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

Oxidative stress induces inflammation of lens cells and triggers immune surveillance of ocular tissues

Recent reports have challenged the notion that the lens is immune-privileged. However, these studies have not fully identified the molecular mechanism(s) that promote immune surveillance of the lens. Using a mouse model of targeted glutathione (GSH) deficiency in ocular surface tissues, we have investigated the role of oxidative stress in upregulating cytokine expression and promoting immune surveillance of the eye. RNA-sequencing of lenses from postnatal day (P) 1-aged Gclc^f/f;Le-Cre^Tg/- (KO) and Gclc^f/f;Le-Cre^-/- control (CON) mice revealed upregulation of many cytokines (e.g., CCL4, GDF15, CSF1) and immune response genes in the lenses of KO mice. The eyes of KO mice had a greater number of cells in the aqueous and vitreous humors at P1, P20 and P50 than age-matched CON and Gclc^w/w;Le-Cre^Tg/- (CRE) mice. Histological analyses revealed the presence of innate immune cells (i.e., macrophages, leukocytes) in ocular structures of the KO mice. At P20, the expression of cytokines and ROS content was higher in the lenses of KO mice than in those from age-matched CRE and CON mice, suggesting that oxidative stress may induce cytokine expression. In vitro administration of the oxidant, hydrogen peroxide, and the depletion of GSH (using buthionine sulfoximine (BSO)) in 21EM15 lens epithelial cells induced cytokine expression, an effect that was prevented by co-treatment of the cells with N-acetyl-l-cysteine (NAC), a antioxidant. The in vivo and ex vivo induction of cytokine expression by oxidative stress was associated with the expression of markers of epithelial-to-mesenchymal transition (EMT), α-SMA, in lens cells. Given that EMT of lens epithelial cells causes posterior capsule opacification (PCO), we propose that oxidative stress induces cytokine expression, EMT and the development of PCO in a positive feedback loop. Collectively these data indicate that oxidative stress induces inflammation of lens cells which promotes immune surveillance of ocular structures.

Posterior capsule opacification: What's in the bag?

Cataract, a clouding of the lens, is the most common cause of blindness in the world. It has a marked impact on the wellbeing and productivity of individuals and has a major economic impact on healthcare providers. The only means of treating cataract is by surgical intervention. A modern cataract operation generates a capsular bag, which comprises a proportion of the anterior capsule and the entire posterior capsule. The bag remains in situ, partitions the aqueous and vitreous humours, and in the majority of cases, houses an intraocular lens (IOL). The production of a capsular bag following surgery permits a free passage of light along the visual axis through the transparent intraocular lens and thin acellular posterior capsule. Lens epithelial cells, however, remain attached to the anterior capsule, and in response to surgical trauma initiate a wound-healing response that ultimately leads to light scatter and a reduction in visual quality known as posterior capsule opacification (PCO). There are two commonly-described forms of PCO: fibrotic and regenerative. Fibrotic PCO follows classically defined fibrotic processes, namely hyperproliferation, matrix contraction, matrix deposition and epithelial cell trans-differentiation to a myofibroblast phenotype. Regenerative PCO is defined by lens fibre cell differentiation events that give rise to Soemmerring's ring and Elschnig's pearls and becomes evident at a later stage than the fibrotic form. Both fibrotic and regenerative forms of PCO contribute to a reduction in visual quality in patients. This review will highlight the wealth of tools available for PCO research, provide insight into our current knowledge of PCO and discuss putative management of PCO from IOL design to pharmacological interventions.

The human capsular bag model of posterior capsule opacification

Posterior capsule opacification (PCO) is the most common complication following cataract surgery and affects millions of patients. PCO is a consequence of surgical injury promoting a wound-healing response. Following surgery, residual lens epithelial cells grow on acellular regions of the lens capsule, including the central posterior capsule. These cells can undergo fibrotic changes, such that cell transdifferentiation to myofibroblasts, matrix deposition and matrix contraction can occur, which contribute to light scatter and the need for further corrective Nd:YAG laser capsulotomy in many patients. It is therefore of great importance to better understand how PCO develops and determine better approaches to manage the condition. To achieve this, experimental systems are required, and many are available to study PCO. While there may be a number of common features associated with PCO in different species, the mechanisms governing the condition can differ. Consequently, where possible, human systems should be employed. The human capsular bag model was established in a laboratory setting on donor eyes. A capsulorhexis is performed to create an opening in the anterior capsule followed by removal of the lens fibre mass. Residual fibre cells can be removed by irrigation/aspiration and if required, an intraocular lens can be implanted. The capsular bag is isolated from the eye and transferred to a dish for culture. The human capsular bag model has played an important role in understanding the biological processes driving PCO and enables evaluation of surgical approaches, IOLs and putative therapeutic agents to better manage PCO.

Misdiagnosed opacification of a hydrophobic acrylic intraocular lens

A 75-year-old woman was referred for decreased visual acuity resulting from "opacification of the IOL" in the immediate period after uneventful bilateral cataract surgery with single-piece AcrySof IQ intraocular lens (IOL) implantation. A neodymium:YAG laser capsulotomy had been performed in both eyes to treat the complication. Anterior segment optical coherence tomography performed at presentation showed an opaque membrane enveloping the IOL. The membrane was peeled from the anterior IOL surface, and all adherences between the IOL and capsular bag were freed. One year later, the eyes remained stable; the uncorrected distance visual acuity was 20/20, the IOL was clear, and there was no evidence of recurrence of the membrane. Appropriate imaging for the diagnosis and surgical peeling with freeing of the adhesions between the IOL and the capsular bag were essential to the success in this case.

