Abstract
Abstract: :
Purpose: Latanoprost has gained popularity as a first–line medication in normal–tension glaucoma. However, ‘nonresponders’ who lack response to latanoprost do exist. The purpose of this study is to investigate the prevalence of nonresponders and contributing factors to nonresponders in normotensive normal subjects. Methods: With informed consent approved by the IRB, baseline intraocular pressure (IOP) was measured by applanation tonometry (Goldmann) at 9 AM, 1:30 PM, 6 PM on day 0 in 46 normotensive normal subjects (40 males, 6 females, mean age 24.5±2.4y.o.). Central corneal thickness and refraction were also measured on day 0. At 9 AM on day 1 and each of the following 6 days, 0.005% latanoprost was applied to one eye. The other eye served as non–treated control. Diurnal IOP measurement was repeated on day 7. IOP decrease was calculated at each time point according to the following formula. IOP decrease ={(Tpre–Tpost)–(Cpre–Cpost)}÷Tpre*100(%), where T and C are IOP of treated and control eyes, respectively, and pre and post mean pre– and post– treatment corresponding to day 0 and day 7, respectively. Nonresponders were defined as subjects with the IOP decrease <10%. Conjunctival hyperemia in the treated eyes was evaluated on day 7. Results: Latanoprost significantly reduced mean diurnal IOP of treated eyes from 13.3±2.1 mmHg to 10.9±2.1 mmHg (p<0.0001, Student’s t–test), but did not alter the extent of diurnal fluctuation of IOP significantly. The magnitude of IOP decrease was similar among 3 time points. Mean diurnal IOP decrease was 18.2±10.2 % for all subjects, 4.4±3.3 % for nonresponders (n=11, 24%), and 22.5±7.3 % for responders (n=35, 76%). IOP at day 0, diurnal fluctuation of IOP at days 0 and 7, refraction, central corneal thickness, and severity of hyperemia of treated eyes were not significantly different between nonresponders and responders. Conclusions: One forth of normotensive normal subjects have little or low response to latanoprost.
Keywords: drug toxicity/drug effects • intraocular pressure • pharmacology