The DIOXXACT Trial(Diurnal IOP and OBF Xalatan vs Xalatan And Cosopt Trial)

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.

Timeline

Start

2009-05-04

Primary completion

2011-09-14

Completion

2012-02

Publications

• Results Hafez AS, Bizzarro RL, Rivard M, Trabut I, Lovasik JV, Kergoat H, Lesk MR. Reproducibility of retinal and optic nerve head perfusion measurements using scanning laser Doppler flowmetry. Ophthalmic Surg Lasers Imaging. 2003 Sep-Oct;34(5):422-32.
• Results Yoshida A, Feke GT, Mori F, Nagaoka T, Fujio N, Ogasawara H, Konno S, Mcmeel JW. Reproducibility and clinical application of a newly developed stabilized retinal laser Doppler instrument. Am J Ophthalmol. 2003 Mar;135(3):356-61. doi: 10.1016/s0002-9394(02)01949-9.
• Results Lesk MR, Hafez AS, Descovich D. Relationship between central corneal thickness and changes of optic nerve head topography and blood flow after intraocular pressure reduction in open-angle glaucoma and ocular hypertension. Arch Ophthalmol. 2006 Nov;124(11):1568-72. doi: 10.1001/archopht.124.11.1568.
• Results Michelson G, Schmauss B. Two dimensional mapping of the perfusion of the retina and optic nerve head. Br J Ophthalmol. 1995 Dec;79(12):1126-32. doi: 10.1136/bjo.79.12.1126.
• Results Sehi M, Flanagan JG, Zeng L, Cook RJ, Trope GE. Anterior optic nerve capillary blood flow response to diurnal variation of mean ocular perfusion pressure in early untreated primary open-angle glaucoma. Invest Ophthalmol Vis Sci. 2005 Dec;46(12):4581-7. doi: 10.1167/iovs.05-0209.

Drugs

Indications