Eye Corneal Transplantation Research Articles

Corneal Higher-order Aberrations and Visual Improvement Following Corneal Transplantation in Treating Herpes Simplex Keratitis

To examine corneal higher-order aberrations (HOAs) and visual improvement following corneal transplantation in treating corneal scar caused by herpes simplex keratitis (HSK). Retrospective consecutive case series. This study included a total of 52 eyes: 18 eyes of normal subjects, and 34 eyes of consecutive patients with corneal scar owing to HSK who underwent penetrating keratoplasty (PKP, 17 eyes) or deep anterior lamellar keratoplasty (DALK, 17 eyes). HOAs of the anterior, posterior surfaces and the total cornea were analyzed by anterior segment optical coherence tomography. The correlations between corneal HOAs and visual improvement were also analyzed. Mean logarithm of the minimal angle of resolution (logMAR) visual acuity significantly improved from 1.40 ± 0.70 to 0.46 ± 0.45 after corneal transplantation (P < .0001). Mean corneal HOAs of the anterior surface significantly decreased after corneal transplantation (PKP: from 1.16 ± 0.59μm to 0.58 ± 0.35μm, P= .035, DALK: from 0.94 ± 0.57μm to 0.37 ± 0.18μm, P= .004). Visual acuity following corneal transplantation was correlated with the corneal HOAs at 12months (r= 0.53, P= .01). Visual improvement at 3, 6, and 12months was positively correlated with preoperative HOAs of the total cornea and posterior surface (all P < .01). Preoperative corneal HOAs were associated with the visual improvement in treating corneal scar caused by HSK. Thus, the preoperative assessment of corneal HOAs, especially of the posterior surface, is important in the decision to perform corneal transplantation in eyes with HSK.

Ulcerative keratitis caused by beta-hemolytic Streptococcus equi in 11 horses.

Purpose To describe 11 clinical cases of ulcerative keratitis in horses associated with beta-hemolytic Streptococcus equi in Florida, USA. METHODS: Retrospective clinical study (1996-99). RESULTS: Beta-hemolytic Streptococcus equi was cultured from 11 horses with deep ulcers, descemetoceles or iris prolapse (n = 8), a suture abscess found with a penetrating keratoplasty for a stromal abscess (n = 1), and ulceration that developed following keratectomy/irradiation for corneal squamous cell carcinoma (n = 2). Beta-hemolytic Streptococcus equi subspecies zooepidemicus was found in 10 eyes and subspecies equi in one. Marked signs of uveitis including miosis and hypopyon were present in 8/11 (72.7%) eyes. Keratomalacia was severe in all eyes. The mean diameter of the ulcers associated with beta-hemolytic Streptococcus was 10.2 +/- 6.1 mm. Eight of the eyes required conjunctival flap surgery (four grafts dehisced) and one eye corneal transplantation. Two eyes were treated with medication only. Isolate sensitivity to antibiotics included ampicillin (6/11), bacitracin (11/11), cephalothin (11/11), chloramphenicol (11/11), gentamicin (5/11), polymyxin B (2/11), and tobramycin (1/11). All isolates were resistant to neomycin. The average healing time was 44.7 +/- 26.7 days. The visual outcome was positive in 8/11 eyes, and the globe retained in 9/11 eyes. CONCLUSIONS: Although Gram-positive bacteria predominate in the normal conjunctival microflora of horses throughout the world, Gram-negative bacteria and fungi are more often isolated from equine ulcers. Beta-hemolytic Streptococcus spp. are associated with a very aggressive ulcerative keratitis with the capability to digest conjunctival graft tissue. Clinical signs are pronounced. Aggressive surgical and intensive medical therapy with topical antibiotics and protease inhibitors is indicated.

Ulcerative keratitis caused by beta‐hemolyticStreptococcus equiin 11 horses

AbstractPurposeTo describe 11 clinical cases of ulcerative keratitis in horses associated with betahemolyticStreptococcus equiin Florida, USA.MethodsRetrospective clinical study (1996–99).ResultsBeta‐hemolyticStreptococcus equiwas cultured from 11 horses with deep ulcers, descemetoceles or iris prolapse (n= 8), a suture abscess found with a penetrating keratoplasty for a stromal abscess (n= 1), and ulceration that developed following keratectomy/irradiation for corneal squamous cell carcinoma (n= 2). Beta‐hemolyticStreptococcus equisubspecieszooepidemicuswas found in 10 eyes and subspeciesequiin one. Marked signs of uveitis including miosis and hypopyon were present in 8/11 (72.7%) eyes. Keratomalacia was severe in all eyes. The mean diameter of the ulcers associated with betahemolyticStreptococcuswas 10.2 ± 6.1 mm. Eight of the eyes required conjunctival flap surgery (four grafts dehisced) and one eye corneal transplantation. Two eyes were treated with medication only. Isolate sensitivity to antibiotics included ampicillin (6/11), bacitracin (11/11), cephalothin (11/11), chloramphenicol (11/11), gentamicin (5/11), polymyxin B (2/11), and tobramycin (1/11). All isolates were resistant to neomycin. The average healing time was 44.7 ± 26.7 days. The visual outcome was positive in 8/11 eyes, and the globe retained in 9/11 eyes.ConclusionsAlthough Gram‐positive bacteria predominate in the normal conjunctival microflora of horses throughout the world, Gram‐negative bacteria and fungi are more often isolated from equine ulcers. Beta‐hemolyticStreptococcusspp. are associated with a very aggressive ulcerative keratitis with the capability to digest conjunctival graft tissue. Clinical signs are pronounced. Aggressive surgical and intensive medical therapy with topical antibiotics and protease inhibitors is indicated.

Cataract Formation Following Corneal Transplantation in Eyes with Fuchs?? Endothelial Dystrophy

In a retrospective analysis, 78 eyes in 58 patients that underwent corneal transplantation for Fuchs' endothelial dystrophy were examined for the presence of cataracts. Follow-up ranged from 1 to 17 years, with an average of 6.62 years. Thirty-four (44.1%) of the eyes developed cataracts sufficient enough to require surgical removal. The mean time from transplant to cataract formation averaged 4.9 years. The average age at the time of transplant surgery in the eyes that did not develop cataracts was 55.6, and in those that developed cataracts, 60.3 (p = 0.049). Thirteen percent of the transplants lost transparency following cataract extraction. The incidence of postkeratoplasty cataract increased at age 50 and occurred in 75% of eyes grafted in patients 60 years of age or older.

Long‐term survival of large diameter penetrating keratoplasties for keratoconus and pellucid marginal degeneration

Corneal transplantation in eyes with keratoconus is known to have an excellent prognosis for graft survival. The favorable prognosis for penetrating keratoplasty in these eyes is in large part attributed to the lack of corneal vascularization or ocular inflammation in this disorder (Arentsen 1983). In some patients with keratoconus, and in patients with pellucid marginal degeneration, which is presumed to be a related disorder (Krachmer et al. 1984), severe stromal thinning extends into the corneal periphery. Penetrating keratoplasty with standard diameter recipient beds of 7.5–8.5 mm in these patients may result in graft‐host tissue disparity, wound leaks, and high post‐keratoplasty astigmatism. Corneal grafts employing a larger than standard diameter recipient bed allows more peripheral placement of the graft‐host interface where the host cornea is less severely thinned. Placement of the graft in closer proximity to the limbal vasculature is, however, thought to increase the probability of allograft rejection reactions (Cherry et al. 1979). In this report, we present our experience with large diameter grafts for keratoconus and pellucid marginal degeneration.