Changes in Angle Configuration After Phacoemulsification Measured by Anterior Segment Optical Coherence Tomography

Abstract

Purpose To measure changes in angle width after phacoemulsification and intraocular lens (IOL) implantation using anterior segment optical coherence tomography (AS-OCT). Materials and Methods Twenty-one patients undergoing cataract surgery were recruited from the National University Hospital, Singapore. AS-OCT images were obtained of nasal and temporal angle quadrants before and at 1-month after surgery. Optical measurements of central anterior chamber depth were obtained, and gonioscopic measurement of angle width was recorded. AS-OCT angle width parameters measured in the nasal and temporal quadrants included the angle opening distance at 500 μm (AOD₅₀₀) anterior to the scleral spur and the trabecular iris surface area at 750 μm (TISA₇₅₀) anterior to the scleral spur. Preoperative and postoperative measurements were compared using paired samples t tests. Results Data were collected from 21 eyes of 21 subjects with cataract. Seven subjects also had gonioscopic evidence of primary angle closure. Mean anterior chamber depth increased from 2.92 (±0.54) to 4.24 (±0.57) mm (P=0.044) after cataract extraction. There was a significant increase in AS-OCT parameters for both nasal and temporal angles after surgery. An 88.2% increase in AOD₅₀₀ was measured for the nasal angle quadrant with a mean difference of 213.9 (±173) μm (P750 increased by 94.4% in the nasal angle with a mean difference of 0.134 (±0.104) μm² (P<0.001). Conclusions AS-OCT imaging demonstrates increases in angle width after cataract extraction.