Posterior chamber intraocular lenses in a series of 75 autopsy eyes. Part I: Loop location

Over a period of 27 months, November 1983 to February 1986, 75 eyes obtained postmortem with posterior chamber intraocular lenses (IOLs) were examined at the Center for Intraocular Lens Research, University of Utah Health Sciences Center. These IOLs were studied by histopathological techniques to determine the location of the loops. The most common combination, found in 47% of the specimens, was one loop in the lens capsular sac (bag) and one loop in the ciliary sulcus. In 32% of the specimens, both loops were in the capsular sac; in 17%, both loops were in the ciliary sulcus. Compared to results observed in other autopsy studies, in which capsular fixation was documented in less than 3% of cases, these findings reflect a trend toward capsular sac (in-the-bag) implantation of open-looped posterior chamber IOLs.     

Prospective experimental study of factors related to posterior chamber intraocular lens decentration.

The effect of posterior chamber intraocular lens (IOL) dimensions, design, style, loop fixation, and anterior capsular tears on decentration were investigated in an experimental model. Nine posterior chamber IOLs of various designs and styles with loop diameters between 12.0 and 14.0 mm and optic diameters between 5.0 and 7.0 mm were implanted in human eyes obtained post mortem. Symmetrical and asymmetrical fixation were investigated in eyes with and without radial tears using the Miyake posterior view technique. Location of IOL loops proved to be the most significant factor in IOL decentration. Decentration was least with symmetrical bag/bag fixation and no radial tears (mean = 0.20 +/- 0.05 mm). Asymmetrical bag/sulcus fixation in the presence of anterior capsular tears was associated with the highest decentration rate (mean 0.68 +/- 0.28 mm). Optic size and total loop diameter had no apparent effect on IOL centration in the immediate postoperative period.     

Histologic findings after successful posterior chamber lens implantation

The eyes of a 50-year-old diabetic hypertensive woman who had had successful bilateral cataract surgery with posterior chamber lens implantation were examined post mortem. On gross examination, each eye was found to contain a Simcoe-style C-loop lens with its optic centered satisfactorily and its inferior loop in the capsular bag. In the right eye the superior loop was in the ciliary sulcus; in the left eye most of the superior loop was in the ciliary sulcus but its distal end was in the capsular bag. Histologic sections confirmed the location of the haptics.     

Location and composition of haptics of posterior chamber intraocular lenses. Histopathologic study of postmortem eyes

Of 110 eyes with posterior chamber intraocular lenses (IOLs) examined postmortem, 37% had both haptics outside of the capsular bag; 57% had one haptic in the capsular bag and the other haptic outside of the bag. Typically, these optics were decentered by 1 to 2 mm. Only six eyes (5%) had both haptics within the capsular bag. Erosion into the ciliary sulcus produced obliteration of the major arterial circle of the iris in 12 eyes (11%). The local tissue response to eroding haptics was similar for haptics composed of polypropylene and haptics composed of polymethylmethacrylate (PMMA). The authors found considerable discrepancy between the actual location of haptics and the surgeon's desired location (i.e., capsular bag or ciliary sulcus). Most of these cases were clinically successful.     

Anterior segment complications and neovascular glaucoma following implantation of a posterior chamber intraocular lens

Lens implantation is now a highly successful operation. Although follow-up over 5 to 10 years with posterior chamber lenses is incomplete, the complication rate appears to be as low or lower than other lens styles. We present an exception: a clinicopathologic analysis of a globe, enucleated 4 years postoperatively, which in spite of uneventful implantation of a posterior chamber lens, developed neovascular glaucoma. Microscopic studies suggest several mechanisms for this rare complication including deep erosion of a prolene loop into the ciliary body, anterior segment ischemia, and breakdown of the blood-aqueous barrier. Scanning microscopy showed cracking of this deeply embedded loop, a finding we interpret as possible stress cracking and/or oxidation. The more flexible loops now used in modern lenses may decrease the chance of deep erosion. Implantation of a loop in the capsular bag may minimize the danger of both erosion and loop degradation. Patients should be followed long-term in order to recognize and treat these rare, but potentially disastrous complications.     

