Royal College of Ophthalmologists Guidelines

Photodynamic Therapy - August 2000

Photodynamic therapy in the management of subfoveal choroidal neovascularisation secondary to age-related macular degeneration.

Recent studies now extending to two years have shown that the treatment known as photodynamic therapy (PDT) is effective in reducing visual loss in the short term in patients with predominantly classic subfoveal choroidal neovascularisation (CNV) in AMD. The Royal College of Ophthalmologists has established a working party consisting of experts in the field of macular degeneration and lay advisors to examine the available evidence in order to provide guidance to College members, the Department of Health and commissioners on the potential use of PDT.

Treatment according to the published TAP protocol requires 7 angiograms and an average of 6 treatments within the first two years. Evidence exists that patients with predominantly classic CNV of AMD will benefit from treatment in terms of a reduction in the risk of losing 3 or more lines of vision over this period.

Whilst accepting that Visudyne is now licensed for use in the European Union, the Working Party believes that there is insufficient evidence at present to support the widespread use of photodynamic therapy in NHS or private settings. Although the TAP study provides strong evidence that PDT with verteporfin influences the visual outcome in the subgroup with predominantly classic choroidal neovascularisation, a number of important questions remain unanswered. These are:

1. The optimal treatment regime: The experimental protocol required retreatment at study visits if any leakage was seen in fluorescein angiogram regardless of location or type of leakage and visual function status. It is unclear if treatment is still necessary if a) residual leakage is located eccentric to the centre of the fovea b) residual leakage is of the occult variety in any location and c) if acuity is stable. Further evaluation is therefore needed to determine the optimal treatment protocol.
2. Quality of life: Whilst it is clear that there was a difference between the treatment group and the placebo group, the extent of the effect and the value of the benefit is still unclear as the quality of life studies were not undertaken until much later in the TAP study.
3. Incidence of early visual loss: There is evidence that a proportion of patients experience transient visual loss with onset during the first week after therapy with recovery by three to four weeks. Choroidal hypoperfusion is likely to be the mechanism but the precise incidence and pathogenesis of this side effect is unknown.
4. The number of patients suitable for treatment: The proportion of patients with AMD who have predominantly classic subfoveal CNV and therefore likely to benefit from PDT with verteporfin is presently unknown. Consequently the number of patients likely to be treated within the country each year is also unknown.

The Working Party would wish to see a controlled introduction of PDT within the UK Health Service whereby these questions can be answered systematically. As the best outcome group consisted of patients with predominantly classic CNV, any treating centre must have personnel with expertise in diagnosis and reading of fluorescein angiograms to make these distinctions. To qualify as a treating centre, the Working Party would recommend that the following requirements are met.

a) retinal specialisation

b)expertise in stereo pair fluorescein angiography to permit accurate classification of lesion components of CNV.

c) experience of collecting data to agreed protocols through participation in clinical trials

The Working Party are currently developing protocols for case selection, investigation, treatment, data collection and monitoring. The Working Party with the support of the College intend to actively seek NHS R & D funding to move forward with this process.

References
TAP Study Group. Photodynamic Therapy of subfoveal choroidal neovascularisation in age-related macular degeneration with verteporfin. One year results of 2 randomized clinical trials. TAP report 1. Arch. Ophathmol., 1999;117:1329-45.

Brief Summary

The Working Party believes that there is insufficient evidence to support the widespread use of PDT in the UK. The treatment effect is undoubted but small. As the protocol stands it requires 7 angiograms and an average of 6 treatments in the first two years and the cost may prove to be unacceptably high. A number of important questions remain unanswered and to address these the Working Party are currently developing protocols for case selection, investigation, treatment, data collection and monitoring. The Working Party with the support of the College intend actively to seek NHS R & D funding to move forward with this process.