- Email: [email protected]
Cataract Surgery for Residual Angle Closure after Peripheral Laser Iridotomy
Cataract Surgery for Residual Angle Closure after Peripheral Laser Iridotomy Atsushi Nonaka, MD, Takehisa Kondo, MD, Masashi Kikuchi, MD, Kenji Yamashiro, MD, Masashi Fujihara, MD, Takuji Iwawaki, MD, Kaoruko Yamamoto, MD, Yasuo Kurimoto, MD Purpose: To investigate the frequency of residual angle closure after resolution of pupillary blocking by laser peripheral iridotomy and the effects of subsequent cataract surgery to resolve angle closure completely. Design: Retrospective, consecutive, interventional study. Participants: Among 70 eyes treated with laser iridotomy, 13 with residual angle closure were treated with cataract surgery. Methods: The provocative test of angle closure by prone position in a dark room for 1 hour was performed; increases in tension of ⱖ8 mmHg, 6 or 7 mmHg, and ⱕ5 mmHg were considered to be positive, suspected positive, and negative, respectively. Configuration of the anterior chamber was examined using ultrasound biomicroscopy (UBM). Main Outcome Measures: Intraocular pressure (IOP), response to the dark room prone position test, and morphologic analysis by UBM were evaluated before and 3 months after cataract surgery. Results: Residual angle closure after iridotomy was seen in 27 (38.6%) of 70 eyes; this was confirmed functionally by the dark room prone position test and morphologically by UBM. Eyes with IOP of ⱖ20 mmHg or with a glaucomatous visual field defect before iridotomy had a significantly higher incidence of residual angle closure after iridotomy than eyes without these findings (P⬍0.05). In all the eyes with residual angle closure after iridotomy, the response to the prone position test became negative after cataract surgery, with significant lowering of IOP (P⬍0.01). Conclusions: Residual angle closure after iridotomy was common, especially in eyes with primary angle closure and poorly controlled IOP or glaucomatous optic neuropathy. Cataract surgery was effective to resolve completely the residual angle closure after iridotomy and lower IOP. Ophthalmology 2005;112:974 –979 © 2005 by the American Academy of Ophthalmology.
Laser iridotomy has been used widely for treating acute or chronic angle-closure glaucoma (ACG) by relieving pupillary blocking, because pupillary blocking has been suggested to be a major cause of primary ACG (PACG). Accordingly, poor control of postiridotomy intraocular pressure (IOP) has been thought to be caused by a combined mechanism of primary open-angle glaucoma or dysfunction of the trabecular meshwork, which is closed by peripheral anterior synechia and damaged by pigmentary cells released from the iridotomy site.1 Recent advances in morphologic assessment of angle closure with ultrasound biomicroscopy (UBM), however, have revealed that multiple mechanism ACG, due primarily to coexistence of pupillary blocking and plateau iris, is Originally received: August 20, 2004. Accepted: December 22, 2004. Manuscript no. 2004-36. From the Department of Ophthalmology, Kobe City General Hospital, Kobe, Japan. Presented in part at: Japanese Ophthalmological Society 108th Annual Meeting, April, 2004; Tokyo, Japan. The authors have no conflict of interest and no financial interest in the subject matter or materials discussed in the article. Reprint requests to Atsushi Nonaka, MD, Department of Ophthalmology, Kobe City General Hospital, 4-6, Minatojima-Nakamachi, Chuo-ku, Kobe, 650-0046, Japan. E-mail: [email protected].
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more common (54.8% in Chinese patients2) than had been thought. In such a multiple mechanism ACG, residual angle closure would result in poor control of IOP even after complete dissolution of pupillary blocking by iridotomy. Despite the fact that postiridotomy residual angle closure is common in Asian patients, little information is available about the diagnosis or management of postiridotomy residual angle closure.3 Several studies have previously evaluated the effect of lens extraction on chronic or acute ACG.4 –10 After lens extraction, whether extracapsular cataract extraction4 – 6 or phacoemulsification,7–10 IOP is reduced substantially, and satisfactory IOP control is obtained in eyes with poorly controlled PACG. A quantitative evaluation of angle configuration using UBM revealed that the anterior chamber (AC) was 1.37 times deeper and the angle 1.57 times wider after cataract surgery.11 Moreover, compared with laser iridotomy, lens extraction has a more potent effect on deepening of the AC and widening of the angle.12 Accordingly, it may be possible that lens extraction is effective in resolving residual angle closure after laser iridotomy by its more potent effect on reconstructuring of the angle. This study was designed to examine the effects of subsequent cataract surgery for eyes with residual angle closure after iridotomy. ISSN 0161-6420/05/$–see front matter doi:10.1016/j.ophtha.2004.12.042
Nonaka et al 䡠 Cataract Surgery for Residual Angle Closure after Iridotomy
