Cellular invasion on the surface of intraocular lenses. In vivo cytological observations following lens implantation

Visual outcomes and risk factors of uveitis cataract eyes after phacoemulsification and manual small-incision cataract surgery

PURPOSE

To examine the visual outcomes and risk factors of uveitis cataract eyes after phacoemulsification and manual small-incision cataract surgery (MSICS).

SETTING

Tertiary-care eye hospital in southern India.

DESIGN

Retrospective interventional case series.

METHODS

Of the uveitis eyes operated for cataract surgery between 2017 and 2020, eyes with a minimum of 6 months postoperative follow-up were included. Eyes with ocular trauma, lens subluxation, lens-induced uveitis, or retinal detachment-induced uveitis were excluded. Demography, visual acuity, intraoperative and postoperative records, and surgical outcomes were analyzed.

RESULTS

191 eyes of 191 patients with a mean age of 51.7 ± 14.4 years were included. Phacoemulsification was performed in 134 eyes, and 57 eyes underwent MSICS. Synechiolysis and pupil-expanding maneuvers were required in 74 eyes (38.7%). No differences were noted in the rates of complications between phacoemulsification and MSICS eyes, except at 1 year, where higher rates of posterior capsular opacification and vitritis were noted in MSICS eyes ( P = .018). The visual outcomes of eyes that underwent MSICS and phacoemulsification were comparable ( P = .463). In 12 eyes (13.5%), improvement in vision was not significant.

CONCLUSIONS

This study shows phacoemulsification may be a preferred technique in uveitis cataracts, given the lesser incidence of postoperative complications. Patients should be counseled for realistic expectations.

The outcomes of cataract surgery in eyes with Fuchs uveitis

BACKGROUND

To evaluate clinical results in eyes undergoing phacoemulsification intraocular lens (IOL) implantation due to Fuchs^, uveitis (FU) related complicated cataract.

METHODS

Post-surgical outcomes of 56 eyes of 55 FU patients were evaluated retrospectively. Three groups were formed according to the IOL model: hydrophilic SAF6125 (Optima fold) acrylic, hydrophobic SN60AT (Alcon), and hydrophobic AAB00 (Abbott). Postoperative posterior capsular opacification (PCO) development and PCO development time, neodymium number: YAG laser posterior capsulotomy rate, giant cell (GC) deposition on the IOL, and the development time of GC deposits were compared among the groups. All patients were followed postoperatively on the 1^st day, 1^st week, 2^nd and 6^th weeks, and then at 3-month intervals.

RESULTS

The hydrophilic SAF6125 IOL was implanted in 10 eyes, hydrophobic SN60AT in 24 eyes and AAB00 IOL in 22 eyes. The mean postoperative follow-up time was 34.1 ± 30.1 (6-144) months. PCO developed in 7 eyes (70%) in the hydrophilic SAF6125 group, 17 eyes (70.8%) in the hydrophobic SN60AT and 13 eyes (59.1%) in the AAB00 group. There was no statistically significant difference among the three IOL groups in the PCO development, the PCO development time and YAG laser capsulotomy rates (P = 0.674, P = 0.111, and P = 0.507, respectively). The PCO development time was significantly longer in the hydrophobic SN60AT than AAB00 group (P = 0.027). GC deposits were detected in 3 eyes (30%) in the hydrophilic SAF6125 group, 7 eyes (29.1%) in the hydrophobic SN60AT and 3 eyes (13.6%) in the AAB00 group. GC deposition and the development time of GC deposits were similar among the three IOL groups (P = 0.575, P = 0.804). At the final follow-up, BCVA was ≥ 20/40 in 41 eyes (73.2%).

CONCLUSION

The GC deposits and PCO development were the most important problems in these eyes with hydrophilic or hydrophobic IOLs despite good visual and postoperative results. New developments are needed in terms of IOL design or content in eyes with FU.

Lens status influences the association between CFH polymorphisms and age-related macular degeneration: findings from two population-based studies in Singapore

Aims

To determine the differential effects of genetic polymorphism in CFH and ARMS2 on risk of age-related macular degeneration (AMD) between phakic vs. pseudophakic/aphakic eyes.

Methods

9,529 eyes of 4,918 participants from the Singapore Malay Eye Study and Singapore Indian Eye Study were analyzed. Participants had detailed eye examinations, including slit-lamp examinations and dilated fundus photography. AMD grading was performed according to the Wisconsin age-related maculopathy grading system. Lens status was defined. Single nucleotide polymorphisms (SNPs) rs10801555 (Y402H) within CFH and rs3750847 in ARMS2 were assessed. The main outcome measure was early AMD or any AMD.

Results

No significant associations between the CFH Y402H genotypes and early AMD were found in phakic individuals. In contrast, among pseudophakic/aphakic individuals, the CFH Y402H risk genotypes were significantly associated with higher odds of early AMD, with an OR of 1.57 (95% CI: 1.07–2.29) for GA genotype and 2.40 (95% CI: 1.25–4.61) for AA genotype, compared to those with GG genotype. There was significant interaction between pseudophakic/aphakic status and CFH Y402H variant on risk of early AMD (p = 0.037), adjusting for age, gender, and the first 5 genetic principal components. No significant interaction was found between lens status and ARMS2 rs3750847.

Conclusions

CFH genetic polymorphism and pseudophakic/aphakic status may have a potential synergistic effect on early AMD, suggesting roles for the complement system and related pathways in the pathogenesis of AMD in eyes after cataract surgery.

