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Ahmad Najafi, Sung Chul Park, Jeffrey M Liebmann, Robert Ritch; Use of a Novel Anterior Segment Swept-Source Optical Coherence Tomography in Assessing Iris and Iridocorneal Angle Structures. Invest. Ophthalmol. Vis. Sci. 2014;55(13):931.
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© ARVO (1962-2015); The Authors (2016-present)
To test a novel high-speed, high-resolution anterior segment swept-source optical coherence tomography (SS-OCT) in assessing the iris and iridocorneal angles in different physiologic conditions.
Horizontal cross-sectional B-scans were obtained for the nasal and temporal iridocorneal angles of normal subjects using a novel anterior segment SS-OCT (Casia SS-1000; Tomey, Nagoya, Japan). Iris and iridocorneal angle structures were assessed in different positions of gaze and during accommodation.
Sixteen normal eyes (8 subjects) were tested. The SS-OCT successfully imaged the cornea, iris and anterior chamber angles and provided semi-automated built-in measurement tools for those structures (Fig 1). Forward movement of the lens, changes in iris curvature, and widening of the iridocorneal angles (increase in angle opening distance [AOD] and trabecular iris angle [TIA]) during accommodation were demonstrated (Fig 1A, 1B). Changes in iridocorneal angle measurements (AOD and TIA) on abduction and adduction of the eyes were also identified (Fig 1C-1E). Regional iris length and thickness also underwent dynamic changes depending on the position of the tested eye and/or regional difference in illumination; in straight forward gaze, the tested eye became slightly adducted and the temporal iris region became longer and thinner than the nasal iris region (Fig 1F, 1G).
This new anterior segment SS-OCT provides high-speed, high-resolution cross-sectional images of the anterior segment structures and may be helpful in investigating and understanding subtle pupillary movement and iridocorneal angle structure changes in various conditions. Eye position relative to the light source of the OCT and accommodation may cause changes in iris and iridocorneal angle structures. A standardized protocol for testing condition is needed for reliable and accurate assessment of the anterior segment structures using SS-OCT.
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