Hyperopic shift caused by capsule contraction syndrome after microincision foldable intraocular Lens implantation: case series

Background

Increasing interest in microincision cataract surgery has led to the use of more flexible intraocular lens (IOL). Flexible IOL may cause more IOL deformation and refractive error when capsule contraction syndrome (CCS) occurred. In this retrospective observational case series study, the aim was to report four cases of hyperopic shift caused by CCS after phacoemulsification with microincision foldable intraocular lens implantation.

Case presentation

All of four patients underwent phacoemulsification and in-the-bag implantation of an Akreos MI60 (Bausch and Lomb) IOL from 2010 to 2016 in our clinic. These patients had been diagnosed with CCS and had undergone Nd:YAG laser anterior capsulotomy. The mean age of the patients with CCS was 66.8 ± 6.7 years and the mean time for development of CCS after the cataract surgery was 9.3 ± 6.9 months. The mean spherical equivalent (SE) value at the time of the CCS diagnosis was 0.88 ± 0.91 D, which had shown a hyperopic shift compared to the SE value of − 0.91 ± 1.29 D after cataract surgery. The mean SE decreased by − 0.47 ± 1.14 D after Nd:YAG laser anterior capsulotomy. The mean age, axial length, anterior chamber depth, and preoperative SE were not significantly different between the patient with CCS and the patients without CCS.

Conclusions

In the case of IOL implantation with flexible materials in microincision cataract surgery, CCS can cause a hyperopic shift. Refractive error caused by CCS can be effectively corrected by Nd:YAG laser anterior capsulotomy.

Improvement of Uveal and Capsular Biocompatibility of Hydrophobic Acrylic Intraocular Lens by Surface Grafting with 2-Methacryloyloxyethyl Phosphorylcholine-Methacrylic Acid Copolymer

Biocompatibility of intraocular lens (IOL) is critical to vision reconstruction after cataract surgery. Foldable hydrophobic acrylic IOL is vulnerable to the adhesion of extracellular matrix proteins and cells, leading to increased incidence of postoperative inflammation and capsule opacification. To increase IOL biocompatibility, we synthesized a hydrophilic copolymer P(MPC-MAA) and grafted the copolymer onto the surface of IOL through air plasma treatment. X-ray photoelectron spectroscopy, atomic force microscopy and static water contact angle were used to characterize chemical changes, topography and hydrophilicity of the IOL surface, respectively. Quartz crystal microbalance with dissipation (QCM-D) showed that P(MPC-MAA) modified IOLs were resistant to protein adsorption. Moreover, P(MPC-MAA) modification inhibited adhesion and proliferation of lens epithelial cells (LECs) in vitro. To analyze uveal and capsular biocompatibility in vivo, we implanted the P(MPC-MAA) modified IOLs into rabbits after phacoemulsification. P(MPC-MAA) modification significantly reduced postoperative inflammation and anterior capsule opacification (ACO), and did not affect posterior capsule opacification (PCO). Collectively, our study suggests that surface modification by P(MPC-MAA) can significantly improve uveal and capsular biocompatibility of hydrophobic acrylic IOL, which could potentially benefit patients with blood-aqueous barrier damage.

Fast in situ enzymatic gelation of PPO-PEO block copolymer for injectable intraocular lens in vivo

Foldable intraocular lenses (IOLs) have been utilized to substitute natural lens of cataract patients. In this study, we developed a fast, in situ gelable hydrogel requiring no toxic agent as an injectable IOL material. A 4-armed PPO/PEO-phenol conjugate by a non-degradable linker was synthesized to form a hydrogel in situ by horseradish peroxidase. The gelation time and modulus could be controlled, ranging from 20 s to 2 min and from 1 to 43 kPa. The adhesion of human lens epithelial cells on the hydrogel was significantly reduced compared to that on commercial IOLs. The hydrogels were injected into the rabbit eyes to evaluate the in vivo biocompatibility for 8 weeks. Corneal endothelial cell loss and central corneal thickness were comparable with the common IOL implantation procedure. Histologically, the cornea and retina showed the intact structure. The change of refraction after application of pilocarpine was +0.42 D preoperatively and +0.83 D postoperatively, which may indicate the maintenance of accommodation amplitude.

Postcataract surgical inflammation

PURPOSE OF REVIEW

To describe the epidemiology, pathogenesis, and recent developments in the diagnosis and management of postcataract surgery inflammation.

RECENT FINDINGS

In patients with pre-existing uveitis, control of inflammation with topical and/or systemic therapy for 3 months preoperatively continues to be important in lessening the risk of postoperative inflammation and complications. During cataract surgery, intraocular lens selection in these patients is important. Recent literature suggests that modern intraocular lenses (IOLs), particularly hydrophilic or hydrophobic acrylic lenses, generally have good uveal biocompatibility in uveitic patients. The postoperative course can be complicated by inflammation and cystoid macular edema (CME), and in uveitic patients, intensive perioperative steroid treatment can lessen these complications. Recent studies show that in uveitic patients, the improvement in CME and inflammation after intravitreal triamcinolone is better than after orbital floor triamcinolone injection, but that a single intraoperative orbital floor injection of triamcinolone is as effective as a 4-week course of postoperative oral prednisolone. Although postoperative inflammation in uveitic patients may be due to recurrence of uveitis, one must recognize other important potential causes of postoperative inflammation and treat accordingly.