Patients and Methods This retrospective study was carried out in the Department of Ophthalmology, Kobe City General Hospital, Kobe, Japan. Between April 1, 2003 and January 31, 2004, we consecutively studied 70 eyes of 39 Japanese patients (men, 15 eyes of 8 patients; women, 55 eyes of 31 patients) with primary angle closure who had already undergone laser peripheral iridotomy and who were being followed up. Patients ranged in age from 35 to 88 years (mean, 67.2⫾9.3), and their conditions included suspected primary angle closure (n ⫽ 16), primary angle closure (n ⫽ 25), and PACG (n ⫽ 29), in accordance with a recent classification of primary angle closure.13 Of these, 13 eyes of 9 patients with residual angle closure (mean age, 70.6⫾7.5 years) had undergone cataract surgery after laser peripheral iridotomy, when we obtained the patient’s consent (mean duration between these treatments, 82.2⫾74.1 months [range, 1–240]). The study included eyes with no sight-disturbing lens opacity when IOP had been poorly controlled even with maximal topical or systematic medications. No eyes were treated with trabeculectomy before or simultaneously with cataract surgery for residual angle closure after iridotomy. The cataract surgical technique consisted of phacoemulsification and aspiration through a 3.0- to 4.1-mm self-sealing incision, followed by implantation of a foldable intraocular lens in the capsular bag. Detailed ophthalmologic examinations included best-corrected visual acuity and refraction, keratometry, slit-lamp biomicroscopy, applanation tonometry, gonioscopy, indirect ophthalmoscopy, and visual field (VF) testing. The provocative test of angle closure by prone positioning in a dark room for 1 hour was performed, as described previously.14 After measurement of ocular tension by an applanation tonometer in the usual manner, patients sat on a chair with the face down by resting the forehead on a pillow placed on a desk for 1 hour in a dark room. They were instructed to keep their eyes open and were observed during the test to make sure they kept a prone position and did not sleep. After an hour, the ocular tension was immediately remeasured. Increases of tension of ⱖ8 mmHg, 6 or 7 mmHg, and ⱕ5 mmHg were considered to be positive, suspected positive, and negative, respectively. At least an hour after the provocative test, configuration of the AC was examined using a UBM 840 instrument (Zeiss-Humphrey Instruments, San Leandro, CA) with a 50-megahertz transducer probe allowing 4- to 5-mm tissue penetration and approximately 50-m resolution.15 Ultrasound biomicroscopy was performed under the same conditions, with patients in the supine position, under the same room illumination, and using the same fixation target for the fellow eye. The section images were obtained at the center of the AC, at the superior and inferior angles of the AC in the vertical meridian, and at the temporal and nasal angles of the AC in the horizontal meridian. From the UBM images, angle opening distances at 500 m from the scleral spur were measured as a parameter of angle width, as defined by Pavlin et al.15 Intraocular pressure, response to the dark room prone position test, and morphologic analysis by UBM were evaluated before and 3 months after cataract surgery. Data are expressed as mean values ⫾ standard deviations of the mean. Differences between the 2 groups were statistically analyzed using the Mann–Whitney U test. The Spearman rank correlation was used to relate the responses to the dark room prone position test to IOP after iridotomy. A probability value of ⬍0.05 was considered significant for all statistical analyses.
Results Prognosis of Laser Peripheral Iridotomy Of 70 eyes in 40 patients who underwent the dark room prone position test after iridotomy, 27 (38.6%) in 17 patients (42.5%) had
positive or suspected positive responses to the test (Table 1). Morphologic examination of the angle configuration of these 27 eyes by UBM showed that the causes of residual angle closure were extreme anterior positioning of the lens–iris diaphragm in 4 eyes (Fig 1, left), and plateau iris with the characteristics of a straight iris profile, anterior positioning of the ciliary processes, and the closed ciliary sulcus in 23 eyes (Fig 1, right). In Table 1, we have shown the relationship between response to the prone position test and IOP control after iridotomy. With higher IOP after iridotomy, the eyes with primary angle closure more commonly had a positive or suspected positive response to the prone position test (P⬍0.01, Spearman rank correlation). More specifically, 6 of 9 eyes (66.7%) with an IOP of ⱖ20 mmHg had positive or suspected positive responses to the dark room prone position test. We also investigated the factors such as IOP and VF change before iridotomy that might worsen the prognosis of iridotomy. Intraocular pressures (numbers of topical medications) after iridotomy were 16.5⫾2.7 mmHg (0.5⫾0.8) and 22.3⫾2.8 mmHg (1.7⫾1.0) in eyes with IOP of ⱕ19 mmHg and ⱖ20 mmHg before iridotomy, respectively (P⬍0.05) (Fig 2A). Similarly, eyes with primary angle closure with IOP of ⱖ20 mmHg before iridotomy had a significantly higher incidence of positive response to the prone position test (P⬍0.05) (Fig 2A) after iridotomy than eyes with IOP of ⱕ19 mmHg before iridotomy. Intraocular pressures (numbers of topical medications) after iridotomy were 16.0⫾3.4 mmHg (0.4⫾0.8) and 17.4⫾3.9 mmHg (1.3⫾1.0) in eyes without and with a glaucomatous VF defect before, respectively (Fig 2B). Although there was no significant difference in IOP after iridotomy between eyes with and without a glaucomatous VF defect before iridotomy, there was a significant difference between the number of topical medications between them (P⬍0.01). Eyes with a glaucomatous VF defect before iridotomy also had a significantly higher incidence of positive response to the prone position test after iridotomy than eyes without a VF defect (P⬍0.01) (Fig 2B).
