Regionally Discrete Aqueous Humor Outflow Quantification using Fluorescein Canalograms

Abstract

Purpose : To quantify conventional outflow directly in its anatomic location in a common anterior segment culture model.

Methods : We obtained fluorescein canalograms in six porcine whole eyes (WhEs) and six porcine anterior segment cultures (ACs). Eyes were perfused with a constant pressure of 15 mmHg using media containing 0.017 mg/ml fluorescein. Flow patterns were visualized using a stereo dissecting microscope equipped for fluorescent imaging as previously described. Canalograms were analyzed for filling time per quadrant using a custom designed R software package and a generalized additive model. Changes in outflow was quantified and compared over time in anterior segment cultures. The code and examples of its use will be publically available at GitHub.com.

Results : In WhEs, quantifiably faster flow was seen nasally compared to other regions. ACs had reduced numbers of functional collectors on day 1 without exhibiting a preferential flow pattern. Statistical analysis revealed correlations and increase in nasal filling in ACs on day 3. Automated imaging analysis algorithm classified areas of perilimbal outflow based on the total amount of flow and the rate of flow. Filling rates uncovered convergent perilimbal flow.

Conclusions : An algorithm was developed that analyzes regional and circumferential outflow patterns. Altered flow was detected in a common anterior segment culture model.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

Quantification of conventional aqueous humor outflow.