Adjunctive povidone-iodine reduces bacterial infection risk after cataract surgery

Three drops applied to the conjunctival sac, in tandem with standard irrigation and antibiotics, significantly reduced positive cultures.

Issue: October 25, 2012

Administration of 10% povidone-iodine drops in addition to irrigation of the conjunctiva significantly reduced conjunctival bacterial contamination during and after cataract surgery, a study found.

Perspective from Marguerite B. McDonald, MD

“Using the conjunctival bacterial contamination rate as a surrogate marker for the risk of infectious postoperative endophthalmitis, this intensified prophylaxis scheme might be helpful to further reduce the rate of infectious postoperative endophthalmitis,” Martin M. Nentwich, MD, the corresponding author, said in an email interview.

Postoperative endophthalmitis is among the most serious complications of cataract surgery and may cause acute vision loss. The conjunctiva, eyelid and nose are thought to be the main sources of infection-causing bacteria. Preoperative reduction of conjunctival bacteria may help prevent infection, the study authors said.

The study was published in the European Journal of Ophthalmology.

Patients and protocols

The prospective, randomized study included 263 eyes of 242 patients who underwent cataract surgery.

An inpatient group comprised a study subgroup of 77 eyes and a control subgroup of 74 eyes. An outpatient group comprised a study subgroup of 55 eyes and a control subgroup of 57 eyes.

“In Germany, significant systemic disease such as poorly controlled diabetes mellitus, severe arterial hypertension or a history of stroke or myocardial infarction are reasons to perform cataract surgery on an inpatient basis. Therefore, the patients of the inpatient group had more systemic comorbidities compared to the outpatient group,” Nentwich said.

Both the inpatient and outpatient groups received preoperative topical antibiotics. In the inpatient group, topical neomycin was initiated on the day before surgery (four times per day) and continued on the day of surgery. The outpatient group received topical neomycin on the day of surgery only.

Study eyes received three drops of povidone-iodine 10% in the conjunctival sac. Control eyes did not receive povidone-iodine drops. All eyes subsequently underwent periorbital disinfection with 10% povidone-iodine and irrigation of the conjunctiva with 10 mL of 1% povidone-iodine.

Culture specimens were collected before application of povidone-iodine, after antibiotic administration, after irrigation but before surgery, and at the end of surgery.

Data and conclusions

Study results showed that the number of positive cultures was significantly reduced in all groups after povidone-iodine disinfection (P < .0001).

At the end of surgery in outpatients, positive cultures were collected from 16% of controls and 4% of study patients; the between-group difference was statistically significant (P = .03).

In the inpatient group, the study subgroup had significantly fewer positive cultures than controls after irrigation but before surgery and at the end of surgery (both P = .03).

Among the inpatient group, positive cultures were collected from 86% of the study subgroup and 69% of the control subgroup after antibiotic administration; the difference was statistically significant (P = .01). After the application of povidone-iodine, 12% of cultures from the study subgroup and 28% of those from the control subgroup tested positive (P = .01).

No cases of endophthalmitis were reported.

Results showed no evidence of povidone-iodine-related toxicity.

“Even though the present study was not designed to assess toxicity of povidone-iodine, neither any intraoperative nor any postoperative obvious signs of toxicity were noted,” Nentwich said. – by Matt Hasson

Reference:

Nentwich MM, Rajab M, Ta CN, et al. Application of 10% povidone iodine reduces conjunctival bacterial contamination rate in patients undergoing cataract surgery. Eur J Ophthalmol. 2012;22(4):541-546.

For more information:

Martin M. Nentwich, MD, can be reached at Ludwig-Maximilians-University Department of Ophthalmology, Klinikum der Universität München, Campus Innenstadt Mathildenstrasse 8, 80336 Munich, Germany; email: martin.nentwich@med.uni-muenchen.de.

Disclosure: Nentwich has no relevant financial disclosures.

Perspective

Marguerite B. McDonald, MD

This is a very important study for all ophthalmic surgeons. Because the postoperative endophthalmitis rate is already low, the only way to study this issue is by studying conjunctival bacterial contamination rates via cultures. Nentwich and colleagues have conclusively proven that the addition of three drops of 10% povidone-iodine is a beneficial addition to the current standard of care.

Marguerite B. McDonald, MD

OSN Refractive Surgery Board Member

Disclosures: McDonald has no relevant financial disclosures.