June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Effect of Latanoprost on Aqueous Humor Dynamics with an Objective Method of Episcleral Venous Pressure Measurement in Normal Eyes
Author Affiliations & Notes
  • Arash Kazemi
    Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
  • Jay W McLaren
    Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
  • Shuai-Chun Lin
    Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
  • Carol B Toris
    Ophthalmology & Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States
    Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States
  • Vikas Gulati
    Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States
  • David M Reed
    Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States
  • Sayoko Eileen Moroi
    Ophthalmology & Visual Sciences, University of Michigan-Kellogg Eye Center, Ann Arbor, Michigan, United States
  • Arthur J Sit
    Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
  • Footnotes
    Commercial Relationships   Arash Kazemi, None; Jay McLaren, None; Shuai-Chun Lin, None; Carol Toris, None; Vikas Gulati, None; David Reed, None; Sayoko Moroi, None; Arthur Sit, None
  • Footnotes
    Support  1-NIH grant EY022124, 2-NIH grant EY007003, 3- Research to Prevent Blindness
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 2099. doi:
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      Arash Kazemi, Jay W McLaren, Shuai-Chun Lin, Carol B Toris, Vikas Gulati, David M Reed, Sayoko Eileen Moroi, Arthur J Sit; Effect of Latanoprost on Aqueous Humor Dynamics with an Objective Method of Episcleral Venous Pressure Measurement in Normal Eyes. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2099.

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

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Abstract

Purpose : Mechanisms of action of latanoprost have not been completely understood. Its primary action appears to be on the uveoscleral outflow pathway, but some studies have also suggested increased outflow facility. As well, the effect of latanoprost on episcleral venous pressure (EVP) remains poorly understood. In this study we evaluated the effect of latanoprost on all aqueous humor dynamic (AHD) parameters in normal subjects.

Methods : Forty-eight eyes from 24 normal subjects (6 males, 18 females; 52±8 years, mean±SD) were included as part of a larger study (NCT01677507, ClinicalTrials.gov) to examine the variation of IOP response. The following AHD parameters were assessed: IOP by pneumatonometry; EVP by using a computer-controlled episcleral venomanometer with video recording and processing to determine the pressure required to initiate collapse of the vein; aqueous humor flow by fluorophotometry; outflow facility by 2-minute pneumatonography and uveoscleral outflow calculated by using the modified Goldmann equation. After 7 days treatment with latanoprost 0.005% OU daily, AHD parameters were remeasured. Changes in IOP, EVP, outflow facility and aqueous flow in response to latanoprost were analyzed by using generalized estimating equation models to account for possible correlation between fellow eyes of the same subject.

Results : IOP decreased from 13.2 ± 2.2 mmHg to 11.4 ± 1.6 (mean ± SD, P<0.001), and EVP decreased from 6.6 ± 1.5 mmHg to 6.1 ± 1.6 (P=0.047). Tonographic outflow facility increased from 0.21 ± 0.07 μl/min/mmHg to 0.26 ± 0.08 (P<0.001). There was no significant change in either aqueous humor flow rate (2.64 ± 0.52 μl/min at baseline and 2.62 ± 0.65 after treatment, P=0.9) or uveoscleral outflow rate (1.31 ± 0.9 μl/min at baseline and 1.24 ±1.0 after treatment, P=0.7).

Conclusions : Our complete assessment of AHD parameters indicates that latanoprost increases tonographic outflow facility but not the pressure-insensitive uveoscleral outflow rate. This suggests that any changes in the uveoscleral pathway with latanoprost treatment may be related to the development of IOP-dependent (not pressure-insensitive) flow. The small decrease in EVP is possibly due to vasodilation of episcleral veins. Future AHD studies in ocular hypertensive and glaucoma patients are required to better understand if the mechanisms of action are similar in other patient populations.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

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