Effects of Cataract Surgery on Residual Angle Closure after Iridotomy Thirteen eyes (9 patients) with a positive or suspected positive response to the dark room prone position test after iridotomy had undergone cataract surgery after laser peripheral iridotomy. Figure 3 shows the effects of cataract surgery on these eyes. The IOP (number of topical medications) after iridotomy but before cataract surgery was 19.3⫾4.1 mmHg (1.5⫾1.3), and that after cataract surgery was 14.8⫾3.0 mmHg (0.4⫾0.8) (Fig 3A). Postiridotomy IOP was lowered significantly after cataract surgery, by 4.5 mmHg Table 1. Residual Angle Closure after Laser Iridotomy
Total (n ⫽ 70) Intraocular pressure after iridotomy ⬉14 mmHg (n ⫽ 18) 15⬃19 mmHg (n ⫽ 43) ⭌20 mmHg (n ⫽ 9)
Negative
Suspected Positive
Positive
43 (61%)
13 (19%)
14 (20%)
14 (78%) 26 (60%) 3 (33%)
4 (22%) 6 (14%) 3 (33%)
0 (0%) 11 (26%) 3 (33%)
The results of the dark room prone position test. Responses to the test were positive or suspected positive in 38.6% of all eyes after iridotomy. There was a significant relationship between the response to the prone position test and intraocular pressure control after iridotomy (P⬍0.01, Spearman rank correlation).
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Figure 1. Ultrasound biomicroscopic images of the angles with positive or suspected positive responses to the prone position test after iridotomy. Left, The anterior chamber is shallowed extremely by anterior positioning of the lens–iris diaphragm, and the angle remains closed (n ⫽ 4). Right, The angle remains closed by characteristics of plateau iris with a straight iris profile, anterior positioning of the ciliary processes, and closed ciliary sulcus (n ⫽ 23).
(P⬍0.01) (Fig 3A), and positive or suspected positive responses to the prone position test after iridotomy became negative in all of the eyes after cataract surgery (Fig 3A). As all eyes achieved satisfactory IOP, no eyes needed additional glaucoma surgery. By UBM assessment, all the eyes with postiridotomy residual angle closure had the angle closed at least 2 quadrants before cataract surgery and the angle widened and opened in all quadrants after cataract surgery (Fig 3B). The angle opening distance at 500 m from the scleral spur after iridotomy but before cataract surgery was 0.07⫾0.07 mm, and that after cataract surgery was 0.25⫾0.10 mm (P⬍0.01) (Fig 3B).
Discussion Laser peripheral iridotomy, which acts by relieving the relative pupil blocking element of PACG, has been advocated as the initial treatment in eyes with this condition because of its noninvasive nature and its safety as an outpatient procedure.16 Although iridotomy has proven to be effective as prophylaxis against attacks of acute ACG,17 it is disputable if it is effective for long-term control of IOP in eyes with chronic asymptomatic ACG, especially in Asians.18
Figure 2. Factors affecting the prognosis of iridotomy. A, Comparison by intraocular pressure (IOP) before iridotomy. Eyes with primary angle closure and IOP of ⱖ20 mmHg before iridotomy had significantly higher IOP and a greater incidence of positive response to the prone position test after iridotomy, compared with the eyes with IOP of ⱕ19 mmHg. B, Comparison by existence of a glaucomatous visual field (VF) before iridotomy. In contrast to the results of IOP after iridotomy, in which there was no significant difference between eyes with and without a glaucomatous VF defect before iridotomy, eyes with a glaucomatous VF defect before iridotomy had a significantly higher incidence of positive response to the prone position test after iridotomy. n.s. ⫽ nonsignificant.
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Nonaka et al 䡠 Cataract Surgery for Residual Angle Closure after Iridotomy
Figure 3. Effects of cataract surgery on eyes with positive or suspected positive responses to the prone position test after iridotomy. A, Postiridotomy intraocular pressure was lowered significantly after cataract surgery by 4.5 mmHg (P⬍0.01) (left). All of the positive and suspected positive responses to the prone position test after iridotomy became negative after cataract surgery (right). B, Analysis of angle configuration by ultrasound biomicroscopy. The angle closed by anterior positioning of the lens–iris diaphragm or plateau iris after iridotomy (left) became open after cataract surgery (right).