Morphology of capsular sack retraction in relation to capsulotomy technique, lens design and sulcus-/saccus fixation

Over a period of several months the dynamics and morphology of capsular retraction were analyzed with various capsulotomy techniques and IOL types implanted into the capsular bag or the sulcus. The techniques compared were peripheral and intermediate canopener capsulotomy, intermediate and small letter-box capsulotomy, intermediate and small capsulorrhexis with and without superior incisions. The posterior chamber IOLs implanted were one-piece and three-piece C-loop lenses and, in a limited pilot study, one-piece disk lenses. The authors' results indicate that capsular retraction and the stable position of the implant depend on the type, form, and size of the capsulotomy, the type of IOL and its fixation in the bag or sulcus. Any irregularity of the anterior capsule induces irregular capsular retraction with the risk of IOL decentration. Free-floating anterior capsular flaps may induce formation of iridocapsular synechiae. Contact between the anterior capsular rim and the posterior capsule results in capsulocapsular adhesions, capsular wrinkling, and capsular opacification of the contact zone. In order to avoid these capsulocapsular adhesions the diameter of the IOL optics should exceed that of the capsular opening in endocapsular implantation. However, peripheral capsulocapsular adhesions are necessary to stabilize IOL haptics, which for this reason must be of open design. Capsulocapsular adhesions may inhibit migration of lens epithelial cells in secondary capsular opacification. The ideal anterior capsulotomy technique seems to be the symmetrical, small, circular, continuous capsulorrhexis, if endocapsular implantation is desired. However, the technique is mainly designed for phacoemulsification, as a small capsulorrhexis inhibits nuclear expression in extracapsular cataract extraction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Incidence and development of decentration of posterior chamber lenses implanted in the capsule sac

A total of 284 patients with posterior chamber lenses (Sinskey-Kratz type) implanted in the capsular bag were re-examined on average 14 months after implantation. In 87% optical centration was excellent; 12% showed a minimal displacement exceeding 0.4 mm. In four patients (1%) gross displacement of the lens within the capsular bag was seen, caused by proliferation of residual lens cortex, asymmetric shrinkage of the capsular bag, and perforation of the bag by a lens loop.     

Anterior chamber depth with sulcus and capsular bag placed IOGEL lenses

The anterior chamber depth was measured in 15 eyes with sulcus placed (Group 1) and 12 eyes with bag placed (Group 2) IOGEL PC-12 lenses, and in 11 eyes with bag placed IOGEL 1103 lenses (Group 3). The mean anterior chamber depth was 3.29 mm in Group 1, 4.17 mm in Group 2, and 4.16 mm in Group 3. The difference between the mean anterior chamber depth with sulcus and bag placed IOGEL PC-12 lenses is statistically significant (P less than .0005). One effect of the different anterior chamber depths was that the anterior surface of a sulcus placed IOGEL lens frequently touched the pupillary border, whereas this rarely occurred when it was placed in the capsular bag. Another effect of differing anterior chamber depths was a different A-constant for the SRK-formula for sulcus or bag placement. In this study it was about 1 diopter greater with bag fixation than with sulcus fixation. It is recommended that each surgeon use specific A-constants to enhance the predictability of the postoperative refraction.     

Pseudophakic posterior iris chafing syndrome

Posterior iris chafing by the loop or the optic portion of sulcusfixated posterior chamber lens implants may cause a spectrum of disorders that include iris-pigment epithelial "window defects," pigment dispersion with or without elevation of intraocular pressure, intermittent microhyphemas with transient visual obscurations, and the UGH syndrome. It appears that secondary pigmentary glaucoma is more likely with planar loop design than with angulated loops. Optic and loop materials may play a role in the development of the disorder. Implantation of both supporting loops of the implant within the capsular bag is suggested to prevent posterior iris chafing.     

Incidence of secondary cataract in sulcus versus capsular bag fixation of posterior chamber lenses]

We present a retrospective study on the incidence of visually impairing secondary posterior capsule opacification following fixation of an intraocular lens implant either in the ciliary sulcus or the capsular bag. One hundred patients in each group were evaluated 3 1/2 to 3 3/4 years following uncomplicated extracapsular cataract extraction. Only implants with convex-plane optics and forward angulated haptics were used. The incidence of capsular opacification was 20% in eyes with sulcus fixation as opposed to 14% for those with capsular bag fixation. This difference was statistically not significant. The difference in average postoperative interval until development of the secondary cataract (21 months for sulcus, 28 months for capsular bag fixation) or the age of patients with capsular opacification was statistically not significant either. However, it was noted that of the younger patients, between 40 and 50 years at the time of operation, only those with sulcus fixated implants developed secondary cataracts.     

Decentration of flexible loop posterior chamber intraocular lenses in a series of 222 postmortem eyes

Two hundred twenty-two postmortem eyes containing posterior chamber intraocular lenses (IOLs) were analyzed for optic decentration in relationship to lens style, implant duration, and loop fixation site. Decentration values were not affected significantly by either lens style or implant duration. In 33.3% of specimens, both loops were situated within the lens capsular sac, 18.0% had both loops fixated in the ciliary sulcus, and in 48.7% one loop was fixated in the lens capsular sac and the opposite loop in the ciliary sulcus or zonular region. There was a statistically significant difference in the amount of decentration in the three fixation groups studied. Capsular fixation provides the best and most consistent centration compared with fixation of both loops in the ciliary sulcus or asymmetrical fixation with only one loop in the capsular sac.     

