Einfluss von Brimonidin auf die zentrale Hornhautdicke

Abstract

Brimonidine, an alpha-2 adrenoceptor agonist, is widely used in glaucoma treatment. Although it is known that it is quickly taken up by the cornea following topical administration and although it is well established that the cornea expresses alpha-2 adrenoceptors there are only few studies available on the impact brimonidine has on the cornea. The aim of the present study was to show if topical application of brimonidine leads to an interaction with corneal alpha-2 adrenoceptors in terms of an increase in central corneal thickness. Ten healthy test persons (five female and five male subjects) - mean age 30±7years - were tested in a pilot study. Measured were intraocular pressure, epithelial, stromal and endothelial thickness before as well as ten minutes, 24, 48, 72 and 96 hours after administration of brimonidine 0.1% eye drops twice daily. To check the impact of this medication, sodium hyaluronate eye drops were administered to the other eye twice daily. Administration of brimonidine 0.1% resulted in a reduction of intraocular pressure from an initial value of 17±2mmHg to 13±4mmHg after four days (p=0.001) as well as an increase in total corneal thickness from 559±8μm from the time of the baseline examination to 581±11μm (p<0.001), an increase of epithelial thickness from 61±1μm to 68±7μm (p=0.008) and stromal thickness from 488±8μm to 503±8μm (p<0.001) after two days each. Another two days later total corneal thickness was 566±10μm (p=0.032), epithelial thickness 64±3μm (p=0.104) and stromal thickness 492±8μm (p=0.139), which means that the values had returned more or less to the initial values measured. In contrast, endothelial thickness did not vary following administration of brimonidine 0.1% (p=0.109). Topical administration of brimonidine 0.1% results in a reversible increase in corneal thickness. The question as towhether this increase is of clinical significance has to be answered by larger studies.