Dynamic volume‐rendered optical coherence tomography pupillometry

Abstract

To assess intrapupillary space (IPS) changes in healthy subjects with regard to decreased iris motility in patients with pseudoexfoliation glaucoma (PEXG) or non-arteritic anterior ischaemic optic neuropathy (NAION) in a feasibility study in a clinical environment.Methods: Scotopic and photopic IPS measurements using three-dimensionally rendered swept-source optical coherence tomography (SS-OCT) data were obtained and compared for all subjects. Intrapupillary space (IPS) parameters were evaluated such as absolute volumetric differences, relative light response for volumetric ratios and pupillary ejection fraction (PEF) for functional contraction measurements.Results: From a total of 122 IPS from 66 subjects, 106 IPS were eligible for comparison providing values for 72 normal, 30 PEXG and 4 NAION eyes. In healthy, PEXG and NAION subjects, scotopic overall mean IPS was 8.90, 3.45 and 4.16 mm 3 , and photopic overall mean IPS was 0.87, 0.74 and 1.13 mm 3 , respectively. Three-dimensional contractility showed a mean absolute difference of 8.03 mm 3 for normals (defined as 100% contractility), 2.72 mm 3 for PEXG (33.88% of normal) and 3.03 mm 3 for NAION (38.50% of normal) with a relative light response ratio between scotopic and photopic volumes of 10.26 (100%), 4.69 (45.70%) and 3.67 (35.78%), respectively. Pupillary ejection fraction (PEF) showed a contractile pupillary emptying of 88.11% for normals, 76.92% for PEXG and 70.91% for NAION patients. Conclusion:This 3D pupillometry OCT assessment allows for quantitative measurements of pupil function, contractility and response to light. More specifically, PEF is presented as a potential (neuro)-pupillary outcome measure that could be useful in the monitoring of ophthalmic disorders that affect pupillary function.

Iris Color Matters—A Contractility Analysis With Dynamic Volume-Rendered Optical Coherence Tomography Pupillometry

“…This retrospective study analyzed a subgroup of participants presented in an earlier publication. 4 In this previous study, a method for dynamic volume-rendered OCT pupillometry was presented by comparing participants with pseudoexfoliation glaucoma or non-arteritic anterior ischemic optic neuropathy to healthy controls. For this analysis, only the healthy eyes were included.…”

“…All data were acquired with dynamic OCT pupillometry using the swept-source DRI OCT-1 Atlantis (Topcon, Tokyo, Japan) with software version 9.12.003.04. 4 To acquire 3D pupillary volumes, the OCT signal was first focused on the corneal epithelium, and the scan area was then shifted posteriorly until the pupil area was centered on the display of the OCT device. Each volume consisted of 256 B-scans with 512 × 992 pixels, covering 6.0 mm × 6.0 mm × 2.6 mm.…”

“… 1 – 3 Recently, three-dimensional (3D) rendering of the pupil has been made possible with a commercially available OCT device. 4 …”

“…The function of the pupils can be regarded as a water pump system that pushes parts of the aqueous humor via contraction further toward the anterior chamber, where the flow through the aperture is regulated. 4 …”

“…Therefore, in this study, we analyzed the natural variability in pupillary contractility derived from a recently reported volumetric OCT acquisition method in a healthy Caucasian subgroup. 4 Because the changes to the aqueous humor inside the pupil cannot be accurately evaluated using planar imaging, a volumetric analysis was required. The pupillary contractility was measured with dynamic OCT pupillometry providing 3D intrapupillary space (IPS) volumes and was evaluated regarding the main factors of iris color, age, and sex.…”