42 Pathology of Complicated Phacoemulsification The Intermountain Ocular Research Center at the John A. Moran Eye Center, University of Utah (Salt Lake City, UT), codirected by Nick Mamalis and myself, is a laboratory specializing in the evaluation of ocular implantable biodevices, particularly intraocular lenses (IOLs), for cataract surgery. Pathological analyses and experiments involving pseudophakic human eyes obtained postmortem, as well as IOLs explanted because of various problems, have proved to be very useful in the understanding of different complications of cataract surgery procedures with IOL implantation. This chapter discusses the pathological aspects of the phacoemulsification procedure with IOL implantation as well as the postoperative complications, based on the most recent work of our laboratory using pseudophakic human eyes and explanted IOLs. These complications may necessitate secondary procedures for lens explantation or repositioning. Multiple conditions may play a role in contributing to inherent zonular weakness and instability. The most commonly correlated conditions include pseudoexfoliation (PXF) syndrome, previous vitreoretinal surgery, trauma, and myopia. Additional causes include connective tissue disorders (Marfan’s syndrome, Ehlers-Danlos syndrome, homocystinuria, Weill-Marchesani syndrome) and retinitis pigmentosa.1–3 PXF is a condition in which abnormal extracellular matrix and basement membrane structural and metabolic proteins are deposited into virtually all structures within the anterior chamber (Fig. 42.1). These accumulations mechanically weaken the zonular lamella and impair zonular anchoring to the epithelial basement membrane at both its origin and insertion. Because zonules are mainly composed of elastic fibers, and because patients with PXF exhibit an increase in elastolysis, the disease likely also enzymatically weakens the zonules.4 We have been receiving an increasing number of specimens in our laboratory from cases of in-the-bag IOL subluxation/dislocation.5–7 The findings of 86 consecutive cases sent for pathological analysis were described in 2009.6 Two of the specimens were submitted before 2003, and all others between 2006 and 2008. The mean time from surgery to spontaneous IOL dislocation was 8.5 years. Associated conditions included PXF (50%), prior vitreoretinal surgery (19%), history of trauma (6%), uveitis (2%), and none/unknown (23%). None of the specimens contained an accompanying capsular tension ring (CTR), which indirectly suggests the efficacy of this device in preventing this complication (Fig. 42.2a).6 In a follow-up study, 23 specimens corresponding to explanted subluxated/dislocated capsular bags containing a CTR and an IOL were evaluated (Fig. 42.2b).7 Explantation was performed 81.5 ± 32.2 months after implantation. Available information on associated ocular conditions included PXF (N = 17), glaucoma (N = 4), vitrectomy/retina surgery (N = 3), and trauma (N = 1). Excessive contraction of the capsular bag with capsulorrhexis phimosis was observed in 11 specimens: one with an associated history of vitrectomy, seven with an associated history of PXF, and three with an associated history of glaucoma (Fig. 42.3). Explantation was performed 72.1 ± 41.3 months after implantation (∼ 6 years) in eyes with capsulorrhexis phimosis.7 It is not surprising that the mean explantation time was shorter in the series of 23 specimens containing a CTR (6.8 or 6 years, without or with capsulorrhexis phimosis, respectively),7 in comparison with the series of 86 specimens without a CTR (8.5 years),6 considering that CTRs are usually implanted when zonular weakness is observed before or during surgery. Stress to the zonules during CTR insertion can also not be ruled out.3 It is noteworthy that histopathological assessment completed in selected specimens showed material consistent with PXF, although there was no history or clinical signs of this condition.7 We hypothesized that the prevalence of PXF in our subluxation/dislocation series may be higher than the rate based on clinical history and clinical examination. Therefore, we undertook a study involving a retrospective case series with complete histo-pathological examination of 40 explanted subluxated/dislocated capsular bags containing an IOL, or a CTR and an IOL.8 Excessive contraction of the capsular bag with capsulorrhexis phimosis was observed in 24 specimens; 