Posterior Chamber Implants Research Articles

Gonioscopic changes after implantation of a posterior chamber lens in phakic myopic eyes

Purpose: To evaluate the effects of posterior chamber implantation of phakic intraocular lenses on angle structures and the correlation with intraocular pressure (IOP). Setting: Department of Ophthalmology, University Hospital of Vienna, Vienna, Austria. Methods: A Staar implantable contact lens (ICL) was implanted in 20 white patients (34 eyes) with high myopia. The patients were followed for a mean of 2.3 years (range 0.8 to 6.0 years). Two subgroups were created: One had a follow-up of 2.4 to 6.0 years and the other, 0.8 to 2.3 years. The mean spherical power of the implanted ICL was −16.8 diopters (D) (range −9.0 to −21.0 D). The angle structures were examined by gonioscopy using the Spaeth technique, and optical pachymetry and IOP were measured in dilated and undilated pupils. Trabecular pigmentation was measured semiquantitatively. The ICL models included a few prototypes (6 eyes), the V2 model (10 eyes), the V3 model (6 eyes), and the V4 model (12 eyes). Results: The anterior chamber angle was between 11 and 20 degrees in 41% of eyes, between 21 and 30 degrees in 21%, larger than 30 degrees in 21%, and 10 degrees or smaller in 17%. An apparent iris root insertion was above Schwalbe’s line in 6% of eyes, behind Schwalbe’s line in 12%, at the scleral spur in 67%, and in a deep angle recess behind the scleral spur in 15%. The curvature of the iris was regular in 19 eyes and steep in 15 eyes. The mean pigmentation in all 4 quadrants was 1.3. (Grade 1 was defined as trace pigmentation.) The mean pachymetry from the endothelium to the ICL anterior surface was 2.7 mm and from the endothelium to the anterior surface of the crystalline lens, 3.2 mm. The mean IOP was 14.1 mm Hg in undilated pupils and 12.1 mm Hg in dilated pupils. There was no correlation between angle pigmentation and IOP. Conclusion: Trace pigmentation in the trabecular meshwork was common after ICL implantation. However, there was no direct influence on IOP. Long-term follow-up is necessary to evaluate the effect and progress of trabecular pigmentation in eyes with an ICL.

Postoperative sterile endophthalmitis (TASS) associated with the memorylens

Purpose To report 10 cases of delayed-onset acute intraocular inflammation following cataract extraction and posterior chamber implantation of the MemoryLens® intraocular lens (IOL). Setting John A. Moran Eye Center, Department of Ophthalmology, University of Utah, Salt Lake City, Utah, USA. Methods This retrospective study evaluated 10 cases of postoperative inflammation that occurred after cataract extraction with placement of the posterior chamber MemoryLens IOL. Protocols of the Intermountain Ocular Research Center used to analyze outbreaks of unexplained postoperative inflammation as well as medical records were reviewed. Results Nine patients had uneventful cataract extraction and 1 had a small anterior capsule tear with placement of the MemoryLens IOL. All 10 patients presented with increased anterior segment inflammation a mean of 7.8 days (range 1 to 21 days) after surgery. Three cases were tapped and were culture negative, and 7 were presumed noninfectious. The anterior segment inflammation improved in all patients. Treatment of the 7 patients included intensive topical steroids. Careful analysis of the inflammation has not revealed an obvious etiology; however, the MemoryLens was associated with all the cases. Conclusions We postulate that these cases of noninfectious postoperative endophthalmitis may be associated with the MemoryLens.

