Patrícia Alessandra Bersanetti

OBJECTIVE To evaluate the effects of electroporation on contact lenses of different compositions, analyzing optical and structural changes induced by electrical stimulation, according to lens type and storage solution. METHODS Hydrogel, corneal rigid, and scleral contact lenses were immersed in multipurpose solution (Opti-Free), phosphate-buffered solution, or no solution (control). Samples were exposed to 2,500 V electric pulses and subsequently analyzed by scanning spectrophotometry (300–800 nm). Data were statistically treated using ANOVA or Kruskal–Wallis tests with Bonferroni correction and linear mixed models (LMM) to control intra-sample variability. RESULTS Electroporation produced discrete but significant changes in light transmission. Hydrogel lenses showed the greatest optical variation, with an average reduction of 12% in the visible range and up to 41% in UV-A. Corneal rigid lenses showed intermediate behavior, while scleral lenses remained stable. The multipurpose solution demonstrated a protective effect, reducing spectral variability, whereas buffer solution and lack of solution resulted in greater instability. CONCLUSION Lens type and immersion medium directly influence optical stability after electroporation. The technique proved valuable for assessing optical and structural resistance of ophthalmic materials, with potential applications in the development and quality control of new contact lenses.

Synthetic hydrogels have been proposed as vitreous substitutes recently. This study aims to evaluate the biocompatibility of polyvinyl alcohol (PVA) crosslinked with trisodium trimetaphosphate (SMTP) hydrogel in rabbit vitrectomized eyes. Seven animals were submitted to pars plana vitrectomy and the vitreous was replaced by PVA/SMTP hydrogel. Optical coherence tomography, fluorescein angiogram, clinical, and electrophysiological (ERG) examinations were analyzed at baseline, on postoperative days 7 and 30. The fellow eye was used as the control group. Hydrogel opacification was observed and ERG recordings were reduced in the hydrogel group in rod response, b‐wave cone response and flicker. A histological analysis showed retinal disorganization, presence of multinucleated cells, and intraretinal hydrogel particles. The PVA/SMTP hydrogel showed poor biocompatibility. Novel biomaterials compounds should be analyzed in vivo.

Hydrogels are made from natural or synthetic polymers and, currently, they have many biomedical applications. In this work, the conditions for obtaining a hydrogel with similar physicochemical characteristics to the vitreous humor were defined using polyvinyl alcohol (PVA) and glutaraldehyde (GLUT) as cross‐linker. The concentration of PVA and GLUT were modified, and their effect was analyzed in terms of the refractive index, density, and dynamic viscosity. The hydrogel which was obtained using 3.98% (w/V) of PVA, 3.13 mL (1.57 g) of GLUT in 100 mL, and the initial pH of 7.2 showed similar characteristics to the vitreous humor (density = 1.0174 ± 0.0050 g mL⁻¹, dynamic viscosity = 3.7425 ± 0.1800 mPa s and refractive index = 1.3410 ± 0.0010). The hydrogels were further investigated by rheological measurements, infrared spectroscopy, differential scanning calorimetry, X‐ray diffraction and determination of swelling degree. The reticulation with GLUT promoted an increase in viscosity and glass transition temperature. On the other hand, it stimulated a decrease in the swelling degree, crystallinity, melting temperature, and intensity of the band related to the ‐OH bond, compared with the PVA without reticulation. The reticulated hydrogel displayed Newtonian behavior and a higher apparent viscosity than the PVA. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1558–1566, 2018.