AFM study for morphological characteristics and biomechanical properties of human cataract anterior lens capsules

The aim of this study was to quantitatively investigate the morphologies (surface roughness) and biomechanical properties (Young's modulus) of human anterior lens capsules (ALCs) for noncataract and cataract groups using atomic force microscopy. Eight human ALCs obtained during phacoemulsification from patients with senile cataracts (72 ± 13 years) were investigated in both the hydrated and dehydrated conditions. The cataract group showed clearly the proliferated lens epithelial cells (LECs) with a monomorphic cell structure, a diameter of 12.54 ± 4.31 μm, and a height of 0.23 ± 0.04 μm, whereas the control group showed no LECs. A substantial amount of false-positive calcification was observed caused by the deposition of remnants of dried salt solution. Cataract group showed significantly higher surface roughness (382.06 nm, p ≤ 0.001) than control group in the anterior side of ALCs, whereas cataract group showed significantly lower surface roughness (353.79 nm, p ≤ 0.001) than control group in their posterior side. Cataract group showed significantly higher Young's modulus (69.52 kPa, p ≤ 0.001) compared to the control group, regardless of the ALC side. Therefore, it is significant that this study provides a new method to examine the nanostructural characteristic and biomechanical property of human ALCs through a nanometer-scale resolution microscopy technique.

Biological compatibility of polymethyl methacrylate, hydrophilic acrylic and hydrophobic acrylic intraocular lenses

PURPOSE

Extensive clinical investigations of the biocompatibility of different intraocular lenses (IOLs) have been made in an effort to optimize the outcome of modern cataract surgery. The aim of this study was to add animal eye experimental implantation data regarding cellular reaction on the anterior surface of IOLs.

METHODS

Thirteen adult albino rabbits had phacoemulsification/aspiration of the crystalline lens followed by implantation of a posterior chamber IOL in each eye. Three types of IOLs were studied: Hydroview (Bausch and Lomb; n = 7), Acrysof (Alcon, USA; n = 7), and polymethyl methacrylate (PMMA; HOYA, Japan; n = 7). The animals were killed by intravenous pentobarbital 1, 4, or 8 weeks later. The IOLs were explanted and stained with hematoxylin and eosin, and observed under a light microscope. The shape of mouse ascites-induced macrophages on the anterior surface of the three different IOL types (Hydroview, PMMA, and Acrysof) was studied after 24 h of oven culture.

RESULTS

Hydrophilic acrylic IOLs showed the highest affinity for lens epithelial cell (LEC) outgrowth, and the lowest and slowest maturation rate reaction of macrophages. PMMA IOLs showed the lowest affinity for LEC outgrowth, and the highest reaction of macrophages. Hydrophobic acrylic IOLs showed intermediate results both regarding LECs and macrophages.

CONCLUSIONS

Results suggest that IOL biomaterial properties are the key factor that influences the quantity of monocytes/macrophages as well as the process of their maturation/senescence. LEC outgrowth is influenced both by the biomaterial of IOLs and by the monocyte/macrophage reaction.

A 1-year study on carbon, titanium surface-modified intraocular lens in rabbit eyes

PURPOSE

To evaluate biocompatibility of Carbon (C) and Titanum (T) surface modified Polymethyl-methacrylate (PMMA) Intraocular Lens (IOLs) in pseudophakic rabbit model.

METHODS

Extracapsule Cataract Extraction (ECCE) and IOLs implantation were performed in Japanese albino rabbit eyes. The white cell concentration from the aqueous humor in the eyes was counted within 3 months post operation. The inflammatory cells in the eyes were noted and graded by slit lamp using a semiquantitive scale up to 1-year post operation. The rabbit eyes were inspected under light microscopy, where pathology of the eyes was caracterized.

RESULTS

The white cell concentration in the aqueous humor was significantly attenuated in C and T IOL-implanted eyes compared with PMMA IOL-implanted eyes 1 week post operation. The exudate levels in the anterior ocular chamber and the posterior synechias were significant lower in T IOL-implanted eyes than in PMMA IOL-implanted eyes 1 week and 2 weeks after surgery. The exudate levels in the anterior chambers and the posterior synechias were not significantly different in C IOL-implanted versus PMMA IOL-implanted eyes.

CONCLUSIONS

This in vivo study provides evidence of effectiveness of Carbon and Titanium IOLs in improving the biocompatibility of PMMA IOLs.

Results of hydrophilic acrylic, hydrophobic acrylic, and silicone intraocular lenses in uveitic eyes with cataract: comparison to a control group

PURPOSE

To evaluate the uveal and capsular biocompatibility of hydrophilic acrylic, hydrophobic acrylic, and silicone intraocular lenses (IOLs) in eyes with uveitis.

SETTING

Department of Ophthalmology, University of Vienna, Vienna, Austria.

METHODS

This prospective study comprised 72 eyes with uveitis and 68 control eyes having phacoemulsification and IOL implantation by 1 surgeon. Patients received 1 of the following IOLs: foldable hydrophilic acrylic (Hydroview, Bausch & Lomb), hydrophobic acrylic (AcrySof, Alcon), or silicone (CeeOn 911, Pharmacia). Postoperative evaluations were at 1, 3, and 7 days and 1, 3, and 6 months. Cell reaction was evaluated by specular microscopy of the anterior IOL surface and the anterior and posterior capsule reaction, by biomicroscopy.