Recent evidence has indicated that laser iridotomy is probably useful only in the early stages of PACG, because the majority of PACG eyes with elevated IOP and glaucomatous optic neuropathy required additional treatment, and about half required surgical or laser treatment, even after iridotomy.19,20 In addition, although the risk is low, laser iridotomy may pose a hazard to the corneal endothelium as a serious late complication.21 Accordingly, there is a need for appropriate screening and treatment recommendations for PACG so that resources and treatments can be allocated appropriately.22 After iridotomy, it is difficult to determine the cause of an asymptomatic progressive VF defect or elevated IOP. In the present study, residual angle closure after iridotomy was confirmed functionally by the dark room prone position test, which had been shown to be positive in a very high incidence (almost 90%) in the PACG eyes,14 and morphologi-
cally by UBM. Previous studies have reported a high incidence of positive response to the prone position test after iridectomy: as high as 38% after laser iridotomy23 and 52.4% after surgical iridectomy.24 Similarly, in our study 38.6% of eyes with primary angle closure after laser iridotomy were positive or suspected positive on dark room prone position testing, with a significant relation to IOP (Table 1). Previous morphologic assessment in Indian eyes by UBM revealed that 40% of eyes with angle closure after laser iridotomy had a narrow angle with an anteriorly placed ciliary process and a narrow ciliary sulcus, characteristic of plateau iris.25 Our examinations using ultrasound microscopy showed that most eyes with postiridotomy residual angle closure had similar characteristics of plateau iris, including an anteriorly placed ciliary process and a narrow ciliary sulcus (Fig 1). Therefore, particularly in Asian patients, it may be common that, after relieving pupillary
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Ophthalmology Volume 112, Number 6, June 2005 blocking by iridotomy, a coexisting nonpupillary blocking mechanism continues to cause appositional angle closure. In this study, as a second intervention after iridotomy, cataract surgery had a potent effect on the resolution of postiridotomy residual angle closure due to plateau iris. According to many previous studies, lens extraction per se has the ability to lower IOP, without the filtering procedure of goniosynechialysis as a primary treatment for ACG.4 –10 A quantitative study of angle configuration using UBM revealed that lens extraction has a more potent effect than iridotomy on deepening of the AC and widening of the angle.11,26,27 In addition, morphologic analysis using UBM revealed that the angle of plateau iris syndrome eyes opened after lens extraction, but that iridociliary apposition persisted.28 Lens extraction would widen the angle even without structural alteration of plateau iris, because the lens plays a central role in the pathogenesis of PACG by means of its anatomic peculiarities, such as its increased thickness, relative anterior positioning, and progression of its thickness.29,30 As a second intervention after iridotomy, the mechanisms by which cataract surgery lowers the increased IOP after iridotomy are undetermined.7–10 Our results suggest that dissolution of residual angle closure by cataract surgery might be a contributory factor to significant lowering of IOP, based on the positive response to the dark room prone position test changing to a negative response in all cases (Fig 3A). As mentioned above, in the advanced stages of PACG with elevated IOP and glaucomatous optic neuropathy, it has been suggested that IOP control after laser iridotomy is quite poor.19,20,31 In the present study, not only poor control of IOP but also residual angle closure was much more common after iridotomy in eyes in these advanced stages (Fig 2). Accordingly, in such eyes residual angle closure would often or commonly cause poor IOP. Therefore, for selected cases such as eyes with primary angle closure in the advanced stages, cataract surgery may be essential and preferable as the initial treatment instead of laser iridotomy with the ability of reconstructing the angle and relieving angle closure completely. Prospective studies comparing lens extraction with iridotomy are needed and invaluable, as Chew and Aung32 stated. The authors acknowledge several limitations to this study. As in any study, a prospective randomized design to evaluate treatment effect would result in stronger evidence and, thus, more definitive recommendations for treatment. Second, the design of this study is suboptimal because it would be optimal not to use data from both eyes of the same patient. However, because some patients had some disparity between right and left eyes in IOP, responses to the prone position test, or VF defect, we used data from all eyes examined (one eye of 8 patients and both eyes of 31 patients). Finally, the study population was Asian (predominantly Japanese), and it is not known if the results could be applied to other racial groups. In conclusion, in this series of patients residual angle closure was common after laser iridotomy in eyes with primary angle closure, resulting in poor IOP control, especially in the advanced stages with elevated IOP or glaucomatous optic neuropathy. Cataract surgery subsequent to
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laser iridotomy was also effective for complete resolution of residual angle closure, which was due to primarily to plateau iris, with concomitant lowering of IOP.
References 1. Sihota R, Lakshmaiah NC, Walia KB, et al. The trabecular meshwork in acute and chronic angle closure glaucoma. Indian J Ophthalmol 2001;49:255–9. 2. Wang N, Wu H, Fan Z. Primary angle closure glaucoma in Chinese and Western populations. Chin Med J (Engl) 2002; 115:1706 –15. 3. Hung PT, Hsieh JW, Chen YF, Wei T. Efficacy of latanoprost as an adjunct to medical therapy for residual angle-closure glaucoma after iridectomy. J Ocul Pharmacol Ther 2000;16: 43–7. 4. Wishart PK, Atkinson PL. Extracapsular cataract extraction and posterior chamber lens implantation in patients with primary chronic angle-closure glaucoma: effect on intraocular pressure control. Eye 1989;3:706 –12. 5. Acton J, Salmon JF, Scholtz R. Extracapsular cataract extraction with posterior chamber lens implantation in primary angle-closure glaucoma. J Cataract Refract Surg 1997;23:930 – 4. 6. Gunning FP, Greve EL. Lens extraction for uncontrolled angleclosure glaucoma: long-term follow-up. J Cataract Refract Surg 1998;24:1347–56. 7. Roberts TV, Francis IC, Lertusumitkul S, et al. Primary phacoemulsification for uncontrolled angle-closure glaucoma. J Cataract Refract Surg 2000;26:1012– 6. 8. Hayashi K, Hayashi H, Nakao F, Hayashi F. Effect of cataract surgery on intraocular pressure control in glaucoma patients. J Cataract Refract Surg 2001;27:1779 – 86. 9. Jacobi PC, Dietlein TS, Luke C, et al. Primary phacoemulsification and intraocular lens implantation for acute angleclosure glaucoma. Ophthalmology 2002;109:1597– 603. 10. Kubota T, Toguri I, Onizuka N, Matsuura T. Phacoemulsification and intraocular lens implantation for angle closure glaucoma after the relief of pupillary block. Ophthalmologica 2003;217:325– 8. 11. Kurimoto Y, Park M, Sakaue H, Kondo T. Changes in the anterior chamber configuration after small-incision cataract surgery with posterior chamber intraocular lens implantation. Am J Ophthalmol 1997;124:775– 80. 12. Kurimoto Y, Miyazawa D, Takeuchi A, Kondo T. Comparative study of laser iridotomy and cataract surgery regarding postoperative changes in the anterior chamber. Atarashii Ganka (J Eye) 1997;14:427–32. 13. Foster PJ, Buhrmann R, Quigley HA, Johnson GJ. The definition and classification of glaucoma in prevalence surveys. Br J Ophthalmol 2002;86:238 – 42. 14. Harris LS, Galin MA. Prone provocative testing for narrow angle glaucoma. Arch Ophthalmol 1972;87:493– 6. 15. Pavlin CJ, Harasiewicz K, Sherar MD, Foster FS. Clinical use of ultrasound biomicroscopy. Ophthalmology 1991;98:287–95. 16. Quigley HA. Long-term follow-up of laser iridotomy. Ophthalmology 1981;88:218 –24. 17. Ang LP, Aung T, Chew PT. Acute primary angle closure in an Asian population: long-term outcome of the fellow eye after prophylactic laser peripheral iridotomy. Ophthalmology 2000; 107:2092– 6. 18. Aung T, Ang LP, Chan SP, Chew PT. Acute primary angleclosure: long-term intraocular pressure outcome in Asian eyes. Am J Ophthalmol 2001;131:7–12.
