Clinical results of three types of intraocular lenses for small incision surgery

We implanted three types of intraocular lens (IOL) in 30 eyes each by small-incision surgery. They were: foldable acryl IOL, foldable silicone IOL and polymethylmethacrylate (PMMA) IOL. We evaluated the following items during three years after surgery: visual acuity, astigmatism, glare disability, contrast sensitivity, tilt and decentering of IOL, corneal endothelial population, aqueous flare and aftercataract. Eyes foldable IOLs were more excellent than PMMA IOLs regarding visual acuity, astigmatism and aqueous flare which are indices for the early postoperative period. PMMA and acryl IOLs were more excellent than silicone IOLs regarding decentration of IOL and aftercataract which are indices for the late postoperative period.     

Accurate determination of effective lens position and lens-capsule distance with 4 intraocular lenses

PURPOSE: To measure effective lens position (ELP) of 4 intraocular lenses (IOLs) using high precision and high resolution dual-beam partial coherence interferometry (PCI) and to assess the tendency of these IOLs to produce a lens-capsule distance (LCD), a possible risk factor for posterior capsule opacification. SETTING: Department of Ophthalmology, Vienna General Hospital; Institute of Medical Physics, University of Vienna, Austria. METHODS: In a retrospective study, PCI was used to measure ELP and LCD in 139 pseudophakic eyes of 110 patients with 4 IOLs: acrylic 3-piece IOL (AcrySof MA60BM); silicone 3-piece IOL without a capsular tension ring (PhacoFlex SI30) and with a capsular tension ring (PhacoFlex SI30 and Morcher Type 14); silicone plate-haptic IOL (Staar AA4203VF); and a hydrogel plate-haptic IOL (logel 1103). RESULTS: The ELP and LCD were determined with a precision of approximately 3 to 4 microns. An LCD was detected in 21% eyes with the AcrySof, 20% of eyes with the SI30 without a capsular tension ring, 10% of eyes with a capsular tension ring, 21% of eyes with the Staar, and 17% of eyes with the logel. The LCDs detected by PCI, but not by slitlamp examination, were significantly smaller than those detected by both. CONCLUSION: The amount of LCD detected by PCI was approximately the same with all IOL types (approximately 20%) except the PhacoFlex SI30 with a capsular tension ring (10%).     

Postoperative cellular reaction on various intraocular lens materials

PURPOSE: The presence of cellular deposits on the surface of intraocular lenses (IOLs) is a manifestation of: (1) the breakdown of the blood-aqueous barrier produced by surgery; and (2) foreign body reaction induced by lens implantation. The purpose of this study was to assess the presence of cellular deposits on the surfaces of various IOL materials. METHODS: Fifty patients scheduled for cataract surgery were randomized into five groups of ten patients each and received IOLs of the following materials: conventional polymethylmethacrylate (PMMA), surface-passivated PMMA, heparin-surface modified PMMA, poly-hydroxyethylmethacrylate (HEMA) hydrogel and silicone. Patients were examined at 7 days, 30 days, 90 days, and 180 days after surgery. All eyes were observed first via slit-lamp and then using a contact specular microscope for photographic documentation. RESULTS: Small, spindle-shaped cells were observed on all IOLs in the early postoperative period. Epithelioid cells appeared approximately 30 days after surgery on all PMMA IOLs, but most particularly on conventional PMMA IOLs. No cells were observed on poly-HEMA and silicone IOLs. CONCLUSIONS: The decreased number of epithelioid cells discovered in the early postoperative period may indicate a reduction in the inflammatory process induced by surgery. The permanence of epithelioid cells on IOL surfaces may be a sign of foreign body reaction. The results of this study indicated that poly-HEMA and silicone IOLs showed fewer cellular deposits than PMMA IOLs, suggesting that they may be better tolerated than PMMA IOLs.     