RESULTS

Small round cell deposition was observed on all IOLs in the immediate postoperative period, especially in eyes with uveitis. This reaction decreased 3 to 6 months after surgery. Although the CeeOn 911 had a higher mean grade of small cells, there was no statistical difference between the 3 IOL types after 6 months in the uveitis and control groups. Foreign-body giant cells (FBGCs) increased after 1 week to 1 month. The AcrySof IOLs had the highest number of FBGCs; after 6 months, there was a statistically significant difference between the AcrySof and Hydroview uveitis groups (P =.036) and the AcrySof and CeeOn 911 uveitis groups (P =.003) but there was no difference among the 3 IOL types in the control group. Lens epithelial cell outgrowth persisted on the Hydroview IOLs in control eyes and regressed on all 3 IOL types in uveitic eyes and on the AcrySof and CeeOn 911 IOLs in control eyes (P =.0001). Anterior capsule opacification (ACO) was more severe on all IOL types in uveitic eyes and on the CeeOn 911 IOL in control eyes. Posterior capsule opacification (PCO) was more severe in uveitic eyes. The Hydroview group had more severe PCO than the AcrySof and the CeeOn 911 groups in uveitis and control eyes. Six months postoperatively, the difference was significant (P =.0001). There was no significant difference between the AcrySof and CeeOn 911 IOLs.

CONCLUSIONS

Intraocular lens biocompatibility is inversely related to inflammation. Hydrophilic acrylic material had good uveal but worse capsular biocompatibility. Hydrophobic acrylic material had lower uveal but better capsular biocompatibility. Silicone showed a higher small cell count (mild) and more severe ACO but achieved PCO results comparable to FBGC results and better than those with the AcrySof lens 6 months after surgery. Despite the differences in IOL biocompatibility, all patients benefited from the surgery.

Uveal and capsular biocompatibility of hydrophilic acrylic, hydrophobic acrylic, and silicone intraocular lenses

PURPOSE

To evaluate the long-term response of 6 types of 3-piece intraocular lenses (IOLs) by assessing the cellular reaction on the anterior IOL surface, the behavior of posterior and anterior capsule fibrosis, and flare.

SETTING

Department of Ophthalmology, Medical School, University of Vienna, Vienna, Austria.

METHODS

One hundred eighty eyes were prospectively randomized to receive 1 of 6 IOLs: hydrophilic acrylic Hydroview (Bausch & Lomb) or MemoryLens (ORC); hydrophobic acrylic AcrySof MA60BM (Alcon) or AMO Sensar AR40 (Allergan); hydrophobic silicone CeeOn 920 or CeeOn 911A (Pharmacia). The patients had standardized cataract surgery, postoperative medication, and follow-up. One year after surgery, 155 eyes were assessed. The cellular reaction was evaluated by specular microscopy of the anterior IOL surface. Anterior and posterior capsule opacification (PCO) was assessed semiquantitatively by biomicroscopy. Flare was measured with a Kowa FC-1000 laser flare-cell meter.

RESULTS

Regarding uveal biocompatibility, the hydrophobic acrylic IOLs showed the highest incidence of late foreign-body cell reaction (AcrySof, 30%; AR40, 17%) followed by the hydrophilic acrylic (MemoryLens, 8%; Hydroview, 4%) and silicone (CeeOn 920, 4%; CeeOn 911A, 0%) (P =.0044). In all cases, the cellular reaction was low grade and clinically insignificant. Regarding capsular biocompatibility, some eyes developed lens epithelial cell (LEC) outgrowth on the anterior IOL surface. The highest incidence was in the hydrophilic acrylic group (Hydroview, 85%; MemoryLens, 27%) followed by the hydrophobic acrylic (AcrySof, 4%; AR40, 3%). No silicone IOL had LECs on the anterior surface. The difference among IOL groups was significant (P =.0001). Anterior capsule opacification was more predominant in the hydrophobic IOL groups. Posterior capsule opacification of the central 3.0 mm area was lowest in the groups with a sharp-edged optic (CeeOn 911A, AcrySof) followed by the round-edged silicone (CeeOn 920), hydrophobic acrylic (AR40), and hydrophilic acrylic IOLs (P =.0001). There was a significant difference in flare between the AR40 lens and the Hydroview, MemoryLens, CeeOn 911A, and CeeOn 920 (P <.004). There was no statistically significant difference in the postoperative cell count at 1 year. The power calculation showed that the sample size was sufficient.

CONCLUSIONS

The differences in cellular reaction, although clinically mild in normal eyes, indicate that there were more giant cells with hydrophobic acrylic IOLs and an increased tendency toward LEC outgrowth with hydrophilic lenses. The incidence of PCO was lowest in the hydrophobic IOL groups, especially in groups with a sharp-edged optic. Second-generation silicone IOLs with a sharp edge had good uveal and capsular biocompatibility 1 year after surgery.

Cellular reaction on the anterior surface of 4 types of intraocular lenses

PURPOSE

To assess the cellular reaction on the anterior surface of 4 types of foldable intraocular lenses (IOLs).

SETTING

Department of Ophthalmology, University Hospital of Vienna, Vienna, Austria.

METHODS

One hundred eyes scheduled for cataract surgery were prospectively randomized into 4 groups of 25 eyes each using random number tables. Group 1 received a Hydroview IOL (Bausch & Lomb), Group 2 an AcrySof IOL (Alcon), Group 3 a MemoryLens IOL (ORC), and Group 4 a CeeOn 920 IOL (Pharmacia). Patients were examined 1, 3, 7, 30, 90, and 180 days postoperatively. Postoperative biomicroscopic examinations were done with a slitlamp, and a specular microscope was used to document the presence of cell deposits and identify areas with the highest density of cells.