SUMMARY

Most patients with postcataract inflammation have good visual outcomes provided that the cause is recognized and that there is adequate perioperative planning in patients predisposed to inflammation.

Ultrastructural investigation of intact orbital implant surfaces using atomic force microscopy

This study examined the surface nanostructures of three orbital implants: nonporous poly(methyl methacrylate) (PMMA), porous aluminum oxide and porous polyethylene. The morphological characteristics of the orbital implants surfaces were observed by atomic force microscopy (AFM). The AFM topography, phase shift and deflection images of the intact implant samples were obtained. The surface of the nonporous PMMA implant showed severe scratches and debris. The surface of the aluminum oxide implant showed a porous structure with varying densities and sizes. The PMMA implant showed nodule nanostructures, 215.56 ± 52.34 nm in size, and the aluminum oxide implant showed crystal structures, 730.22 ± 341.02 nm in size. The nonporous PMMA implant showed the lowest roughness compared with other implant biomaterials, followed by the porous aluminum oxide implant. The porous polyethylene implant showed the highest roughness and severe surface irregularities. Overall, the surface roughness of orbital implants might be associated with the rate of complications and cell adhesion.

Surface roughness of intraocular lenses with different dioptric powers assessed by atomic force microscopy

PURPOSE

To analyze the optic surface roughness and morphology of 2 types of hydrophobic acrylic intraocular lenses (IOLs) with various dioptric powers using atomic force microscopy (AFM).

SETTING

Technical University of Cluj-Napoca, Faculty of Mechanics, Cluj-Napoca, Romania.

METHODS

Atomic force microscopy was used to characterize the topography of 2 types of hydrophobic acrylic IOLs from a single manufacturer (SN60AT and SA30AL) with dioptric powers ranging from 10.0 diopters (D) to 30.0 D. The AFM analysis was performed in contact mode using a V-shaped silicon nitride cantilever with a pyramidal tip curvature of 15 nm and a nominal spring constant of 0.2 N/m. Detailed surface characterization of the IOL optic was obtained using 6 quantitative parameters provided by the AFM software.

RESULTS

Five of 6 roughness parameters indicated statistically significant differences (P<.05) between IOLs with different dioptric powers, with the 10.0 D IOL in both models providing the smoothest optic surface. Between models with the same dioptric power, the SN60AT model had lower values of each surface roughness parameter than the SA30AL model.

CONCLUSIONS

Atomic force microscopy was an accurate tool for assessing the surface properties of IOL optics. Manufacturing processes were responsible for introducing detectable differences in the topography of IOL biomaterials with identical copolymer constituents but different dioptric powers. Nanometric analysis may assist IOL manufacturers in developing IOLs with optimal surface characteristics.

Biocompatibility of intraocular lens materials

PURPOSE OF REVIEW

To provide an update on currently available materials used in the manufacture of intraocular lenses, as well as new materials under development, especially with regard to their uveal and capsular biocompatibility.

RECENT FINDINGS

The biocompatibility of intraocular lens materials should be assessed in terms of uveal biocompatibility, related to the inflammatory foreign-body reaction of the eye against the implant, as well as in terms of capsular biocompatibility, determined by the relationship of the intraocular lens with remaining lens epithelial cells within the capsular bag. This situation may result in different entities, e.g. anterior capsule opacification, interlenticular opacification (between piggyback intraocular lenses), posterior capsule opacification and lens epithelial cell ongrowth. Reports on intraocular lens opacification suggest that the potential to calcify should also be taken into consideration when evaluating the long-term biocompatibility of a new material.

SUMMARY

Intraocular lenses are being progressively implanted in much earlier stages of life (refractive lens exchange, pediatric implantation) and are expected to remain in the intraocular environment for many decades. Materials used in intraocular lens manufacture should, therefore, insure long-term uveal and capsular biocompatibility, as well as ultimate transparency after implantation.

Effect of primary posterior continuous curvilinear capsulorhexis on clinical performance of ACR6D SE single-piece hydrophilic acrylic intraocular lenses

PURPOSE

To evaluate the effects of a primary posterior continuous curvilinear capsulorhexis (PCCC) on the clinical performance of a single-piece hydrophilic acrylic intraocular lens (IOL) with haptic angulation.

SETTING

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

METHODS

A prospective study of 52 patients with bilateral age-related cataract was conducted. Patients had standard cataract surgery with implantation of the same IOL in both eyes. Randomly, a PCCC was created in 1 eye and the posterior capsule was left intact in the fellow eye. Assessed parameters were visual axis opacification (VAO) in eyes with a PCCC or regeneratory posterior capsule opacification (PCO) in eyes without PCCC (scale 0 to 10) in the central (3.0 mm eccentricity), intermediate (3.0 to 4.5 mm eccentricity), and peripheral (>4.5 mm eccentricity [capsulorhexis edge]) areas; neodymium:YAG (Nd:YAG) laser capsulotomy or laser polishing of ongrowing lens epithelium; anterior capsule opacification (ACO); best corrected visual acuity (BCVA); and contrast sensitivity.