The effect of polymethylmethacrylate, silicone, and polyacrylic intraocular lenses on posterior capsular opacification 3 years after cataract surgery

OBJECTIVE: To compare the visual outcome, neodymium:YAG (Nd:YAG) capsulotomy rates, and percentage of posterior capsular opacification (PCO) seen with polymethylmethacrylate (PMMA), silicone, and polyacrylic intraocular lens implants 3 years after surgery. DESIGN: Randomized, prospective trial. PARTICIPANTS: Ninety eyes of 81 patients were examined at a British teaching hospital. INTERVENTION: Ninety eyes were prospectively randomized to receive a PMMA, silicone, or polyacrylic (AcrySof, Alcon, Fort Worth, TX) implant. All lenses had 6-mm disc optics with PMMA haptics. A standardized surgical protocol was performed by a single surgeon using an extracapsular technique with capsulorhexis; any surgical complications were excluded and all patients had standardized postoperative medication and follow-up. MAIN OUTCOME MEASURES: Patients were seen at 6 months and 1, 2, and 3 years after surgery. At 3 years, logarithm of the minimum angle of resolution (LogMAR) visual acuity and Pelli-Robson contrast sensitivity were measured and YAG capsulotomy rates determined. Posterior capsular opacification was assessed objectively by digital retroillumination imaging using dedicated software and calculated as the percentage area of opacified capsule. RESULTS: At 3 years, the overall follow-up rate was 71%: 19 patients were available for examination with polyacrylic lens implants, 22 with silicone, and 23 with PMMA. There was a significant difference in percentage PCO at 3 years among the lens types (P = 0.0001). Polyacrylic lenses were associated with less PCO (10%) than silicone (40%) and PMMA lenses (56%). The YAG capsulotomy rate was 0% for polyacrylic, 14% for silicone, and 26% for PMMA (P = 0.05). The visual acuity and contrast sensitivity were not significantly different among the three groups if patients with age-related macular degeneration and those requiring YAG capsulotomies are excluded. CONCLUSIONS: Intraocular lenses made from polyacrylic are associated with a significantly reduced degree of PCO and lower YAG rates.     

An evaluation of the biocompatibility of intraocular lenses

BACKGROUND AND OBJECTIVE: The degree of cell adhesion to intraocular lenses (IOLs) was studied through the cell culture system and the morphology of adhering cells was studied using a light electron microscope and a scanning electron microscope. MATERIALS AND METHODS: Human lens epithelial cells were used as materials. The IOL materials were classified into four groups: polymethylmethacrylate (PMMA), heparin surface modified PMMA, surface passivated PMMA, and silicone. RESULTS: PMMA showed greater adhesion than did the other materials. Cells hardly adhered to silicone. Use of a light electron microscope and a scanning electron microscope revealed that cells adhered uniformly to the surface of PMMA and were elongated, but did not adhere uniformly to IOLs of other materials. Only a few cells without the tendency of elongation were noted on the silicone the second day after culture. The 14th day after culture, the surfaces of IOLs, except those of silicone, were covered with cells. CONCLUSION: Such differences in the surface adhesion and morphology of cells adhering to the IOL surface are important in evaluating IOL biocompatibility.     

Fixation elements on plate intraocular lens: large positioning holes to improve security of capsular fixation

OBJECTIVE: This study aimed to evaluate in rabbit eyes the effects of large positioning holes in one-piece silicone plate-haptic intraocular lenses (IOLs) with respect to security of capsular bag fixation. Mechanical strength of capsular fixation is correlated with the histologic findings of regenerating lens material and fibrous tissue ingrowth through the positioning holes on silicone plate IOLs, comparing capsules implanted with large-hole style plate IOLs to fellow capsules implanted with small-hole style plate IOLs. DESIGN: The study design was a prospective, randomized, experimental study. PARTICIPANTS: A total of 40 fellow capsular bags from 20 New Zealand white rabbits were examined. Capsules implanted with conventional small-hole silicone plate IOLs were used as the control in all pairs of fellow capsules. INTERVENTION: Phacoemulsification and implantation of a silicone plate IOL with small positioning holes in one eye and implantation of a silicone plate IOL with large positioning holes in the fellow eye were measured. All rabbits were killed at 2 months. The force required to extract the IOLs from the capsular bag was measured. All capsular bags underwent histopathologic analysis. MAIN OUTCOME MEASURES: Extraction force measurements and histopathologic examination, comparing capsules implanted with small-hole plate IOLs with fellow capsules implanted with large-hole plate IOLs, were measured. RESULTS: The large-hole style IOL required significantly more force to extract from the capsular bag compared to the conventional small-hole style (P = 0.003). Histologically, proliferating lens epithelial material and fibrous tissue were observed growing through all of the large positioning holes (synechia formation) but not through any of the small positioning holes. CONCLUSIONS: Silicone plate IOLs with large positioning holes become affixed more firmly within the capsular bag compared to conventional small-hole plate IOLs. These findings suggest that large holes in silicone plate IOLs allow for superior capsular bag fixation. This should reduce the rates of decentration and dislocation.     

