Ultrasound Biomicroscopy Findings Related To Corneal Graft Rejection

To determine anatomical factors in Ultrasound Biomicroscopy (UBM) related to corneal graft rejection in patients with corneal opacities without anterior segment visibility

National Ophthalmology Unit of Guatemala, Cornea Department

Observational clinical case study of patients who underwent penetrating corneal transplantation and had corneal graft rejection. Indication of surgery was severe corneal opacity of different etiologies without anterior segment visibility. Preoperative UBM was performed and data from 6 months of follow-up were noted. UBM data were: peripheral, central, anterior and posterior synechiae; extent of synechia and anterior chamber depht (ACD). 
The extent of synechia were defined as broad if more than 30 grades were involved. Failure of corneal transplant was defined as irreversible loss of transparency of corneal graft. The statistical tests that were used were multivariate regression analysis and odds ratio with significance level of alfa 0.05.

Thirty-five eyes who underwent preoperative UBM were noted. Mean age was 42.5 ±18.2 years, and 71% were male. Graft rejection ocurred in 57% of cases and primary indication for surgery was previous graft rejection. 

UBM reported mean ACD of 1.66mm (±1.05), without difference between sex groups. Peripheral Anterior Synechiae (PAS) were found in 97.1% of cases, Central Synechiae (CS) in 54.3% and Posterior Synechiae (PS) in 42.9%. The extent of PAS was broad in 68.6% of cases. In both univariate and multivariate analyses, the presence of broad PAS was significantly associated with corneal graft rejection (odds ratio [OR], 6.48; 95% confidence interval [CI], 1.32–31.83; P < .05).  No association was found between CS or PS and graft rejection.

Ultrasound Biomicroscopy (UBM) is a valuable modality in assesing risk of corneal graft rejection in selected cases where corneal opacity is severe or conjuctival tissue precludes adequate visualization of the anterior segment. There is particularly a strong association with extensive peripheral anterior synechiae. These findings support the systematic use of anterior segment imaging modalities, such as UBM, in patients undergoing corneal transplantation who are at high risk for rejection, to better inform clinical decision-making and potentially improve outcomes.  Larger prospective studies are warranted to further validate these observations.