RESULTS

Thirty patients completed the 2(1/2)-year follow-up. Visual axis opacification was significantly lower in the central region in the PCCC group (mean 0.5 +/- 0.7 [SD]) than PCO in the central region of the non-PCCC group (mean 1.1 +/- 1.1) (P = .02). Forty percent in the non-PCCC group had an Nd:YAG laser capsulotomy during the follow-up period; none in the PCCC group had laser polishing. There were no significant differences in ACO, SE, BCVA, or contrast sensitivity. There was no additional gain in BCVA or contrast sensitivity in eyes with a PCCC compared with eyes without a PCCC when VAO and PCO were low.

CONCLUSION

A PCCC significantly reduced PCO formation within the central 3.0 mm eccentricity as well as the need for Nd:YAG laser capsulotomy in eyes with a single-piece hydrophilic acrylic IOL with angulated haptics.

Clinical effects of primary posterior continuous curvilinear capsulorhexis in eyes with single-piece hydrophilic acrylic intraocular lenses with and without haptic angulation

PURPOSE

To evaluate the clinical effects of a primary posterior continuous curvilinear capsulorhexis (PCCC) on the intraocular performance of hydrophilic acrylic single-piece intraocular lenses (IOLs) with and without haptic angulation.

SETTING

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

METHODS

A prospective study comprised 52 patients with bilateral age-related cataract who had standard cataract surgery including a PCCC. One eye of each patient was randomized to receive a hydrophilic acrylic IOL with haptic angulation (ACR6D SE, Laboratoires Cornéal) and the contralateral eye, a hydrophilic acrylic IOL without haptic angulation (C-flex 570C, Rayner). The following parameters were assessed: regeneratory posterior opacification (RPO) in the central, intermediate, and peripheral areas (scale 0 to 10); anterior capsule opacification (ACO); best corrected visual acuity (BCVA); and contrast sensitivity (CSF).

RESULTS

Thirty-one patients completed the 1(1/2)-year follow-up. In both IOL groups, RPO within the PCCC was slight in the central area, with a mean score of 0.33 +/- 0.84 (SD) in the angulated IOL group and 0.16 +/- 0.57 in the nonangulated IOL group (P = .29). The mean RPO score in the peripheral area was 2.07 +/- 1.37 and 2.35 +/- 1.45, respectively (P = .12). The difference between the central and peripheral areas was 1.74 in the angulated IOL group (P<.00001) and 2.19 in the nonangulated IOL group (P<.00001). Haptic deformation occurred in 9 eyes (29%) with an angulated IOL and no eye with a nonangulated IOL. There was significantly more ACO in the nonangulated IOL group (P = .012). There were no significant differences in BCVA or CSF between the 2 groups.

CONCLUSIONS

Creating a PCCC led to significantly lower RPO intensity within the PCCC area than in the peripheral area in eyes with hydrophilic acrylic IOLs with and without haptic angulation. Haptic angulation had no apparent significant influence on the intensity of RPO or on BCVA and CSF. Haptic deformation may occur in hydrophilic IOLs with angulated haptics.

Effect of the hydrophilicity of acrylic intraocular lens material and haptic angulation on anterior capsule opacification

AIM

To evaluate the influence of hydrophilic and hydrophobic acrylic material and haptic angulation on anterior capsule opacification (ACO).

METHODS

Prospective study on 53 patients with bilateral age-related cataract. Patients underwent standard cataract surgery by the same surgeon and randomly received a hydrophilic acrylic intraocular lens (IOL) in one eye and a hydrophobic acrylic IOL in the other eye. Forty five of these patients completed the one-year follow-up. The following parameters were assessed: decentration, buttonholing, anterolenticular gap (ALG), ACO, outgrowth and refractive outcome.

RESULTS

At the one-year follow-up, ACO was seen in 80% of the hydrophilic and 100% of the hydrophobic IOLs. ACO was more intense in the hydrophobic IOLs (p<0.001). Outgrowth was seen in 42% of the hydrophilic and 2% of the hydrophobic IOLs (p = 0.0003). No case of persisting ALG was seen in the hydrophobic IOLs, but in 42% of the hydrophilic IOLs. The refractive outcome was -0.29 (SD 0.56) dioptres for the hydrophilic and 0.003 (SD 0.44) dioptres for the hydrophobic IOLs (p<0.001).

CONCLUSION

These results suggest that there is less ACO in hydrophilic acrylic than in hydrophobic acrylic IOLs. Although material properties might play a role, the angulated haptics of the hydrophilic IOLs exert an additional effect by the persisting ALG and a lack of contact between the IOL and the anterior capsule.

Modification of the surface properties of a lens material to influence posterior capsular opacification

PURPOSE

To study the effect of surface properties of materials on cellular behaviour and the formation of posterior capsular opacification (PCO).

METHODS

Polymethylmethacrylate, silicone and a hydrophobic acrylic were plasma treated and used in tissue culture. The changes in surface properties were quantified by dynamic contact angle measurements. Bovine lens epithelial cells (BLECs) were seeded onto these materials and cultured for 1 month. Serial photographs were taken. The cells were then fixed and stained to facilitate counting.