Noncorneal astigmatism related to poly(methyl methacrylate) and plate-haptic silicone intraocular lenses

PURPOSE: To evaluate noncorneal astigmatism after implantation of a one-piece, plate-haptic silicone or one-piece poly(methyl methacrylate) PMMA intraocular lens (IOL). SETTING: Klinik und Poliklinik für Augenheilkunde der Universit?t Regensburg, Germany. METHODS: After a follow-up of at least 3 months, the degree of postoperative noncorneal astigmatism was calculated using the data from an auto refractometer. Sixty patients were evaluated: 30 with silicone IOLs (Group A) and 30 with PMMA lenses (Group B). RESULTS: Mean noncorneal astigmatism in Group A was 0.78 diopter (D) +/- 0.51 (SD), which was statistically significantly higher than that in Group B (0.51 +/- 0.27 D) (P = .013). The highest noncorneal astigmatism, 2.32 D, occurred in Group A. CONCLUSIONS: Based on these findings, we recommend noncorneal astigmatism be considered in eyes with a one-piece, plate-haptic silicone IOL and postoperative astigmatism. A prospective study with a standardized capsulorhexis size is needed to ascertain whether this IOL-related noncorneal astigmatism is caused by capsular shrinkage, which may then be treatable with a laser capsulotomy of the anterior capsule.     

Inhibition of migrating lens epithelial cells at the capsular bend created by the rectangular optic edge of a posterior chamber intraocular lens

BACKGROUND AND OBJECTIVE: To study the mechanism of the reportedly low incidence of posterior capsule opacification (PCO) in eyes treated with a posterior chamber intraocular lens (PC IOL). MATERIALS AND METHODS: Various IOL designs, including the PC IOL, were studied using scanning electron microscopy. Rabbit lens capsules were studied histopathologically 2, 3, and 4 weeks after implantation of a PC IOL in one eye and a biconvex polymethylmethacrylate (PMMA) IOL in the contralateral eye as a control. RESULTS: The optic edge of the PC IOL was sharp and rectangular, whereas that of the biconvex PMMA or silicone IOLs from various manufacturers had been smoothed and rounded by polishing. PCO was significantly reduced in the eye with a PC IOL in all rabbits. The lens capsule wrapped tightly around the optic edge of the PC IOL so that it conformed to the same shape and thereby created a distinct rectangular bend in the capsule or a rectangle between the optic edge and the posterior capsule. Migrating lens epithelial cells (LECs) were obviously inhibited at that site. CONCLUSIONS: A discontinuous capsular bend or rectangle created by the sharp, square optic edge of the PC IOL may have induced contact inhibition to migrating LECs and reduced PCO. How, whether, and to what extent this design-dependent effect is influenced by features of the IOL material needs to be clarified by comparison with results achieved with an IOL made from the same material in a different design and vice versa.     

Involvement of macrophage scavenger receptors in protection against murine malaria

OBJECTIVE: This study aimed to determine whether heparin surface-modified (HSM) intraocular lenses (IOLs) with a hydrophilic surface would reduce cell adherence and other postoperative changes compared with the conventional polymethylmethacrylate (PMMA) IOLs in patients with either diabetes mellitus or inactive uveitis. DESIGN: The study design was a randomized, double-masked, clinical trial. PARTICIPANTS: Twenty-five patients with bilateral cataracts, 14 with inactive anterior uveitis and 11 with diabetes, with an age range of 11 to 81 years (mean, 52.8 years) participated. INTERVENTION: Bilateral cataract extraction with posterior chamber IOL implantation was measured, each patient receiving an HSM lens in one eye and a PMMA lens in the other. Pharmacia one-piece HSM and PMMA IOLs were used. Postoperative ocular changes were evaluated at regular intervals for 24 months in patients with inactive uveitis and for 6 months in patients with diabetes. Patients and physicians alike were unaware of which eye contained which lens until postoperative results were compiled. Records were kept by a study coordinator. MAIN OUTCOME MEASURES: Comparisons of posterior synechiae, IOL cellular deposits, and posterior capsular fibrosis between PMMA and HSM IOLs were measured. RESULTS: Using the chi-square test, no statistically significant difference was found between the HSM and PMMA IOLs in the number of cellular deposits found on the anterior IOL surface, the number of adhesions between the iris and IOL, or the incidence of capsular opacification. CONCLUSION: The HSM and PMMA IOLs showed similar postoperative results in patients with inactive uveitis or diabetes mellitus.     

