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Ajay Kolli, David Reed, Jesse Gilbert, Carol B Toris, Arthur J Sit, Vikas Gulati, Arash Kazemi, David C Musch, Sayoko Eileen Moroi; Effects of Timolol and Latanoprost on Ocular Perfusion Pressure in Eyes of Healthy Volunteers. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5624.
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© ARVO (1962-2015); The Authors (2016-present)
Low ocular perfusion pressure (OPP) is an emerging risk factor for glaucoma development and progression. Our purpose was to test the hypothesis that timolol (TT) and latanoprost treatment (LT) increase OPP, but TT has a more limited effect due to its potential to reduce blood pressure (BP).
This is a multi-center prospective study (NCT01677507) of both eyes in 121 eligible healthy volunteers 40-81 years old (55.1+8.8 years, mean+SD). Each volunteer underwent baseline evaluation followed by a randomized crossover 1-week treatment with timolol 0.5% dosing twice daily and latanoprost 0.005% dosing once nightly separated by a 6-week washout between drugs. Primary outcome measures included IOP measured by pneumatonometry and systolic and diastolic BPs (SBP and DBP), all of which were evaluated at baseline and after 1-week TT and LT. OPP was calculated as 2/3×[DBP+1/3×(SBP−DBP)]–IOP. Multiple ANOVA with repeated measures (MANOVA) was used to compare IOP, SPB, DBP, and OPP under baseline, TT and LT. Linear regression analysis (LRA) was used to assess variables that may modulate the effect of TT and LT on OPP.
There were no significant differences in baseline characteristics between the 111 TT and 116 LT participants. MANOVA showed a significant difference in baseline, TT, and LT measurements of SBP, IOP and OPP (Table 1). Mean OPP was 49.2±7.9 mmHg at baseline. TT increased OPP to 50.1±7.9 mmHg and LT increased OPP to 51.3±7.9 mmHg. TT reduced SBP by 3.5±8.5mmHg (p<0.001) compared to baseline. LRA found that diagnoses of thrombotic disorder and depression were respectively associated with greater and lesser increases in OPP by TT, however further research is needed to determine clinical significance.
While TT and LT conferred statistically significant increases in OPP in this crossover study of healthy volunteers, timolol’s benefit to OPP was limited in part because it also significantly reduced systemic SBP. Given the growing evidence of the role of low OPP on glaucoma risk, assessing BP effects of glaucoma medical treatment may be an important complement to IOP.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
Table 1: Effects of Timolol and Latanoprost on IOP, BP, and OPP.
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