RESULTS

The local tissue response revealed 2 patterns: a nonspecific foreign-body reaction to the IOL (small round, fibroblast-like, epithelioid, and giant cells) and a lens epithelial cell (LEC) reaction. The highest incidence of LECs was in the Hydroview group, in which LECs were present on 81.8% of lenses 180 days postoperatively. During the first postoperative days, small round and fibroblast-like cells were found on all IOLs. From 7 days on, the incidence and density of these cells were less severe in the Hydroview and CeeOn 920 groups. After several weeks, epithelioid cells and foreign-body giant cells were seen on some IOLs. These cells appeared more often on AcrySof, MemoryLens, and CeeOn IOLs.

CONCLUSION

This study found IOL-related differences in cellular reaction after cataract surgery. The incidence of a nonspecific foreign-body reaction to 4 IOLs is consistent with the results of previous studies. The incidence of LECs was highest in the Hydroview group and lowest in the AcrySof group. The CeeOn 920 group had the lowest incidence of all types of cells.

Effect of poly(ethylene glycol) graft polymerization of poly(methyl methacrylate) on cell adhesion

PURPOSE

To investigate the effect of surface modification of poly(methyl methacrylate) (PMMA) by poly(ethylene glycol) (PEG) grafting on cell adhesion.

SETTING

Department of Ophthalmology, Seoul National University Hospital, Seoul, Korea.

METHODS

The PMMA surface was oxidized with ozone, and PEG acrylate was then graft polymerized. To verify the PEG grafting on the surface, the oxygen content was measured by electron spectroscopy for chemical analysis. The contact angle was measured using the Wilhelmy plate method. The adhesion of keratocytes on modified PMMA was investigated in vitro. Cultured rabbit keratocytes (4 x10(5) cells/mL) were layered on each PMMA disk, cultured in a carbon dioxide incubator for 24 hours, harvested by trypsinization, and counted. A commercially available intraocular lens was modified as described and then inserted in the anterior chamber of a white rabbit. The cell adherence pattern on the modified IOL was examined by scanning electron microscopy.

RESULTS

The PEG-grafted PMMA revealed a higher oxygen content and lower dynamic receding contact angles than the untreated PMMA. The mean number of adhered cells was 72.5 +/- 22 x 10(4)/mL for untreated PMMA. After PEG grafting of 1 hour and ozone oxidation of 2 hours, the adherent cell counts significantly decreased to 6.5 +/- 1.7 x 10(4)/mL and 7.6 +/- 1.6 x 10(4)/mL, respectively (P =.002). Scanning electron microscopy showed small round cells sparsely scattered on the modified PMMA in contrast to the untreated PMMA.

CONCLUSION

Surface modification of PMMA using PEG grafting reduced cell adhesion. This may decrease the incidence of retroprosthetic membrane formation after keratoprosthesis surgery.

Inflammatory cell adhesion and surface defects on heparin-surface-modified poly(methyl methacrylate) intraocular lenses in diabetic patients

PURPOSE

To evaluate the incidence of surface scratches on heparin-surface-modified (HSM) poly(methyl methacrylate) (PMMA) intraocular lenses (IOLs) and the possible influence of these alterations on the biocompatibility of HSM PMMA.

SETTING

University Eye Clinic of Trieste, Trieste, Italy.

METHODS

Twenty-six diabetic patients had phacoemulsification and implantation of an HSM PMMA IOL (809C, Pharmacia & Upjohn). Patients with proliferative diabetic retinopathy or iridopathy were excluded from the study. On postoperative days 7, 30, 90, and 180, specular microscopy was performed to study and photograph the anterior IOL surface. The presence of scratches on the anterior IOL surface was assessed and the inflammatory cell reaction noted and graded using a semiquantitative scale. Finally, the location of the inflammatory cells in relation to the surface scratches was established.

RESULTS

Scratches and other surface defects were found in 88.4% of cases. All patients had small cells on the IOL surface 7 days after surgery. At 30 days, small cells were observed in 88.4% of cases. The inflammatory cells were mainly located inside the scratches rather than throughout the IOL surface.

CONCLUSIONS

This in vivo cytology study provides further evidence of the effectiveness of heparin surface modification in improving the biocompatibility of PMMA. In diabetic patients, inflammatory cells adhered to the exposed PMMA surface more than to the HSM surface, suggesting that the use of HSM PMMA in patients with conditions predisposing them to increased postoperative blood-aqueous barrier breakdown is beneficial.

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.

In vivo human lens epithelial cell proliferation on the anterior surface of PMMA intraocular lenses

AIMS

To study in vivo human lens epithelial cell proliferation on the anterior surface of PMMA implants and its interaction with postoperative blood-aqueous barrier breakdown in eyes undergoing cataract surgery.

METHODS

A prospective study was carried out on three consecutive patient cohorts undergoing cataract surgery with intraocular lens implantation using three different surgical techniques which produce different anatomical relations between the implant and lens capsule. Specular microscopy of the anterior implant surface was used to document the natural history, topography, and density of lens epithelial cells and the laser flare and cell meter were used to measure postoperative blood-aqueous barrier breakdown.

RESULTS

All groups showed lens epithelial cell proliferation onto the anterior surface of PMMA implants. This was initiated by and restricted to the region of anterior capsule-implant contact and decreased with the onset of anterior capsular opacification. Significant correlation was found in all groups between lens epithelial cell proliferation and postoperative blood-aqueous barrier breakdown.

CONCLUSIONS

Human lens epithelial cell behaviour on PMMA surfaces in vivo differs from that seen in culture studies. Humoral factors in the aqueous, biomaterial properties of the implant, and its anatomical relations with the anterior and posterior lens capsule influence lens epithelial cell behaviour in vivo.