A selective approach to the management of gunshot wounds to the back

PURPOSE: To study corneal changes after endocapsular phacoemulsification cataract extraction and intraocular lens (IOL) implantation with a 3.5 mm clear corneal sutureless incision or a 5.0 mm clear corneal incision with an absorbable suture. SETTING: Northwest Kansas Eye Clinic, Hays, Kansas, USA. METHODS: In a prospective study, 200 eyes were randomly distributed into two groups. Group A comprised 100 eyes that had a silicone IOL inserted through a 3.5 mm sutureless clear corneal incision. Group B comprised 100 eyes that had a 5.0 mm poly(methyl methacrylate) (PMMA) IOL inserted through a 5.0 mm clear corneal incision; one half of the closures used a single radial suture (Group B1), and the other half, an X suture (Group B2). Preoperatively, corneal topography and corneal endothelial cell counts were performed. Six to 8 months postoperatively, they were repeated and evaluated. Differential topography was used to determine the difference between the preoperative and postoperative corneas. During the final postoperative visit, IOL centration was evaluated. RESULTS: All closures produced only minimal changes in the corneal topographic indices. The postoperative corneas closely resembled the preoperative corneas. Polar K values showed a slight astigmatic shift in all groups. Group B2 was the only one to exhibit a with-the-rule shift. The change in endothelial cell counts was minimal and comparable in all three groups. CONCLUSION: The small amount of change in the corneal indices, especially in surface regularity, indicates that all corneas were relatively comparable and stable 6 to 9 months postoperatively regardless of the type of incision and closure method.     

Security of capsular fixation: small-versus large-hole plate-hepatic lenses

PURPOSE: To assess the effect of relatively large positioning holes on the security of capsular bag fixation of plate-haptic silicone intraocular lenses (IOLs). SETTING: Center for Research on Ocular Therapeutics and Biodevices, Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: This study tested the hypothesis that larger holes allow ingrowth of lens material, fibrous tissue, or both through them, which helps fixate the lens more firmly in the capsular bag. Five rabbits had bilateral continuous curvilinear capsulorhexis, phacoemulsification, and implantation of a plate-haptic silicone IOL. An IOL with a small, round positioning hole (Staar AA-4203V) was implanted in the right eye in each rabbit, and a large-hole IOL (Staar AA-4203VF) was implanted in the left eye. After 2 months, all rabbits were killed. The force required to extract one haptic from the capsular bag was measured with a digital force meter. All eyes had histopathological analysis. RESULTS: It was slightly more difficult to extract a large-hole IOL from the capsular bag, although this trend was not statistically significant. However, histopathological analysis consistently showed 360 degree synechia formation through the holes, showing that the IOL could be securely fixed in position. CONCLUSIONS: Proliferation of lens epithelial cells through a large positioning hole in a plate-haptic silicone IOL may improve the long-term security of capsular bag fixation. This will help reduce the incidence of IOL decentration and dislocation.     

Substance abuse: infant and childhood outcomes

IOL implantation in childhood is still controversial. INTENTION: The purpose of this retrospective study was to evaluate functional results and complications in children after IOL implantation. METHODS AND RESULTS: Posterior chamber IOLs were implanted in 52 eyes of 45 children. Cataract extraction was necessary because of traumatic, congenital/developmental and secondary lens opacities. Nine IOLs were implanted in children between the ages of 1.9 and 4 years, 17 IOLs from 4 to 8 years and 26 IOLs in patients 8 to 14.3 years old. In 38 of the 52 eyes (73%) vision improved after the surgery. Fifty-four percent had an acuity of at least 0.5. The functional results of children more than 8 years old were superior to those of younger patients. Children with traumatic cataracts had better visual acuities than those with other types of cataract. Except for secondary capsular opacities (75%) that could not be prevented by performing a primary posterior capsulotomy or capsulectomy and iris capture (31%), postoperative complications were rare. CONCLUSION: Favorable functional results can be achieved by IOL implantation in children with cataracts. Many patients require secondary surgical procedures because of capsular opacities and iris capture.     

