Exfoliation Syndrome and Exfoliative Glaucoma 209been proposed [65]. Since energy absorption by melanin in the trabecular
meshwork is necessary for ALT to be effective, patients with XFG are usually
good candidates for this treatment because their eyes typically have debris
laden, heavily pigmented anterior chamber angles.
ALT commonly provides significant IOP reduction in XFG eyes with high
untreated IOP, at least in the first post-laser months or years [66-70].
Unfortunately, the hypotensive effect diminishes over time, conceivably due to
the continuous accumulation of pigment granules and exfoliation material on
the trabecular meshwork. A retrospective study evaluated the efficacy of ALT
on 28 POAG and 26 XFG patients poorly controlled on medical treatment
[70]. Failure was defined as IOP >22 mmHg after 4 to 6 months following
ALT, or need for filtering surgery. The authors found that despite an initially
better response to ALT, patients with XFG eventually failed faster than
patients with POAG. For instance, the cumulative probability of success after
approximately 8 months was 59% and 77% for the XFG and POAG groups,
respectively.
Another retrospective study compared the efficacy of ALT on 29 XFG
eyes (mean follow-up time 23 months) and 66 POAG eyes (mean follow-up
time 27 months) [67]. XFG patients had a greater percentage of IOP reduction
in the first post-laser year compared to POAG patients. The IOP reduction in
the XFG group varied between 28% and 38% (mean pre-laser IOP 25.8
mmHg), whereas in the POAG group it varied between 19% and 27% (mean
pre-laser IOP 23.2 mmHg). The 1-year rate of failure (need for glaucoma
filtering surgery; or an additional laser treatment; or IOP ≥22 mmHg; or IOP
elevations up to 15% of the baseline IOP value in at least 2 visits) was 40% for
POAG and 18% for XFG, while the 3-year failure rate for the groups was 58%
and 47%, respectively (P=0.89). The effect of ALT diminished over time and
by three years both groups had comparable measures of success.
ALT was eventually proposed as primary treatment in patients with
POAG [71]. A retrospective study also investigated the efficacy of ALT as
primary therapy on 75 XFG and 93 POAG patients [66]. Using customized
clinical criteria based on each patient’s need for additional IOP lowering
therapy, the probability of success (defined as no need for additional
treatment) in the XFG group was 80% after 2 years, 54% after 5 years, and
36% after 8 years. The existing evidence suggests that in eyes with XFG and
pre-laser IOP between 23 and 30 mmHg, clinicians can expect an
approximately 20-40% pressure reduction from ALT during the first 4 post-
laser years [66-68,70].