Noncicatricial oval deformation of the pupil induced by sulcus-fixated one-piece posterior chamber lenses

A retrospective analysis of 40 cases of sulcus-fixated one-piece poly(methyl methacrylate) posterior chamber lenses revealed ten cases (25%) that demonstrated oval deformation of the pupil, similar to the condition associated with anterior chamber lenses. This complication was not noted until several weeks after surgery, appears to be progressive, and might be the cause of glare symptoms. Possible mechanisms of the pupillary deformation include mechanical stretching of the iris by oversized lenses and fibroproliferation on the posterior iris surface. Prevention rests upon firm capsular bag fixation aided by capsulorhexis and reduction of the overall lens loop diameter.     

Diabetes: cataract extraction and intraocular lenses

New findings concerning the use of anterior chamber angle-fixated lenses, especially with flexible loops, and posterior chamber lenses placed in the ciliary sulcus and in the bag reinforce previous findings that the safest procedure for diabetics is controlled extracapsular surgery with careful cleaning of the cortical material and in-the-bag implantation of a posterior chamber intraocular lens.     

Posterior capsular opacification and intraocular lens decentration. Part I: Comparison of various posterior chamber lens designs implanted in the rabbit model

Experimental phacoemulsification procedures were performed in 54 Rex rabbits. In 96 eyes, posterior chamber intraocular lenses (IOLs) were implanted in the capsular sac, and 12 eyes served as controls with no lens implantation. The IOLs were divided into eight groups consisting of both one-piece and three-piece styles with various optic designs. Each lens was evaluated for the relative effect on posterior capsular opacification (PCO) and optic decentration, two of the most common complications of modern cataract surgery and IOL implantation. Optics with a convex-anterior, plano-posterior design (the type of IOL optic most frequently implanted today) had the highest incidence of PCO. With capsular fixated IOLs, the features that have a statistically significant impact on reducing PCO include (1) one-piece, all-polymethylmethacrylate (PMMA) IOL styles, (2) a biconvex or posterior convex optic design, and (3) angulated loops. Lens decentration was not affected by the optic design, but statistical analysis showed that one-piece, all-PMMA IOL construction provided the most consistent centration.     

白内障术中后囊破裂的Ⅰ期后房型人工晶状体植入术

目的评价白内障囊外摘出术中后囊破裂行前段玻璃体切割联合Ⅰ期后房型人工晶状体植入的手术效果。方法对１４８０例白内障囊外摘出联合后房型人工晶状体植入术中４９例后囊破裂,行前段玻璃体切割联合Ⅰ期后房型人工晶状体植入的手术技巧、术后并发症和术后视力等进行分析。结果手术后囊破裂率为３．３％,７０％患者人工晶状体植入囊袋内,３０％患者为睫状沟,８９．９％患者出院时裸眼视力≥０．５。结论白内障囊外摘出术中后囊破裂,行前段玻璃体切割联合Ⅰ期后房型人工晶状体植入是安全有效的。     

Intraocular lens implantation in the absence of capsular support: a report by the American Academy of Ophthalmology

OBJECTIVE: This review was conducted to determine the safety and efficacy of open-loop anterior chamber, scleral-sutured posterior chamber, and iris-sutured posterior chamber intraocular lenses (IOLs) in eyes with inadequate capsular support for posterior chamber implantation in the capsular bag or ciliary sulcus. It also attempted to determine whether there is a preferred IOL or fixation site of choice in eyes with inadequate capsular support. METHODS: A literature search conducted for the years 1980 to 2001 yielded 189 citations related to IOL implantation in the absence of capsular support. An update search, conducted in March 2002, yielded an additional 28 articles. The Anterior Segment Panel members reviewed these abstracts and selected 148 articles of possible clinical relevance for review. Of these, 89 were considered sufficiently clinically relevant for the panel methodologist to review and rate according to the strength of evidence. A level I rating was assigned to properly conducted, well-designed, randomized clinical trials; a level II rating was assigned to well-designed cohort and case-control studies; and a level III rating was assigned to case series. Articles comparing the safety and efficacy of the IOL type and fixation site were further evaluated for the quality of the statistical methods used in the study. Studies with a rating of A or B were considered acceptable, C was borderline, and D and F were considered unacceptable as medical evidence. RESULTS: Forty-three articles with data concerning outcome of IOL insertion in eyes with inadequate capsular support had an evidence rating of level III or higher and were used in the final review of the safety and efficacy of one or more lens types and/or fixation sites. Seven articles had data about more than one lens type. Six had a statistical method rating of C or higher and were used to evaluate differences in visual outcomes and complication rates between lens types and fixation sites. CONCLUSIONS: The literature supports the safe and effective use of open-loop anterior chamber, scleral-sutured posterior chamber, and iris-sutured posterior chamber IOLs for the correction of aphakia in eyes without adequate capsular support for placement of a posterior chamber lens in the capsular bag or ciliary sulcus. At this time, there is insufficient evidence to demonstrate the superiority of one lens type or fixation site. Precise determination of small differences in visual outcome or complication rates will require a large prospective, randomized clinical trial.     

