Sampling aqueous humor: anterior segment anatomy, anesthetic and surgical technique, and rates of yield

To evaluate anterior segment anatomy and anesthetic and surgical techniques with respect to the amount of aqueous humor (AH) that can be sampled out of the anterior chamber (AC) at the beginning of standard cataract removal procedures (phacoemulsification).

In a prospective survey, volumes of sampled AH from 123 eyes (110 patients) were analyzed in regard to AC anatomy (anterior chamber depth, ACD) and different anesthetic techniques (local and general anesthesia).

107 eyes (87%) were included into our analysis, and 16 eyes (13%) had to be excluded due to failure of AH collection. We found a significant positive association between ACD and obtained AH volume (p=0.007). In general anesthesia, a strong trend to acquire more AH in comparison to local anesthesia was apparent, but statistical significance failed (p=0.167). Different anesthetic techniques seem to have no significant influence on ACD (p=0.169). No training curve for the individual surgeon was obtained. No complications were observed.

When AH sampling is performed in eyes with a deep AC and when the procedure is performed under general anesthesia, more AH can be aspirated.