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

Research Progress Concerning a Novel Intraocular Lens for the Prevention of Posterior Capsular Opacification

Posterior capsular opacification (PCO) is the most common complication resulting from cataract surgery and limits the long-term postoperative visual outcome. Using Nd:YAG laser-assisted posterior capsulotomy for the clinical treatment of symptomatic PCO increases the risks of complications, such as glaucoma, retinal diseases, uveitis, and intraocular lens (IOL) pitting. Therefore, finding how to prevent PCO development is the subject of active investigations. As a replacement organ, the IOL is implanted into the lens capsule after cataract surgery, but it is also associated with the occurrence of PCO. Using IOL as a medium for PCO prophylaxis is a more facile and efficient method that has demonstrated various clinical application prospects. Thus, scientists have conducted a lot of research on new intraocular lens fabrication methods, such as optimizing IOL materials and design, and IOL surface modification (including plasma/ultraviolet/ozone treatment, chemical grafting, drug loading, coating modification, and layer-by-layer self-assembly methods). This paper summarizes the research progress for different types of intraocular lenses prepared by different surface modifications, including anti-biofouling IOLs, enhanced-adhesion IOLs, micro-patterned IOLs, photothermal IOLs, photodynamic IOLs, and drug-loading IOLs. These modified intraocular lenses inhibit PCO development by reducing the residual intraoperative lens epithelial cells or by regulating the cellular behavior of lens epithelial cells. In the future, more works are needed to improve the biosecurity and therapeutic efficacy of these modified IOLs.

Surface Modification of Intraocular Lenses

Objective:

This paper aimed to review the current literature on the surface modification of intraocular lenses (IOLs).

Data Sources:

All articles about surface modification of IOLs published up to 2015 were identified through a literature search on both PubMed and ScienceDirect.

Study Selection:

The articles on the surface modification of IOLs were included, but those on design modification and surface coating were excluded.

Results:

Technology of surface modification included plasma, ion beam, layer-by-layer self-assembly, ultraviolet radiation, and ozone. The main molecules introduced into IOLs surface were poly (ethylene glycol), polyhedral oligomeric silsesquioxane, 2-methacryloyloxyethyl phosphorylcholine, TiO₂, heparin, F-heparin, titanium, titanium nitride, vinyl pyrrolidone, and inhibitors of cytokines. The surface modification either resulted in a more hydrophobic lens, a more hydrophilic lens, or a lens with a hydrophilic anterior and hydrophobic posterior surface. Advances in research regarding surface modification of IOLs had led to a better biocompatibility in both in vitro and animal experiments.

Conclusion:

The surface modification is an efficient, convenient, economic and promising method to improve the biocompatibility of IOLs.

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.

Hydrophobic acrylic versus polymethyl methacrylate intraocular lens implantation following cataract surgery in the first year of life

PURPOSE

To evaluate complication rates following implantation of hydrophobic acrylic versus polymethyl methacrylate (PMMA) intraocular lens (IOL) with cataract surgery in infants.

METHODS

Records of children undergoing cataract surgery with IOL implantation in first year of life were retrospectively reviewed. Infants were divided into two groups--hydrophobic acrylic IOLs were implanted in group A, and PMMA IOLs in group B. Outcome measures included incidence of complications, additional surgical procedures, and refractive error changes.

RESULTS

One hundred and thirteen eyes of 113 children (75 males) with mean age of 6.49 ± 3.56 months were included. Group A included 62 eyes, and group B included 51 eyes. The two groups did not differ significantly in terms of age and axial length. There was no significant difference between the groups for incidence of posterior capsular opacification (PCO), pupillary membranes, glaucoma, fibrin on IOL surface or IOL malposition (p = 0.09). Development of PCO was delayed in group A (p = 0.049). Thirteen eyes of group A and 18 eyes of group B required additional surgical intervention (p = 0.20) in the follow-up visits.

CONCLUSION

Comparable complications may be expected in infants with PMMA and hydrophobic acrylic lenses. Children implanted with PMMA IOLs may require earlier surgical re-intervention for PCO.