Background: Postoperative complications after high-risk corneal grafting are decisively associated with corneal neovascularization (CNV). This study aimed to identify the incidence, extent, speed, localization, and influence of surgery-related factors on CNV after high-risk penetrating keratoplasty (PK) and to evaluate the effect of removing the angiogenic stimulus, i.e., residual components of herpes simplex virus (HSV) on postkeratoplasty CNV in patients with herpetic stromal keratitis (HSK).
Methods: All primary high-risk PK performed for HSK and non-herpetic keratitis (controls) between 1 January 1998 and 31 December 2003 at our department with available standardized corneal photographs taken preoperatively as well as 6 weeks, 3, 6 and 12 months postoperatively were evaluated (n (herpes) = 19, n (controls) = 5 patients). Maximal extension of CNV, limbus suture distance (LSD), limbus graft distance (LGD) and graft size in digitalized pictures were measured in each of the 16 sectors of the cornea at every visit.
Results: One hundred percent of the prevascularized corneas (n = 24) showed further CNV outgrowth within 1 year after keratoplasty, while 58 % of these patients featured high-grade CNV reaching the host-graft junction or invading the donor tissue. Overall, CNV outgrowth was fastest during the first 6 weeks after PK, with a mean speed of 48 μm/week. Mean CNV growth speed within 6 months post-PK was significantly lower in the herpes group (13 μm/week) than in the non-herpes group (25 μm/week, p = 0.017). Corneal location around the 12 o'clock position showed the most intense vessel outgrowth, which proved to be an independent risk factor for high-grade CNV (p = 0.025). Inverse correlation was evident between CNV growth speed and LSD (p = 0.032).
Conclusions: Additional intense CNV outgrowth is a common phenomenon after high-risk keratoplasty, strongly marked in the early postoperative period. The removal of residual HSV components representing a potential angiogenic stimulus leads to a reduction in corneal angiogenesis not in the short term, but in the long term after PK in patients with HSK. In addition to preferable atraumatic operation techniques, modern antiviral prophylaxis and anti-angiogenic therapy should be applied early, possibly even prior to transplantation. Short LSD seems to be an intraoperative adjustable risk factor for CNV in high-risk setting. Attention should also be paid to the superior site around the 12 o'clock position.