Posterior chamber intraocular lens implantation in the absence of posterior capsular support

Because of the high incidence and great variety of complications associated with anterior chamber intraocular lenses, we have developed a technique for the implantation of a posterior chamber intraocular lens in the absence of posterior capsular support. The posterior chamber IOL is placed in the ciliary sulcus by suturing the superior haptic to the iris and the inferior haptic to the sclera at the ciliary sulcus. We have used this technique successfully in both complicated extracapsular surgery and secondary intraocular lens implantation.     

Surgical management of posteriorly dislocated silicone plate intraocular lenses

Silicone plate intraocular lenses do not adhere to the lens capsule and are placed under tension by postoperative contraction of the capsular bag. Recent reports suggest that a defect anywhere in the capsular bag can potentially lead to delayed posterior dislocation of silicone plate intraocular lenses. These implants are more difficult to grasp and manipulate inside the eye than traditional polymethylmethacrylate lenses and therefore, require special microsurgical techniques. Given sufficient anterior capsular support, posteriorly dislocated silicone plate implants can be repositioned in the ciliary sulcus and do not necessarily require intraocular lens exchange. With proper vitreoretinal surgical techniques, posteriorly dislocated silicone plate intraocular lenses can be repositioned or exchanged with excellent visual results and an acceptably low complication rate.     

Extracapsular cataract extraction and implantation in the capsular sac during vitrectomy in diabetics]

Removal of the lens is often performed during pars plana vitrectomy for complications of proliferative diabetic retinopathy, but correction of aphakia often remains unsatisfactory. Some authors have reported posterior chamber intraocular lens implantation during pars plana vitrectomy in diabetic patients who presented with coexisting cataract and vitreoretinal complications from proliferative diabetic retinopathy. Some patients were operated by pars plana lensectomy and vitrectomy followed by posterior chamber intraocular lens implantation in the ciliary sulcus, others by extracapsular extraction, posterior chamber intraocular lens implantation in the ciliary sulcus, and pars plana vitrectomy. Other authors have described phacoemulsification through the limbus, pars plana vitrectomy and implantation in the capsular bag in one operation in various indications, including complications of proliferative diabetic retinopathy. We inserted a posterior chamber intraocular lens into the capsular bag in 18 eyes of 16 patients with complications of proliferative diabetic retinopathy after extracapsular cataract extraction and pars plana vitrectomy in a single session. A standard extracapsular cataract extraction was performed before pars plana vitrectomy. Sufficient anterior capsule was left in place in order to facilitate implantation in the capsular bag after pars plana vitrectomy. The anterior chamber was filled with sodium hyaluronate in order to maintain anterior chamber depth, corneal clarity, and good mydriasis during the continuation of the procedure. A standard three port pars plana vitrectomy was performed in all cases. After closure of superior sclerotomies, superior corneal incision was partially reopened, an intraocular lens specifically designed for the capsular bag with an optic size of 7 mm was inserted, and the corneal incision was closed with interrupted 10/0 sutures.(ABSTRACT TRUNCATED AT 250 WORDS)     

One year follow-up of IOGEL intraocular lenses with ciliary sulcus fixation

Fifty-one soft hydrogel posterior chamber intraocular lenses (IOLs) were implanted in the ciliary sulcus after planned extracapsular cataract extractions. In nine cases the IOLs were positioned with one haptic in the capsular bag and the other in the ciliary sulcus. During a one-year follow-up, Nd:YAG capsulotomy was performed on five eyes and cystoid macular edema was present in two cases. No other serious complications were encountered. At one year, visual acuity was 20/30 or better in all eyes that did not have preexisting secondary eye problems. To prevent postoperative rotation, decentration, and deformation of the IOL, unnecessary intraocular manipulation and "in-out" positioning of the IOL should be avoided.