In vivo study of cell reactions on poly(methyl methacrylate) intraocular lenses with different surface properties

PURPOSE

To evaluate the biocompatibility of three poly(methyl methacrylate) (PMMA) intraocular lenses (IOLs) with different surface properties.

SETTING

University Eye Clinic, Vienna, Austria.

METHODS

Cell reactions on the surfaces of unmodified, heparin-surface-modified (HSM), and surface-passivated (SP) PMMA IOLs were documented in vivo using a Zeiss specular microscope. Risk factors for such reactions were also determined.

RESULTS

During the first postoperative days, small round and spindle-shaped cells were found on all IOLs. Cell density was higher in eyes with increased postoperative inflammation. After several days, epithelioid and foreign-body giant cells were seen on some IOLs. Cells appeared significantly less often on the IOLs with hydrophilic surfaces (HSM) than on those with hydrophobic surfaces (unmodified, SP).

CONCLUSION

The significantly lower incidence of foreign-body reactions on hydrophilic than on hydrophobic IOL surfaces is consistent with the results of previous studies on hydrogel and silicone IOLs.

Cellular reaction on the anterior surface of poly(methyl methacrylate) intraocular lenses

PURPOSE

To assess the cellular reaction on the anterior surface of poly(methyl methacrylate) (PMMA) intraocular lenses (IOLs) implanted by phacoemulsification with continuous curvilinear capsulorhexis (CCC) or by extracapsular cataract extraction (ECCE) with a linear capsulotomy.

SETTING

Cataract and Refractive Surgery Research Unit. Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom.

METHODS

To document morphology, topography, and severity of the cellular reaction, specular microscopy of the anterior IOL surface was performed at 1 day, 1 week, and 1 and 3 months postoperatively in two parallel groups of 31 consecutive cataractous eyes operated on by phacoemulsification with CCC or by ECCE with a linear capsulotomy.

RESULTS

The local tissue response consisted of a nonspecific foreign-body reaction to the IOL and a lens epithelial cell reaction. The foreign-body reaction was significantly less severe in the phacoemulsification group than in the ECCE group, and the number of IOLs without inflammatory cells was significantly higher.

CONCLUSION

The foreign-body reaction to PMMA IOLs is significantly reduced when the lens is implanted by phacoemulsification with CCC. This could be of clinical benefit in high-risk eyes prone to the inflammatory complications of cataract surgery.

Four year follow-up of the MemoryLens

PURPOSE

To determine whether the long-term results of implantation of thermoelastic MemoryLens intraocular lenses (IOLs) are comparable to those of conventional poly(methyl methacrylate) (PMMA) IOLs.

SETTING

St. Elisabeth Hospital, Dillingen, Germany.

METHODS

This retrospective study compared visual acuity, astigmatism, lens decentration, biocompatibility, and posterior capsule opacification in 36 eyes with a MemoryLens with those in 36 eyes with a conventional PMMA IOL over 4 years. The MemoryLenses were implanted in 1991 after cataract extraction by phacoemulsification.

RESULTS

Four years postoperatively, best corrected visual acuity was 20/20 to 20/25 in 63.9% of the MemoryLens group and 55.6% of the PMMA group. Mean astigmatism was 0.84 diopters (D) in the MemoryLens group and 1.20 D in the PMMA group. No cellular precipitates, as evaluated by biomicroscopy, or lens decentration greater than 0.5 mm were found in either group. Posterior capsule opacification, which developed in 22.2% in the MemoryLens group and 38.9% in the PMMA group, was treated with a neodymium: YAG laser capsulotomy.

CONCLUSION

The MemoryLens allows small incision cataract surgery and long-term results that compare favorably with those of PMMA IOLs.

Continuous curvilinear capsulorhexis and intraocular lens biocompatibility

PURPOSE

To study the influence of continuous curvilinear capsulorhexis (CCC) on poly(methyl methacrylate) (PMMA) intraocular lens (IOL) biocompatibility.

METHODS

Biocompatibility was assessed by measuring the postoperative blood-aqueous barrier breakdown and the cellular reaction at the anterior capsule-IOL interface. In a prospective study, 30 consecutive eyes, normal except for having extracapsular cataract extraction (ECCE) with CCC by a single surgeon, has laser flare and cell measurements and specular microscopy of the anterior IOL surface at 1 day, 1 week, and 1 and 3 months postoperatively.

RESULTS

In addition to the foreign-body reaction previously described in eyes that had other capsulotomy types, the eyes in this study also had a lens epithelial cell (LEC) reaction. The severity of the foreign-body reaction and postoperative aqueous flare and cells was significantly less in eyes with an intact CCC than in those with rim tears in the capsulorhexis and in those having an ECCE with a linear or can-opener capsulotomy, as previously reported.

CONCLUSIONS

Continuous curvilinear capsulorhexis improves the biocompatibility of PMMA IOLs to a degree that could be of clinical benefit. In eyes with CCC, most cells seen on the anterior IOL surface were LECs.