RESULTS

Plasma treatment significantly increased the hydrophilicity of surfaces. BLECs grew on all surfaces but significantly more cells adhered to the treated than the untreated surfaces. On the untreated surfaces the BLECs had a fibroblastic morphology whereas on the treated surfaces the cells maintained their epithelial morphology.

CONCLUSIONS

Posterior capsular opacification is a form of wound healing and the behaviour of lens epithelial cells is central to its progression. Emphasis has been on the elimination of residual lens epithelial cells to combat PCO. This study demonstrated that the phenotype of BLECs was influenced by the surface properties of the intraocular lens materials. Gas plasma treatment of the materials increased their hydrophilicity and allowed the adhered BLECs to maintain their normal epithelial morphology. We believe that controlled growth of lens epithelial cells may reduce the incidence of PCO.

Analysis of intraocular lens surface properties with atomic force microscopy

PURPOSE

To analyze the surface optics of 4 currently available intraocular lenses (IOLs) with atomic force microscopy.

SETTING

Licryl Laboratory, University of Calabria, Rende, Italy.

METHODS

The surface roughness and topography of poly(methyl methacrylate) (PMMA), silicone, hydrophobic, and hydrophilic acrylic IOLs were evaluated with atomic force microscopy in contact mode. The analysis was performed in a liquid environment using cantilevers with a 0.01 Newtonw/meter nominal elastic constant. Measurements were made over areas of 10 microm2 on different locations of the posterior optic surface of the IOL.

RESULTS

Atomic force microscopy permitted high-resolution imaging of IOL optic surface characteristics. Surface topography showed different features with respect to the lens biomaterial. The root-mean-square roughness of the IOL optic surface was significantly different between lenses of various materials (P < .001). The hydrophobic acrylic and silicone IOLs had the lowest mean surface roughness, 3.8 nm +/- 0.2 (SD) and 4.0 +/- 0.5 nm, respectively, and the 2 PMMA IOLs had the highest mean surface roughness, 6.6 +/- 0.3 nm and 7.0 +/- 0.6 nm.

CONCLUSIONS

Atomic force microscopy was effective and accurate in analyzing IOL optics. The surface topography of IOLs may vary with different manufacturing processes.

Identification of a retrolental membrane during laser capsulotomy in eyes with a Hydroview intraocular lens

We report our observation of a distinct membrane on the posterior surface of the Hydroview (Bausch & Lomb Surgical) intraocular lens during laser capsulotomy in 6 patients. In 3 patients, the retrolental membrane was noted during 4 to 6 weeks of follow-up after laser capsulotomy. The technique of a 2-stage laser capsulotomy in this group of patients is described. The possible cause and significance for this observation are also discussed.

Tissue reaction to hydrophilic intraocular lenses

The implant of intraocular lenses (IOLs) following cataract surgery induces a foreign body reaction to the IOL and a lens epithelial cell reaction. The host response to the IOL is mainly influenced by biomaterial properties. With the increasing use of phacoemulsification and small incision cataract surgery, there is growing interest in the use of foldable IOLs made of different materials. Hydrophilic acrylic IOLs include a wide group of foldable biomaterials different in terms of water content. These lenses have been reported to show a good biocompatibility after implantation. Nevertheless, tissue reaction to the implant of hydrophilic lenses is variable and not directly related to the hydrophilicity of their surface. A different adsorption of proteins on the IOL optic surface might be responsible for the different cellular reaction and lens epithelial cell response. Other properties besides hydrophilicity should be taken into account to classify IOL biomaterials.

Uveal and capsular biocompatibility of a single-piece, sharp-edged hydrophilic acrylic intraocular lens with collagen (Collamer): 1-year results

PURPOSE

To analyze uveal and capsular biocompatibility 1 year following implantation of a sharp-edged, hydrophilic, collagen-containing posterior chamber intraocular lens (IOL).

SETTING

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

METHOD

In a prospective study, a Collamer CC4204BF IOL was implanted in 30 eyes of patients with senile cataract. A standardized surgical technique and postoperative regimen were applied. To assess uveal biocompatibility, cellular inflammation on the anterior IOL surface was evaluated with a specular microscope. Capsular biocompatibility was registered semiquantitatively with a biomicroscope, based on an assessment of fibrosis on the anterior and posterior capsules. Tyndall values were measured with the Kowa FC-1000 laser flare-cell meter. Decentration of the lens was also registered.

RESULTS

One year after implantation, the values of flare and cell count in the anterior chamber were lower than preoperatively. Round and spindle-shaped, epithelioid, and foreign-body giant cells were not found on the anterior surface of the IOL. The capsulorhexis rim was moderately fibrosed in 56.6% of cases. Fibrosis of the capsule over the optic was also moderate in 36.6%. The central portion of the posterior capsule was devoid of fibrosis in 43.3% and mildly fibrosed in 50%. Three lenses revealed outgrowth of lens epithelial cells to the anterior surface of the IOL. A neodymium:YAG capsulotomy had to be performed in 1 case. All lenses were well centered in the capsular bag 1 year after implantation.

CONCLUSIONS

The absence of inflammatory cells on the anterior surface of the IOL indicates the high uveal biocompatibility of the lens. In terms of capsular biocompatibility, the results were satisfactory.

