Gold Nanocomposite Contact Lenses for Color Blindness Management

Abstract

Color vision deficiency (CVD) is an ocular congenital disorder that affects 8% of males and 0.5% of females. The most prevalent form of color vision deficiency (color blindness) affects protans and deutans and is more commonly known as "red-green color blindness". Since there is no cure for this disorder, CVD patients opt for wearables that aid in enhancing their color perception. The most common wearable used by CVD patients is a form of tinted glass/lens. Those glasses filter out the problematic wavelengths (540-580 nm) for the red-green CVD patients using organic dyes. However, few studies have addressed the fabrication of contact lenses for color vision deficiency, and several problems related to their effectiveness and toxicity were reported. In this study, gold nanoparticles are integrated into contact lens material, thus forming nanocomposite contact lenses targeted for red-green CVD application. Three distinct sets of nanoparticles were characterized and incorporated with the hydrogel material of the lenses (pHEMA), and their resulting optical and material properties were assessed. The transmission spectra of the developed nanocomposite lenses were analogous to those of the commercial CVD wearables, and their water retention and wettability capabilities were superior to those in some of the commercially available contact lenses used for cosmetic/vision correction purposes. Hence, this work demonstrates the potential of gold nanocomposite lenses in CVD management and, more generally, color filtering applications.

Keywords: biomaterials; color blindness; contact lenses; nanocomposites; wearables.

Figure 1

Visual perception in color vision deficiency. (a) Photoreceptor cone and rod cells inside the eye. (b) Images of colored materials as seen by normal color vision and different types of CVDs. Photoreceptor cells’ activation percentage at 520 nm for (c) normal, (d) protan, and (e) deutan. (f) Mie theory simulated absorption spectra of gold nanoparticles as a function of their diameters.

Figure 2

Prepolymerization characterization of the (a) 12 nm GNPs, (b) 40 nm GNPs, and (c) 80 nm GNPs: (i) TEM micrographs of the nanoparticles with their size distribution histograms; (ii) transmission spectrum of the nanoparticles in their solution; (iii) effect of varying the nanoparticles solution’s refractive index on the position of the surface plasmon resonance both experimentally and as predicted by the Mie theory.

Figure 3

Polymerized 12 nm GNCs, 40 nm GNCs, and 80 nm GNCs (from left to right): (a) transmission spectra of the polymerized nanocomposites; (b) solutions of the nanocomposites prior to polymerization (scale: 10 mm); (c) steps carried out in polymerizing the solutions and obtaining the nanocomposite lenses; (d) polymerized nanocomposite lenses at different concentrations (scale: 10 mm). Note that A and D have the lowest and highest concentration of added nanoparticles, respectively.

Figure 4

SEM micrographs of the (a) 12 nm GNCs, (b) 40 nm GNCs, and (c) 80 nm GNCs, where images (i) and (ii) refer to the lowest and highest concentrated samples denoted as A and D in Figure 3.

Figure 5

Wettability and water content measurements of the (a) 12 nm GNCs, (b) 40 nm GNCs, and (c) 80 nm GNCs: (i) contact angle measurements of the four nanocomposites, denoted as A–D in Figure 3, using the sessile drop method; (ii) effect of nanoparticle concentration on the water content and contact angle of the gold nanocomposites.

Figure 6

Performance evaluation of the nanocomposite lenses. (a) Transmission spectra of the 12, 40, and 80 nm gold nanocomposites in comparison to the spectral sensitivity of a protan’s or deutan’s photoreceptor cones. (b) Transmission spectra of the 12, 40, and 80 nm gold nanocomposites in comparison to the spectra of Enchroma, VINO, and the Atto dyed lens developed by. (c) Illustration of the contact angle and water content of some common commercial contact lenses in comparison to the developed nanocomposite lenses.

Figure 7

Schematic of the fabrication process of the nanocomposite contact lenses. (a) Ultrasonication of the nanoparticles to break initial agglomerates and clusters. (b) UV polymerization of the nanocomposite solution and formation of the nanocomposite lens.