Recent noteworthy studies to stimulate discussion and debate
Recent noteworthy studies to stimulate discussion and debate.
■ In pursuit of 27-g. As 25-g vitrectomy systems gain in popularity, the question of whether an even smaller-gauge system can become the standard remains. Thanks to a study from Japan, we may be closer to an answer.
A team of surgeons published in the January 2010 issue of Ophthalmology an article testing a 27-g trans-conjunctival sutureless vitrectomy system. In an experimental interventional case series, this 27-g system was tested in 31 patients with a variety of conditions, including epiretinal membrane, idiopathic macular hole, diabetic vitreous hemorrhage, and others. The authors examined duty cycle of the vitreous cutters, infusion and aspiration rates, and surgical results.
The authors found that, while rates of infusion and aspiration with the 27-g system were inferior to those seen with 25-g systems, the duty cycle was superior (38% vs 28% at 1,500 cuts per minute). Furthermore, all 31 surgeries were successful, with 20 patients experiencing improvement in visual acuity of three lines or more. All wounds self-healed and there was no need for the surgeons to switch to larger-gauge instruments in any surgery.
While the authors remain concerned about the lower infusion and aspiration rates of the system, they are optimistic about the future of 27-g surgery, given the high success in wound closure and the complications of vitrectomy that can arise from complications in wound healing.
■ More on small-gauge. A study by several UK-based physicians in the January 2010 issue of the British Journal of Ophthalmology reports on a trial that compared postoperative pain in 20-g vs 25-g surgery. The article's authors used a visual scale and verbal reporting by patients to determine pain levels in 40 patients randomized to one of the two gauges compared.
Patients were surveyed 12 hours after vitrectomies were performed, and postop pain was found to be similar in both groups, with about half of each scoring > 1 cm on the visual analogue scale used for the study. One week after surgery, 38 of the 527 scores recorded >1 cm, with 10 of these scores coming from three patients and the rest spread out over both groups and different recovery times.
Despite the absence of statistically significant factors, the study authors observed that significant pain was present more in the 20-g group. That point notwithstanding, the authors conclude there is no significant advantage to 25-g vitrectomy over 20-g vitrectomy. The controversy continues.
■ Good news/bad news. The good news for bevacizumab is that a study in the December 2009 issue of Eye found that the anti-VEGF agent produced statistically significantly better outcomes in VA than a combo therapy of PDT combined with intravitreal triamcinolone. Twenty-eight patients at the Medical University of Vienna were randomized to either the bevacizumab or PDT-triamcinolone treatment, and mean VA increased in the bevacizumab group by 1.5 lines, while it actually decreased by three letters in the PDT-triamcinolone group. Both treatments reduced central retinal thickness. Furthermore, there were no adverse effects in either group.
Sadly, the same cannot be said for bevacizumab in another article in the same issue of Eye. While the end results were not grave, three cases of acute endophthalmitis were detected in a retrospective study conducted in Turkey of 3022 intravitreal injections for 1822 eyes. Two of the three cases were identified as culture-positive, yielding an overall postinjection culture-proven rate of endophthalmitis of 0.066%.
While this rate may seem very low, the authors of the study warn that endophthalmitis remains a potential complication of intravitreal injection of bevacizumab, even when sterility protocols are followed to the letter. Because endophthalmitis has a rapid onset and can permanently compromise vision, prompt recognition and treatment are urged.
■ NSAIDs in CME. Doctors at the University of Kansas School of Medicine studied the use of four topical NSAIDs as an adjunct to a combination therapy of intravitreal triamcinolone and bevacizumab to treat cystoid macular edema. They report their findings in the February 2010 issue of Retina.
Four NSAIDs (diclofenac 0.1%, ketorolac 0.4%, nepafenac 0.1%, and bromfenac 0.09%), along with a placebo, were administered daily for 16 weeks to 39 patients with chronic pseudophakic CME. These patients all received the combo therapy plus an injection of bevacizumab one month later. Visual acuity was measured at four weeks, eight weeks, 12 weeks and 16 weeks, as were central retinal thickness (measured by OCT) and IOP.
By the 12-week and 16-week visits, the nepafenac and bromfenac groups had a statistically significant reduction in mean central retinal thickness compared to the placebo group; however, only nepafenac was able to maintain the decrease in thickness. Nepafenac was also the only NSAID administered that resulted in a statistically significant improvement in visual acuity at 12 weeks. None of the NSAID groups had a mean increase in IOP.
The study authors link nepafenac's seemingly greater effectiveness to its proven ability to penetrate the cornea more easily than other topical NSAIDs, as well as greater posterior-segment activity. They also point to a recent study that showed that nepafenac suppressed VEGF mRNA production in the retina. RP
Retinal Physician, Issue: March 2010