• Use of Confocal Microscopy to Diagnose Corneal Graft Rejection

    By Jean Shaw
    Selected By: Richard K. Parrish II, MD

    Journal Highlights

    American Journal of Ophthalmology, July 2019

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    Chirapapaisan et al. investigated whether laser in vivo confocal micros­copy can help support the diagnosis of corneal graft rejection. They found that it could, as immune cell density was significantly higher in rejected grafts than in those that were not rejected.

    For this prospective case-control study, the researchers enrolled 38 pa­tients who had undergone penetrating keratoplasty (15 with graft rejection; 23 without) and nine age-matched healthy controls. Full-thickness confocal mi­croscopy scans were performed in the central cornea of all eyes with grafts and in one eye of each of the nine con­trol subjects. In addition, multiple scans were taken of the epithelial, sub-basal, stromal, and endothelial layers, and five representative images of each layer were selected for analysis of immune cell density by a masked observer. The main outcome was the immune cell density in the corneal layers and its associations with any clinical signs and symptoms of graft rejection.

    Significant differences in immune cell densities were found among normal control patients, nonrejected grafts, and rejected grafts: Total immune cell density was 48.60 ± 10.67 cells/mm2 in controls, 187.70 ± 22.80 cells/mm2 in nonrejected grafts, and 285.32 ± 53.23 cells/mm2 in rejected grafts. When immune cell densities were compared layer by layer, higher densities were seen only in the sub-basal and endothelial layers of the rejected grafts than in the nonrejected ones.

    With regard to clinical signs and symptoms of graft rejection, all of the 15 patients who had experienced graft rejection experienced decreased vision, 10 had ocular irritation, nine com­plained of light sensitivity, and seven reported ocular pain. Those with pain, ocular irritation, and light sensitivity were more likely to have increased immune cell density in the sub-basal layer, and those with pain were also more likely to have a higher density in the epithelial layer.

    In addition, all patients with rejected grafts had one or more typical clinical signs of rejection, with specific signs associated with increased density in particular corneal layers. Patients with anterior chamber cells and the Kho­dadoust line were more likely to have elevated immune cell density in every corneal layer.

    The results suggest that confocal microscopy may be useful as an adjunct tool for diagnosing corneal graft rejection during the early stages of immunologic reaction, particularly in questionable or subtle cases, the authors said.

    The original article can be found here.