Quantitative Assessment of Aqueous Flare After Descemet Membrane Endothelial Keratoplasty for Fuchs Endothelial Dystrophy

Purpose: To assess aqueous flare as a measure of subclinical inflammation after Descemet membrane endothelial keratoplasty (DMEK) for Fuchs endothelial dystrophy. Methods: In this prospective cross-sectional and longitudinal case series at a tertiary referral center, 173 DMEK eyes of 169 patients and 19 age-matched healthy control eyes were included. Aqueous flare [photon count per millisecond (ph/ms)] was assessed by laser flare photometry at 1 day, 1 week, and 1 month after DMEK in group I (evaluation of postsurgical blood-aqueous barrier recovery; n = 25) and on average 28 (+/- 19) months (range, 3-86 months) after DMEK in group II (evaluation of long-term inflammation; n = 148). Results: In group I, flare levels decreased from 1 day to 1 week [25.1 (+/- 9.1) ph/ms vs. 13.4 (+/- 4.8) ph/ms; P = 0.003] and remained stable up to 1 month after DMEK [12.1 (+/- 3.2) ph/ms; P = 0.387]. However, average flare at 1 month was higher than that in healthy controls (P < 0.001). The long-term flare value after DMEK (group II) was 9.6 (+/- 4.2) ph/ms and was higher in eyes associated with allograft rejection (n = 6) versus those without rejection [16.7 (+/- 7.8) ph/ms vs. 9.3 (+/- 3.8) ph/ms, respectively, P < 0.001]. All eyes associated with rejection had flare values above 10 ph/ms. Conclusions: Aqueous flare after DMEK quickly decreased within the first postoperative month, indicating fast recovery of the blood- aqueous barrier. Long-term flare levels were higher in eyes associated with rejection, suggesting persistent subclinical inflammation. A flare level above 10 ph/ms may be used as a threshold for identifying eyes associated with or at risk of allograft rejection after DMEK.