Bilateral penetrating keratoplasty for keratoconus.

PURPOSE: To determine the effect of bilateral surgery on the rejection-free survival of penetrating keratoplasties (PK) performed for keratoconus. METHODS: The records of 587 patients with a PK for keratoconus who attended a single center over a 7-year period were reviewed. Details on 400 patients were sufficiently complete to permit a multivariate analysis of the factors suspected to influence graft survival. In 165 of these patients with bilateral grafts, the effect of a contralateral PK on graft survival was evaluated using actuarial methods. RESULTS: In first grafts for all patients, there was an increased rate of graft rejection with a host trephine greater than 7.50 mm in diameter and in patients with severe allergic eye disease (P < 0.01). In patients who had bilateral grafts, a graft to the contralateral eye increased the risk of rejection in the first eye to be grafted, and although this effect reduced with time, it was still present after an interval of up to 6 years between surgeries. A rejection episode in the first eye to be grafted increased the risk of rejection in the second eye (P < 0.001), but overall the second eye had a significantly lower risk of rejection when compared with either the first grafted eye or unilaterally grafted eyes (P < 0.001). The risk to the second grafted eye further reduced as the interval between the surgeries increased. CONCLUSIONS: In keratoconus, the diameter of the host trephine, severe allergic eye disease, and a graft surgery to the contralateral eye determine the risk of rejection in the index eye. The reasons the second grafted eye of patients receiving bilateral PKs appears to have an enhanced rejection-free survival are discussed.

Bacterial contamination of nylon corneal sutures.

We report the findings of a prospective study into the bacterial contamination of monofilament nylon sutures removed from corneal wounds following cataract surgery. Sutures were classified as tight, loose or broken at the time of removal. Loose and broken sutures showed significantly more bacterial contamination than tight sutures (p < 0.001, chi squared). Positive cultures were obtained from 2 (6.2%) of 32 tight sutures, 14 (38.9%) of 36 loose sutures and 11 (37.9%) of 29 broken sutures. Staphylococcus epidermidis was the most commonly isolated organism (isolated in pure growth from 22 (81.5%) of 27 positive cultures). These findings may explain the occasional association of biodegraded corneal monofilament nylon sutures and suppurative keratitis and highlight the potential risk of seeding a suture track infection at the time of suture removal. They also emphasise the need for prophylactic topical antibiotic when removing biodegraded sutures.

Prognostic factors for the progression of keratoconus.

PURPOSE: The progression of keratoconus to a stage where penetrating keratoplasty (PK) is required for visual rehabilitation has considerable implications for affected patients. To assist with counselling, the authors have attempted to identify which factors measurable early in the course of the disease may indicate the likelihood of subsequent surgery. METHODS: The authors reviewed the records of all patients who attended a single center over a 7-year period for contact lens management of their keratoconus. The influence of clinical variables on the time taken for the worst eye to progress to PK was evaluated by actuarial methods and multivariate analysis. RESULTS: Included in the study were 2723 patients with a mean follow-up for unoperated eyes from the first visit of 4.5 years (range, 3 months to 28 years). Data were available for multivariate analysis in 2363 patients. At the end of the study period, 757 eyes (21.6% of all patients) had been grafted. The number of eyes progressing to PK was independently related to both the maximum and minimum keratometry, a corneal cylinder of more than 1.9 mm, the Snellen acuity, the racial group (P < 0.0001), and the age at presentation (P = 0.0006). Sex, laterality, systemic atopic disease, maternal or paternal age at birth, joint hypermobility, and a family history of keratoconus were not statistically related to outcome. Progression to PK in one eye increased the risk of progression in the contralateral eye (P < 0.0001) and a linear model of disease progression is proposed. CONCLUSIONS: Several clinical variables can be measured in patients at the presentation of keratoconus that influence the probability of a subsequent PK.

Infective endophthalmitis following vitreoretinal surgery.

Eleven cases of endophthalmitis occurring after vitreoretinal surgery are described. At Moorfields Hospital, London, from 1986 to 1990 the incidence of endophthalmitis after explant surgery with or without drain was 0.19% and after vitrectomy was 0.15%. We conclude that the parity may be due to the intraocular instrumentation of most conventional retinal detachment repair procedures. The best indicator of poor prognosis was speed of onset of symptoms, those with rapid evolution having the worst outcome; 2 of these cases were enucleated. Those presenting at 2-3 days had the best outcome, consistent with infection due to a less virulent organism. Delays in diagnosis were in part due to the posterior location of signs of infection. Potential risk factors amenable to prophylactic strategy were identified in 10 of the 11 patients. Supplementary prophylaxis using ciprofloxacin or imipenem is proposed for cases with an identifiable risk factor. After systemic administration these antibiotics achieve vitreous levels that exceed the MIC90 of the commonest causative pathogens.

Conjunctival necrosis after administration of topical fortified aminoglycosides.

We treated 11 episodes of bulbar conjunctival necrosis that occurred in ten patients after therapy for suppurative keratitis with topical fortified aminoglycosides. Chemosis and mucous discharge preceded the development of an area of conjunctival pallor, which stained with fluorescein and was 5 to 10 mm from the corneoscleral limbus. Typical lesions developed in the inferior bulbar conjunctiva after a mean of 4.8 days and 112 mg of gentamicin sulfate (109 drops). The fortified aminoglycoside was the only agent common to all cases. The conjunctival defects healed completely between five and 13 days after treatment was modified to reduce or eliminate aminoglycoside exposure.