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Iridolenticular Contact Decreases Following Laser Iridotomy for Pigment Dispersion Syndrome

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Iridolenticular Contact Decreases Following Laser Iridotomy for Pigment Dispersion Syndrome CLINICAL SCIENCES Iridolenticular Contact Decreases Following Laser Iridotomy for Pigment Dispersion Syndrome Peter J. Breingan, MD; Kohji Esaki, MD; Hiroshi Ishikawa, MD; Jeffrey M. Liebmann, MD; David S. Greenfield, MD; Robert Ritch, MD Objective: Toevaluatechangesinanteriorsegmentanatomy mean±SD refractive error was −5.0 ± 3.9 diopters. Angle after laser iridotomy for pigment dispersion syndrome. recess area (mean±SD, 0.78 ± 0.28 vs 0.35 ± 0.11 mm2; P=.001, paired t test) and iris-lens contact distance (2.05 Methods: Ultrasound biomicroscopy was performed on ± 0.28 vs 0.79 ± 0.13 mm; P,.001) decreased following 7 eyes of 7 untreated patients with reverse pupillary block iridotomy. Central anterior chamber depth did not change. and pigment dispersion syndrome. A radially oriented im- age with the probe perpendicular to the eye in the supe- Conclusion: Flattening of the iris following laser iri- rior meridian was obtained before and at least 1 week af- dotomy for pigment dispersion syndrome causes a de- ter laser iridotomy in each eye. We assessed changes in crease in iris-lens contact and angle width while lens po- angle recess area and iris-lens contact distance. sition remains constant. Results: Mean ± SD patient age was 31.3 ± 5.7 years and Arch Ophthalmol. 1999;117:325-328 PERIPHERAL iris concavity RESULTS facilitates iridozonular contact and pigment lib- Seven eyes of 7 patients (5 men, 2 wom- eration in pigment disper- en) were enrolled (Table 1). Mean pa- sion syndrome and pig- tient age was 31.3 ± 5.7 years (range, 23-37 Amentary glaucoma. In reverse pupillary years). All patients were white. There were block, this concavity is due to greater aque- 5 left eyes and 2 right eyes. The mean ous humor volume or pressure in the an- spherical equivalent refractive error was terior chamber relative to the posterior −5.0 ± 3.9 diopters (range, plano to −10.75 chamber, which pushes the iris posteri- diopters). Mean axial length was 26.1 ± 2.1 orly.1 How and why reverse pupillary block mm (range, 24.1-29.0 mm). Before iri- develops, however, remains poorly eluci- dotomy, all irides had a concave configu- dated. It is believed analogous to relative ration between the iris root and the point (forward) pupillary block, which leads to of iris-lens contact. After iridotomy, all iri- angle-closure glaucoma. Like pupillary des assumed a planar configuration from block, is relieved by laser iridotomy, which the insertion at the ciliary face to the point From the Departments of produces a planar iris configuration in both of peripheral contact with the anterior lens Ophthalmology, New York Eye disorders. In relative pupillary block, the capsule (Figure 2). and Ear Infirmary, New York loss of iris convexity after iridotomy is ac- Mean angle recess area decreased (Drs Breingan, Esaki, 2 Ishikawa, Liebmann, companied by increased iris-lens con- from 0.78 ± 0.28 mm before laser iri- 2 Greenfield, and Ritch); and tact, as the central iris falls backward with dotomy to 0.35 ± 0.11 mm after laser iri- New York Medical College, the elimination of the aqueous pressure in dotomy (P=.001) (Table 2). Iris-lens con- Valhalla the posterior chamber.2 If the reverse pu- tact distance decreased from 2.05 ± 0.28 (Drs Ishikawa, Liebmann, pillary block in pigment dispersion syn- mm to 0.79 ± 0.13 mm after laser iri- Greenfield, and Ritch). drome is analogous to this, then iris-lens dotomy (P,.001). There was no signifi- Dr Esaki is now affiliated with contact should decrease and the central iris cant change in central anterior chamber the Department of should move anteriorly with the elimina- depth before (3.4 ± 0.2 mm) vs after (3.3 Ophthalmology, Mie University tion of the aqueous pressure gradient from ± 0.2 mm) iridotomy. School of Medicine, Mie, Japan. the anterior to the posterior chamber. To Dr Greenfield is now affiliated with Bascom-Palmer Eye test this hypothesis, we used ultrasound Institute, Miami, Fla. The biomicroscopy to evaluate the effect of la- ser iridotomy on angle width and irido- This article is also available on our authors have no financial Web site: www.ama-assn.org/ophth. interest in any device described lenticular contact distance in eyes with pig- in this article. ment dispersion syndrome. ARCH OPHTHALMOL / VOL 117, MAR 1999 325 ©1999 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/29/2021 SUBJECTS AND METHODS C All patients with pigment dispersion syndrome who had undergone ultrasound biomicroscopic imaging S at the New York Eye and Ear Infirmary, New York, both before and after laser iridotomy were included. All patients had had elevated intraocular pressure ARA AC with or without glaucomatous damage. The use of