26 specimens had histopathological evidence of PXF, whereas only 13 had a clinical history/evidence of PXF. Therefore, PXF may be implicated in a larger proportion of late in-the-bag IOL subluxations/dislocations than previously thought due to significant clinical underdiagnosis. This may impart a need to consider new factors during the preand postoperative cataract surgery assessments and follow-up. It is also noteworthy that different IOL materials and designs were represented in the above-mentioned studies performed in our laboratory, with no apparent preference. Also, the amount of Soemmering’s ring (SR) formation within the capsular bags varied from mild to severe.5–8 One-piece and three-piece hydrophobic acrylic AcrySof lenses (Alcon, Fort Worth, TX) have a square optic edge on the anterior and posterior optic surfaces. The finishing of the square edges of these lenses was modified to give the side walls an unpolished or “textured” appearance, which was found to improve postoperative glare phenomena.9 This feature was extended along the length of the optic and haptics in the one-piece lenses. Because of the flexibility and thickness/bulk of its haptics, the square optic and haptic edges, and the unpolished side walls, implantation of the one-piece AcrySof lens in the sulcus is not recommended, mended, and this design is not indicated for sulcus fixation, according to the directions-for-use labeling. Furthermore, the haptics of the one-piece lens are planar and therefore do not vault the optic posteriorly from the iris. The overall lens diameter is up to 13.0 mm, which is too short for many eyes; if the haptics do not fully extend because of their low compressive force, the IOL will be prone to decentration in the ciliary sulcus of larger eyes.10 A study from our laboratory reported on three one-piece lenses that were explanted because of pigmentary dispersion syndrome related to the presence of their haptics in the ciliary sulcus (Fig. 42.4).11 These cases revealed the presence of significant amounts of iris pigment on the anterior surface of the lens (optics and haptics). Other similar cases of pigmentary dispersion with this lens have been described in the literature, which were generally managed with explantation/exchange of the lens, or by surgical repositioning within the capsular bag.10 Fig. 42.1 Histopathological sections of capsular bags from in-the-bag subluxation/luxation cases (Masson’s trichrome stain). The arrows show the Pseudoexfoliation material on the anterior capsules. There are significant amounts of fibrotic material attached to the inner surface of the anterior capsules, with contraction and folds. (a,b) Original magnification ×400. Fig. 42.2 Gross photographs of in-the-bag subluxation/luxation cases. (a) In-the-bag luxation of a one-piece hydrophobic acrylic lens. There is capsulorrhexis phimosis and mild Soemmering’s ring formation. (b) In-the-bag luxation of a three-piece hydrophobic acrylic lens with a capsular tension ring (CTR). There is significant fibrosis of the rhexis edge and moderate Soemmering’s ring formation. Fig. 42.3 Light photomicrographs from in-the-bag subluxation/luxation cases (three-piece hydrophobic acrylic lenses). There are different degrees of capsulorrhexis phimosis, capsular contraction, and capsular folds. (a) Without a CTR. (b) With a CTR. Fig. 42.4 A case of asymmetric (bag-sulcus) fixation of a one-piece hydrophobic acrylic lens. (a) Clinical photograph showing the loop in the sulcus through a transillumination defect (arrows). (b) Gross photograph of the explanted lens. (c) Light photomicrograph of the lens showing pigmentary dispersion (×200). (d) Scanning electron photomicrograph showing the thick loop with rough edges. (From LeBoyer RM, Werner L, Snyder ME, et al. Acute haptic-induced ciliary sulcus irritation associated with single-piece AcrySof intraocular lenses. J Cataract Refract Surg 2005;31:1421–1427. Reprinted by permission.) In a retrospective study, Chang et al10 described the findings in 30 eyes with sulcus-fixated one-piece lenses (29 of those were one-piece AcrySof; one was a Rayner [Kansas City, MO] model 570C hydrophilic acrylic design). Posterior capsule rupture and IOL decentration were observed in approximately two thirds of the eyes. No IOL was suture fixated to the iris or sclera. Approximately one third of the patients were taking at least one intraocular pressure (IOP)-lowering