Nonaka et al 䡠 Cataract Surgery for Residual Angle Closure after Iridotomy 19. Alsagoff Z, Aung T, Ang LP, Chew PT. Long-term clinical course of primary angle-closure glaucoma in an Asian population. Ophthalmology 2000;107:2300 – 4. 20. Rosman M, Aung T, Ang LP, et al. Chronic angle-closure with glaucomatous damage: long-term clinical course in a North American population and comparison with an Asian population. Ophthalmology 2002;109:2227–31. 21. Schwartz AL, Martin NF, Weber PA. Corneal decompensation after argon laser iridectomy. Arch Ophthalmol 1988;106: 1572– 4. 22. Friedman DS. Who needs an iridotomy? Br J Ophthalmol 2001;85:1019 –21. 23. Karmon G, Vender T, Savir H. Evaluation of laser iridectomy in angle-closure glaucoma: provocative tests. Br J Ophthalmol 1982;66:471–3. 24. Hung PT, Chou LH. Provocation and mechanism of angleclosure glaucoma after iridectomy. Arch Ophthalmol 1979;97: 1862– 4. 25. Garudadri CS, Chelerkar V, Nutheti R. An ultrasound biomicroscopic study of the anterior segment in Indian eyes with primary angle-closure glaucoma. J Glaucoma 2002;11:502–7. 26. Hayashi K, Hayashi H, Nakao F, Hayashi F. Changes in
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anterior chamber angle width and depth after intraocular lens implantation in eyes with glaucoma. Ophthalmology 2000; 107:698 –703. Pereira FA, Cronemberger S. Ultrasound biomicroscopic study of anterior segment changes after phacoemulsification and foldable intraocular lens implantation. Ophthalmology 2003;110:1799 – 806. Tran HV, Liebmann JM, Ritch R. Iridociliary apposition in plateau iris syndrome persists after cataract extraction. Am J Ophthalmol 2003;135:40 –3. Lowe RF. Causes of shallow anterior chamber in primary angleclosure glaucoma. Ultrasonic biometry of normal and angleclosure glaucoma eyes. Am J Ophthalmol 1969;67:87–93. Marchini G, Pagliarusco A, Toscano A, et al. Ultrasound biomicroscopic and conventional ultrasonographic study of ocular dimensions in primary angle-closure glaucoma. Ophthalmology 1998;105:2091– 8. Nolan WP, Foster PJ, Devereux JG, et al. YAG laser iridotomy treatment for primary angle closure in East Asian eyes. Br J Ophthalmol 2000;84:1255–9. Chew PT, Aung T. Primary angle-closure glaucoma in Asia. J Glaucoma 2001;10(suppl):S7– 8.
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Laser iridotomy has been used widely for treating acute or chronic angle-closure glaucoma (ACG) by relieving pupillary blocking, because pupillary blocking has been suggested to be a major cause of primary ACG (PACG). Accordingly, poor control of postiridotomy intraocular pressure (IOP) has been thought to be caused by a combined mechanism of primary open-angle glaucoma or dysfunction of the trabecular meshwork, which is closed by peripheral anterior synechia and damaged by pigmentary cells released from the iridotomy site.1 Recent advances in morphologic assessment of angle closure with ultrasound biomicroscopy (UBM), however, have revealed that multiple mechanism ACG, due primarily to coexistence of pupillary blocking and plateau iris, is Originally received: August 20, 2004. Accepted: December 22, 2004. Manuscript no. 2004-36. From the Department of Ophthalmology, Kobe City General Hospital, Kobe, Japan. Presented in part at: Japanese Ophthalmological Society 108th Annual Meeting, April, 2004; Tokyo, Japan. The authors have no conflict of interest and no financial interest in the subject matter or materials discussed in the article. Reprint requests to Atsushi Nonaka, MD, Department of Ophthalmology, Kobe City General Hospital, 4-6, Minatojima-Nakamachi, Chuo-ku, Kobe, 650-0046, Japan. E-mail: [email protected].
