chamber cells demonstrated a significant increase in total IC density (p<0.05) whereas patients with symptoms of irritation, light sensitivity, and pain revealed a specific increase in IC density in the subbasal layer (p<0.05).

Conclusions : Patients with corneal graft rejection demonstrate a significant increase in corneal IC as compared to patients with non-rejected grafts and controls by IVCM, which is specifically increased in the subbasal and endothelial layers. While symptoms associated with endothelial rejection demonstrate a general increase in IC, pain, irritation and light sensitivity are associated with increased IC in the subbasal layer. Assessment of patients with corneal graft rejection by IVCM may serve as an adjunctive tool in the diagnosis and management of corneal graft rejection.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.