Abstract
PurposeTo distinguish the frequently misdiagnosed plateau iris eyes from pupillary block group and normal group, we compared the ocular biometrical parameters of them by A-scan ultrasongraphy.MethodsIn total, we retrospectively reviewed general characteristics and ocular findings including ocular biometric measurements of 71 normal, 39 plateau iris, and 83 pupillary block eyes.ResultsThe normal controls, plateau iris group and pupillary block group were significantly different in age, but not in gender. The anterior chamber depth tended to decrease and the lens thickness tended to increase from normal to plateau iris to pupillary block eyes. Compared to those of plateau iris group, the pupillary block group had significantly shallower anterior chamber depth (2.90mm vs. 2.33mm; p<0.001), thicker lens (4.77mm vs. 5.11mm; p<0.001), shorter axial length (23.16mm vs. 22.63mm; p<0.001), smaller relative lens position (2.28 vs. 2.16; p<0.001) and larger lens/axial length factor (2.06 vs. 2.26; p<0.001). However, when comparing plateau iris and normal eyes, only axial length and lens/axial length factor were significantly different (23.16 vs. 23.54; p<0.05 and 2.06 vs. 1.96; p<0.05).ConclusionsMeasured by A-scan ultrasonography, the ocular biometrics of plateau iris were significantly different from those of pupillary block eyes. However, our A-scan ultrasongraphy generally found no significant biometric differences between plateau iris and normal eyes. These findings suggest that while A-scan ultrasonography might be used as a practical tool for differentiating plateau iris and papillary block eyes, a more meticulous gonioscopy and other assessments may be necessary to distinguish plateau iris from normal eyes.
Highlights
Aqueous humor, the water content inside the eye, is produced by the ciliary body, and leaves the eye at the anterior chamber angle (Fig. 1a)
The normal controls, plateau iris group and pupillary block group were significantly different in age, but not in gender
Our A-scan ultrasongraphy generally found no significant biometric differences between plateau iris and normal eyes. These findings suggest that while A-scan ultrasonography might be used as a practical tool for differentiating plateau iris and papillary block eyes, a more meticulous gonioscopy and other assessments may be necessary to distinguish plateau iris from normal eyes
Summary
The water content inside the eye, is produced by the ciliary body, and leaves the eye at the anterior chamber angle (Fig. 1a). If there is angle closure, the outflow pathway will be impeded and the accumulated aqueous inside the eye will cause intraocular pressure to rise. Plateau iris and pupillary block are both classified as angle closure. They cause primary angle-closure glaucoma (PACG) through different mechanisms. The iris-lens contact impedes the aqueous flow from posterior chamber to anterior chamber [2]. The resultant increased pressure gradient between posterior and anterior chamber makes the iris more convex and brings it into apposition with the angle structure [3] (Fig. 1c)
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