Natural history of cellular deposits on the anterior intraocular lens surface

Previous cytopathological studies have demonstrated the presence of cellular deposits on the poly(methyl methacrylate) (PMMA) intraocular lens (IOL) surface. In this prospective study, IOL surface specular microscopy was used to document the natural history of these deposits in the first year following PMMA IOL implantation. Intraocular lens surface specular microscopy was performed 1, 3, 6, and 12 months after endocapsular cataract surgery in 27 otherwise normal eyes. Postoperatively, IOLs were assessed for the presence of inflammatory cells, with the number of cells graded from 0 (none) to 4 (many). Two inflammatory cell types were visualized: small and giant cells. Small cells were found on 81.5% of IOLs at 1 month, 73.1% at 3 months, and 30.4% at 12 months. Small cells were found in only small numbers (peak mean cell score of 1.26 +/- 0.94 at 1 month). Giant cells were found on 59.3% of lenses at 1 month, 73.1% at 3 months, and 39.1% at 12 months. The number of giant cells on each lens peaked at 3 months (mean cell score 2.0 +/- 1.55), when 50% of lenses achieved a giant cell score of 3 or 4. Inflammatory cell deposits are, therefore, a normal occurrence on the PMMA IOL surface for up to 1 year after surgery. This cellular response consists of two distinct processes: a small cell response, which peaks by 1 month, and a later giant cell response, which peaks at 3 months.

Correlations between aqueous flare and cells and lens surface cytology in eyes with poly(methyl methacrylate) and heparin-surface-modified intraocular lenses

A prospective, single-surgeon study was performed on 59 patients randomized to receive a poly(methyl methacrylate) intraocular lens or a heparin-surface-modified lens after standardized endocapsular cataract surgery with a routine postoperative regimen. The anterior chamber laser flare and cell measurements and the cellular reaction on the anterior lens surface were monitored for a year following surgery. This report examines the correlations between the anterior chamber flare and cell reaction and the anterior IOL surface cellular reaction. The findings suggest that the early postoperative blood-aqueous barrier breakdown is primarily caused by surgical trauma; by one month the blood-aqueous barrier function is determined by inflammatory mediators released by small monocyte-derived cells on the IOL surface. Giant cells on the IOL surface did not correlate with aqueous flare, which suggests an insignificant capacity to release inflammatory mediators.

In vivo documentation of cellular reactions on lens surfaces for assessing the biocompatibility of different intraocular implants

This prospective study was undertaken to assess the biocompatibility of different intraocular implants and to determine factors influencing cellular reactions on intraocular lenses (IOLs). Cellular reactions seen on the surface of 653 IOLs have been documented by specular microscopy. Various types of IOLs were used with different surgical procedures in humans. The 11 lens types used fall into five groups of materials: polymethylmethacrylate (PMMA), heparin surface-modified PMMA, surface-modified PMMA, poly Hema and silicone. Factors influencing the cellular reaction on intraocular implants were elaborated on in this study. Besides the foreign-body reaction itself, cellular reactions were influenced by an increased inflammatory disposition, surgical trauma, peri-operative treatment, implant positioning and lens style. A significant correlation was found between the development of posterior synechiae and the existence of giant cells on the anterior lens surface. The incidence of cellular reactions on IOLs revealed significant differences specific to lens and material. Hydrophilic surfaces show cellular reactions in a lower percentage of cases compared with hydrophobic surfaces. An accurate and individual selection of lens material and style is mandatory to guarantee optimal after surgery.

Clinical results with three different kinds of small optic PMMA-IOLs

In this prospective study the clinical results using three different small optic IOLs are presented. The best results were achieved in those cases with an anterior capsule rim overlapping the entire optic periphery. In those cases with sulcus fixation, haptic in/out and optic in/out positions a higher percentage of capsule fibrosis (Soemmering's rings) was documented (sulcus fixation: 100%, haptic in/out position: 75%, optic in/out position: 65.5%, bag: 7.3%). The fibrosis developed because of contact between the anterior and the posterior capsule leaf. These cases also showed decentrations of the intraocular lens (IOL) more often (sulcus fixation: 50%, haptic in/out position: 75%, optic in/out position: 34.5%, bag: 31.7%). Only one patient was disturbed by glare and halo phenomenons. Cellular reactions on the lens surface were moderate in most cases. Differences specific to lens type were found between the three IOLs implanted. The clinical results were comparable to the results of other comprehensive IOL studies. Under certain indication small optic IOLs represent an alternative to flexible implants for small incision surgery.

Specular microscopy of the anterior intraocular lens surface

Until recently the cytological assessment of the intraocular lens (IOL) surface was only possible using in vitro cytopathological techniques on explanted lenses or in animal models. Specular microscopy provides an in vivo method for the observation of the IOL surface at high magnification. We have used this technique to examine the IOL surface of 27 normal pseudophakic eyes in the first 3 months following implantation. Cellular deposits consisting of small and giant inflammatory cells were found to be a normal occurrence in otherwise clinically successful cataract surgery. It was also possible to visualise the anterior capsule and its attachment to the IOL surface, an amorphous surface membrane, pigment, surface contaminants (starch granules and fibres), and the markings caused by instrumentation at the time of implantation. The technique of IOL surface specular microscopy therefore provides a useful method for the visualisation of the IOL surface and the cytological reaction that occurs there, and thus allows an assessment of IOL biocompatibility.

Comparing the cell population on different intraocular lens materials in one eye

We developed a method to evaluate cell adherence to different intraocular lens (IOL) materials in one eye in which we coated one half of the anterior surface of a poly(methyl methacrylate) (PMMA) IOL with poly(dimethyl siloxane), a silicone material. The lenses were implanted in the anterior chamber of rabbit eyes without lens extraction. Postoperative cellular reaction on the IOL surfaces was studied by specular microscopy. The IOLs were fixed in situ, removed from the eyes, and stained with hematoxylin-eosin so we could evaluate the cell population on the silicone and PMMA surface. Fewer cells were scattered on the silicone surface than on the PMMA surface. This method excludes surgical effects and allows a comparison of various IOL materials in the same eye.