medication. The most common complications were pigment dispersion and iris transillumination defects, followed by IOL edge symptoms and elevated IOP. Intraocular hemorrhage and cystoid macular edema were relatively infrequent. The authors hypothesized that the latter may have been underreported because of the retrospective nature of the data collection. Similar complications have also been reported with three-piece AcrySof lenses, in a piggyback configuration or standard sulcus fixation.12–16 In piggyback implantation, fixation of the anterior lens in the sulcus has been recommended to prevent interlenticular opacification. However, a previous publication from our laboratory described a case of pigmentary dispersion syndrome resulting from secondary piggyback implantation of a low power three-piece hydrophobic acrylic, square-edged IOL in the ciliary sulcus (AcrySof IOL model MA60MA; +5 D).12 Chang and Lim,13 as well as Iwase and Tanaka,14 have also described cases of pigmentary dispersion syndrome with the same three-piece hydrophobic acrylic lens implanted in a piggyback configuration. Wintle and Austin15 reported a case of pigmentary dispersion syndrome 1 month following implantation of a three-piece hydrophobic acrylic lens (AcrySof IOL model MA60BM, 6.0 mm optic, 13.0 mm overall length) placed electively in the ciliary sulcus following a posterior capsule tear. A similar case was also described by Almond et al.16 Other studies did not show excessive interaction between these three-piece, sulcus-fixated lenses and the posterior iris surface.17,18 We performed a donor eye study in our laboratory that provided pathological evidence of complications related to out-of-the-bag fixation of one- or three-piece hydrophobic acrylic IOLs with anterior and posterior square optic edges.19 Eighteen eyes with the targeted lenses exhibited asymmetric or sulcus IOL fixation (6 one-piece, and 12 three-piece IOLs). These eyes underwent complete histopathological evaluation and were compared with the contralateral eyes with symmetric in-the-bag IOL implantation. The pathological findings were IOL decentration and tilt, pigmentary dispersion within the anterior segment and on the IOL surface, iris transillumination defects, iris changes including vacuolization/disruption/loss of the pigmented layer, iris thinning, and iris atrophy, as well as synechiae and loop erosion in the case of three-piece lenses. Findings were more significant in comparison with the control contralateral eyes and were particularly evident in relation to the sulcus-fixated haptic in the case of one-piece lenses (Fig. 42.5). The majority of the eyes with three-piece lenses in the above-mentioned study showed signs of complicated surgery; therefore, all pathological findings in those cases could not be strictly attributed to the out-of-the-bag fixation of the IOL. To further understand these findings, we compared the pathological findings from 13 eyes with three-piece hydrophobic acrylic IOLs with anterior and posterior square optic edges to those from 14 eyes with three-piece lenses with anterior round edges (13 silicone lenses, and one hydrophobic acrylic lens) (Fig. 42.6). All lenses had sulcus fixation or asymmetric fixation.20 In both groups, more significant defects were especially evident in relation to the side of the IOL fixated in the sulcus (in asymmetric fixation cases). Gross/macroscopic decentration, tilt, pigment dispersion, and iris transillumination defects were statistically similar in both groups, and to a great extent could have been related to the complicated surgery itself. However, the most striking findings in this second study came from the analyses of the histopathological sections of the eyes. The severity of the iris changes was more prominent in relation to three-piece lenses with square anterior optic edges. Also, all eyes with these lenses had pigmentary dispersion within the trabecular meshwork, in comparison to only one eye in the group of lenses with round anterior edges. This indicates continuous trauma to the posterior surface of the iris, likely related to rubbing by the square optic edge.20 Our pathological findings, therefore, appear to confirm that IOLs with round anterior edges are more suitable for sulcus fixation.
In-the-Bag Intraocular Lens Subluxation/Dislocation
Sulcus Intraocular Lenses and Pigmentary Dispersion
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