Contact lenses for color blindness

In a recent study published in the journal Scientific reportsbiologically compatible and elastic two-dimensional plasmonic contact lenses have been created using polydimethylsiloxane (PDMS).

Study: Two-dimensional biocompatible plasmonic contact lenses for the correction of color blindness. Image Credit: Sergey Ryzhov/Shutterstock.com

Here, an inexpensive basic design based on soft nano-lithography technology was designed and tested for the correction of red-green color blindness.

Color blindness, explained

Human color perception is derived from three types of cone-shaped photoreceptor cells, namely long (L), medium (M) and short (S) cones, which are essential for seeing red, green and blue hues with spectral sensitivity maxima at 430, 530 and 560 nanometers, respectively.

Color blindness, also known as color vision deficiency (CVD), is an eye condition that impairs the detection and interpretation of distinct colors by three photoreceptor cells that are functional and operate at their maximum spectral sensitivity in normal vision. This eye condition, which can be contracted or genetic, is caused by a loss or deficiency of cone-shaped photoreceptor cells.

(a) A schematic table of the manufacturing process of the proposed PDMS-based lenses, (b) the image of the fabricated PDMS-based lenses, and (c) the immersion of the PDMS-based lenses in a solution of or HAuCl4 3H2O for different incubation times.

Figure 1. (a) A schematic table of the manufacturing process of the proposed PDMS-based lenses, (b) the image of lenses made from PDMS, and (vs) immersing the PDMS-based lenses in HAuCl43 hours2O gold solution for different incubation times. © Roostaei, N., & Hamidi, SM (2022)

Different types of color blindness

CVDs are classified into three categories: dichromacy, monochromacy and abnormal trichromacy.

Dichromacy develops if one of the three types of cone-shaped photoreceptor cells is entirely absent; and is classified as protanopia (absence of red cone-shaped photoreceptors), deuteranopia (absence of green cone-shaped photoreceptors), or tritanopia (missing blue cone-shaped photoreceptors).

Monochromacy is the rarest type of color blindness, characterized by the absence of at least two types of cone-shaped photoreceptor cells.

Monochromats are either completely color blind (achromatopsia) or have only blue cone-shaped photoreceptor cells. Abnormal trichromacy, the third category, occurs if one of the cone-shaped photoreceptor cell types is defective.

Abnormal trichromacy is classified into three types based on the type of cone-shaped photoreceptor cell that is defective: deuteranomaly (defective green cone-shaped photoreceptors), protanomaly (defective red cone-shaped photoreceptors), and tritanomaly ( defective blue cone photoreceptors).

Protans (protanomaly and protanopia) and deutans (deuteranomaly and deuteranopia), commonly known as red color blindness, are the most typical types of color blindness.

In the protanomaly, the sensitivity peak of the red cone-shaped cell spectrum is blue-shifted, while the maximum sensitivity of the green cone-shaped cells is red-shifted. Due to the conflicting spectral sensitivities of green and red photoreceptors, patients are unable to differentiate between distinct hues.

(a) A schematic of the manufacturing process of the proposed 2D plasmonic contact lenses based on PDMS, and (b) the actual image of the fabricated 2D flexible plasmonic contact lens.

Figure 2. (a) A schematic of the manufacturing process of the proposed PDMS-based 2D plasmonic contact lenses, and (b) the actual image of the fabricated 2D flexible plasmonic contact lens. © Roostaei, N., & Hamidi, SM (2022)

Corrective actions

Despite extensive and valuable work to develop a surefire cure for color blindness based on several medical pathways for this condition, significant lifestyle adjustments remain an open debate. Gene therapy, colored glasses, lenses, optical filters, photoelectronic glasses, and enhanced functionality on computers and mobile devices were among the topics covered in previous research.

Tinted glasses with color filters have been researched extensively and appear to be widely available for CVD processing.

Although these glasses are successful in increasing color perception in people with color blindness, they have drawbacks such as high price, weight and bulk, and a lack of integration with other corrective glasses.

For CVD correction, contact lenses developed with chemical pigments, plasmon meta-surfaces and plasmonic nanoparticles have recently been studied.

However, these contact lenses face a number of obstacles, including lack of biocompatibility, limited use, poor stability, higher prices, and the complexity of the production process.

PDMS based lenses to correct color blindness

The present work proposes biologically compatible and elastic two-dimensional plasmonic contact lenses based on polydimethylsiloxane (PDMS) for the rectification of color blindness, with particular emphasis on deuteranomaly (red-green) color blindness, the most common type of color blindness.

PDMS is a biologically compatible, bendable and transparent polymer that could be used to make contact lenses. This harmless and biologically compatible substance has found several uses in the biological, medical and chemical industries.

A schematic table of the simulated 2D plasmonic contact lens based on PDMS.

Picture 3. A schematic table of the simulated 2D plasmonic contact lens based on PDMS. © Roostaei, N., & Hamidi, SM (2022)

Main results of the study

In this work, biologically compatible and elastic two-dimensional plasmonic contact lenses made of PDMS were developed with a low-cost and simple design using the nanoscale soft lithography approach and tested for deuteranomaly rectification.

The lens was made of PDMS, a hypoallergenic, harmless, elastic and transparent polymer. This plasmonic contact lens, which is based on the surface plasmon lattice resonance (SLR) phenomenon, can be used as an excellent color filter for deuteranomaly rectification.

The suggested lens has good characteristics such as durability, biocompatibility and elasticity, which makes it suitable for color blindness corrective applications.

Reference

Roostaei, N., & Hamidi, SM (2022). Two-dimensional biocompatible plasmonic contact lenses for the correction of color blindness. Scientific reports, 12. Available at: https://www.nature.com/articles/s41598-022-06089-8

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