Immunological reactions against PMMA lens material?

We investigated the kind of reactions that occur after injection of a PMMA lens powder into the back skin of rabbit. The lens powder was suspended in NaCl and incomplete Freund's adjuvant to reinforce the immunological reaction. The ELISA test was carried out to detect antibodies against the lens material as a whole and against the UV absorber Tinuvin in particular. We also performed histological and immunohistochemical examinations of the back skin. We did not detect antibodies against either the lens material or against Tinuvin. Histological examination showed a foreign-body or delayed allergic reaction against the lens material. Lymphocytes surrounding the PMMA were found to be mainly of the T-type, which supports the results of the ELISA test.

Long-term results and biocompatibility of heparin-surface-modified intraocular lenses

A prospective in vivo study of 50 intraocular lenses was done to document the long-term results and biocompatibility of heparin-surface-modified poly(methyl methacrylate) posterior chamber lenses. Continuous curvilinear capsulorhexis and phacoemulsification were performed throughout and examinations were by slit-lamp and specular microscopy. Decentrations of more than 1 mm were seen in 4% of eyes. Stress folds from the haptic traction forces were detected in 16%. A posterior capsulotomy was performed in 10% because of fibrosis or Elschnig pearl formation. Fine fibers were found on the lens surface in 76%. During the first postoperative days only a moderate number of fibroblast-like cells was observed. Foreign-body giant cells were seen in 8%. All cases with foreign-body giant cells had posterior synechias. Visual performance and clinical results were comparable to those of other well-approved intraocular lenses. The low percentage of cellular reaction on the lens surface suggests good biocompatibility.

Evaluation of a one-piece poly(methyl methacrylate) intraocular lens with a 7 mm biconvex optic and a total diameter of 10 mm

To find out how large the total diameter of an open-loop intraocular lens (IOL) should be, we studied 90 consecutive implantations of a one-piece poly(methyl methacrylate) IOL with a 7 mm biconvex optic and a total diameter of 10 mm (Adatomed 75 ST). The lens design made implantation simple, even through a small capsulorhexis. In 85% of the cases, the IOL remained well centered. One case with asymmetric placement of the IOL showed a decentration of more than 1 mm. In 14% of the eyes slight decentrations occurred because the capsular bag was too large. Contact between the iris and IOL was found in 15%. In 4% there were folds in the posterior capsule, and in 35% there was a small space between the IOL and the posterior capsule because the capsular bag was too large. Although the ST lens has a small total diameter, it remained at a distance from the iris in most cases. In-the-bag implantation through a continuous central capsulorhexis is mandatory to avoid secondary displacement; nevertheless, slight decentrations cannot be excluded. For a large capsular bag, the total diameter of an IOL should exceed 10 mm. Clinical results, cellular reaction on the lens surface (26.6%), biocompatibility, and visual performance are comparable to those of other well-approved poly(methyl methacrylate) IOLs.

The Binkhorst Medal Lecture. Biologic relationship between poly(methyl methacrylate) intraocular lenses and uveal tissue

Implantation of a poly(methyl methacrylate) (PMMA) intraocular lens (IOL) after cataract surgery is associated with breakdown of the blood-ocular barrier and a foreign body inflammatory response. Although the material is biocompatible, it is not inert. The history of PMMA IOL implantation has reflected mechanical, chemical, and immunological interactions between the IOL and ocular tissues. The common link in these events is instability of the blood-ocular barrier. In this lecture, I discuss the nature of these interactions and present evidence that currently investigated methods of surface modification and capsular bag IOL implantation are effective in stabilizing the blood-ocular barrier.

Variations in manufacturing quality of diffractive multifocal lenses

The new generation of multifocal intraocular lenses (IOLs) based on diffraction optics is characterized by a stepped discontinuity at zone boundaries on the posterior surface of the IOL optic. The step height at the zone boundaries is less than 2 microns. There are approximately 30 zones on a 6 mm diameter lens, requiring manufacturing precision of about 0.02 mm. Various companies produce this type of lens. On two implanted lenses we found, in addition to the 2 microns boundaries, many small circular rims that appeared to be manufacturing artifacts. The presence of these artifacts may explain the variable clinical acceptance of these IOLs.

Surface properties of intraocular lens materials and their influence on in vitro cell adhesion

An in vitro model to assess lens epithelial cell adhesion to a variety of intraocular lens materials was developed. Rabbit anterior lens capsules were isolated and cultured in serum-containing medium. Test surfaces included poly(methyl methacrylate), two new silicones (SLM-1/UV, SLM-2/UV), two hydrogels (HEMA, Lidofilcon A), and polytetrafluoroethylene (PTFE). Following the application and culturing of cells on the test surfaces, adherent cells were removed by trypsinization and counted at eight and 24 hours. The material surfaces were characterized by electron spectroscopy for chemical analysis and scanning electron microscopy. The captive bubble technique was also used to assess interfacial free energy. More cells adhered to PMMA than to the other materials tested (P less than .01). The two silicones, HEMA, and PTFE did not differ significantly from each other; Lidofilcon A had the lowest cell adhesion of all materials tested. Cell adhesion results were related to the interfacial free energy of each material. Materials of low (less than 5 ergs/cm2) or high (greater than 40 ergs/cm2) interfacial free energies had lower cell adhesion than materials of intermediate free energies (5 to 40 ergs/cm2) which exhibited the highest cell adhesion.

