Digital Imaging Analysis of Pupil Shape and Size in Reference to Cornea Apex in Cataract Surgery
Narrative Responses:
Purpose
To implement digital analysis of pupil imaging (shape and size) in relation to cornea apex position and compare preoperative and postoperative data to measure the extent of pupil centration changes following cataract surgery.
Methods
Thirty-five consecutive cataract cases (70 eyes) were digitally imaged pre- and post-operatively by Placido Topography (Vario Topolyzer, WaveLight, Erlagen, Germany) providing accurate pupil imaging and cornea apex identification. Digital analysis implemented on the images investigated the Cartesian coordinates (nasal – temporal being the horizontal, and superior-inferior the vertical axis) of the corneal apex (approximating the intersection of line of sight with the cornea) to the pupil geometric center (approximating the visual axis). The Cartesian changes of the differences were associated with postoperative pupil centroid shift.
Results
The photopic pupil measurements indicated a pre-operative temporal location of 0.24 ± 0.15 (0.03 to 0.44) mm and a superior of 0.01±0.14 (-0.22 to +0.18) mm. Postoperatively, the pupil center was located temporally by 0.15 ± 0.12 (0.27 to -0.01) mm and superiorly by +0.06 ± 0.21 (-0.33 to 0.22) mm. The scotopic pupil measurements were preoperatively temporally by 0.28 ± 0.15 (0.41 to 0.03) mm, and inferiorly by 0.02 ± 0.20 (-0.24 to 0.29) mm. Postoperatively the pupil center was temporally by 0.20 ± 0.10 (0.04 to 0.28) mm and superiorly by 0.04 ± 0.19 (-0.26 to +0.27) mm.
Conclusion
There was a similar shift of both the photopic and scotopic pupil measurements from temporal location of 0.24 ± 0.15 (0.03 to 0.44)mm and superior of 0.01±0.14 (-0.22 to +0.18) mm, to temporally by 0.15 ± 0.12 (0.27 to -0.01)mm and superiorly by +0.06 ± 0.21 (-0.33 to 0.22) mm.