topical medications other than cholinergic agonists was not grounds for exclusion. Informed consent was obtained from all patients using forms CB approved by the institutional review board of the Ir New York Eye and Ear Infirmary. Argon laser iri- dotomy was performed within 1 clock hour of the LC 12-o’clock meridian in the peripheral iris. The size of the aperture attained was approximately 100 µm in diameter. Ultrasound biomicroscopy (Humphrey Sys- Figure 1. Anterior segment anatomy in pigment dispersion syndrome. The cornea (C), iris (Ir), sclera (S), anterior chamber (AC), scleral spur (arrow), tems Inc, San Leandro, Calif) was performed using ciliary body (CB), lens capsule (LC), anterior chamber angle (white arrow) a 50-MHz transducer with tissue penetration of 4 and angle opening distance are shown. Iris-lens contact distance (white line) to 5 mm. All scanning was done with the patient and angle recess area (ARA) are shown. in the supine position, while room illumination, fixation, and accommodation were held constant by having the patient fixate with the fellow eye on Table 1. Patient Data* a ceiling target. A radially oriented image in the superior meridian was obtained before and at least Patient No./ Axial Refractive 1 week after laser iridotomy. Anterior chamber Age, y/Sex Eye Length, mm Error, D† depth was obtained by A-scan ultrasonography (Auto Ref-Keratometer RK2; Canon, Tokyo, 1/23/M Left 26.2 −1.25 2/36/M Left NA −8.00 Japan). Recorded data included age, sex, race, 3/33/M Right NA Plano refractive error, axial length, and central anterior 4/37/M Left 26.0 −5.00 chamber depth. 5/29/F Right 29.0 −10.75 Captured image files were exported as PCX- 6/25/F Left 25.2 −7.25 formatted data via floppy disks into a personal com- 7/36/M Left 24.1 −3.00 puter. Images were analyzed using a software pro- gram of our own design running on Microsoft *All patients were white. D indicates diopters; NA, not applicable. Windows95 (Microsoft Corp, Seattle, Wash). The †Spherical equivalent. position of the scleral spur was defined as the inner- most point of a line separating ciliary muscle and scleral fibers and localized on the ultrasound biomi- COMMENT croscopic image by the observer. Angle recess area was defined as the triangular area bordered by the Pigment dispersion syndrome is an autosomal dominant anterior iris surface, corneal endothelium, and a disorder in which iridozonular friction resulting in disrup- line perpendicular to the corneal endothelium tion of the posterior pigment epithelium of the iris is fa- drawn from a point 750 µm anterior to scleral spur cilitated by a concave iris configuration,4,5 which is accen- to the iris surface (Figure 1). This parameter tuated by accommodation6,7 and reversed by inhibition of improves on simple measurement of the angle in 7 5 5,8 degrees by taking irregularities of anterior iris con- blinking, miotic therapy, or laser iridotomy. The epi- tour into account.3 Angle recess area was automati- thelial disruption, the dispersion of pigment within the an- cally calculated following localization of scleral spur terior chamber, and pigment deposition on anterior seg- by the observer. ment structures result in the classic triad of midperipheral, Iris-lens contact distance was measured along slitlike, radially oriented transillumination defects, Kruken- the iris pigment epithelium from the pupillary bor- berg spindle, and dense trabecular pigmentation. The iris der centrally to the point at which the iris can be dis- concavity is believed to result from reverse pupillary block cerned to separate from the anterior lens capsule. An- due to increased aqueous pressure or volume in the ante- terior chamber depth was also measured along a single rior chamber relative to the posterior chamber.1,9 We have A-scan line that penetrated the center of the cornea hypothesized that blinking results in transfer of a bolus of and the pupil. These 2 variables were measured us- 10 ing a caliper provided in the ultrasound biomicro- aqueous humor into the anterior chamber and that sub- scopic software. sequent equilibration between the 2 chambers is pre- Postoperative changes in anterior segment vented by an increased iridolenticular contact distance,11 anatomy were evaluated statistically using the paired which might possibly result from a disproportion in the t test. All values are given as mean±SD. size of the iris relative to that of the anterior segment.12 Al- ternatively, the reverse pupillary block itself might flatten the iris against the lens surface. ARCH OPHTHALMOL / VOL 117, MAR 1999 326 ©1999 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/29/2021 ARA ARA Figure 2. Left, Iris configuration before laser iridotomy. The iris has a concave configuration. There is a long region of iris-lens contact (white arrow). Black arrow indicates scleral spur. Right, After laser iridotomy and elimination of reverse pupillary block.
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