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© 2005 by the American Academy of Ophthalmology Published by Elsevier Inc.
more common (54.8% in Chinese patients2) than had been thought. In such a multiple mechanism ACG, residual angle closure would result in poor control of IOP even after complete dissolution of pupillary blocking by iridotomy. Despite the fact that postiridotomy residual angle closure is common in Asian patients, little information is available about the diagnosis or management of postiridotomy residual angle closure.3 Several studies have previously evaluated the effect of lens extraction on chronic or acute ACG.4 –10 After lens extraction, whether extracapsular cataract extraction4 – 6 or phacoemulsification,7–10 IOP is reduced substantially, and satisfactory IOP control is obtained in eyes with poorly controlled PACG. A quantitative evaluation of angle configuration using UBM revealed that the anterior chamber (AC) was 1.37 times deeper and the angle 1.57 times wider after cataract surgery.11 Moreover, compared with laser iridotomy, lens extraction has a more potent effect on deepening of the AC and widening of the angle.12 Accordingly, it may be possible that lens extraction is effective in resolving residual angle closure after laser iridotomy by its more potent effect on reconstructuring of the angle. This study was designed to examine the effects of subsequent cataract surgery for eyes with residual angle closure after iridotomy. ISSN 0161-6420/05/$–see front matter doi:10.1016/j.ophtha.2004.12.042
Nonaka et al 䡠 Cataract Surgery for Residual Angle Closure after Iridotomy
Patients and Methods This retrospective study was carried out in the Department of Ophthalmology, Kobe City General Hospital, Kobe, Japan. Between April 1, 2003 and January 31, 2004, we consecutively studied 70 eyes of 39 Japanese patients (men, 15 eyes of 8 patients; women, 55 eyes of 31 patients) with primary angle closure who had already undergone laser peripheral iridotomy and who were being followed up. Patients ranged in age from 35 to 88 years (mean, 67.2⫾9.3), and their conditions included suspected primary angle closure (n ⫽ 16), primary angle closure (n ⫽ 25), and PACG (n ⫽ 29), in accordance with a recent classification of primary angle closure.13 Of these, 13 eyes of 9 patients with residual angle closure (mean age, 70.6⫾7.5 years) had undergone cataract surgery after laser peripheral iridotomy, when we obtained the patient’s consent (mean duration between these treatments, 82.2⫾74.1 months [range, 1–240]). The study included eyes with no sight-disturbing lens opacity when IOP had been poorly controlled even with maximal topical or systematic medications. No eyes were treated with trabeculectomy before or simultaneously with cataract surgery for residual angle closure after iridotomy. The cataract surgical technique consisted of phacoemulsification and aspiration through a 3.0- to 4.1-mm self-sealing incision, followed by implantation of a foldable intraocular lens in the capsular bag. Detailed ophthalmologic examinations included best-corrected visual acuity and refraction, keratometry, slit-lamp biomicroscopy, applanation tonometry, gonioscopy, indirect ophthalmoscopy, and visual field (VF) testing. The provocative test of angle closure by prone positioning in a dark room for 1 hour was performed, as described previously.14 After measurement of ocular tension by an applanation tonometer in the usual manner, patients sat on a chair with the face down by resting the forehead on a pillow placed on a desk for 1 hour in a dark room. They were instructed to keep their eyes open and were observed during the test to make sure they kept a prone position and did not sleep. After an hour, the ocular tension was immediately remeasured. Increases of tension of ⱖ8 mmHg, 6 or 7 mmHg, and ⱕ5 mmHg were considered to be positive, suspected positive, and negative, respectively. At least an hour after the provocative test, configuration of the AC was examined using a UBM 840 instrument (Zeiss-Humphrey Instruments, San Leandro, CA) with a 50-megahertz transducer probe allowing 4- to 5-mm tissue penetration and approximately 50-m resolution.15 Ultrasound biomicroscopy was performed under the same conditions, with patients in the supine position, under the same room illumination, and using the same fixation target for the fellow eye. The section images were obtained at the center of the AC, at the superior and inferior angles of the AC in the vertical meridian, and at the temporal and nasal angles of the AC in the horizontal meridian. From the UBM images, angle opening distances at 500 m from the scleral spur were measured as a parameter of angle width, as defined by Pavlin et al.15 Intraocular pressure, response to the dark room prone position test, and morphologic analysis by UBM were evaluated before and 3 months after cataract surgery. Data are expressed as mean values ⫾ standard deviations of the mean. Differences between the 2 groups were statistically analyzed using the Mann–Whitney U test. The Spearman rank correlation was used to relate the responses to the dark room prone position test to IOP after iridotomy. A probability value of ⬍0.05 was considered significant for all statistical analyses.
