Aqueous Humor Dynamics Changes and Predictors of IOP Response to Latanoprost

Abstract

Purpose : The variable responses to latanoprost among patients are poorly understood. The goal of this study was to evaluate the relationships between different IOP responses to latanoprost and baseline characteristics of participants, baseline aqueous humor dynamics (AHD) parameters, and changes in these parameters after treatment.

Methods : This study assessed 226 eyes from 113 normal participants in the EDEN Study (29 males, 84 females; 55±9 years, ±SD). Measured AHD parameters at baseline included: IOP by pneumatonometry, episcleral venous pressure (EVP) by venomanometry, aqueous humor flow rate by fluorophotometry, outflow facility by 2-minute pneumatonography, and uveoscleral outflow calculated by using the modified Goldmann equation. After 7 days of daily treatment with latanoprost 0.005% OU, all measurements were repeated. IOP responses were categorized into 3 groups based on the percent IOP reduction from baseline: non-responders (<10% reduction), medium-responders (10% to 20% reduction), and high-responders (≥20% reduction). Changes in AHD parameters in each group were analyzed by using generalized estimating equation models.

Results : There were no significant differences in age, axial length, central corneal thickness, EVP, outflow facility, aqueous flow rate, and uveoscleral outflow at baseline between the 3 groups (P>0.05, Table 1). Baseline IOP was higher in high-responders than medium-responders and non-responders (P=0.007 and P<0.001, respectively). Also, body mass index (BMI) was higher in high-responders compared to non-responders (P=0.01). IOP decreased while outflow facility and uveoscleral outflow increased after latanoprost treatment in high-responders and medium-responders but did not change in non-responders (Table 2). EVP and aqueous flow rate did not change significantly in any group. The change in uveoscleral outflow was greater in high-responders than in non-responders (P=0.03). Changes in outflow facility were not different between the 3 groups (P>0.4).

Conclusions : In normal subjects, higher baseline IOP and higher BMI may predict a greater IOP reduction by latanoprost. Increases in outflow facility and uveoscleral outflow are responsible for this larger response. Additional studies are needed to determine the parameters that predict a stronger response to latanoprost in patients with ocular hypertension and glaucoma.

This is a 2020 ARVO Annual Meeting abstract.

 

Table 1. Comparison of Baseline Characteristics

 

Table 2. AHD Changes by Group