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; PϽ.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 image 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 (PϽ.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 laser 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.

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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 iridotomy 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 program 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.

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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. Arrow indicates laser iridotomy; ARA indicates angle recess area.

Table 2. Anterior Chamber Anatomy Before and After Laser Iridotomy*

P, Before Laser After Laser Paired Parameter Iridotomy Iridotomy % Change t Test AC depth, mm 3.4 ± 0.2 3.3 ± 0.2 1.2 ± 2.4 .4 ARA, mm2 0.78 ± 0.28 0.35 ± 0.11 53.0 ± 10.0 .001 Anterior chamber angle, degrees 58.4 ± 9.5 42.9 ± 10.7 27.4 ± 9.9 .0001 Angle opening distance, mm 1.1 ± 0.3 0.5 ± 0.2 50.0 ± 8.4 .00017 Iris-lens contact distance, mm 2.05 ± 0.28 0.79 ± 0.13 61.7 ± 6.4 Ͻ.000

*Data are presented as mean ± SD unless otherwise indicated. AC indicates anterior chamber; ARA, angle recess area.

Eyes with forward pupillary block have a smaller than normal anterior segment; relative pupillary block typi- cally occurring in hyperopic eyes, which have a shorter than average axial length; a more shallow anterior chamber; a thicker lens; a more anterior lens position; and a Figure 3. Composite ultrasound biomicroscopy of an eye with forward smaller radius of corneal curvature.13-17 Eyes with pig- (relative) pupillary block angle-closure. Top, Before iridotomy. Bottom, After ment dispersion syndrome are usually myopic and have iridotomy. a greater than normal anterior chamber depth and volume.18 Eyes with forward pupillary block have a convex ber depth, similar to what has been reported in forward iris configuration and decreased iridolenticular contact. pupillary block.19 After iridotomy, the angle width increases, iris configu- Although our knowledge as to why relative pupil- ration becomes planar or even concave, and iridolen- lary block develops in pigment dispersion syndrome is ticular contact increases (Figure 3).2 If reverse pupil- incomplete, all evidence supports the concept that a “flap lary block is analogous to forward pupillary block, the valve” effect allows aqueous to move in a forward direc- angle width should decrease, the iris configuration should tion only. Whether the increased iridolenticular appo- become planar, and iridolenticular contact should de- sition is due to an abnormality of iris size or iris rigidity crease, which is what we have found. In both disorders, remains to be elucidated. The development of software iridotomy creates a communication between the ante- to measure iris volume under varying circumstances rior and posterior chambers, equalizing pressures across should facilitate further understanding. the iris (which can be analogized to an impermeable mem- brane between 2 solutions) leading to a planar configu- Accepted for publication November 17, 1998. ration and decreased iridolenticular contact. We found This study was supported in part by the New York Glau- no significant effect of iridotomy on central anterior cham- coma Research Institute, the Department of Ophthalmology

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©1999 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/29/2021 Research Fund of the New York Eye and Ear Infirmary (Dr 7. Liebmann JM, Tello C, Chew S-J, et al. Prevention of blinking alters iris configu- Esaki), and The David Warfield Fellowship Program in Oph- ration in pigment dispersion syndrome and in normal eyes. Ophthalmology. 1995; 102:446-455. thalmology of the New York Community Trust and the New 8. Haynes WL, Alward WLM, Tello C, et al. Incomplete elimination of exercise- York Academy of Medicine (Dr Ishikawa), New York, NY. induced pigment dispersion by laser iridotomy in pigment dispersion syn- Presented in part at the annual meeting of the Asso- drome. Ophthalmic Surg Lasers. 1995;26:484-486. ciation for Research in Vision and Ophthalmology, Fort Lau- 9. Karickhoff JR. Reverse pupillary block in pigmentary glaucoma: follow up and new developments. Ophthalmic Surg. 1993;24:562-563. derdale, Fla, May 12, 1998. 10. Chew SJ, Tello C, Wallman J, Ritch R. Blinking indents the cornea and reduces Reprints: Robert Ritch, MD, Glaucoma Service, De- anterior chamber volume as shown by ultrasound biomicroscopy [abstract]. In- partment of Ophthalmology, New York Eye and Ear Infir- vest Ophthalmol Vis Sci. 1994;35(suppl):1573. mary, 310 E 14th St, New York, NY 10003 (e-mail: 11. Liebmann JM, Langlieb A, Stegman Z, et al. Anterior chamber anatomy in asym- [email protected]). metric pigment dispersion syndrome [abstract]. Invest Ophthalmol Vis Sci. 1995; 36(suppl):S562. 12. Ritch R. A unification hypothesis of pigment dispersion syndrome. Trans Am REFERENCES Ophthalmol Soc. 1996;94:381-409. 13. Lowe RF. Primary angle-closure glaucoma: a review of ocular biometry. Austral J Ophthalmol. 1977;5:9-17. 1. Karickhoff JR. Pigmentary dispersion syndrome and pigmentary glaucoma: a new 14. Delmarcelle Y, Franc¸ois J, Goes F, et al. Biometrie oculaire clinique (oculomet- mechanism concept, a new treatment, and a new technique. Ophthalmic Surg. rie). Bull Soc Ophthalmol Belge. 1976;1:172. 1992 ;23:269-277. 15. Tomlinson A, Leighton DA. Ocular dimensions in the heredity of angle-closure 2. Caronia RM, Liebmann JM, Stegman Z, et al. Iris-lens contact increases follow- glaucoma. Br J Ophthalmol. 1973;57:475-486. ing laser iridotomy for pupillary block angle-closure. Am J Ophthalmol. 1996; 16. Lowe RF, Clark BAJ. Posterior corneal curvature: correlations in normal eyes and 122:53-57. in eyes involved with primary angle-closure glaucoma. Br J Ophthalmol. 1973; 3. Ishikawa H, Liebmann JM, Ritch R. Quantitative ultrasound biomicroscopy. Oph- 57:475-478. thalmic Pract. 1998;16:133-138. 17. Lee DA, Brubaker RF, Ilstrup DM. Anterior chamber dimensions in patients 4. Campbell DG. Pigmentary dispersion and glaucoma: a new theory. Arch Oph- with narrow angles and angle-closure glaucoma. Arch Ophthalmol. 1984;102: thalmol. 1979;97:1667-1672. 46-50. 5. Potash SD, Tello C, Liebmann J, Ritch R. Ultrasound biomicroscopy in pigment 18. Davidson JA, Brubaker RF, Ilstrup DM. Dimensions of the anterior chamber in dispersion syndrome. Ophthalmology. 1994;101:332-339. pigment dispersion syndrome. Arch Ophthalmol. 1983;101:81-83. 6. Pavlin CJ, Macken P, Trope G, et al. Accommodation and iridotomy in the pig- 19. Jacobs IH, Krohn DL. Central anterior chamber depth after laser iridectomy. Am ment dispersion syndrome. Ophthalmic Surg Lasers. 1996;27:113-120. J Ophthalmol. 1980;88:865-867.

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