Results Prognosis of Laser Peripheral Iridotomy Of 70 eyes in 40 patients who underwent the dark room prone position test after iridotomy, 27 (38.6%) in 17 patients (42.5%) had
positive or suspected positive responses to the test (Table 1). Morphologic examination of the angle configuration of these 27 eyes by UBM showed that the causes of residual angle closure were extreme anterior positioning of the lens–iris diaphragm in 4 eyes (Fig 1, left), and plateau iris with the characteristics of a straight iris profile, anterior positioning of the ciliary processes, and the closed ciliary sulcus in 23 eyes (Fig 1, right). In Table 1, we have shown the relationship between response to the prone position test and IOP control after iridotomy. With higher IOP after iridotomy, the eyes with primary angle closure more commonly had a positive or suspected positive response to the prone position test (P⬍0.01, Spearman rank correlation). More specifically, 6 of 9 eyes (66.7%) with an IOP of ⱖ20 mmHg had positive or suspected positive responses to the dark room prone position test. We also investigated the factors such as IOP and VF change before iridotomy that might worsen the prognosis of iridotomy. Intraocular pressures (numbers of topical medications) after iridotomy were 16.5⫾2.7 mmHg (0.5⫾0.8) and 22.3⫾2.8 mmHg (1.7⫾1.0) in eyes with IOP of ⱕ19 mmHg and ⱖ20 mmHg before iridotomy, respectively (P⬍0.05) (Fig 2A). Similarly, eyes with primary angle closure with IOP of ⱖ20 mmHg before iridotomy had a significantly higher incidence of positive response to the prone position test (P⬍0.05) (Fig 2A) after iridotomy than eyes with IOP of ⱕ19 mmHg before iridotomy. Intraocular pressures (numbers of topical medications) after iridotomy were 16.0⫾3.4 mmHg (0.4⫾0.8) and 17.4⫾3.9 mmHg (1.3⫾1.0) in eyes without and with a glaucomatous VF defect before, respectively (Fig 2B). Although there was no significant difference in IOP after iridotomy between eyes with and without a glaucomatous VF defect before iridotomy, there was a significant difference between the number of topical medications between them (P⬍0.01). Eyes with a glaucomatous VF defect before iridotomy also had a significantly higher incidence of positive response to the prone position test after iridotomy than eyes without a VF defect (P⬍0.01) (Fig 2B).
Effects of Cataract Surgery on Residual Angle Closure after Iridotomy Thirteen eyes (9 patients) with a positive or suspected positive response to the dark room prone position test after iridotomy had undergone cataract surgery after laser peripheral iridotomy. Figure 3 shows the effects of cataract surgery on these eyes. The IOP (number of topical medications) after iridotomy but before cataract surgery was 19.3⫾4.1 mmHg (1.5⫾1.3), and that after cataract surgery was 14.8⫾3.0 mmHg (0.4⫾0.8) (Fig 3A). Postiridotomy IOP was lowered significantly after cataract surgery, by 4.5 mmHg Table 1. Residual Angle Closure after Laser Iridotomy
Total (n ⫽ 70) Intraocular pressure after iridotomy ⬉14 mmHg (n ⫽ 18) 15⬃19 mmHg (n ⫽ 43) ⭌20 mmHg (n ⫽ 9)
Negative
Suspected Positive
Positive
43 (61%)
13 (19%)
14 (20%)
14 (78%) 26 (60%) 3 (33%)
4 (22%) 6 (14%) 3 (33%)
0 (0%) 11 (26%) 3 (33%)
The results of the dark room prone position test. Responses to the test were positive or suspected positive in 38.6% of all eyes after iridotomy. There was a significant relationship between the response to the prone position test and intraocular pressure control after iridotomy (P⬍0.01, Spearman rank correlation).
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Figure 1. Ultrasound biomicroscopic images of the angles with positive or suspected positive responses to the prone position test after iridotomy. Left, The anterior chamber is shallowed extremely by anterior positioning of the lens–iris diaphragm, and the angle remains closed (n ⫽ 4). Right, The angle remains closed by characteristics of plateau iris with a straight iris profile, anterior positioning of the ciliary processes, and closed ciliary sulcus (n ⫽ 23).
(P⬍0.01) (Fig 3A), and positive or suspected positive responses to the prone position test after iridotomy became negative in all of the eyes after cataract surgery (Fig 3A). As all eyes achieved satisfactory IOP, no eyes needed additional glaucoma surgery. By UBM assessment, all the eyes with postiridotomy residual angle closure had the angle closed at least 2 quadrants before cataract surgery and the angle widened and opened in all quadrants after cataract surgery (Fig 3B). The angle opening distance at 500 m from the scleral spur after iridotomy but before cataract surgery was 0.07⫾0.07 mm, and that after cataract surgery was 0.25⫾0.10 mm (P⬍0.01) (Fig 3B).
Discussion Laser peripheral iridotomy, which acts by relieving the relative pupil blocking element of PACG, has been advocated as the initial treatment in eyes with this condition because of its noninvasive nature and its safety as an outpatient procedure.16 Although iridotomy has proven to be effective as prophylaxis against attacks of acute ACG,17 it is disputable if it is effective for long-term control of IOP in eyes with chronic asymptomatic ACG, especially in Asians.18
Figure 2. Factors affecting the prognosis of iridotomy. A, Comparison by intraocular pressure (IOP) before iridotomy. Eyes with primary angle closure and IOP of ⱖ20 mmHg before iridotomy had significantly higher IOP and a greater incidence of positive response to the prone position test after iridotomy, compared with the eyes with IOP of ⱕ19 mmHg. B, Comparison by existence of a glaucomatous visual field (VF) before iridotomy. In contrast to the results of IOP after iridotomy, in which there was no significant difference between eyes with and without a glaucomatous VF defect before iridotomy, eyes with a glaucomatous VF defect before iridotomy had a significantly higher incidence of positive response to the prone position test after iridotomy. n.s. ⫽ nonsignificant.
