Large Amplitude Iris Fluttering Detected by Consecutive Anterior Segment Optical Coherence Tomography Images in Eyes with Intrascleral Fixation of an Intraocular Lens

Abstract

Saccadic eye movements induce movements of the aqueous and vitreous humor and iris fluttering. To evaluate iris fluttering during eye movements, anterior segment optical coherence tomography (AS-OCT) was used in 29 eyes with pars plana vitrectomy (PPV) and intrascleral fixation of an intraocular lens (ISF group) and 15 eyes with PPV and an IOL implantation into lens capsular bag (control group). The height of the iris from the iris plane (the line between the anterior chamber angles) was compared every 0.2 s after the eye had moved from a temporal to the primary position (time 0). The height of the nasal iris in the ISF group decreased to −0.68 ± 0.43 mm at 0 s (p < 0.001) and returned to −0.06 ± 0.23 mm at 0.2 s. The height of the temporal iris increased to 0.45 ± 0.31 mm at 0 s (p < 0.001) and returned to −0.06 ± 0.18 mm at 0.2 s. The height of the nasal iris at 0 s in the ISF group was significantly lower, and that of the temporal iris was significantly higher than the control (−0.05 ± 0.09 mm, 0.03 ± 0.06 mm, p < 0.001, respectively). Iris fluttering can act as a check valve for aqueous and vitreous humor movements and can be quantified by consecutive AS-OCT images. Large amplitude iris fluttering in eyes with intrascleral fixation is important because it can lead to a reverse pupillary block.

Keywords: anterior segment optical coherence tomography; intraocular lens; intrascleral fixation; iris capture; peripheral iridectomy; reverse pupillary block.

Figure 1

Anterior segment optical coherence tomographic (AS-OCT) images are taken when the eye is fixed on a temporal target and then moves to the primary position. Also shown are images that show the parameters of the AS-OCT images that are measured. (a). AS-OCT image when the patient is looking at a point located 30 degrees temporal from the visual axis. (b). AS-OCT image taken immediately after the patient has moved the eye to the primary position and holds this position for 3 s. (c). The heights of the temporal and nasal sectors of the iris are defined as the distance from the iris plane (the line between anterior chamber angles) to the anterior surface of the nasal and temporal sectors of the mid-iris.

Figure 2

A plot of changes in the height of the temporal and nasal sectors of the iris immediately after a movement of the eye from a 30° temporal position to the primary position in an eye with an intrascleral fixation (ISF) of an intraocular lens (IOL). Also plotted are the values of an eye in which the IOL was implanted in the lens capsule, the control group. (a). The height of the nasal sector of the iris of eyes in the ISF group decreases significantly from the baseline at 0 s (p < 0.001) and returns at 0.2 s. The height of the temporal sector in eyes of the ISF group increases significantly from the baseline at 0 s and returns to the baseline at 0.2 s. (b). The height of the nasal sector of the iris in the ISF group at 0 s was significantly smaller than that of the control group (p < 0.001). The temporal height of the ISF group at 0 s was greater than that of the control (p < 0.001). The nasal height of the ISF group at 0 s was smaller than that of the control (p < 0.001). (* p < 0.01).

Figure 3

AS-OCT images of a 72-year-old woman in the ISF group. The nasal height of the iris (white arrow) decreases, and the temporal height (yellow arrow) increases at 0 s (b) from the baseline (a). The height of the nasal and temporal iris (yellow arrows) remains at the lower level at 0.2 s (c) and 0.4 s (d) and returns to the baseline level at 1.0 s (e,f).

Figure 4

AS-OCT images of a 67-year-old man in the control group who had undergone vitrectomy combined with cataract surgery for an idiopathic macular hole and had the IOL implanted in the capsular bag. The nasal height of the iris (white arrow) decreases at time 0 s (b) immediately after the eye stops at the primary position from the baseline (a). The nasal height (white arrows) increases at 0.2 s (c) and decreases (white arrows) at 0.4 s (d). The nasal height returns at 1.0 s (e) to the baseline position (f). The temporal height of the iris (yellow arrow) increases at 0 s and remains higher at 0.2 s (yellow arrow, c) and then returns to the baseline position at 0.4 s (d–f).

Figure 5

Changes in the height of the iris in the eyes after intrascleral fixation with and without peripheral iridectomy (PI). The nasal height of the iris in eyes with and without PI is significantly lower than the baseline position at 0 s and returned to the baseline position at 0.2 s (* p < 0.01). The temporal height in eyes with and without PI was significantly higher than the baseline position and also returned to the baseline position at 0.2 s. The nasal and temporal height of the iris in eyes with PI was not significantly different from that without PI at any time point.

Figure 6

AS-OCT images of a 55-year-old man with an impending pupillary block after intrascleral fixation of an IOL without a peripheral iridectomy. (a). AS-OCT image indicates that there is an excessive iris retraction and the anterior chamber depth is 7.07 mm. (b). Analysis of the AS-OCT images indicates that the nasal and temporal heights of the iris changes induced by the eye movements, but the height is maintained very low.