Vitreoretinal surgery through multifocal intraocular lenses compared with monofocal intraocular lenses in fluid-filled and air-filled rabbit eyes

Purpose To compare vitrectomy procedures and visualization of posterior segment structures through multifocal silicone intraocular lenses (IOLs) with the same procedures through monofocal silicone IOLs in rabbit eyes. Design Experimental study. Participants Twelve eyes of six rabbits. Methods Each rabbit eye underwent phacoemulsification of the lens and posterior chamber implantation of a silicone multifocal or silicone monofocal IOL. The type of IOL (monofocal vs. multifocal) implanted in the first eye of each rabbit was randomly decided. The fellow eye then received the other IOL type. Vitrectomy procedures were performed through the IOLs by using a flat contact lens (part 1) or wide-angled contact lens (part 2) for visualization through fluid-filled (parts 1 and 2) and air-filled (part 2) eyes. Main outcome measures Image quality, stereopsis, and contrast were subjectively graded on a scale of 0 (none) to 4 (excellent) for each eye by each surgeon. Results In part 1, image quality averaged 4 for the monofocal IOL and 3.6 for the multifocal IOL. Stereopsis averaged 4 for the monofocal IOL and 4 for the multifocal IOL. Contrast averaged 4 for the monofocal IOL and 3.9 for the multifocal IOL. Vitrectomy with retinal surface maneuvers was successfully performed in both pigmented and nonpigmented rabbit eyes through both IOL types. In part 2, image quality, stereopsis, and contrast were rated as 4 for both multifocal and monofocal silicone IOLs. Air-fluid exchange was performed without difficulty. Image quality, stereopsis, and contrast were rated as 4 for air-filled eyes. Conclusions Visualization of posterior segment structures through multifocal silicone IOLs was sufficient for retinal surface maneuvers during vitrectomy procedures in both fluid-filled and air-filled rabbit eyes.

Stereopsis after primary in-the-bag posterior chamber implantation in children

Purpose: The purpose of this study was to evaluate visual acuity and binocular function after primary posterior chamber intraocular lens (IOL) implantation in children. Patients and Methods: A retrospective chart review of 39 eyes of 31 children was performed. Fifteen eyes with traumatic, 17 with developmental, and 7 with congenital cataracts without any other ophthalmologic problems were examined before and after cataract surgery (irrigation/aspiration procedure with implantation of a posterior chamber IOL). Twelve eyes also received a posterior capsulorrhexis and anterior vitrectomy. The mean age at surgery was 6.9 ± 3 years (range, 3-12 years). Results: Twenty (51%) of 39 eyes achieved a best-corrected postoperative visual acuity of 20/40 or better (range, 20/200-20/20). The mean postoperative visual acuity was 20/40 in the traumatic and developmental cataract groups and 20/100 in the congenital cataract group. There was a positive correlation between cataract morphology and visual acuity ( P <.05). Bilateral cataracts had a better postoperative visual acuity than unilateral cataracts ( P <.005). Nineteen (70%) of 27 eyes in which no primary posterior capsulorrhexis had been performed had posterior capsule opacification. Stereopsis was found in 10 of the 31 patients: 43% of the traumatic cataract group, 30% of the developmental cataract group, and 14% of the congenital cataract group. Conclusions: After capsular bag-fixated IOL, visual acuity and binocular function in children older than 3 years were favorable and the complication rate, excluding posterior capsule opacification, was low. (J AAPOS 1999;3:227-33)

Transscleral suture fixation and anterior chamber intraocular lenses implanted after removal of posteriorly dislocated crystalline lenses.

The surgical technique is described for simultaneous removal of posteriorly dislocated crystalline lenses and implantation of anterior chamber (AC) or scleral fixation posterior chamber (PC) intraocular lenses (IOL) using pars plana vitrectomy. Twenty-two patients underwent this complex operation. Observation time ranged from 2 to 10 months (mean 5 months). Best-corrected post-operative visual acuity was 1.0 in half the patients in the AC group (n = 12), and in 80% of the PC group (n = 10). It was less than 0.5 in 25% of cases in the AC group whereas all PC patients had visual acuity 0.5 or better. In nine cases with pre-operative ocular hypertension, post-operative intraocular pressure became normal, although topical glaucoma therapy was necessary in three patients in the AC group and in one from the PC group. No severe complications were found. Removal of posteriorly dislocated crystalline lens using pars plana vitrectomy and limbal incision is a safe procedure. Simultaneous AC or transscleral PC lens implantation is a good alternative to contact lenses. Visual rehabilitation was good in both groups of patients, although post-operative visual acuity was better after PC transscleral fixation than after AC surgery.

