Diode laser cyclophotocoagulation favored in study for treating refractory glaucoma

This method of cyclodestruction resulted in a lower complication rate and required less invasive anesthesia.

Despite higher re-treatment rates and slightly lower success rates for treating refractory glaucoma, diode laser cyclophotocoagulation was preferred over cyclocryotherapy in a study.

“When more conservative or less aggressive treatment modalities fail to adequately control IOP, more radical options like cyclodestruction are needed,” lead author Argyrios Tzamalis, MD, an ophthalmology resident and research fellow at Papageorgiou General Hospital in Thessaloniki, Greece, told Ocular Surgery News.

Dr. Tzamalis has “watched, tried and experienced” many different techniques that attempt to control IOP in refractory glaucoma.

“In those cases in which surgical procedures for increasing aqueous outflow only have a small chance of success, cyclodestructive procedures, which are oriented toward reducing aqueous inflow, appear to be a solution,” Dr. Tzamalis said. “Therefore, I would have to say that our main inspirational source for our study was our previous surgical failure.”

Two methods of cyclodestruction

Coagulation or destruction of the ciliary body for the treatment of glaucoma was first proposed in the 1930s. Presently, two common methods of cyclodestruction are diode laser cyclophotocoagulation (DCPC) and cyclocryotherapy (CCT).

“In our clinical experience, DCPC and CCT have both proved to be effective and safe procedures for the treatment of advanced refractory glaucoma, with comparable IOP-lowering effect and surgical outcome,” Dr. Tzamalis said. “However, in our study, DCPC revealed a slightly lower rate of complications and the same level of postoperative discomfort by using a less invasive subconjunctival anesthesia, in contrast to retrobulbar anesthesia used to perform CCT.”

The prospective study, which was published in the European Journal of Ophthalmology, involved 40 eyes of 40 patients with refractory glaucoma. Twenty eyes were randomly assigned to receive DCPC and 20 received CCT. Follow-up exams were scheduled on the first 3 days, at 1 week, and at 1, 3, 6 and 12 months. Complications and postop discomfort, measured with a visual pain analogue scale, were also recorded.

Study results

In the DCPC group, mean IOP decreased from 44.3 mm Hg preoperatively to 22.5 mm Hg at 12 months, whereas in the CCT group, mean IOP decreased from 46.5 mm Hg to 20.6 mm Hg.

The mean postoperative pain for the two groups was nearly identical: 5.6 for DCPC and 5.7 for CCT. “This proves DCPC to be equally tolerated using a less invasive anesthesia type,” Dr. Tzamalis said.

Moreover, no severe complications were found in either group at 1 year.

“The absence of severe complications after we performed the cyclodestructive procedures is the result that surprised us because a higher complications rate is described in the literature,” Dr. Tzamalis said. “Most of our reported complications, including anterior chamber reactions, hyposphagma, corneal epitheliopathy, IOP spikes, conjunctival burns and slight hyphema, were mild and transient.”

Although the complication rate was slightly higher with a more prolonged interval in patients who received CCT, this did not influence the final therapeutic outcome, according to Dr. Tzamalis.

Thirty-five percent of DCPC eyes required re-treatment to achieve a satisfactory IOP, as opposed to no eyes in the CCT group.

The presence or absence of neovascularization was also noteworthy.

“In our study, DCPC was found to have a statistically significant better outcome in eyes without neovascularization: a success rate of 87.9% at 1 year,” Dr. Tzamalis said. “This compared to a success rate of only 30% at 1 year in eyes with neovascularization.”

The success rate of CCT was not affected by the presence of neovascularization.

“Although our sample size is relatively small after dividing the eyes into subgroups, neovascularization represents an interesting fact that raises the need for additional investigation,” Dr. Tzamalis said.

The authors may further analyze the effect of previous surgical interventions on IOP regulation when succeeded by DCPC. – by Bob Kronemyer

Reference:

• Tzamalis A, Pham DT, Wirbelauer C. Diode laser cyclophotocoagulation versus cyclocryotherapy in the treatment of refractory glaucoma. Eur J Ophthalmol. 2011;21(5):589-596.

• Argyrios Tzamalis, MD, can be reached at Papageorgiou General Hospital, 56403 Thessaloniki, Greece; 30-694-20-60-467; email: argyriostzamalis@yahoo.com.
• Disclosure: Dr. Tzamalis has no relevant financial disclosures.