Gábor Holló and Andreas Katsanos
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baseline) by 34.4% (9.8 mmHg), while the evening-dosed latanoprost/timolol
fixed combination by 31.2% (8.9 mmHg) [58]. This difference was
statistically significant (P< 0.001) [58]. In another crossover study, the mean
24 - hour baseline IOP in a mixed population of POAG and XFG patients was
27.7 mmHg [59]. After 2 months of therapy, the mean 24-hour IOP was
19.2±3.5 mmHg when the travoprost/timolol fixed combination was dosed in
the morning, and 18.4±3.3 mmHg when dosed in the evening (P=0.001) [59].
In a 3-month, multicenter, prospective, single-masked, 24-hour crossover
study conducted on XFG patients [60] the bimatoprost/timolol fixed
combination was administered in the morning in one study phase, and in the
evening in the other phase. The mean 24-hour IOP reduction from the mean
untreated 24-hour value (29.03 mmHg) was 33.9% (9.84 mmHg) with
morning dosing and 35.3% (10.2 mmHg) with evening dosing. This difference
was statistically significant (P=0.005). These results suggest that in XFG
topical prostaglandin analog/timolol therapy is more effective when the drop is
administered in the evening. Recently, the IOP lowering efficacy of morning-
dosed preservative-free tafluprost/timolol fixed combination was evaluated in
XFG patients who participated in a 6-month, randomized, double-masked,
active controlled, parallel group, multicenter phase III study [61]. The mean
untreated baseline IOP varied between 26.5 mmHg (4 p.m.) and 28.1 mmHg
(8 a.m.). The mean time-wise IOP reduction ranged between 8.62 and 10.25
mmHg (31.8 to 36.7%), and the overall IOP reduction was 34.1%.The results
discussed in this paragraph suggest that an IOP reduction of 31 to 36% from
untreated baseline can be expected with once daily administration of all
prostaglandin analogue/timolol fixed combinations. Currently there are no
controlled data on the efficacy of combination therapy with 3 or more IOP
lowering medications in XFG (e.g., a prostaglandin analogue and a topical
carbonic anhydrase inhibitor/timolol fixed combination or a prostaglandin
analogue/timolol fixed combination and a topical carbonic anhydrase
inhibitor).
Laser Treatment
Argon laser trabeculoplasty (ALT) exerts its IOP lowering effect by
enhancing aqueous humor egress through the trabecular meshwork. It was
initially hypothesized that the mode of action is mechanical distention of the
collapsed trabecular meshwork [64,65]. However, laser-inducedenhancement
of extracellular matrix turnover due to stimulation of trabecular cells has also