Cellular invasion on hydrogel and poly(methyl methacrylate) implants. An in vivo study

Over a two-year postoperative period, cells on hydrogel (poly HEMA) and poly(methyl methacrylate) (PMMA) intraocular lenses (IOLs) were observed by specular microscopy. First small, round cells and fibroblast-like cells and later epithelioid-like cells and foreign-body giant cells could be seen on both IOL types. In eyes with prolonged postoperative inflammation a greater number of cells was observed and the cells remained on the IOL surface for a longer period. We found fewer cell reactions on hydrogel IOLs during the postoperative period of our follow-up. Foreign-body giant cells were observed on only 9%. These cells were smaller than those on PMMA IOLs. This finding may suggest that poly HEMA demonstrates greater biocompatibility, with regard to this foreign-body cell reaction, than PMMA. However, we found more pigment dispersion (50%) on the surface of hydrogel IOLs. These pigment deposits induced no cell reactions and there was less phagocytosis of the pigment debris. In 7% of the cases, dust-like, white precipitates of uncertain origin were seen; in 5% amorphous debris was seen. Fine scratches caused by polishing during the manufacturing process were seen in some cases. The postoperative clinical signs for PMMA and hydrogel IOLs were similar.

Spontaneous breaks in proteinaceous membranes on intraocular lenses

Spontaneous breaks in proteinaceous membranes on the surface of intraocular lenses are demonstrated with pathological and clinical methods. These breaks appear to be the result of traction and can be a horseshoe or radial-traction type. The breaks are repaired by the natural process of protein film deposition on the newly exposed area.

Postoperative cellular reaction on surface modified intraocular lenses in living human eyes

Specular microscopy was performed to evaluate the postoperative cellular reaction on surface modified poly(methyl methacrylate) intraocular lenses (IOLs) (Ioptex Research, Inc., model U370) in 40 eyes of 36 patients who had extracapsular cataract extraction with implantation of the surface modified IOLs. The cellular elements observed were fibroblast-like cells, histiocytes, and giant cells. Gray amorphous depositions, part of which were sometimes recognized as interference fringes or interference colors, formed a layer in the center of the optics. These depositions were probably caused by the adsorption from aqueous humor. In subclinical cases, only a few histiocytes and giant cells were recognized in the optic center and the optic periphery was free of the cells during our observation. Within two months of surgery most of the cells had disappeared. In vivo specular microscopy showed no manufacturing defects on the implanted lenses. Our findings suggest that, although there was a postoperative cellular reaction on the surface modified IOLs, they were biocompatible.

Cellular reactions on heparin surface-modified versus regular PMMA lenses during the first postoperative month. A double-masked and randomized study using specular microphotography

Specular microscopy was used for investigation of cellular reactions on the intraocular lens (IOL) anterior surface of Heparin surface-modified (HSM) versus regular polymethylmethacrylate (PMMA) lenses (Pharmacia types 700C versus 700B, respectively). The double-masked randomized study included 53 patients investigated at 1 and 4 weeks postoperatively. Giant cells were only found on control lenses and more frequently at 4 weeks. Small cells were found on both lens types, but in a higher frequency on the control lenses. The number of small cells decreased during the first 4 weeks on both the control and HSM lenses. However, those control lenses that had giant cells on their surface showed an increase in the number of small cells during the same time. The results of the current study show that HSM lenses give rise to less postoperative inflammatory cellular reactions than regular PMMA lenses.

Improved biocompatibility of intraocular lenses by heparin surface modification: a 12-month implantation study in monkeys

To evaluate the long-term biocompatibility and potential side effects of heparin surface modification of a poly(methyl methacrylate) intraocular lens (IOL), a heparin surface modified IOL was implanted in the left posterior chamber of 24 cynomolgus monkeys and a reference IOL (without surface modification) was implanted in the right eye in 12 of these animals. Twelve eyes were not operated on. Eleven eyes in seven monkeys were lens extracted as a control of the surgical method. Slitlamp examinations and intraocular pressure recordings were made one day, one and two weeks, and 1, 2, 2 1/2, 3 1/2, 6, 8, 10, and 12 months after the operation. Eleven monkeys were sacrificed after 3 1/2 months and the remaining animals after 12 months for morphological examination of the eyes. Slitlamp and morphological examinations showed that cell deposits, pigmentation, and posterior synechias were significantly less in eyes with heparin surface modified IOLs than in eyes with reference IOLs throughout the 12-month observation period. The intraocular pressure was equally reduced in eyes with heparin surface modified IOLs and reference IOLs for about one month, after which it returned to normal. No side effects following the implantation of heparin surface modified IOLs were observed. We concluded that heparin surface modification of IOLs is efficient for long-term reduction of cell deposits and posterior synechias after implantation in monkey eyes and may also be effective in lowering the degree of side effects to IOL implantation in humans.

Capsular bag distension after endophacoemulsification and posterior chamber intraocular lens implantation

Six cases of capsular bag distension after capsulorhexis, endophacoemulsification, and posterior chamber intraocular lens (IOL) implantation are presented. Five cases had prominent posterior subcapsular cataracts preoperatively. In three cases, the anterior chamber depths were shallower and the apparent refractive errors were more myopic than normal after surgery. All six cases exhibited an apparent early complete sealing of the anterior capsular remnant against the anterior IOL optic. In each case, the capsular bag contained moderate particulate debris and flare while the adjacent vitreous and anterior chambers were clear. I suspect the particles are epithelial cell and cortical debris suspended in a fluid comprising lens epithelial protein, cellular breakdown products, balanced salt solution, and water. Five cases have received no specific treatment. In one case, a neodymium:YAG laser anterior capsulotomy allowed a forward egress of fluid from the distended capsular bag and a return to normal pseudophakic anatomy.