Secondary implantation of angle-supported anterior chamber and scleral-fixated posterior chamber intraocular lenses

Purpose: To compare the results of secondary implantation of angle-supported anterior chamber intraocular lenses (IOLs) and scleral-fixated posterior chamber lenses.Setting: Eye Clinic, University of Verona, Italy.Methods: This study of 68 eyes of 60 patients comprised two groups. In Group A (n = 35), an angle-supported anterior chamber IOL was implanted and in Group B (n = 33), a scleral-fixated posterior chamber IOL. Follow-up was from 12 to 45 months.Results: In Group A, one eye developed a retinal detachment and another, pseudophakic bullous keratopathy. In Group B, one eye had a major intraoperative choroidal hemorrhage and two developed a retinal detachment postoperatively. All other complications were minor.Conclusion: Although the rate of sight-threatening complications was about 6% for both groups, scleral-fixated posterior chamber IOLs were associated with more intraoperative and postoperative complications than angle-fixated anterior chamber IOLs, and surgery took longer. Thus, anterior chamber IOL implantation should be considered for older patients with relatively good endothelial cell counts.

Intraocular lens implantation in children in the West Bank and Gaza.

In order to evaluate the efficacy and safety of intraocular lens (IOL) implantation in paediatric aphakia, we reviewed the records of a consecutive series of 40 children, under 15 years of age, who had IOLs inserted for congenital and developmental cataracts between September 1990 and December 1992. Visual results and lens-induced complications were evaluated in 67 eyes with a mean follow-up of 27 months (range 12-38 months). In 52 eyes the cataract was removed by limbal lens aspiration and in 15 eyes by pars plicata lens aspiration. One-piece PMMA Sinskey-type posterior chamber implants were used in all cases. Sixty-three eyes had primary and 4 eyes secondary implants. Seventeen (49%) of 35 eyes with congenial cataract and 25 (78%) of 32 eyes with developmental cataract achieved a visual acuity of 6/18 or better. Marked anterior uveitis with pupillary membrane formation occurred in 9 (13%) of the 67 eyes. Visually significant posterior capsule opacification occurred in 5 (28%) of the 18 eyes with intact capsule. Our results demonstrate the suitability of IOL implantation in children from an area of low socioeconomic background, and suggest that IOL implantation is an effective and safe procedure for correction of paediatric aphakia. This may have implications for similar populations.

5-fluorouracil and Mitomycin C in Pseudophakic Patients

Purpose: Previous studies have shown that 5-fluorouracil (5-FU) and mitomycin C enhance the success rate of filtration surgery in aphakic eyes. However, eyes with posterior chamber implants have not been specifically studied. This study was performed to compare the safety and efficacy of 5-FU with that of mitomycin C in eyes that have posterior chamber implants and undergo filtration surgery for uncontrolled glaucoma.Methods: Eighty eyes of 74 patients who had previous cataract surgery with posterior chamber implants and who subsequently required trabeculectomy for uncontrolled open-angle glaucoma were randomized to receive either subconjunctival postoperative 5-FU or intraoperative mitomycin C.Results: Twelve months after surgery, intraocular pressures (IOPs) averaged 12.8 ± 5.5 mmHg (mean ± standard deviation) in the mitomycin C group and 14.8 ± 3.8 mmHg in the 5-FU group (P = 0.001). Mitomycin C-treated eyes received an average of 0.6 medications for IOP control, and 5-FU-treated eyes received an average of 1.05 medications (P = 0.03). There was no significant difference in complications between the two groups.Conclusion: Mitomycin C appears be a viable alternative to 5-FU in patients with posterior chamber implants with uncontrolled glaucoma who require filtration surgery.

