May 2004
Volume 45, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2004
Continuous measurement by telemetry system of circadian IOP variations during 12 weeks treatment with beta–blockers in rabbits
Author Affiliations & Notes
  • N. Ishida
    Research & Development Center, Santen Pharmaceutical Co Ltd, Ikoma, Japan
  • T. Akaishi
    Research & Development Center, Santen Pharmaceutical Co Ltd, Ikoma, Japan
  • H. Hara
    Research & Development Center, Santen Pharmaceutical Co Ltd, Ikoma, Japan
  • Y. Kuwayama
    Ophthalmology, Osaka Koseinenkin Hospital, Osaka, Japan
  • Footnotes
    Commercial Relationships  N. Ishida, Santen Pharmaceutical Co Ltd E; T. Akaishi, Santen Pharmaceutical Co Ltd E; H. Hara, Santen Pharmaceutical Co Ltd E; Y. Kuwayama, None.
  • Footnotes
    Support  none
Investigative Ophthalmology & Visual Science May 2004, Vol.45, 2099. doi:
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      N. Ishida, T. Akaishi, H. Hara, Y. Kuwayama; Continuous measurement by telemetry system of circadian IOP variations during 12 weeks treatment with beta–blockers in rabbits . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2099.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Abstract: : Purpose: Continuous recording of intraocular pressure (IOP) by telemetry is useful for the evaluation of the efficacy of ocular hypotensive drugs and for monitoring circadian IOP variations. The aim of this study was to examine the effect of 12 weeks treatment with beta–blockers on circadian IOP fluctuations. Methods: A commercial telemetry system was used as described previously. IOP data from Japanese White rabbits were recorded over the whole 24–hour period under a controlled light–and–dark cycle. The IOP value was calculated every 2.5 minutes, and one–hour recordings were averaged. The animals were treated topically with Timoptol® 0.5% twice daily, Timoptol®XE 0.5% once daily, or saline (control) twice daily for 12 weeks, and circadian IOP variations were examined every week. Results: Baseline IOP was higher in the dark phase (7 p.m. to 7 a.m.; 23.3 +/– 1.0 mmHg) than in the light phase (7 a.m. to 7 p.m.; 17.1 +/– 1.1 mmHg), and this circadian rhythm continued throughout this study. The mean dark phase IOP in the last week of treatment was 23.4 +/– 1.1 mmHg for control, 21.1 +/– 1.1 mmHg for Timoptol®, and 22.2 +/– 0.7 mmHg for Timoptol®XE. The mean light phase IOP was 16.9 +/– 1.1 mmHg for control, 16.8 +/– 1.0 mmHg for Timoptol®, and 17.6 +/– 0.8 mmHg for Timoptol®XE. The mean maximal IOP reduction with Timoptol® and Timoptol®XE was 3.1 +/– 0.9 mmHg and 3.2 +/– 1.1 mmHg, respectively. The range of the circadian IOP fluctuations in the last week of treatment was 10.6 +/– 0.8 mmHg for control, 8.7 +/– 0.7 mmHg for Timoptol®, and 8.5 +/– 0.8 mmHg for Timoptol®XE. There was no tachyphylaxis during this study. No increase in IOP occurred immediately after cessation of the treatments. Conclusions: Our system can provide long–term evaluation of circadian IOP. Over 12 weeks, Timoptol® and Timoptol®XE showed similar efficacy in reducing both the dark phase IOP and the circadian IOP fluctuations, but not the light phase IOP, indicating that these beta–blockers provide a steady, flat circadian IOP curve.

Keywords: intraocular pressure • circadian rhythms • pharmacology 
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