Study finds capsule wrinkling is common in patients with PACG
by Matt Young EyeWorld Contributing Editor
Capsule wrinkling is common in patients with primary angle-closure glaucoma (PACG); surgeons should exercise extra caution when performing capsulorhexis in these patients. That's according to research published in the September 2010 issue of the Japanese Journal of Ophthalmology. Capsule wrinkling has been a known phenomenon in patients with pseudoexfoliation syndrome, and inadvertent propagation of the capsule tear could occur among such patients. Although less is known about capsule wrinkling and PACG patients, this study found a link. "Capsule wrinkling during cataract surgery was more common in eyes with PACG, especially those with a higher IOP on presentation and iris atrophy," wrote study co-author Yong Yeon Kim, M.D., ophthalmology department, Korea University Guro Hospital, Seoul, South Korea.
The wrinkle effect
Dr. Kim analyzed 91 eyes of 91 patients. Twenty-six eyes had PACG versus 65 control eyes that had undergone cataract surgery. "PACG was defined as any eye that had both a primary anatomic narrow anterior chamber angle and evidence, such as peripheral anterior synechiae, elevated IOP, sector iris atrophy, or glaukomflecken lens opacities, for trabecular obstruction by the peripheral iris, with glaucomatous optic disc changes or a glaucomatous visual field defect," Dr. Kim noted. All patients with PACG underwent laser iridotomy or trabeculectomy before cataract surgery. Capsule wrinkling was detected initially by one surgeon and then confirmed by blinded investigators who watched a video of the surgery. The rate of capsule winkling was higher in the PACG group, occurring in seven of 26 patients (29.6%), than in the control group, which experienced no capsule wrinkling. "Among the PACG patients, capsule wrinkling was associated with a higher IOP on presentation (54.71 ± 16.15 mm Hg) than in patients without capsule wrinkling (32.95 ± 11.21 mm Hg)," Dr. Kim reported. "Iris atrophy was significantly related to capsule wrinkling (P=0.028), and the location of iris atrophy correlated with that of capsule wrinkling in 80% of cases (4/5)."
Dr. Kim identified three specific factors associated with capsule wrinkling in patients with PACG: ischemic damage to the lens capsule, ichemic damage to the ciliary body complex, and surgery or laser-related zonule damage. "Instability in the lens capsule, ciliary body, or zonule may exist in patients with PACG," Dr. Kim noted. "Because in normal eyes the zonule is firmly attached between the ciliary body and lens capsule, any instability in the lens capsule, ciliary body, or zonule can cause capsule wrinkling, if the anterior capsule is pulled centrally. Therefore, when capsular wrinkling occurs during capsulorhexis, the possibilities of weakness in the lens capsule, ciliary body, or zonule should be considered."
Experimental research has found that the iris and ciliary body are the most sensitive to pressure-induced ischemia of all ocular tissues, Dr. Kim noted. "A high proportion of patients with acute PACG develop signs of anterior segment ischemia, including iris whirling or stromal atrophy," Dr. Kim reported. "The presence of iris atrophy is an indirect sign of ischemic insult to the ciliary complex."
Iris atrophy was more commonly found in PACG eyes with capsule wrinkling, and IOP on presentation was also higher. "Moreover, the location of most iris atrophy correlated with the capsule wrinkling," Dr. Kim reported. "Therefore, it is possible that the mechanism of capsule wrinkling during capsulorhexis in cataract patients with PACG may be ischemic damage to the ciliary body or zonule."
Lens capsule impairment can also lead to capsule wrinkling. "The lens capsule is virtually inelastic, and instability can occur by changes of the lens capsule itself," Dr. Kim reported. "Ischemia can occur in an attack of acute PACG, leading to lens capsule necrosis and subsequent lens capsule instability. Therefore, the lens capsule cannot be stretched tightly and the capsule can be wrinkled either in the direction of the capsulorhexis needle or forceps."
Zonule damage can occur during laser iridotomy or trabeculectomy. "Among the seven patients with capsule wrinkling, three (patients 2, 4, and 5) had capsule wrinkling in the same region where either the LI [laser iridotomy] or trabeculectomy was performed. Therefore, the possibility of zonular damage due either to laser or surgical procedures should also be considered."
Meanwhile, don't forget the link between capsule wrinkling and pseudoexfoliation. "For patients experiencing pseudoexfoliation, capsule wrinkling is a prominent occurrence," reported Mohan Rajan, M.D., medical director, Rajan Eye Care Hospital, Chennai, India. When you see capsule wrinkling, you should consider that the patient might have undiagnosed pseudoexfoliation. "In India, pseudoexfoliation is more common than we think," Dr. Rajan said. "Pseudoexfoliation also can lead to open-angle glaucoma. But sometimes with pseudoexfoliation, the pupils don't dilate well. Sometimes we miss the condition. If you look for capsule wrinkling, you can diagnose these missed pseudoexfoliation patients."
Editors' note: Dr. Kim has no financial interests related to this study. Dr. Rajan has no financial interests related to his comments.
Contact information
Kim: yongykim@korea.ac.kr
Rajan: rajaneye@vsnl.com
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