Continued Endothelial Cell Loss Ten Years after Lens Implantation

To investigate the effects of cataract extraction and lens implantation on the central corneal endothelium 10 years after surgery. The authors conducted a prospective study of 253 consecutive eyes that underwent cataract extraction with or without lens implantation by one surgeon from 1976 to 1982. Three types of lens implant were used during this period. The protocol included ophthalmic examinations and specular microscopy on all eyes preoperatively, and 2 months and 1, 3, 5, and 10 years postoperatively. The 10-year analysis was conducted on 67 (26%) of the 253 total eyes. The remaining patients died (86 eyes [34%]), were unable to return 10 years later (93 eyes [37%]), or had secondary implants (5 eyes [2%]) or penetrating keratoplasty (2 eyes [1%]). There were no statistically significant differences among the median 10-year endothelial cell losses of 36% in 17 control cataract extractions without lens implantation (15 extracapsular and 2 intracapsular), 40% in 15 medallion iris suture implants, 32% in 28 transiridectomy clip implants, and 32% in 7 posterior chamber implants. The median exponential rate of chronic cell loss from 1 to 10 years after surgery was 2.5% per year, which did not differ significantly among the three implant groups or between the implants (2.4% per year) and controls (2.7% per year). The chronic cell loss rate was significantly higher (7.2% per year) in six eyes with cornea guttata, which was the only preoperative endothelial morphologic feature that was significantly associated with the chronic cell loss rate. Ten years after cataract extraction, eyes continued to lose endothelial cells from the central cornea at a rate of 2.5% per year, 2.5 to 8.0 times the rate in healthy unoperated eyes. The rate was not affected significantly by the presence of the three types of lens implants that the authors used. Postoperative eyes with cornea guttata continued to lose cells at more than twice this rate. Preoperative specular microscopy did not provide additional information helpful in predicting postoperative endothelial status or outcome.

Aniseikonia in Intraocular Lens (IOL) Implants: An Optical Analysis

OBJECTIVE: Analyze conditions leading to aniseikonia in patients with IOL implants using a simple model eye. BASIC PROBLEM: A number of different factors contribute to aniseikonia in pseudophakia. What are the optical factors that influence aniseikonia and the resultant consequences? Is it possible to predict the effects of errors in axial length and anterior chamber depth measurements? METHODS: Computer ray-trace analysis of a model eye. Aniseikonia is computed with respect to the emmetropic model eye. RESULTS: We have theoretically calculated the amount of anisekonia in eyes with a posterior chamber IOL. SIGNIFICANCE: Currently favoured posterior chamber implantation of IOLs may result in some degree of aniseikonia. Certain general trends of aniseikonia are predicted which can be used as a ‘rule-of-thumb’ by the clinician. Our theoretical results support recent clinical findings of aniseikonia in the pseudophakic patient population.

Sulcus Fixation without Flaps

Numerous techniques for sulcus fixation of posterior chamber implants in the absence of capsular support have been reported. All rely on partial thickness scleral flaps or the conjunctiva to prevent the requisite polypropylene knot from eroding. The author compares their success with that of a new surgical procedure. This new technique buries the knot within the eye. One hundred scleral-sutured, sulcus-fixated cases were studied retrospectively. Each case was performed by the author or by a resident under this direction. Suture erosion was defined as the absence of scleral or conjunctival cover on part of the polypropylene suture. On 60 patients, partial thickness scleral flaps were used to protect the knot from exposure. Twelve (20%) of these patients had some degree of externalization of the suture. Of the 40 patients in whom knots were buried and no scleral flap was used, no (0%) erosion was observed. Sulcus fixation of posterior chamber knots has been criticized for increasing the risk of endophthalmitis. The track formed by an exposed suture allows an infectious agent to pass from the external eye to the supported intraocular lens (IOL). Scleral flaps add a degree of safety, but the knot can erode after several months. The author advocates burying the knot within the eye to avoid erosion and therefore endophthalmitis.

