Effects of Pigment Location in Tinted Contact Lenses on the Ocular Surface

Use of Soft Contact Lens for Esthetic and Functional Rehabilitation

OBJECTIVE

To report the outcomes and complications of colored soft contact lenses (SCLs) to improve esthetic or eye function in visually impaired (VI) or blind patients.

METHODS

This retrospective study enrolled consecutive patients with unilateral or bilateral VI or blindness who had received colored SCLs to improve appearance or ocular function. Data were collected on demographics, complaints, complete ophthalmological examinations, types of SCL, follow-ups, and complications.

RESULTS

The study sample was comprised of 109 patients (ages 4-80 years). Eighty-six patients (78.89%) had unilateral blindness, and 14 patients (12.84%) had functional disorder. Most of the patients presenting for improved esthetic had anterior segment pathology (74/67.88%), mainly secondary to trauma (55/50.5%) resulting in leukoma (73/66.97%). Patients with functional VI (19/17.43%) received filtered SCLs for color blindness (7/6.42%), diplopia (7/6.42%), or photophobia (5/4.58%). No serious complications were observed in any cases, and 94.49% of patients were satisfied with the SCLs.

CONCLUSION

Colored SCLs can cover ocular surface imperfections in VI or blind eyes of patients who are seeking better cosmesis or improvement functional VI. Soft contact lenses with only one filter can cover imperfections of the ocular surface and improve vision in functional VI. Appropriate follow-up of these patients can reduce complication rates, resulting in good cosmesis and patient satisfaction with a positive impact on the lives of patients suffering from functional VI or blindness.

Tear Inflammatory Molecules in Contact Lens Wearers: A Literature Review

Background:

Numerous studies have analysed the effect of using different Contact Lenses (CLs) or care solutions, and suffering discomfort or diseases associated with CL wear on the inflammatory mediator release into the tears.

Objective:

To summarize the published data on tear inflammatory molecules related to CL use.

Methods:

A PubMed-NCBI search has been conducted and those publications which carried out original investigations including the analysis of tear inflammatory mediators in CL wearers were selected.

Results:

Forty-three articles, from 1990 to 2019, have been included. Wearing hydrogel CLs, rigid gas permeable CLs, and special designs for irregular corneas in keratoconus patients (CLs with keratoconic design, hybrid CLs, piggyback fit, and scleral CLs) have been reported to alter the concentration of several molecules in tears. Moreover, there seems to be an effect of the wearing time and schedule, CL materials and designs, and care solutions used. Regarding CL discomfort, its relation with inflammatory mediators is not clear. However, some diseases associated to CL wear, such as giant papillary conjunctivitis, CL induced acute red eye, CL induced peripheral ulcer, and acanthamoeba keratitis have been related to the release of certain inflammatory mediators, which may serve as potential biomarkers.

Conclusion:

There is evidence suggesting that different aspects of CL wear alter the inflammatory mediator profile in tears, which may indicate an inflammatory state of the lacrimal functional unit. However, more studies need to be carried out to better understand how this inflammatory process works and its repercussion on the different aspects of CL wear.

ToF-SIMS and AFM Characterization of Brown Cosmetic Contact Lenses: From Structural Analysis to the Identification of Pigments

Over the years, soft contact lenses for vision correction and cosmetic and therapeutic purposes have been greatly improved. For cosmetic contact lenses, the pigments need to be nontoxic, and the position of the pigment layer is particularly important because of the risks posed by pigment elution and the roughness of the lens surface. In this paper, we characterized the properties of brown cosmetic contact lenses made by three different manufacturers using surface analytical techniques. The surface topographies of the noncolored and colored parts were obtained by atomic force microscopy (AFM), and the position and composition of the pigment layer were determined by analyzing the cross section of the contact lenses using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). The influence of pigment location on surface roughness was also examined. In addition, to find the method of the evaluation for the risk of surface elution of the pigments in the colored parts, the mass spectra and ion images of the surfaces were obtained by time-of-flight secondary ion mass spectrometry (ToF-SIMS) with a new sample preparation. From the ToF-SIMS spectra, we observed specific fragment ions of the poly(hydroxyethyl methacrylate) (PHEMA) polymer and found differences in the composition of the pigment layer depending on the manufacturers. The cross-sectioned image and 3D chemical characterizations of metallic and specific ions in the brown cosmetic contact lenses clearly indicated the spatial distribution and location of the pigment layer that can be used for the evaluation of pigment elution.

