Descemet Rejection Index: Novel Index for Diagnosis of Corneal Graft Rejection
Narrative Responses:
Purpose
To evaluate the use of Descemet’s rejection index (DRI) in the diagnosis of corneal graft rejection.
Methods
Seventy-one eyes; 27 functional grafts, 9 actively rejecting grafts, 9 rejected grafts, 7 failed grafts secondary to non-immunological causes and 19 age-matched control eyes were imaged using spectral domain optical coherence tomography. Descemet’s membrane thickness (DMT) and host central corneal thicknesses (CCT) were measured. Descemet’s rejection index (DRI) was formulated to isolate the intrinsic thickening of Descemet’s membrane from the generalized thickening of the whole cornea and was computed as DMT divided by CCT multiplied by a constant. This constant was chosen to be 33 so that the mean DRI of the age matched control group equates to 1.
Results
DRI of functional grafts showed no statistically significant difference from DRI of the control group (1.09 vs. 1; P=0.06). In actively rejecting grafts, DRI was significantly higher than in functional grafts (1.7 vs. 1.09; P<0.001). Rejected grafts showed significantly higher DRI than functional and actively rejecting grafts (1.95; P<0.001 and P=0.02, respectively). Despite that CCT of rejected grafts and grafts failed secondary to non-immunological causes were not significantly different (P=0.4), DRI showed a highly significant difference between the two groups (1.95 vs. 1.04; P<0.001).
Conclusion
Descemet’s membrane undergoes thickening in corneal graft rejection that can be quantified using DRI. DRI can detect active rejection and differentiate between rejection and failure secondary to non-immunological causes. Evaluating the use of DRI to detect subclinical active rejection and response to treatment for rejection reversal is warranted.