Bilateral Ciliochoroidal Detachments After Valsalva Maneuver

We had the opportunity to examine a woman with bilateral ciliochoroidal detachments. Report of a Case. —A 63-year-old white woman presented 3 days after several severe and prolonged episodes of emesis from a presumed viral gastroenteritis. She complained of a droplet-shaped scotoma in the right eye and blurred vision in both eyes. Her ocular history was significant for cataract surgery with intraocular implant in her right eye in 1985 and in her left eye in 1986. Best-corrected visual acuity was 20/25 OD and 20/20 OS. Results of slit-lamp examination revealed well-centered posterior chamber implants. Applanation pressures were 15 mm Hg OU. Results of fundus examination of the right eye were remarkable for a dome-shaped orange-brown choroidal elevation in the inferonasal quadrant (Fig 1) associated with a low-lying inferior and nasal choroidal detachment. The disc, macula, and vessels were otherwise normal. Results of examination of the periphery of the left eye

Bacterial Contamination of the Eye during Extracapsular Cataract Surgery

OBJECTIVE: To ascertain the nature and degree of bacterial and fungal contamination of the eye immediately before, during and after extracapsular cataract extraction and posterior chamber implantation. DESIGN: Prospective single blind study. SETTING: Ophthalmic operating theatre in District General Hospital. PATIENTS: 54 patients undergoing routine extracapsular cataract surgery and lens implantation. MAIN OUTCOME MEASURES: The proportion of eyes from which bacterial (or fungal) growth was obtained and the nature of the organisms isolated. RESULTS: Bacterial growth was obtained from at least one source in 48 of the 54 eyes (89% despite prophylactic antibiotic drops. However only four eyes (7r4) had organisms isolated from the anterior chamber paracentesis taken at the end of surgery. Staphylococcus epidermidis was by far the most common organism isolated (881/0. Corynebacterium spp. were found in 14% of cases but Propionibacterium spp. were not specifically identified. Brain-heart infusion enrichment medium produced a marked increase in the yield of organisms isolated in comparison with the other culture media used. Despite the high degree of apparent bacterial contamination there were no cases of endophthalmitis. CONCLUSION: The results indicate that bacterial contamination of the surface of the eye is present during extracapsular cataract extraction and lens implantation in a large number of cases. However, the incidence of contamination of the anterior chamber at the end of surgery is very low and endophthalmitis remains a rare complication. The organism isolated is usually Staphylococcus epidermidis . Use of an enrichment medium is recommended to maximize the isolation of bacterial contaminants.

An Improved Technique for Management of Dislocated Posterior Chamber Implants

Many techniques for repositioning dislocated posterior chamber implants described in the recent literature involve intricate intraocular manipulation of a needle or other sharp instrument. The author describes an improved sulcus fixation technique, which combines the best features of external and internal approaches. Its main features involve temporary externalization of the haptics for easy and secured placement of suture knots, and subsequent reinternalization of the same haptics through horizontal sclerotomies directly external to the ciliary sulcus for precise fixation of the dislocated posterior chamber implant with consistency. Between May 1989 and December 1990, this technique was successfully used for posterior chamber intraocular lens repositioning in 12 cases. The main advantages of this technique include: (1) easy suture placement, (2) less chance of suture slippage with the secured knots, and (3) avoidance of difficult intraocular maneuvers and possible tissue injury. This improved technique expedites the process of posterior chamber implant repositioning.

Gonioscopic changes in eyes with posterior chamber intraocular lenses.