Light and scanning electron microscopy of rabbit lens capsules with intraocular lenses

PURPOSE: To examine postoperative changes in the lens capsules of rabbit eyes after phacoemulsification and aspiration of the crystalline lens and implantation of posterior chamber intraocular lenses (IOLs) using light and scanning electron microscopy. SETTING: Research Laboratory, Department of Ophthalmology, Wakayama Medical College, Japan. METHODS: The crystalline lens was emulsified and aspirated and an IOL implanted in the capsular bag or ciliary sulcus of each eye in adult albino rabbits under general anesthesia. Animals were killed after 4 weeks, and the lens capsules were removed. The specimens were observed under phase-contrast microscopy and processed for light and scanning electron microscopy. RESULTS: Phase-contrast microscopy revealed presumed lens epithelial cells (LECs) on the central posterior capsules in association with regenerating lenticular fibers and Elschnig pearls in the peripheral capsules. Scanning electron microscopy showed the accumulation of fibrous extracellular matrix on the surface of the posterior capsule in eyes in which the IOL was implanted in the ciliary sulcus. Deposition of packed material attached to the surface of IOLs and of Soemmering's ring were observed in eyes with in-the-bag IOL fixation. At a higher magnification, a parallel arrangement of lenticular fibers was seen in the regenerated lens structure on posterior capsules. An identical structure was observed under light microscopy. Outgrowth of presumed LECs from residual anterior lens capsules and adhesion of macrophages and giant cells were observed on the IOL surface. CONCLUSION: Two types of postoperative changes were observed in lens capsules after implantation of IOLs: accumulation of fibrous extracellular matrix and newly formed lenticular fibers. These changes are attributed to the proliferation of LECs and can induce posterior capsule opacification after IOL implantation.     

Extracts of Prevotella intermedia and Actinobacillus actinomycetemcomitans inhibit alkaline phosphatase activity in osteoblastic cells in vitro

A prospective, randomized study was carried out to evaluate functional and biomicroscopic long-term results of different posterior chamber intraocular lenses (IOLs) over a period of two years after clear corneal cataract surgery. PATIENTS AND METHODS: 2 years after phacoemulsification through a temporal two-step clear corneal incision a total of 67 patients were examined. In 26 eyes (group A) a foldable plate-haptic silicone IOL (Chiron Adatomed, C10), in 25 eyes (group B) a foldable disc silicone IOL (Chiron Adatomed, 90D) had been implanted through a 3.5 (group A) or 4 mm (group B) corneal incision using a cartridge injector. In 16 eyes (group C) a one-piece PMMA-IOL (Pharmacia & Upjohn, 809C) had been implanted through a 5 mm incision. All eyes underwent functional and biomicroscopic examinations, as well as computerized videokeratographic analysis to obtain corneal topography data. RESULTS: In group A uncorrected visual acuity valued 0.64 (+/-0.29 SD), in group B 0.59 (+/-0.24) and in group C 0.56 (+/-0.27). Median of uncorrected visual acuity was 0.6 for all groups. Corrected visual acuity was 0.81 (+/-0.29) in group A, 0.8 (+/-0.25) in group B and 0.83 (+/-0.3) in group C. Intraocular pressure (mm Hg) was 13 (+/-2.5) in group A, 14.7 (+/-2) in group B and 15.1 (+/-2.5) in group C. Fibrosis of the anterior capsular rim occurred in 42% of the cases. One eye demonstrated folds in the posterior capsule (group B). Posterior capsular opacification valued 11.9% for all groups. In one eye a Nd:YAG-capsulotomy had already been performed. In group A a decentration of more than 1 mm was objected in one case, in group B in two cases and in group C in one case, but no patient complained about any functional impairment. Two years postoperatively, no signs of a re-flattening in the incision area could be detected using difference mapping tools in the videokeratographic analysis. CONCLUSION: Two years after implantation of foldable silicone IOLs and PMMA-IOLs via a temporal clear corneal tunnel incision after phacoemulsification only slight functional and morphologic differences between the three IOL-types could be observed.     

Management of complications in eyes containing two intraocular lenses

OBJECTIVE: To describe the management of complications in eyes containing two intraocular lenses (IOLs). DESIGN: A retrospective noncomparative case series. PARTICIPANTS: Eight patients having a dislocated posterior chamber intraocular lens (PC IOL) and a secondary anterior chamber intraocular lens (AC IOL) participated. INTERVENTION: Surgical treatment of complications, including mobile dislocated PC IOLs in five eyes and retinal detachment in three eyes, was performed. MAIN OUTCOME MEASURES: Visual acuity and anatomic status were evaluated. RESULTS: Dislocated PC IOLs were removed through a pars plana incision in five eyes and a limbal incision in three eyes. Retinal detachments were repaired in three eyes. With follow-up from 7 months to 6.5 years, visual acuities ranged from 20/25 to 20/40 in five eyes and 20/60 to 20/400 in the three eyes undergoing retinal detachment repair. CONCLUSION: Eyes in which dislocation of a PC IOL occurs during or after cataract surgery may have significant complications develop. Successful surgical repair is more complex in the presence of a secondary AC IOL.     

