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Antiglaucomatous drugs effects on optic nerve head flow: design, baseline and preliminary report
J Sampaolesi1, J Tosi, V Darchuk
1Department of Ophthalmology, University of Buenos Aires, School of Medicine, Fundación Argentina Oftalmológica Juan Sampaolesi and Instituto de la Visión.
Purpose:
To determine the effect of the most frequent used antiglaucomatous drugs on the optic nerve head flow. To see the response of the autoregulation system in hypertensive, preperimetric and advanced perimetric glaucomas.
Materials:
In this preliminary report, optic nerve head parameters and retinal perfusion values were measured in 25 healthy controls as well as in 72 glaucomatous optic nerve heads. The glaucomatous sample was divided into three groups: 24 eyes treated with Betaxolol, 24 with Brinzolamide and 24 treated with Brimonidine (each of these groups was conformed by 8 hypertensive glaucomas, 8 preperimetric glaucomas, and 8 perimetric glaucomas).
Methods:
Patients were examined with scanning laser Doppler flowmetry (wave length 638 nm), and flow, volume and velocity indices were assessed in each report. Perfusion maps were analyzed with the new SLDF software, version 3.2 (automatic full field perfusion image analizer). Examinations were also performed with the Heidelberg Retina Tomograph (wave length 638 nm), using the new standard reference plane. Visual fields were performed with the Octopus 123 or 101 perimeters, programs Glx and G2, with 3 phases completed. Diurnal pressure curve with applanation tonometry and gonioscopy (for classification) were also performed.
Results:
In this preliminary report, it was found that eyes in Hypertensive or preperimetric stages of glaucoma, seem to use their regulation systems in order to preserve their optic nerve head circulation, while advanced perimetric glaucomas seem not be able to preserve their optic nerve head flow. And that antiglaucomatous drugs were not able to increase optic nerve head flow neither.
Discussion:
Optic nerve head blood supplies is regulated by an autoregulation system. This phenomenon may act in normals, hypertensive and preperimetric glaucomas, but it seems not be able to preserve blood flow in advanced glaucomas. Optic nerve head flow returns to normal values with treatment in glaucoma first stages, while it seems that it could not be restored in advanced glaucomas.