Macular Photocoagulation Study Group (MPSG): extrafoveal lesions.
The first study was performed by the MPSG in patients with well-defined extrafoveal neovascular lesions (located 200 to 2500 µm from the foveal centre), with drusen, age ≥ 50 years and VA ≥ 20/100.
No differentiation was made between classic and occult membranes in this study.
Choroidal neovascularization was angiographically defined as the presence of leakage in the external retina.
Patients were enrolled in the study between 1979 and 1982 and treated with blue-green Argon laser.
The first results were published in the latter year (MPS, 1982)(1,2).
The MPS concluded that laser photocoagulation with blue-green or green Argon laser of sufficient intensity to produce nearly white lesions in the retina and cover the entire neovascular lesion, as well as adjoining blood, reduces the risk of additional and severe loss of vision, when compared to natural progression of the disease.
The benefits of laser were greater during the first year following treatment, having persisted after 5 years(5).
The probability of stabilizing or increasing VA doubled for treated eyes; a 58% reduction in the risk of severe loss of vision (6 lines in the ETDRS scale) was also observed.
After 5 years, 48% of treated eyes and 62% of non-treated eyes had lost ≥ 6 lines.
These results show reduced efficacy when evaluated in terms of the number needed to treat(20).
It was necessary to treat 7 patients for one patient to benefit from the treatment.
Average VA after 5 years was 20/125 in the treated group and 20/200 in the non-treated group (MPS, 1982, 1986).
After 5 years, 54% of treated eyes had shown recurrence with severe loss of vision most of them occurring in the first 2 years after treatment, they have been responsible for the majority of cases of severe loss of vision in the treated group.
Smokers had a greater risk of recurrence (recurrence was observed in 85% of patients smoking more than 10 cigarettes per day, compared to 51% of non-smokers).
Similar results were obtained in two other studies performed in the United Kingdom(17) and France(19).