164
100% occult membranes. Therefore, treatment of occult
membranes and the classic component of mixed mem-
branes was not effective in reducing loss of vision
(14,16)
.
In conclusion, the MPS showed that laser photocoagu-
lation of well-defined extrafoveal choroidal membranes
and classic extra and juxtafoveal membranes secondary
to AMD may prevent of delay loss of vision in patients
fulfilling the inclusion criteria.
2.4 Macular Photocoagulation Study Group (MPSG):
subfoveal neovascular lesions
In 1986, the MPS started two studies
(12,13)
to determine
the efficacy of laser photocoagulation in subfoveal cho-
roidal neovascularization. In the first study, the effect of
laser photocoagulation (Argon or Krypton) was evalu-
ated in eyes with subfoveal exudative AMD not previ-
ously treated; in the second study, the efficacy of laser
treatment in subfoveal recurrence in eyes with extra or
juxtafoveal membranes was evaluated. The results of this
study and treatment recommendations generated a great
deal of controversy. In fact, treated eyes displayed a very
marked loss of vision immediately after treatment. After
4 years, 30% of treated eyes and 60% of non-treated eyes
displayed VA ≤ 20/400, whereas 45% of non-treated eyes
and 23% of treated eyes has suffered severe loss of vision.
The efficacy of this treatment in terms of the number
needed to treat was 4.5
(20)
.
A large percentage of ophthalmologists did not agree
with the MPS recommendations for treating subfoveal
lesions. In fact, patients were losing 3 lines immediately
after treatment. The MPS re-evaluated treatment efficacy
in terms of lesion size and difference from baseline VA,
having established treatment groups and criteria accord-
ing to these two variables
(13)
. Ophthalmologists could
advise their patients and help them choose whether or
not to undergo treatment according to lesion size and
baseline VA.
With the emergence of photodynamic therapy with
Verteporfin, laser photocoagulation for subfoveal lesion
became obsolete. It remains indicated only for extrafo-
veal lesions and the angiographic control should be per-
formed 15 days after treatment.
2.5. Treatment
2.5.1 Preparation for treatment
Regarding preparation for treatment, the MPS rec-
ommended that patients should be informed that
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 per-
formed in the United Kingdom
(17)
and France
(19)
.
2.3 Macular Photocoagulation Study Group (MPSG):
juxtafoveal neovascular lesions
A second study was performed with juxtafoveal mem-
branes and using a Krypton laser
(11)
. Inclusion criteria
allowed treatment of well-defined choroidal neovascular
lesions located 1 to 199 µ from the foveal centre, or 200
to 2500 µm from the foveal centre but showing blood
or pigmentation less than 200 microns from the foveal
centre (resulting in a barrier effect in fluorescence). As
opposed to the study with Argon laser in extrafoveal
membranes, this trial did not require treatment of the
entire area where bleeding occurred. Under no circum-
stances should treatment reach the foveal centre. After
3 years, severe loss of vision (≥6 lines) had occurred in
49% of treated eyes and 58% of non-treated eyes
(14)
. The
efficacy of this treatment in terms of the number needed
to treat
(20)
was very low: 11.1. This treatment reduced
the risk of severe loss of vision by 10%. However, this
benefit was not observed in patients with hypertension
or taking antihypertensive medication. Nevertheless, the
MPS maintained the indication to treat for these non-
normotensive patients due to the absence of similar find-
ings in other MPS studies. After 5 years, the number of
eyes with final VA ≥ 20/40 was double for treated eyes
(14)
.
Persistence (incomplete treatment) and recurrence (neo-
vascularization later than six weeks after treatment)
were responsible for the majority of loss of vision in the
treated group.
The MPS reclassified membranes as 100% classic, clas-
sic with an occult component and 100% occult. Results
were better in classic membranes: 54% of treated eyes
and 72% of non-treated eyes lost 6 or more VA lines. No
statistically significant differences were observed between
the treated and non-treated groups in cases of mixed
membranes (only the classic component was treated) and
