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Conducting Polymers for Ophthalmic Applications
Published in Ram K. Gupta, Conducting Polymers, 2022
The eye can be split into two parts, called the anterior and posterior segments. The anterior segment includes the cornea, the iris, the ciliary body, the conjunctiva, the crystalline lens, and a chamber filled with aqueous humor [5]. The cornea is the outermost surface of the eye and consists of five layers, transparent to allow light refraction and transmission to the retina. In addition, it covers the eye surface to provide a protective layer. The iris is the colored circular part surrounding the pupil. The pupil changes its size in response to light levels, allowing the proper amount of light to reach the retina through muscular contraction and relaxation. The ciliary body produces the aqueous humor that has immunological and nutritional tasks as well as maintaining a 10–21 mmHg intraocular pressure (IOP) in a healthy eye. The conjunctiva is a clear mucous membrane that covers the front of the eye up to the cornea and the inner surfaces of the eyelids, responsible for tear production and preservation of the tear film. The human crystalline lens has a clear and biconvex shape that helps in focusing light onto the retina. The lens is flexible and can vary its shape and focusing power based on the distance between the object and the eye thanks to muscles called zonules.
Computer and Human Vision Systems
Published in Sheila Anand, L. Priya, A Guide for Machine Vision in Quality Control, 2019
The conjunctiva is a thin, translucent membrane that lines the inside of the eyelids and covers the sclera. The conjunctiva folds over itself to allow unrestricted eyeball movement. The conjunctiva has its own nerve and blood supply. The main function of the conjunctiva is to keep the eye lubricated by producing mucus and some level of tears. It protects the eye by preventing microbes and other foreign particles from entering the eye. The limbus forms the border between the transparent cornea and opaque sclera.
Application of radiochromic film for dosimetric and quality assurance of the brachytherapy sources
Published in Indra J. Das, Radiochromic Film, 2017
Ali S. Meigooni, Sharifeh A. Dini
The nonmalignant disease known as pterygium is generally developed on the conjunctiva, or clear membrane that covers the eye. Pterygium is a red growth of excessive blood vessels on white part of the eye that can also grow onto the cornea. This disease is treated with surgery or radiation using a β-emitter contact applicator such as 90Sr [63,64]. These applicators are generally calibrated by the ADCL using the RCF to measure the dose rate as well as the uniformity of the activity distributions.
Effect of different tinted soft contact lenses on the tear quality and ocular surface properties
Published in International Journal of Optomechatronics, 2021
Min-Yen Hsu, Yu-Ping Wang, Pei-Yu Hong, Pei-Ying Chen, Connie Chen
In conclusion, the subjective experience of lens wear did not differ significantly between the two groups in this study. For subjects who wear tinted soft contact lens, the frequency of blinking after lens wear may significantly increase relative to the frequency before lens wear. The health of the anterior ocular region, such as the bulbar conjunctiva, may deteriorate while eyelid redness may increase after lens wear. Moreover, lens designs could result in insufficient oxygen permeability of the lenses. We suggest that individuals requiring lens should educate themselves regarding appropriate contact lens wear and care systems and avoid selecting different brands of contact lens or purchasing them on the internet. Proper disinfection, handling, insertion, and removal of soft contact lens are crucial for successful lens wear. These must be combined with appropriate hygiene, including thorough hand washing. New wearers and experienced wearers are not necessarily compliant wearers. In the global market, contact lens are perhaps one of the most commonly used medical devices, and the eye care community must do everything to maintain the ocular health of patients/lens wearers.
Risk assessment of benzalkonium chloride in cosmetic products
Published in Journal of Toxicology and Environmental Health, Part B, 2018
Seul Min Choi, Tae Hyun Roh, Duck Soo Lim, Sam Kacew, Hyung Sik Kim, Byung-Mu Lee
Xiong et al. (2008) established a rabbit dry eye model with topical application of BAC. One eye of each rabbit (16 rabbits) was instilled with 0.1% BAC twice a day for 14 days, and untreated eyes served as controls. BAC treatment resulted in significant decreases in the Schirmer scores, but increases in fluorescein scores from 5 days after treatment compared with untreated controls. In addition, reduced mucin 5AC (MUC5AC) levels and histopathological and ultrastructural disorders of corneas and conjunctivae were noted in the BAC-treated group. These findings suggested that BAC induced dry eye syndrome in rabbits through damage to the cornea and conjunctiva, decreased aqueous tear basal secretion, goblet cell loss, and induced MUC5AC deficiency.
A comprehensive summary of disease variants implicated in metal allergy
Published in Journal of Toxicology and Environmental Health, Part B, 2022
It has been estimated that 40–60% of allergic subjects exhibit ocular symptoms concurrent with other clinical manifestations of hypersensitivity reactions; however, ocular allergy is also known to occur independently of other allergic conditions (Bucolo et al. 2015). Most allergic responses implicating the eyes involve exposed ocular surfaces like the eyelid, conjunctiva, limbus, and cornea (Chigbu 2009). Similarly, some of the most common hypersensitivity responses that remain localized to the eye area include allergic conjunctivitis, contact dermatitis of the eyelids, atopic keratoconjunctivitis, and contact blepharoconjunctivitis (Bielory 2008). These ocular hypersensitivity responses might emerge as a result of various underlying mechanisms that may be either IgE- or non-IgE-mediated. Major causative agents of ocular allergy include seasonal aeroallergens such as pollens and ragweed, animal proteins, reactive chemicals, and drugs (Bielory 2008; Soparkar et al. 1997). Occasional reports have also cited various metals as potential causative agents of ocular allergy. For example, occupational exposure to Au was found associated with the emergence of delayed-type blepharoconjunctivitis, while Cr and Ni have been implicated in cases of allergic conjunctivitis (Estlander et al. 1998; Gibb et al. 2000; Mancuso and Berdondini 2002). In addition, eyelid dermatitis is a common manifestation of contact hypersensitivity to Ni, Co, Au, iron (Fe), and Cr that merge following application of cosmetics and in response to dental metal exposure (Goossens 2004; Huang et al. 2021; McDaniel and Couch 2017; Oh et al. 2016; Poziomkowska‐Gęsicka et al. 2018; Saxena, Warshaw, and Ahmed 2001).