Pseudoexfoliation: Impact on cataract surgery and long-term intraocular lens position

Cataract surgery with intraocular lens (IOL) implantation has gained a surpassing sophistication since the first IOL implantation in 1949. Although IOL removal techniques and IOL technology rapidly evolved, challenging situations in complicated eyes remain. Difficult cases include flat anterior chambers, small pupils, dense hard nuclear cataracts, zonular dehiscence, dislocated lenses, and pseudoexfoliation (PXF). Pseudoexfoliation syndrome is an age-related disease in which abnormal fibrillar extracellular material is produced and accumulates in many ocular tissues. The ocular manifestations involve all anterior segment structures, as well as conjunctiva and orbital structures. There is increasing evidence of an etiological association between PXF syndrome and cataract formation, and glaucoma occurs more commonly in eyes with PXF syndrome than in those without it.1 Pseudoexfoliation syndrome is now thought to be a systemic disorder and has been associated preliminarily with transient ischemic attacks, stroke, systemic hypertension, and myocardial infarction. Deposits of white material on the anterior lens surface are the most consistent and important diagnostic features of the PXF syndrome. The classic pattern consists of 3 distinct zones that become visible when the pupil is fully dilated. Next to the lens, exfoliation material is most prominent at the pupillary border. Pigment loss from the iris sphincter region and deposition on anterior chamber structures is a hallmark of the PXF syndrome.1 Presence of the PXF syndrome should alert the physician to increased risks of intraocular surgery, most commonly zonular dehiscence, capsule rupture, and vitreous loss during cataract extraction.1 In this issue, Shingleton et al. (pages 1261–1269) investigated the frequency and results of cataract surgery with concurrent vitrectomy due to zonule weakness in PXF eyes. In 1059 consecutive PXF eyes, they found 38 eyes that needed vitrectomy. Concurrent vitrectomy was required in 19 (15.6%) of 122 high-risk eyes and 19 (2.0%) of 937 non-high-risk eyes (P<.00001). This trend has been reported in similar studies. Once a cataract surgeon detects PXF, some of the following questions arise: Will the small pupils and flat anterior chambers in many PXF eyes complicate surgery? What is the preferred capsulorhexis size for safe surgery and good long-term fixation of the IOL? Is there zonular dehiscence or capsule weakness that may complicate the surgical intervention? Should a capsular tension ring (CTR) be implanted to provide long-term fixation and centration in the capsular bag? In the article by Lorente et al. (pages 1270–1282), we can learn more about these questions. The authors investigated late spontaneous in-the-bag IOL dislocation and found that PXF was the main risk factor for in-the-bag IOL dislocation. The presence of a CTR in the bag did not prevent dislocation. However, Lorente et al. concluded that satisfactory results were achieved with a low rate of complications using different surgical techniques to correct the IOL position. In my daily practice, I have observed an increase in PXF patients, particularly in PXF-related complications such as dislocation or decentration of the IOL–capsular bag complex. Over the past few years, cases of late spontaneous in-the-bag IOL dislocation2 have increased in our clinic. Explantation of the entire IOL–capsular bag complex is sometimes the only way to regain acceptable visual acuity. Because IOLs with premium optics of asphericity, toricity, or bifocality require good centration,3 it is important to look for PXF. Although the classic picture of manifest PXF syndrome has been described, the early stages of exfoliation are not well defined. Despite extensive research, the exact chemical composition of exfoliation material remains unknown. Overproduction and abnormal metabolism of glycosaminoglycans have been suggested as one of the key changes in the PXF syndrome. The protein components of exfoliation material include noncollagenous basement membrane components and epitopes of the elastic fiber system such as fibrillium. Regardless of the etiology, typical exfoliation fibers have been demonstrated by electron microscopy in close association with the preequatorial lens epithelium, the nonpigmented ciliary epithelium, the iris pigment epithelium, the corneal endothelium, the trabecular endothelium, and with almost all cell types of the iris stroma, such as fibrocytes, melanocytes, vascular endothelial cells, pericytes, and smooth muscle cells. Enhanced awareness of this condition and its associated clinical signs are therefore important not only for the detection and management of glaucoma, but also for a sophisticated outcome after cataract extraction. Preoperative determination of PXF patients is crucial to reduce intraoperative surgical complications and provide good long-term outcome.