The DIOXXACT Trial(Diurnal IOP and OBF Xalatan vs Xalatan And Cosopt Trial)
Status:
Completed
Trial end date:
2012-02-01
Target enrollment:
Participant gender:
Summary
Diurnal and intervisit fluctuations in IOP are strongly associated with progression of open
angle glaucoma and therefore need to be minimized. Control of diurnal fluctuations of IOP
with different ocular hypotensive medications has been studied in some detail. But how do IOP
changes contribute to progressive glaucomatous optic nerve damage? It is reasonable to assume
that there are two principal effects of IOP changes. First, IOP fluctuations result in
changes in the stresses and strains on the ONH which in turn result in morphological changes
to the ONH. These morphological changes could in turn result in stretching and damage to
axons of the ONH. Secondly, IOP fluctuations results in changes to the forces acting on the
ONH vasculature, leading to changes in ONH vascular perfusion. These changes to perfusion
could in turn result in relative ischemia of the ONH and consequent ONH damage.
The investigators propose to monitor diurnal fluctuations in IOP and choroidal blood flow
(Pulsatile Ocular Blood Flow,POBF), and intervisit ONH topographical and blood flow
changes-ie to monitor the direct ONH consequences of IOP . Open angle glaucoma patients are
commonly prescribed topical latanoprost as first line therapy. The EXACCT study, for which I
was the principal investigator and which is now submitted for publication, demonstrated that
COSOPT was an efficacious choice as second line therapy for patients not controlled on
latanoprost monotherapy. The investigators will therefore recruit 20 OAG patients on
latanoprost monotherapy, perform diurnal curves of IOP, as well as a.m. ONH morphology and
ONH blood flow. Cosopt will then be added and at the next visit the same measurements will be
repeated.
The investigators expect that when Cosopt is added the investigators will demonstrate
improved IOP, morphology and blood flow compared to the latanoprost baseline. Furthermore the
investigators expect the the diurnal fluctuation of IOP and choroidal blood flow will be
stabilized on Cosopt therapy. The implications are that adding Cosopt to latanoprost can
stabilize not only the IOP but also the damaging consequences of IOP to the optic nerve head.