Ocular features of the congenital cataracts facial dysmorphism neuropathy syndrome

OBJECTIVE

To determine the nature and course of ophthalmologic abnormalities in congenital cataracts facial dysmorphism neuropathy (CCFDN) syndrome in a genetically verified group of 9 patients.

STUDY DESIGN

Observational case series.

PARTICIPANTS

Nine affected male individuals of 5 pedigrees aged 1.3 to 16.8 years were examined. Four individuals were recruited during an ongoing prospective study of congenital cataracts; 5 individuals could be assigned to the CCFDN group on the basis of our retrospective data.

MAIN OUTCOME MEASURES

Linkage and haplotype analysis, neurologic examinations, bilateral cataracts, axial length, corneal diameter, pupil diameter and pupillary reactions, intraoperative and postoperative complications, lid changes, aphakic correction problems, refractive results, and visual function.

RESULTS

All families originated from the eastern part of Serbia, close to the border with Romania. The 8 tested individuals were homozygous for the conserved ancestral CCFDN haplotype in the telomeric region of chromosome 18q. All patients showed a peripheral, demyelinating neuropathy and varying degrees of ataxia. In the older patients, muscular atrophy in distal muscles and facial dysmorphism was evident. Early-onset bilateral congenital cataracts associated with microcornea, microphthalmos, and micropupil could be found in all patients. All children had floppy eyelid syndrome and pseudoptosis. An increased inflammatory reaction to contact lenses and intraocular lenses could be documented in all. All patients had syndrome-associated nystagmus and congenital esotropia. Distant visual acuity could be classified as severe to moderate impairment, whereas near visual acuity was much better (mild to moderate impairment).

CONCLUSIONS

Early-onset congenital cataracts associated with microcornea, microphthalmos, and micropupil are essential ocular features of the CCFDN syndrome and are the first recognizable signs during early infancy. Awareness of this syndrome by pediatric ophthalmologists is important, because these typical findings, combined with information on ethnic origin, may lead to very early diagnosis at an age when the nature and severity of nonophthalmologic features are not apparent. Affected individuals may benefit from careful ophthalmologic treatment and follow-up, as well as from early management of the neurologic problems and developmental delay. Affected families will benefit from genetic counseling and predictive testing.

Posterior capsule opacification after implantation of a hydrogel intraocular lens

AIM

To compare the degree of posterior capsule opacification (PCO) in eyes with a hydrophilic hydrogel intraocular lens (IOL) with that in eyes with a hydrophobic acrylic IOL.

METHODS

Ninety five patients underwent a hydrogel IOL implantation in one eye and an acrylic IOL implantation in the opposite eye. The PCO value of these patients was measured using the Scheimpflug videophotography system at 1, 6, 12, 18, and 24 months postoperatively. The rate of neodymium:YAG (Nd:YAG) laser posterior capsulotomy and visual acuity were also evaluated.

RESULTS

The mean PCO value in the hydrogel group increased significantly (p<0.0001), while that in the acrylic group did not show significant change. The PCO value in the hydrogel group was significantly greater than that in the acrylic group throughout the follow up period. Kaplan-Meier survival analysis determined that the Nd:YAG capsulotomy rate in the hydrogel group was significantly higher than that in the acrylic group (p<0.0001). Mean visual acuity in the hydrogel group decreased significantly with time (p<0.0001), and became significantly worse than that in the acrylic group at 18 and 24 months postoperatively.

CONCLUSION

Posterior capsule opacification in eyes with a hydrophilic hydrogel IOL is significantly more extensive than that in eyes with a hydrophobic acrylic IOL, and results in a significant impairment of visual acuity.

Material Properties of Various Intraocular Lenses in an Experimental Study

INTRODUCTION

With the recent introduction of small-incision cataract surgery, requirements for intraocular lens (IOL) flexibility, strength and hydrophilicity have rapidly evolved. The IOL surface, however, remains a critical factor influencing uveal biocompatibility.

PURPOSE

To objectively quantify factors of material properties of various IOLs using contact angle measurements, differential scanning calorimetry, dynamic-mechanical measurements and scanning electron microscopy.

MATERIAL AND METHODS

In our study, 17 currently available IOLs were investigated using contact angle measurements to assess hydrophilicity and biocompatibility, as well as differential scanning calorimetry for the estimation of glass transition temperature. Mechanical capacity and flexibility were investigated using dynamic-mechanical measurements. Additional analysis of the IOL surface was performed using scanning electron microscopy.

RESULTS

The contact angle measurements of the studied IOLs revealed similar values within each group. The silicone IOLs had values between 106 and 119 degrees. The PMMA IOLs were found to have a narrower range of values, between 73.2 and 75.5 degrees. Lenses made of hydrogel had values between 59.2 and 69.1 degrees. The heparin-modified surface showed the lowest contact angle of 56.5 degrees. The glass transition temperature was determined by dynamic differential scanning calorimetry. The resulting values were between 118.8 and 113.5 degrees C for PMMA IOLs, 15.5 and 14.0 degrees C for acrylic IOLs, and -91.7 and -119.6 degrees C for silicone IOLs. The dynamic-mechanical measurements revealed that PMMA lenses manifested characteristics similar to glass, whereas silicone lenses had characteristics similar to rubber. Acrylic lenses were between rubber and glass. Scanning electron microscopy revealed smooth dispersion of fibrin on hydrophobic IOLs and a relative lack of fibrin adhesion on hydrophilic materials.