Scanning electron microscopic characteristics of small-incision intraocular lenses

PURPOSE: To evaluate the surface characteristics of commonly used, small-incision, intraocular lenses (IOLs). METHODS: Representative samples of five groups of foldable IOLs (4 silicone and 1 acrylic) underwent surface and edge-finish examination using a slit lamp. The IOLs were folded using a folding block and forceps. All the IOLs then were examined using a scanning electron microscope. A one-piece polymethylmethacrylate IOL was used for comparing surface-finish characteristics. The IOLs were examined for optic surface quality, edge finish, haptic, haptic/optic junction, and possible post-folding modifications. RESULTS: Slit-lamp evaluation of the surface quality of all of the silicone lenses demonstrated a smooth finish of the optic surface, edge, and haptics. Scanning electron microscopic analysis of the IOLs demonstrated adequately finished haptics or footplates and optics. Excess molding flash was seen on the edges of the some of the silicone IOLs, and no molding flash was observed on others. The acrylic IOL had a somewhat sharper optic edge. Irregular finish of the haptic/optic junctions of some of the IOLs (both silicone and acrylic) was noted. CONCLUSIONS: Currently available foldable IOLs have demonstrated adequate lens finish. However, irregularities of the haptic/optic junctions and molding flash are present on most IOLs evaluated, indicating room for improvement in the finish of foldable IOLs. Phacoemulsification with capsular bag IOL placement may decrease the clinical significance of these relatively subtle lens finish irregularities.     

Neonatal lensectomy and intraocular lens implantation: effects in rhesus monkeys

PURPOSE: To compare the effects of a lensectomy with and without intraocular lens (IOL) implantation on a neonatal rhesus monkey eye. METHODS: A lensectomy and anterior vitrectomy was performed on 75 monkeys during the first 16 days of life; 21 of these monkeys also had an IOL implanted into the posterior chamber. The eyes were examined at regular intervals using biomicroscopy, applanation tonometry, and ophthalmoscopy. RESULTS: The pseudophakic monkeys were studied until they were 92.5 +/- 5.8 weeks of age and the aphakic monkeys until they were 80.4 +/- 5.7 weeks of age. Pupillary membranes (100% versus 55.5%; P < 0.01) and lens regeneration into the pupillary aperture (28.6% versus 5.6%; P = 0.02) occurred more often in the pseudophakic than the aphakic eyes. As a result, the pseudophakic eyes required more reoperations than the aphakic eyes to keep the visual axis clear (P < 0.01). There was not a significant difference in the incidence of ocular hypertension between the pseudophakic and aphakic eyes (9.5% versus 12.7%; P = 0.34). Pupillary capture of the IOL optic occurred in 52% and haptic breakage in 33% of the pseudophakic eyes. All of the eyes with broken haptics had a prominent Soemmerring's ring varying in maximum thickness from 0.6 to 2 mm. Nine of the haptics from the seven eyes with broken IOLs had eroded into the iris, two into the ciliary body, and one into the anterior chamber. CONCLUSIONS: Implanting an IOL into a neonatal monkey eye after a lensectomy and anterior vitrectomy increases the likelihood of a reoperation being necessary. Haptics frequently erode into the iris and ciliary body and may break because of stress placed on the optic-haptic junction by forward movement of the IOL.     

