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Abstract #5801 Published in IGR 2-1
The effects of betaxolol hydrochloride ophthalmic solution on intraocular pressures during transient microgravity
Pattinson TJ; Gibson CR; Manuel FK; Bishop SL; March WFAviation Space and Environmental Medicine 1999; 70:1012-1017
BACKGROUND: Intraocular pressure (IOP) has been found to increase during microgravity. After peaking in the first few hours of orbital flight, IOP slowly decreases to a level that is slightly elevated above baseline IOPs. These modest elevations in IOP do not require treatment. Just as in 1-G, a clinically significant elevation of IOP that occurred during spaceflight would require treatment. The authors are not aware of previous studies of the efficacy of IOP lowering agents under conditions of microgravity. METHODS: This double-masked, placebo-controlled study measured the IOPs of 11 adult subjects (22 eyes) at baseline, preflight, and zero-gravity aboard the NASA KC-135 aircraft, and postflight. One eye of each of the subjects was treated with betaxolol hydrochloride ophthalmic solution 0.5%, while the contralateral eye was treated with normal saline placebo, for seven days prior to parabolic flight. IOPs were measured by the Tono-Pen 2, a gravity independent tonometer. RESULTS: A modest, but statistically significant reduction of 2.4 mmHg in mean IOP was noted in betaxolol treated eyes at the time of preflight measurement. During zero-G, the mean IOPs of both betaxolol treated eyes and placebo treated eyes increased approximately 20% over preflight levels. Postflight IOPs were similar to preflight IOPs. CONCLUSIONS: The effect of betaxolol on the IOP of eyes treated with for one week prior to exposure to microgravity was statistically significant, but may lack clinical significance in normal eyes. Further research needs to be done to determine the efficacy during microgravity of betaxolol and other agents, in subjects who have upper normal to slightly elevated IOPs at 1 G.
Dr. T.J. Pattinson, University of Texas Medical Branch, Galveston, TX, USA tpattins@ems.jsc.nasa.gov
Classification:
11.3.4 Betablocker (Part of: 11 Medical treatment > 11.3 Adrenergic drugs)