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Figure 3. Effects of cataract surgery on eyes with positive or suspected positive responses to the prone position test after iridotomy. A, Postiridotomy intraocular pressure was lowered significantly after cataract surgery by 4.5 mmHg (P⬍0.01) (left). All of the positive and suspected positive responses to the prone position test after iridotomy became negative after cataract surgery (right). B, Analysis of angle configuration by ultrasound biomicroscopy. The angle closed by anterior positioning of the lens–iris diaphragm or plateau iris after iridotomy (left) became open after cataract surgery (right).
Recent evidence has indicated that laser iridotomy is probably useful only in the early stages of PACG, because the majority of PACG eyes with elevated IOP and glaucomatous optic neuropathy required additional treatment, and about half required surgical or laser treatment, even after iridotomy.19,20 In addition, although the risk is low, laser iridotomy may pose a hazard to the corneal endothelium as a serious late complication.21 Accordingly, there is a need for appropriate screening and treatment recommendations for PACG so that resources and treatments can be allocated appropriately.22 After iridotomy, it is difficult to determine the cause of an asymptomatic progressive VF defect or elevated IOP. In the present study, residual angle closure after iridotomy was confirmed functionally by the dark room prone position test, which had been shown to be positive in a very high incidence (almost 90%) in the PACG eyes,14 and morphologi-
cally by UBM. Previous studies have reported a high incidence of positive response to the prone position test after iridectomy: as high as 38% after laser iridotomy23 and 52.4% after surgical iridectomy.24 Similarly, in our study 38.6% of eyes with primary angle closure after laser iridotomy were positive or suspected positive on dark room prone position testing, with a significant relation to IOP (Table 1). Previous morphologic assessment in Indian eyes by UBM revealed that 40% of eyes with angle closure after laser iridotomy had a narrow angle with an anteriorly placed ciliary process and a narrow ciliary sulcus, characteristic of plateau iris.25 Our examinations using ultrasound microscopy showed that most eyes with postiridotomy residual angle closure had similar characteristics of plateau iris, including an anteriorly placed ciliary process and a narrow ciliary sulcus (Fig 1). Therefore, particularly in Asian patients, it may be common that, after relieving pupillary
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Ophthalmology Volume 112, Number 6, June 2005 blocking by iridotomy, a coexisting nonpupillary blocking mechanism continues to cause appositional angle closure. In this study, as a second intervention after iridotomy, cataract surgery had a potent effect on the resolution of postiridotomy residual angle closure due to plateau iris. According to many previous studies, lens extraction per se has the ability to lower IOP, without the filtering procedure of goniosynechialysis as a primary treatment for ACG.4 –10 A quantitative study of angle configuration using UBM revealed that lens extraction has a more potent effect than iridotomy on deepening of the AC and widening of the angle.11,26,27 In addition, morphologic analysis using UBM revealed that the angle of plateau iris syndrome eyes opened after lens extraction, but that iridociliary apposition persisted.28 Lens extraction would widen the angle even without structural alteration of plateau iris, because the lens plays a central role in the pathogenesis of PACG by means of its anatomic peculiarities, such as its increased thickness, relative anterior positioning, and progression of its thickness.29,30 As a second intervention after iridotomy, the mechanisms by which cataract surgery lowers the increased IOP after iridotomy are undetermined.7–10 Our results suggest that dissolution of residual angle closure by cataract surgery might be a contributory factor to significant lowering of IOP, based on the positive response to the dark room prone position test changing to a negative response in all cases (Fig 3A). As mentioned above, in the advanced stages of PACG with elevated IOP and glaucomatous optic neuropathy, it has been suggested that IOP control after laser iridotomy is quite poor.19,20,31 In the present study, not only poor control of IOP but also residual angle closure was much more common after iridotomy in eyes in these advanced stages (Fig 2). Accordingly, in such eyes residual angle closure would often or commonly cause poor IOP. Therefore, for selected cases such as eyes with primary angle closure in the advanced stages, cataract surgery may be essential and preferable as the initial treatment instead of laser iridotomy with the ability of reconstructing the angle and relieving angle closure completely. Prospective studies comparing lens extraction with iridotomy are needed and invaluable, as Chew and Aung32 stated. The authors acknowledge several limitations to this study. As in any study, a prospective randomized design to evaluate treatment effect would result in stronger evidence and, thus, more definitive recommendations for treatment. Second, the design of this study is suboptimal because it would be optimal not to use data from both eyes of the same patient. However, because some patients had some disparity between right and left eyes in IOP, responses to the prone position test, or VF defect, we used data from all eyes examined (one eye of 8 patients and both eyes of 31 patients). Finally, the study population was Asian (predominantly Japanese), and it is not known if the results could be applied to other racial groups. In conclusion, in this series of patients residual angle closure was common after laser iridotomy in eyes with primary angle closure, resulting in poor IOP control, especially in the advanced stages with elevated IOP or glaucomatous optic neuropathy. Cataract surgery subsequent to
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laser iridotomy was also effective for complete resolution of residual angle closure, which was due to primarily to plateau iris, with concomitant lowering of IOP.
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