CONCLUSION

These results demonstrate that material properties of various IOL materials are consistent within classes of IOL materials. This suggests that the intraoperative and postoperative behavior of an IOL is predictable and related to its composition, thus allowing surgeons to choose IOLs more appropriate for different surgical situations and individual patient characteristics.

Lens epithelial cell reaction after implantation of different intraocular lens materials

PURPOSE

To determine the influence of intraocular lens (IOL) material on anterior capsular opacification and membrane growth over the anterior IOL surface in patients who have undergone standardized small-incision cataract surgery and foldable IOL implantation in the capsular bag.

DESIGN

Randomized controlled trial.

PARTICIPANTS

Eighty-eight cataract patients (88 eyes).

METHODS

Patients were randomly assigned to receive one of four different foldable IOLs after phacoemulsification: Storz Hydroview H60M, Corneal ACR6D, AMO SI40NB, and Alcon AcrySof MA60BM. Examinations on days 7, 30, 90, 180, 360, and 720 after surgery included ophthalmologic examination, slit-lamp biomicroscopy, and photography using red reflex and focal illumination of the anterior IOL surface.

MAIN OUTCOME MEASURES

Best-corrected visual acuity was measured at each examination. In addition, the anterior capsule opacification and the membrane growth on the anterior IOL surface were graded according to a subjective method by the same researcher.

RESULTS

The fibrosis of the anterior capsule was more frequently observed in the group using Corneal ACR6D and AMO SI40NB. The Hydroview and ACR6D groups showed a higher percentage of cases with membrane growth from the rhexis edge on the anterior IOL surface. AcrySof showed the lowest presence of fibrosis of the anterior capsule, and no membrane growth was noted.

CONCLUSIONS

Anterior capsule opacification is an index of IOL biocompatibility. The natural location of lens epithelial cells (LECs) precludes the possibility of the IOL's design influencing the anterior capsule behavior. The local response of LECs varies according to the IOL studied. This may be related to the chemical and physical properties of the materials used in the different IOLs.

Hydrophobic acrylic versus heparin surface-modified polymethylmethacrylate intraocular lens: a biocompatibility study

BACKGROUND

The implant of intraocular lenses (IOLs) following cataract surgery induces a foreign-body reaction to the IOL and a response on the part of the lens epithelial cells (LECs). The purpose of this study was to compare these aspects after the implantation of two different IOL materials.

METHODS

Thirty-six cataract patients were randomised to receive two different foldable lens: an acrylic hydrophobic IOL (Acrysof MA30BA) and a heparin surface-modified (HSM) polymethylmethacrylate IOL (Pharmacia & Upjohn 809C) after phacoemulsification. Slit-lamp biomicroscopy with specular technique was used to assess the inflammatory cell adhesion on the anterior IOL surface, anterior capsule opacification (ACO) and membrane growth from the rhexis edge at 7, 30, 90, 180 and 360 days after surgery.

RESULTS

The 809C group showed a higher percentage of patients with slight inflammatory cell adhesion on the anterior cell surface and a higher small cellular density during the whole follow-up period. The epithelioid cell response was greater in the 809C group than the Acrysof group but the difference between the two groups was not statistically significant. The ACO increased during the follow-up in both groups but was significantly higher in the 809C group.

CONCLUSION

Acrysof lenses are more biocompatible than HSM IOLs, showing a lower grade of inflammatory cell adhesion and ACO. The implantation of these lenses may be particularly indicated in patients with pathologies predisposing to blood-aqueous barrier damage.

Biocompatibility of intraocular lenses

PURPOSE

The choice of intraocular lens (IOL) implanted by cataract surgeons has significant implications for the effectiveness of the operation and the subsequent need for capsulotomy.

METHODS

Comparison of pertinent peer-reviewed literature published from 1996 through 2001 obtained from a MEDLINE literature search on biocompatibility indicators and IOLs. This review pertains to routine, uncomplicated cataract surgery, and thus, the findings may not be relative to complicated surgeries. Currently available IOLs were not included in this review if no published data on the IOL were available. However, representative lenses from all the major biomaterial classes were included.

RESULTS

Overall results of a comparison of published accounts of posterior capsular opacification, Nd:YAG capsulotomies, anterior capsular opacification, aqueous flare, cellular reaction, capsular adhesion, and capsular stability show a polyacrylic elastomer to be the most highly biointegrated IOLs by the human eye.

CONCLUSIONS

Most evidence published in peer-reviewed journals suggests a clear IOL choice for cataract surgeons. In the field of implantable medical devices, one device in a category does not usually provide consistently superior performance of its intended function. The ability of the biomaterial to maintain a clear optical axis not only by suppressing the proliferation of lens epithelial cells, and thus inhibiting posterior capsular opacification formation and obviating the need for an Nd:YAG capsulotomy, but also by adhering to and stabilizing the capsular bag is, to date, unmatched by any other IOL available.

Morphological and functional results of AcrySof intraocular lens implantation in children: prospective randomized study of age-related surgical management

PURPOSE

To evaluate the prevalence and severity of posterior capsule opacification (PCO) in pediatric eyes with a foldable acrylic AcrySof (Alcon) intraocular lens (IOL) and age-related surgical methods.