The aim of this study is to determine the effects of posterior chamber implantation on angle structures. First, without previous knowledge of the position of lens haptics, 360 degrees gonioscopy was performed and any changes in the angle structures were recorded. Then, the pupil was dilated to determine the exact position of the intraocular lens haptics. The apposition of peripheral iris to angle structures or, at least, the narrowing of the angle corresponding to the lens haptic position was observed in almost all of the 117 examined eyes, with no difference found between bag and sulcus implantation. Peripheral anterior synechia overlying the lens haptic was observed in 49 (41.8%) of 117 eyes. Interestingly, we also noted that there was marked and well-limited clumping of pigment in the angle at 6 o'clock position in 67 (57.2%) of 117 eyes. In conclusion, we feel that posterior chamber intraocular lenses are not completely innocuous to the angle structures.

Microendoscopic ocular surgery: A new intraoperative, diagnostic and therapeutic strategy: Part I: Endoscopic equipment/methodology applied to cataract surgery with intraocular lens implantation

During posterior chamber implantation, endoscopy is the only direct method that allows objective observation of the retroiridal space. We use it to define the parameters of the posterior chamber intraocular lens (isolation, inertia, centering). An oval endoscopic probe is preferred and the multivision system allows observation of the endoscopic images under the operative microscope eyepiece. Beside “blind” posterior chamber implantation, a “controlled” endoscopic posterior implantation can be defined.

Management of Dislocated Posterior Chamber Intraocular Lenses

AbstractManagement options for posteriorly dislocated posterior chamber intraocular lenses include observation, removal, exchange, and repositioning. Many microsurgical techniques have been developed for repositioning posterior chamber implants. These include repositioning into the ciliary sulcus without suturing if adequate posterior capsule support remains, iris fixation suturing techniques, and scleral fixation suturing techniques. The indications, timing, and techniques for intervention are reviewed in a series of 32 cases with posteriorly dislocated posterior chamber implants. A final visual acuity of 20/40 or better was achieved in 15 (79%) of 19 IOL repositioned cases, in 6 (75%) of 8 IOL exchanged cases, and in 1 (33%) of 3 IOL removed cases. In two patients observed without surgery, final visual acuity was 20/25 and 20/300, respectively.

Aniseikonia: a method of objective assessment in pseudophakia using geometric optics

There have been various reports in the literature regarding the limits that separate acceptable from disturbing aniseikonia. A criterion value of 5% is often quoted but actual values in pseudophakia may vary from 2% to 10%, depending on the type and position of implant used. In the accompanying paper we have reported a method by which image size can be calculated in the pseudophakic eye. Using this method a series of patients with anterior and posterior chamber implants were analysed and the image size for both eyes of each patient determined. This was compared with the patient's subjective appreciation.

Posterior Chamber Implants in Unilateral Congenital and Developmental Cataracts

Lens implantation in infant and young children has always been a controversial subject, mainly because there is, as yet, no consensus on the surgical approach or the choice of the lens and its dioptric power. Between June 1983 and June 1989, 45 posterior chamber intraocular lenses (IOLs) were implanted in unilateral congenital and developmental cataract patients aged 2 months to 8 years. Prior to the insertion of the lens, a cataract aspiration followed by an elective posterior capsulotomy and anterior vitrectomy were performed in all the cases. The implants were lathe-cut one-piece PMMA lenses of reduced diameter and were inserted either in the bag remnants or in the ciliary sulcus. For infants and toddlers the power of the inserted IOL was 3 to 6 diopters, less than needed for emmetropia. Spectacles were provided to correct residual refractive error. The best visual results were obtained in the developmental cataract group whereas the congenital cataract patients achieved lower visual acuities.

Accelerated ocular neovascularisation in diabetics following posterior chamber lens implantation.

Two well controlled non-insulin dependent diabetics with background retinopathy underwent endocapsular lens extraction with in-the-bag posterior chamber implantation. In the postoperative period rubeosis iridis set in abruptly. The fellow eyes showed no progression of retinopathy and the diabetic status showed no deterioration. The cause of neovascularisation and the role of intra- versus extracapsular extraction with implantation are discussed.