Influence of latanoprost on retinal microcirculation in glaucoma

Abstract

Purpose: To test whether latanoprost has an influence on ocular haemodynamics, considering the general reputation of prostaglandins which is frequently associated with vasoconstriction. The effect of latanoprost on the retinal blood supply of treatment-naïve glaucoma patients was tested.

Materials and methodology: 13 patients (7 male, 6 female) who had just recently been diagnosed with primary open-angle glaucoma (POAG) were treated with latanoprost (0.005%). The average age of our study group was 63.8 years (+/- 2.9 years). The drug's effect on retinal autoregulation was assessed by flicker test using the Dynamic Vessel Analyzer (DVA). Examinations took place before initializing treatment, after 4 weeks and once again after 4 to 6 months.

Results: In our group of POAG patients, the IOP under treatment was significantly reduced about 25%. No intraindividual differences in systemic blood pressure and heart rate were observed. In DVA measurements of glaucoma patients, the maximum flicker dilation of the arteries was significantly lower than reported for healthy volunteers. Beyond that, POAG patients did not show significant differences in vessel diameters, peak amplitudes as well as maximum dilations of retinal arteries and veins before and under treatment with latanoprost (0.005%).

Conclusion: Latanoprost markedly lowered the IOP but it did not exert a significant effect on retinal haemodynamics. There was neither a tendency towards vasoconstriction nor towards vasodilation. Sustaining reperfusion damage after topical latanoprost therapy thus seems to be highly unlikely. Further studies must show if sole IOP lowering or a dual positive effect - IOP lowering and improvement of retinal vessel autoregulation - have a more positive impact on the long term follow-up of glaucoma patients.

Keywords: Autoregulation; dynamic vessel analyzer (DVA); glaucoma; haemodynamics; latanoprost; vascular dysregulation..

Fig. (1)

(a) Intraocular pressure before (0) and after (1 and 2) beginning of the treatment with latanoprost; highly significant (p<0,01) reduction of IOP by approximately 25%. Bars show mean +/- SEM. (b) Maximum dilation of the retinal artery (in %) as measured by DVA after flicker stimulation before (0) and after (1 and 2) beginning of the treatment with latanoprost (+/- SEM); non-significant changes. (c) Initial baseline value for the width of artery (A) and vein (V) given in measuring units (MU) assessed by DVA preceding flicker stimulation before (0) and after (1 and 2) beginning of the treatment with latanoprost (+/- SEM); non-significant changes.