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

The Boston Keratoprosthesis: comparing corneal epithelial cell compatibility with titanium and PMMA

PURPOSE

To determine in vitro whether titanium is superior in corneal cell compatibility to standard polymethyl-methacrylate (PMMA) for the Boston Keratoprosthesis (KPro).

METHODS

Human corneal-limbal epithelial (HCLE) cells were cultured 24, 48, 72, 96, 120, 144, or 168 hours in culture plates alone (controls) or with PMMA or titanium discs. Experiments were performed in triplicate and repeated (final n = 6). To determine if a soluble, toxic factor is emitted from materials, concurrent experiments at 48 and 144 hours were performed with discs placed in Transwell Supports, with HCLE cells plated beneath. As an additional test for soluble factors, cells were incubated 24 hours with disc-conditioned media, and number of viable cells per well was quantified at each timepoint by proliferation assay. To determine if delayed cell proliferation was attributable to cell death, HCLE cell death was measured under all conditions and quantified at each timepoint by cytotoxicity assay. The effects of material on HCLE cell proliferation over time was determined by repeated measures ANOVA. P < 0.05 was statistically significant.

RESULTS

HCLE cell proliferation was greater in wells with titanium discs compared to PMMA. Differences between the test discs and control non-disc cocultures were statistically significant over time for both cell proliferation (P = 0.001) and death (P = 0.0025). No significant difference was found using Transwells (P = 0.9836) or disc-conditioned media (P = 0.36).

CONCLUSION

This in vitro HCLE cell model demonstrates significantly increased cell proliferation and decreased cell death with cell/titanium contact compared to cell/PMMA contact. Moreover, differences are unlikely attributable to a soluble factor. Prospective in vivo analysis of the two KPro biomaterials is indicated.

Improved Performances of Intraocular Lenses by Poly(ethylene glycol) Chemical Coatings

Cataract surgery is a routine ophthalmologic intervention resulting in replacement of the opacified natural lens by a polymeric intraocular lens (IOL). A main postoperative complication, as a result of protein adsorption and lens epithelial cell (LEC) adhesion, growth, and proliferation, is the secondary cataract, referred to as posterior capsular opacification (PCO). To avoid PCO formation, a poly(ethylene glycol) (PEG) chemical coating was created on the surface of hydrogel IOLs. Attenuated total reflectance Fourier transform infrared spectroscopy, "captive bubble" and "water droplet" contact angle measurements, and atomic force microscopy analyses proved the covalent grafting of the PEG chains on the IOL surface while keeping unchanged the optical properties of the initial material. A strong decrease of protein adsorption and cell adhesion depending on the molar mass of the grafted PEG (1100, 2000, and 5000 g/mol) was observed by performing the relevant in vitro tests with green fluorescent protein and LECs, respectively. Thus, the study provides a facile method for developing materials with nonfouling properties, particularly IOLs.

The efficacy of an acrylic intraocular lens surface modified with polyethylene glycol in posterior capsular opacification

To investigate if the surface modification of intraocular lens (IOL) is efficient in the prevention of posterior capsular opacification (PCO), the acrylic surface of intraocular lens (Acrysof) was polymerized with polyethylene glycol (PEG-IOL). The human lens epithelial cells (1 x 10(4) cells/mL) were inoculated on PEG grafted or unmodified acrylic lenses for the control. The adherent cells on each IOL surface were trypsinized and counted. The every PEG-IOL was implanted in 20 New Zealand rabbits after removal of crystalline lens. The formations of PCO were checked serially through retroilluminated digital photography, and the severity scores were calculated using POCOman. The cell adherence patterns on each IOL were examined by scanning electron microscopy. As a result, the mean number of adherent cells of PEG-IOL (3.2+/-1.1 x 10(3)) tended to be smaller than that of the acrylic controls (3.6+/-1.9 x 10(3)) without a statistical significance (p=0.73). However, the mean severity of PCO formation in PEG-IOL was significantly lower than that in the control during the third to sixth weeks after surgery. Scanning electron microscopy revealed that the more patch-like cells were found firmly attached to the IOL surface in control than in the PEG-IOL. Conclusively, PEG polymerization to the acrylic IOL would possibly lessen the formation of PCO after cataract removal.