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Indications for photodynamic therapy use are broadening, researchers say
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FORT LAUDERDALE, Fla. — Photodynamic therapy is showing usefulness for treating other retinal conditions, beyond the ones for which it was initially studied, according to researchers speaking here.
Photodynamic therapy with Visudyne (verteporfin for injection, Novartis), which has demonstrated efficacy for patients with predominantly classic choroidal neovascularization (CNV) in age-related macular degeneration (AMD), is also showing efficacy in patients with minimally classic lesions in AMD, according to Susan Bressler, MD, of Baltimore.
Dr. Bressler discussed the results of a retrospective study in a subgroup of patients from the large Treatment of AMD in Photodynamic Therapy (TAP) investigation here at the Association for Research in Vision and Ophthalmology (ARVO) meeting.
The substudy showed that the small number of patients with minimally classic CNV in the TAP study benefited from Visudyne treatment, in addition to the majority of patients who had predominantly classic CNV. A prospective study is needed to confirm the finding in this subgroup, she said. As of now, the therapy is approved in the United States only for patients with predominantly classic CNV.
Another obstacle to overcome with verteporfin therapy for newer indications is regulatory acceptance, Dr. Bressler added. Photodynamic therapy for applications other than predominantly classic CNV in AMD is currently not reimbursed by Medicare in the United States. It is, however, an accepted therapy for patients with occult and no classic CNV in more than 30 countries.
Dante Pieramici, MD, also discussed newer applications for Visudyne treatment here at the meeting. He presented a retrospective analysis showing that patients with smaller lesions or those with lower visual acuity may also benefit from the therapy. Dr. Pieramici said verteporfin therapy is usually reserved for patients with larger lesions.
Other trials being conducted on Visudyne therapy include manipulation of the fluence and duration of light exposure. Shorter intervals of 15 minutes are being investigated, as well as delayed intervals of 30 minutes.
Variations of the amount of light used to stimulate the verteporfin are also being weighed. The standard fluence is 600 mW/cm2. A retrospective analysis showed that a reduced fluence of 300 mW/cm2 was beneficial to patients with smaller, minimally classic CNV lesions, Dr. Pieramici said.