One of the growing issues in treating age-related macular degeneration (AMD) is to reduce the burden of treatment for the patients, many of whom are elderly, and may require injections of VEGF inhibitors every 4-8 weeks. A long-standing tradition in ophthalmology has been to avoid bilateral same-day surgical intervention. The rationale has been that if you operate on two eyes on the same day, any infection that develops in one eye may spread to the other eye, and that if there is any contamination of instruments or compounds used during the surgery, operating on both eyes on the same day increases the likelihood that both eyes will be adversely affected.
Intravitreal injections, which have become standard of care for treatment of AMD are fairly innocuous in terms of surgical insult. The “wound” is a 31 gauge needle entry site. Nevertheless, endophthalmitis may develop. For example, in the VISION study of intravitreal pegaptanib, the incidence of endophthalmitis was 0.16%. In the MARINA study of intravitreal ranibizumab, it was 0.05%. And in the ANCHOR study of ranibizumab, it was 0.05% (3 cases our of 5,921 injections). A study by Pilli et all reported an incidence of 0.029% (3 cases in 10,254 injections). These incidences were for unilateral injections.
So, is there an increased risk for bilateral same-day injections? Lima et al (Yannuzzi’s group) out of New York published their retrospective analysis of bilateral same-day intravitreal injections of VEGF inhibitors in the October 2009 issue of Retina. They report that of 1,534 bilateral injections (3,068 injections total), the incidence of culture-proven endophthalmitis was 0.065%, and the incidence of acute intraocular inflmaation was 0.033%. None of those cases were bilateral. There were no cases of retinal breaks. They conclude that it appears that there is no increased risk for same-day bilateral injections of VEGF inhibitors, as the complication rates are similar.
It’s noteworthy that all patients in their study were done in the office, and received surface disinfection with 5% providone-iodine solution, followed by 2 days of either polytrim or ofloxacin qid.
The study is very useful and gives comfort to those of us considering bilateral same-day injections. In any disease process where the incidence of an occurence is very low, large numbers of patients are needed to determine whether or not there is a difference in incidence between groups, and so, it is fair to say that there is no obvious increase in the risk of complications from bilateral VEGF inhibitor injections, while recognizing the limitation of the comparison.