Incidence, causes, and neodymium:YAG laser treatment of pupillary capture

OBJECTIVE: To report the incidence of and factors associated with pupillary capture after cataract surgery and evaluate the outcomes of treatment with the neodymium:YAG (Nd:YAG) laser. SETTING: Unit of Ophthalmology, University of Edinburgh, and Royal Infirmary of Edinburgh Trust Hospital, Edinburgh, United Kingdom. METHODS: This prospective study comprised 792 consecutive patients having cataract extraction by one surgeon from 1989 to 1993. Outcome measures were incidence of pupillary capture associated with eye disease and treatment, surgical technique, and intraocular lens (IOL) placement and style; postoperative progress; and results of Nd:YAG treatment. RESULTS: Pupillary capture developed in 30 of the 764 patients (3.9%) having implantation of a posterior chamber IOL a mean of 14 weeks postoperatively (range 2 to 44 weeks). The incidence was significantly higher in eyes with angle-closure glaucoma, combined glaucoma and cataract surgery, can-opener capsulotomy, manual extraction, sulcus IOL implantation, large-optic IOLs, and one-piece IOLs. Neodymium:YAG laser treatment was successful in 8 of 12 eyes. CONCLUSION: Pupiliary capture may be anticipated and when recognized at an early stage, treated successfully with an Nd:YAG laser in most cases.     

Experimental and clinical evaluation of incision size and shape following forceps and injector implantation of a three-piece high-refractive-index silicone intraocular lens

BACKGROUND: Previous studies have demonstrated that incision sizes required for insertion of various foldable intraocular lenses (IOLs) vary according to the IOL/inserter combination. The purpose of this study was to compare incision sizes and wound shape for both forceps and injector implantation of high-refractive-index silicone IOLs. METHODS: In fresh human cadaver eyes, limbal corneal tunnel incisions were created, and 12 foldable high-refractive-index silicone (dimethyldiphenylsiloxane) IOLs were inserted in a randomized fashion using either a forceps or an injector. Using incision calipers, internal and external measurements of the tunnel incisions were obtained before and after IOL insertion. Scanning electron microscopy (SEM) was performed on selected corneas following IOL insertion. Additionally, in 12 cataract procedures, the incision sizes following forceps or injector implantation were evaluated intraoperatively. RESULTS: In the experimental setting, the external and internal tunnel widths (in mm) before insertion were 3.05 mm (+/-0.07) and 3.02 mm (+/-0.03), respectively, with the forceps and 3.06 mm (+/-0.04) and 3.01 mm (+/-0.04) with the injector. Following IOL implantation, the external and internal incision sizes were 3.33 mm (+/-0.07) and 3.33 mm (+/-0.04) with the forceps and 3.32 mm (+/-0.08) and 3.33 mm (+/-0.07) with the injector. SEM showed tearing of corneal structures after implantation through the smallest possible incisions with both devices. In the clinical study, the incision sizes before and after implantation were 3.23 mm (+/-0.10) and 3.36 mm (+/-0.06) with the forceps and 3.11 mm (+/-0.08) and 3.21 mm (+/-0.10) with the injector. CONCLUSIONS: This study confirms that high-refractive-index silicone IOLs provide one of the smallest currently achievable incisions before and after IOL implantation. In clinical use, the new injector reduces the mean incision size required by approximately 0.1 mm.     

Adherence of staphylococci of different hydrophobicity. Study of various intraocular lenses

BACKGROUND: A major goal in research on intraocular lenses (IOL) is the development of new polymers and modifications to reduce foreign-body reactions after implantation. This effect may be achieved by a reduction in the surface hydrophobicity of the polymers. To illustrate the influence of surface modifications on bacterial adhesiveness, the most often isolated organism in "low-grade" postoperative endophthalmitis, Staphylococcus epidermidis, was used. MATERIALS AND METHODS: For this reason three strains of this species, the type strain ATCC 14990 and two clinical isolates (8687, 6579 I) with different hydrophobic surface properties were studied. IOL, used in the experiments were either made of PMMA or silicone with modified surfaces (unpolished, polished, heparinized). The adhesiveness of H3-thymidin-labeled bacteria was calculated/mm2 of lens surface. Each experiment was performed in triplicate and repeated three times. RESULTS: The hydrophobic-type strain showed stronger adherence to unpolished PMMA surface (8000 bacteria per mm2) compared to the polished (5200 bacteria/mm2). In contrast, the hydrophilic strain adhered with 2000 bacteria/mm2 to the unpolished and with 4200 bacteria/mm2 to the polished surface. Polishing PMMA lenses diminished the differences between the three strains. However, surface passivation of silicone lenses increased the adhesion rate of the hydrophilic strain up to 9600 bacteria/mm2. Treatment of PMMA lenses with heparin increased the adhesiveness of the hydrophilic strain and reduced the adhesion rate of the hydrophobic type strain to 250 bacteria/mm2. CONCLUSIONS: It was demonstrated that bacterial adherence to IOL also involves hydrophobic interactions. Obviously, however, that adherence reflects a complex of interactions between the two surfaces.