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Contact lenses and UV light phototoxicity



Introduction


Contact lenses are an effective solution for correcting visual problems such as myopia, hyperopia, astigmatism, and presbyopia. In addition to improving vision, these lenses have the ability to filter ultraviolet (UV) radiation that reaches the eye, thereby protecting the ocular structures from damage caused by this radiation. In this blog, we will explore the effect of UV light on the eyes and how contact lenses can mitigate phototoxicity.


Impact of UV Light on the Eye


Ultraviolet (UV) light can have harmful effects on ocular structures, and one of the main risks is phototoxicity. Phototoxicity refers to the ability of UV light to damage eye cells due to its high energy and the generation of reactive oxygen species. The cornea, lens, and retina are particularly vulnerable to this damage. Prolonged exposure to UV light can lead to the development of pterygium, an abnormal growth on the surface of the eye. Additionally, UV light can induce the formation of cataracts, causing opacity in the lens and resulting in a significant decrease in vision. Moreover, the light-sensitive retina can suffer damage from UV radiation, leading to phototoxicity and negatively impacting visual function. Therefore, it is crucial to protect the eyes from UV light through preventive measures, such as the proper use of contact lenses that filter this radiation.


Types of Contact Lenses and the Contact Lens Specialty


Contact lenses play a crucial role in limiting the amount of UV radiation that reaches the ocular structures. There are different types of contact lenses available in the market, each with variations in their ability to filter UV light. By using suitable contact lenses, we can protect our eyes from the damage caused by UV radiation.


Contact lenses are a popular and effective option for correcting visual problems such as myopia. There are two main types: rigid lenses and soft lenses. Rigid lenses offer precise and long-lasting correction, while soft lenses are disposable and comfortable, being popular for their ease of use and comfort. Technological advancements in the field have improved the quality, transparency, and compatibility of contact lenses with our eyes. New materials allow for greater oxygen transmission, and more efficient care solutions have been developed. It is essential to seek guidance from a visual health professional to select the most suitable option for our needs.


In this regard, the Interdisciplinary Center in Health Sciences, Santo Tomás Unit of the IPN, offers a specialty in contact lenses that provides visual health professionals with comprehensive and specialized training in the management and fitting of contact lenses. As a guest lecturer in this specialty, I can affirm that this program of study focuses on providing the theoretical and practical knowledge necessary to offer patients optimal care in the use of contact lenses. Professionals trained in this specialty have the ability to perform thorough visual examinations, select and fit the most appropriate contact lenses for each case, and provide comprehensive follow-up to ensure the visual health and comfort of patients who opt for this visual correction alternative. Thanks to the contact lens specialty taught at this center, visual health professionals can offer quality care to their patients and guarantee a satisfying experience in the use of contact lenses.


Research on the Effectiveness of Contact Lenses in Phototoxicity


Recent studies have demonstrated the positive effect of certain types of contact lenses in reducing phototoxicity caused by ultraviolet (UV) light. During the International Congress of the Association for Research in Vision and Ophthalmology in 2018, findings on the phototoxic impact of light and how certain contact lenses can contribute to reducing this adverse effect were presented.


The objective of this research was to calculate the safe exposure time when using contact lenses in different outdoor environments. Three scenarios were evaluated: city (Los Angeles, CA), beach (Miami, FL), and snowy mountains (Aspen, CO) at noon in winter, calculating the environmental irradiance that reaches the unprotected eye. Four types of soft contact lenses with UV protection were analyzed, measuring their transmission curves. The results revealed that the safe exposure times without lenses were 10 minutes in the city of Los Angeles, 7 minutes on the beach in Miami, and 9 minutes in the mountains of Aspen. However, when using contact lenses, the safe exposure times significantly increased, with improvements ranging from 38 times to 834 times, depending on the type of lens and location. Thus, it was concluded that all types of contact lenses tested provided adequate protection for a normal day of activity, with a minimum protection of 6.4 hours on the beach. It is crucial to highlight that the lenses only cover the central region of the eye, so it is recommended to complement their use with additional measures such as wearing glasses, using umbrellas, or wearing hats to protect the conjunctiva and the skin around the eye from UV radiation.


Final Remarks


In conclusion, maintaining good visual health and regularly visiting an ophthalmologist or optometrist to assess our visual status is essential. Contact lenses are a viable and aesthetic option compared to glasses, as they can go unnoticed. Furthermore, according to the work presented at the International Congress of the Association for Research in Vision and Ophthalmology (ARVO), certain types of contact lenses, including those used in the contact lens specialty taught at the Interdisciplinary Center in Health Sciences, Santo Tomás Unit of the IPN, have been shown to provide effective protection against UV-induced phototoxicity. As a guest lecturer in this specialty, I can confirm the importance of selecting the most effective contact lenses to reduce this risk and ensure adequate protection for our eyes.


Emiliano Terán

Referencias

Emiliano Teran, Pablo De Gracia, Efrain Romo-Garcia, Jesus Ortega; UV protection of contact lenses under outdoor light environments: beach, snow and city. Invest. Ophthalmol. Vis. Sci. 2019;60(9):3891. link

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