Cornea
-
A great deal of controversy and concern exists over potential transmission of central nervous system diseases by corneal transplant. The purpose of this study was to evaluate the available data relative to this question, pertaining especially to transmission of infectious dementia. From these data, determination of conveyance risks are possible, and rational policies for donor inclusion criteria can be constructed. ⋯ That this case represents an extremely rare event is supported by a lack of successful transmission via corneal transplant in monkeys; lower levels of infectious agent in cornea than in brain; lack of successful transmission of similar human dementias, including Alzheimer's disease to primates; the apparent requirement for homozygosity at codon 129 of chromosome 20 for transmission; lack of transmission in 5-10% of CJD cases even after brain inoculation; and low numerical risk of transmission based on population data. Only 0.5-4 CJD infected donors per year would be expected. Current Eye Bank Association of America criteria for donor exclusion based on suspicious history are adequate to protect against accidental conveyance of transmissible dementia.
-
Case Reports
Iris ischaemia following penetrating keratoplasty for keratoconus (Urrets-Zavalia syndrome)
A fixed and dilated pupil is an uncommon postoperative complication after penetrating keratoplasty (PK) for keratoconus. Although the clinical features have been well described, the precise aetiology is uncertain. ⋯ All of the eyes had severe iris ischaemia. A possible role for a postoperative rise in intraocular pressure in the aetiology of this syndrome is discussed.
-
Eighteen eyes with wound dehiscence after penetrating keratoplasty were studied. Keratoplasty was performed for corneal scarring (n = 8), dystrophies (n = 6), graft failure (n = 2), and corneal edema (n = 2). The mean duration between keratoplasty and wound dehiscence was 6.54 months. ⋯ Trivial trauma resulted in dehiscence in 10 of the 18 eyes. The major determinants of visual outcome were the force of trauma and status of the posterior segment. Dehiscence of the graft-host junction in all cases reflects its persistent weakness after surgery.
-
Contaminated allograft donor tissue represents a potential source of infection unique to keratoplasty. We prospectively studied perilimbal cultures of drowning victims over 30 months to determine if the ocular surface flora of drowning victims was unique. Twenty-eight donor eyes were cultured from 14 drowning victims. ⋯ The incidence of gram-negative isolates was also markedly higher in drowning victims, compared to previous studies of donor globes. This prospective study has shown that the ocular surface flora of drowning victims harbors markedly increased numbers of streptococcal species as well as gram-negative organisms. These findings demand careful globe decontamination, and emphasize the need for appropriate antibiotic coverage in corneal storage media.
-
The treatment of herpes simplex keratitis has ranged from simple debridement to the use of prototypic antiviral agents specific to the herpes family, such as acyclovir. The various treatment modalities for dendritic keratitis, for the most part, have been effective. However, in recent years numerous reports of antiviral-resistant strains of herpes simplex have appeared, particularly in immunocompromised patients receiving chronic acyclovir. ⋯ After 7 weeks without improvement on multiple treatment regimens, including trifluridine, vidarabine, debridement, and topical and systemic acyclovir, interferon alpha-2a was added to topical acyclovir therapy, and the keratitis quickly resolved. Topical interferon alpha-2a appears to be an effective treatment adjunct for refractory herpes simplex keratitis in patients with cell-mediated immune dysfunction and subsequent lack of endogenous interferon. Its value in nonimmunocompromised patients remains to be determined.