Ultraviolet Radiation & Eye PDF

Arquivos Brasileiros de REVIEW ARTICLE Ultraviolet radiation and the human eye Radiações ultravioletas e o olho humano Carlos Yuji Nunomura1...

Arquivos Brasileiros de REVIEW ARTICLE Ultraviolet radiation and the human eye Radiações ultravioletas e o olho humano Carlos Yuji Nunomura1 , Sidney Julio de Faria e Sousa2 1. Department of Ophthalmology, Hospital das Clínicas, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil. 2. Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil. ABSTRACT | This work is a critical review of the current meters (nm). The relationship between frequency and understanding of the effect of ultraviolet radiation on the eye. wavelength can be demonstrated as follows: It deals with the classification of this radiation, environmental level, and the factors that determine it, along with penetration into the human eye, toxicity to ocular structures, associated morbidities, events that may increase the vulnerability of the Where, v is the frequency, c is the speed of light, eye, and artificial eye filters. and λ is the wavelength. Keywords: Electromagnetic radiation; Ultraviolet rays; Eye Electromagnetic radiation behaves either as a wave burns; Ultraviolet filters; Visual disorders or as a stream of photons. The first behavior is adequate for the study of energy transport, whereas the second RESUMO | Esta é uma revisão crítica do efeito da radiação is suitable for analyzing the light interaction with the ul­­travioleta no olho. Trata da classificação dessa radiação, nível no meio ambiente e os fatores que o determinam, penetração no matter, making it easier to understand the toxicity of wa­ olho humano, toxicidade às estruturas dos oculares, morbidades velengths. The expression that relates the photon energy associadas, eventos passíveis de aumentar a vulnerabilidade to the wave characteristics can be depicted as follows: do olho e filtros oculares artificiais. Discute, ainda, o risco real dessas radiações ao olho humano à luz do conhecimento atual. Descritores: Radiação eletromagnética; Raios ultravioleta; Quei­ Where, E is the photon energy expressed in ergs, maduras oculares; Filtros ultravioletas; Transtornos da visão hv is Plank’s constant, c is the speed of light, v is the frequency, and λ is the wavelength. Based on this ex­ INTRODUCTION pression, the higher the frequency and shorter the wave­ Electromagnetic radiation is a form of energy found length, the higher the energy of the radiation. That fact in our environment that includes seven bands that are explains why ultraviolet light has more energy than IR. associated with attributes familiar to us, such as radio­ Of the entire electromagnetic spectrum, solar ra­ therapy (gamma rays), radiography (X-rays), tanning diation, despite being only a tiny fraction of it, is the (ultraviolet radiation), vision (visible light), heat (infra­ one that interacts most with our ecosystem. It compri­ red radiation; IR), microwave oven (microwaves), and ses three groups of wavelengths: ultraviolet radiation radio (radio waves). Typically, low-energy radiations, (100-400 nm), visible light (400-760 nm), and IR such as radio waves, are expressed in frequency (cycles (760-10,000 nm). Under normal conditions, the human per second), while high-energy radiations, such as ultra­ eye detects only visible light (Figure 1). The terms ultra violet radiation, are conveyed as wavelength in nano­ and infra refer to frequencies and not wavelengths. Submitted for publication: September 15, 2021 Accepted for publication: April 12, 2022 Funding: This study received no specific financial support. Disclosure of potential conflicts of interest: None of the authors have any potential conflicts of interest to disclose. Corresponding author: Carlos Yuji Nunomura. Figure 1. Sunlight spectrum. UVR, ultraviolet radiation; IRR, E-mail: [email protected] infrared radiation This content is licensed under a Creative Commons Attributions 4.0 International License. http://dx.doi.org/10.5935/0004-2749.2021-0354 Arq Bras Oftalmol. 2023;86(6):e2021-0354 1  Ultraviolet radiation and the human eye Classification of ultraviolet radiation Reflection on the ground - fresh snow reflects up to Ultraviolet radiation was classified into three sub­ 80%, dry beach sand about 15%, and seafoam about groups at the Second International Light Congress in 25% of the UV radiation. Copenhagen in 1932(1) (Table 1). Penetration of electromagnetic radiation into the eye Levels of ultraviolet radiation in the environment The cornea and crystalline lens are the transparent Before attenuation by the atmosphere, solar radia­ media in the eye that absorbs the most UV radiation. tion is composed of 52.8% IR, 38.9% visible light, 6.3% The cornea filters out all UV radiation