Identifying Pigment Enclosure in Cosmetic Contact Lenses

Supplemental Digital Content is Available in the Text.

The presence of surface pigment in cosmetic contact lenses may influence possible ocular health issues and contact lens discomfort. Two in vitro test methods were developed to investigate whether a variety of cosmetic contact lenses are manufactured with a visible clear layer, indicating that the pigment bulk is enclosed within the lens matrix.

Evaluation of Pigment Distribution and Depth Analysis Methods for Decorative Soft Contact Lenses

OBJECTIVES

This study evaluates pigment component distribution and depth in decorative soft contact lenses (DSCLs) using a variety of analytical methods.

METHODS

We sampled 18 DSCLs using optical microscopy, optical coherence tomography analysis, Z-stack analysis, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX), and time-of-flight secondary ion mass spectrometry (TOF-SIMS) to evaluate the distribution and depth of pigment components.

RESULTS

Pigment distribution in DSCLs was easily observed with optical methods including Z-stack analysis. X-ray photoelectron spectroscopy, SEM/EDX, and TOF-SIMS were used to evaluate the level of pigment exposure on the lens surface and the results showed significant differences between the methods. Pigment components were detected in 16 samples by SEM/EDX, but not by XPS. Pigment components were only detected in eight samples using TOF-SIMS.

CONCLUSIONS

It may be necessary to show that a nanometer-thick monomolecular film does not exist on the surface of DSCLs, to demonstrate the exposure of a pigment particle. Taking into account the principle behind each of the measurement methods and the resolution and sensitivity of each of the analytical methods compared, TOF-SIMS may be the most appropriate method to accurately judge pigment exposure on DSCLs. The Z-stack method may be useful for estimating the depth of pigment components in DSCLs.

Comparison of the Lubricity and Surface Roughness of 5 Cosmetic Contact Lenses

OBJECTIVES

Cosmetic contact lenses are increasingly popular because of their eye enhancing cosmetic benefits. The pigment particles used in these lenses can impact lens surface characteristics. This article examines the surface characteristics and the differences between the clear and the pigmented regions among five limbal ring design lenses.

METHODS

Scanning electron microscopy was used to determine the location and depth of the pigment particles from the lens surface. The coefficient of friction (CoF) was determined with a Basalt-MUST microtribometer at clear and pigmented regions on either the front or the back surface. Atomic force microscopy was used to determine the surface roughness of each lens in root-mean-square (RMS) units at clear and pigmented regions. A linear mixed model for repeated measures was used for the analysis of the CoF and RMS roughness to compare all lenses.

RESULTS

Four lens types had pigments exposed on the surface and one lens type had pigment fully enclosed. The CoF difference between clear and pigmented regions were similar and not statistically significant (P=0.0124) for the lens type with pigments enclosed, whereas the CoF difference for the other four lens types showed statistically significant difference (P<0.0001).

CONCLUSIONS

Of the lenses tested here, cosmetic contact lenses with pigments enclosed in the lens matrix provided a more consistent surface between clear and pigmented regions compared with lenses that had exposed pigments.

Therapeutic Contact Lenses with Polymeric Vehicles for Ocular Drug Delivery: A Review

The eye has many barriers with specific anatomies that make it difficult to deliver drugs to targeted ocular tissues, and topical administration using eye drops or ointments usually needs multiple instillations to maintain the drugs’ therapeutic concentration because of their low bioavailability. A drug-eluting contact lens is one of the more promising platforms for controllable ocular drug delivery, and, among various manufacturing methods for drug-eluting contact lenses, incorporation of novel polymeric vehicles with versatile features makes it possible to deliver the drugs in a sustained and extended manner. Using the diverse physicochemical properties of polymers for nanoparticles or implants that are selected according to the characteristics of drugs, enhancement of encapsulation efficiency and prolonged drug release are possible. Even though therapeutic contact lenses with polymeric vehicles allow us to achieve sustained ocular drug delivery, drug leaching during storage and distribution and the possibility of problems related to surface roughness due to the incorporated vehicles still need to be discussed before application in a real clinic. This review highlights the overall trends in methodology to develop therapeutic contact lenses with polymeric vehicles and discusses the limitations including comparison to cosmetically tinted soft contact lenses.