ENDOPHTHALMITIS FOLLOWING PENETRATING KERATOPLASTY

Visual outcomes and graft survival are very poor in patients who develop endophthalmitis following penetrating keratoplasty, according to a study presented by Sonika Gupta MD, New Delhi, India, at the 16th ESCRS Winter Meeting. The study involved a retrospective review of 258 consecutive penetrating keratoplasties with the aim of determining the incidence of endophthalmitis, its predisposing factors, the microbial spectrum causing the infections, and the visual outcomes and graft survival rates, Dr Gupta said.

The researchers found that there were four cases of post-penetrating keratoplasty endophthalmitis in the series, or 1.5 per cent, over a mean follow-up period of 7.75 months.

The age of the patients varied from 33 years to 68 years and the complication occurred in three men and one woman. The predisposing factors included contaminated donor tissue in two cases, wound dehiscence in one case, and loose suture removal in one case. In addition, the donor cornea was stored in McCarrey-Kaufman medium in all four cases.

The microbial pathogens isolated from the vitreous aspirates included culture-positive streptococcus in two cases, staphylococcus in one case, and aspergillus in one case.

Two eyes received intravitreal vancomycin 1mg/0.1ml and ceftazidime 2.25mg/0.1ml, one received amphotericin B, and one underwent pars plana vitrectomy.

The outcomes were failed grafts in two eyes, phthisis bulbi in one eye and a visual acuity of 20/80 in one eye.

Dr Gupta noted that the incidence of endophthalmitis was unusually high in her case series. Published case series show an incidence ranging from 0.8 per cent to 0.77 per cent. Possible reasons for the high incidence may be related to the difficulty of obtaining good donor tissue in her part of the world, she said.

In addition, all four eyes were aphakic, which means that vitreous incarceration was a possible risk factor. There may have also been inadequate compliance with treatment and follow-up after surgery. Furthermore, the only antibiotic in the type of storage media used was gentamicin. The microorganisms responsible for the infection were resistant to gentamicin in both cases where contaminated donor tissue was the predisposing factor.

Dr Gupta noted that the finding of contaminated donor tissue as the causative factor of endophthalmitis in half of cases was similar to other case series reported in the literature. The same was true of the visual outcomes the patients in this series.

An unusual finding was aspergillus as the infective agent in one case. In fact, in other case series the incidence of rim cultures positive for fungal contamination was only one or two per thousand. There is at present no evidence whether antifungal prophylaxis will present such infections, Dr Gupta said.

On the other hand, she stressed that there are several measures that can be taken to prevent post-keratoplasty endophthalmitis. They include the routine screening of donor rim tissue and the treatment of all patients with prophylactic intraoperative and postoperative broad-spectrum antibiotics. She added that early detection of the complication is essential for achieving optimum outcomes.

“In our set-up, detection and treatment of complications like endophthalmitis is delayed due to inadequate compliance with follow-up after surgery. Early diagnosis and aggressive intervention is mandatory to salvage the eye,†she said.