SETTING

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

METHODS

This prospective randomized study comprised 50 eyes of 34 children aged between 2 and 16 years. Eyes of children between 2 and 5.9 years were consecutively randomized to Group 1a (primary posterior capsulotomy and anterior vitrectomy) or Group 1b (optic capture in addition). Eyes of children between 6 and 16 years were consecutively randomized to Group 2a (primary posterior capsulotomy without anterior vitrectomy), Group 2b (optic capture in addition), or Group 2c (in-the-bag IOL implantation without opening the posterior capsule). Main outcome parameters were the incidence and severity of PCO formation, early postoperative complications, pigmented cell deposits on the IOL surface, and cataract morphology.

RESULTS

The visual axis was clear at the last follow-up in all eyes in Groups 1a, 1b, 2a, and 2b except in 1 eye in Group 1a. Sixty-percent of eyes in Group 2c had PCO. The incidence of early postoperative complications was significantly higher in eyes that developed PCO than in those that maintained a clear visual axis. There was no evidence that cataract morphology influenced PCO rates.

CONCLUSIONS

The AcrySof IOL was well tolerated in pediatric eyes. Optic capture was not necessary to ensure a clear visual axis. Primary posterior capsulotomy should be performed in preschool and uncooperative children and in eyes expected to have relatively high postoperative inflammation. Implanting the AcrySof in the bag and leaving the posterior capsule intact is acceptable for school children and juveniles with isolated developmental cataract.

Cell response to AcrySof intraocular lenses in an Indian population

PURPOSE

To evaluate the quantitative cytological response to AcrySof (Alcon) intraocular lenses (IOLs) in an Indian population by studying the incidence, fate, progression, and severity of cell deposits after uneventful phacoemulsification.

SETTING

Iladevi Cataract & IOL Research Center, Ahmedabad, India.

METHOD

This clinical prospective study comprised 64 eyes of 64 healthy patients with senile cataract and no other ocular pathology having phacoemulsification and implantation of an AcrySof IOL. The eyes were observed for cell deposits. One week and 1, 3, 6, 12, and 15 months postoperatively, specular reflex was obtained by slitlamp biomicroscopy under x 20 magnification to record the incidence, progression, morbidity, and severity of small and large (including giant) cells on the IOLs.

RESULTS

The highest incidence of small cells was 18.7%. The cell deposits appeared at 1 week, peaked at 1 month, and were gone after 6 months. The severity was never more than grade 2 (5 to 10 cells). The highest incidence of large cells, including giant cells, was 23.4%. The deposits appeared at 1 month, peaked at 3 months, and were gone after 12 months. The severity was never more than grade 2 (3 to 5 cells). The highest incidence of giant cells was 6.2%. The deposits appeared at 3 months and were gone by 15 months. Severity was never more than grade 1 (2 cells). No IOL had cell deposits at the last follow-up (mean 14 months +/- 3.25 [SD]).

CONCLUSIONS

The incidence, and especially the severity, of cell deposits in the Indian population was low. All cell types, including giant cells, disappeared within 12 months. This could reflect the biocompatibility of the AcrySof IOL and the appropriate surgical technique.

Biocompatibility of hydrophilic intraocular lenses

PURPOSE

To assess the biocompatibility of 3 hydrophilic acrylic intraocular lenses (IOLs) by evaluating the postoperative cell reaction on the IOL surface, anterior capsule opacification (ACO) rate, and presence of membrane growth over the anterior IOL surface.

SETTING

University Eye Clinic of Trieste, Trieste, Italy.

METHODS

In this prospective study, 73 patients were randomized to receive 1 of 3 types of hydrogel IOLs after phacoemulsification: Storz Hydroview H60M, Corneal ACR6D, or Ioltech Stabibag. To analyze and photograph the anterior IOL surface, slitlamp biomicroscopy and specular microscopy were performed 7, 30, 90, and 180 days after surgery. Small, epithelioid, and giant inflammatory cell reaction was evaluated. In addition, ACO and membrane growth on the anterior IOL surface were assessed.

RESULTS

Low inflammatory cell adhesion was observed on the anterior surface of all 3 IOLs. The Stabibag group had a significantly higher grade of small inflammatory cell reaction 7 and 30 days after surgery. A significantly higher rate of ACO was observed in the ACR6D group. The Hydroview and ACR6D groups had a significantly higher percentage of membrane growth from the capsulorhexis edge onto the anterior IOL surface than the Stabibag group.

CONCLUSIONS

Clinically, the 3 hydrophilic IOLs behaved in a different manner, showing the different forms of biocompatibility. Results indicate that a different chemical composition determines correspondingly different protein absorption on IOL surfaces. This might result in a different adhesion pattern and spreading of lens epithelial and inflammatory cells.

Survey of intraocular lens material and design

Modern cataract surgery is constantly evolving and improving in terms of lens material and design. Researchers and physicians strive to obtain better refractive correction with smaller wound size and minimizing host cell response to limit the proliferation of lens epithelial cells leading to opacification of the lens capsule. Intraocular lens material varies in water content, refractive index, and tensile strength. Intraocular lens design has undergone revisions to prohibit lens epithelial cell migration and reflection of internal and external light. The evolution of intraocular lens and extracapsular cataract surgery has lead to faster postoperative recovery and better visual outcomes.

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.