Role of light emitted by incandescent or fluorescent lamps in the development of myopia and astigmatism

Transcription

1 Med Sci Monit, 2004; 10(4): CR PMID: Clinical Research Received: Accepted: Published: Authors Contribution: A Study Design B Data Collection C Statistical Analysis D Data Interpretation E Manuscript Preparation F Literature Search G Funds Collection Role of light emitted by or lamps in the development of myopia and astigmatism Damian Czepita 1 acdef, Wojciech Gosławski 1 c, Artur Mojsa 1 b, Izabela Muszyńska-Lachota 2 f 1 1 st Department of Ophthalmology, Pomeranian Medical Academy, Szczecin, Poland 2 Department of Hygiene and Epidemiology, Pomeranian Medical Academy, Szczecin, Poland Source of support: Department sources. Background: Material/Methods: Results: Conclusions: key words: Summary The purpose of our study was to determine if the development of refractive errors might be associated with exposure to light emitted by or lamps students from elementary schools, junior high schools and high schools were examined, aged 6 19 years. Visual acuity was measured, and retinoscopy was performed after cycloplegia. The parents of all students examined completed a questionnaire concerning the child s exposure to light emitted by or lamps before the age of two. The data was analyzed using the chi-squared test. Sleeping till the age of two with a room light turned on leads to an increase in the occurrence of myopia (P<0.01). It was also found that light emitted by lamps leads to more frequent occurrence of astigmatism (P<0.01). Disturbance of the daily light/dark cycle over the time during which refraction develops may disrupt emmetropization and lead to refractive errors. light lamps lamps myopia astigmatism Full-text PDF: Word count: 1027 Tables: 2 Figures: References: 19 Author s address: Damian Czepita MD PhD, 1 st Department of Ophthalmology, Pomeranian Medical Academy, Al. Powstańców Wlkp. 72, Szczecin, Poland, czepita@pro.onet.pl CR168

2 Med Sci Monit, 2004; 10(4): CR Czepita D et al Light and refractive errors BACKGROUND Light is one of the important factors taking part in the development of the whole vision system. Recently there have been several papers published on the influence of light on the development of myopia. Based on parental questionnaires and refractions, Quinn et al [1] indicated that myopia occurs frequently among children who sleep in lighted rooms before the age of 2 years. These investigations, carried out on 479 people ranging from two to sixteen years of age, have stirred considerable interest around the world. In the years following several papers have been published concerning the purported relationship. Examining 177 students at a law school in Philadelphia, Loman et al. [2] described a greater progression of myopia among persons more exposed to light. On the other hand, Gwiazda et al. [3] and Mutti et al. [4] from the US, Saw et al. [5] from Singapore, and Sugimoto et al. [6] from Japan did not observe a frequent occurrence of myopia among persons who during their childhood slept in lighted rooms. In 2001, Czepita et al. [7], having examined 6000 students ranging from 6 to 19 years of age, demonstrated that myopia occurs more frequently among persons who till the age of two slept with the light turned on. Moreover, they described a more frequent occurrence of hyperopia among students who till the age of two slept in a lighted room or with a night lamp. However, to date no research has been done on the influence of the type of artificial light on the etiology of myopia, hyperopia and astigmatism [8,9]. Accordingly, in the present study we decided to address the question as to whether there is any relationship between the occurrence of refractive errors and exposure to light emitted by or lamps. MATERIAL AND METHODS 3377 students were examined (1521 boys and 1856 girls, mean age 11.1, SD 3.5, range 6 19 years). The examined children, students in elementary schools, junior high schools and high schools, were examined in the schools consulting rooms. All were Caucasian and lived in the same city: Szczecin, Poland. Distant visual acuity was measured using Snellen s charts following the standard protocol. Cycloplegia was effected by administering two drops of 1% tropicamide instilled 5 minutes apart. Thirty minutes after the last drop, retinoscopy was performed. Myopia was defined as a refractive error 1.0 D, hyperopia as a refractive error +1.0 D, and astigmatism as a refractive error 1.0 DC. The parents of all the students examined completed a questionnaire on the child s light exposure before the age of two. The questionnaire was written in the Polish language. The questions asked whether the child slept at night in darkness or with light turned on. Other questions asked what type of artificial light was used in the living room, dining room, child s room, parents bedroom, kitchen, and bathroom. Informed consent was obtained from the parents. The experiment was approved by the Ethics Committee of the Pomeranian Medical Academy. The study group involved persons with emmetropia, myopia, hyperopia, and astigmatism. Students with other eye problems were not taken under consideration in statistical analysis. The data was analyzed statistically by the chi-squared test. P values of less than 0.05 were considered statistically significant. RESULTS It was found that among the examined students myopia occurred in 6%, hyperopia in 30%, and astigmatism in 5%. The acquired data are quite similar to the results obtained by other Polish authors as well, and corresponds with the most common refractive error distribution among persons of Caucasian race all over the world [9-14]. In our research we observed that sleeping till the age of two with a room light turned on leads to an increase in the occurrence of myopia (P<0.01). It was also found that light emitted by lamps leads to more frequent occurrence of astigmatism (P<0.01) (Table 1). The use of lamps in the parents bedroom increases the prevalence of astigmatism (P<0.01). Incandescent lamp lighting in kitchens leads to frequent occurrence of emmetropia (P<0.03) (Table 2). DISCUSSION In our investigation it was confirmed that sleeping till the age of two with a room light turned on leads to an increase in the occurrence of myopia. It was also found that light emitted by lamps leads to more frequent occurrence of astigmatism. In experimental investigations it has been concluded that rearing chicks in continuous light creates flattening of the cornea, profound enlargement of the eyeball, decrease of the thickness of the cornea, sclera, retina and choroidea, as well as extensive anatomical changes in the retina [8,15 17]. Boelen and Cottriall [18] have indicated that rearing chicks in light creates a decrease of the level of 3, 4-dihrodroxiphenylacetic acid (DOPAC) in the vitreous. That is why it seems likely that among humans the process of sleeping with a light turned on can lead to the lowering of dopaminergic activity and a consequent lower release of dopamine, as well as augmentation of eye growth. This may be why in the our investigations it was found that among people who till the age of two slept with a light turned on myopia occurs more frequently. However, it is impossible to exclude the possibility that the results we obtained were influenced by the parents refractive state, the socioeconomic status of the family, or other environmental factors [8,9,14,15]. In our study, more frequent occurrence of astigmatism was observed among people who lived with light emitted by lamps, in comparison to those who lived with light emitted by lamps. This was clearly seen among people whose parents bedrooms were lighted by lamps. The development of CR169 CR

3 Clinical Research Med Sci Monit, 2004; 10(4): CR Table 1. Prevalence of refractive errors in relation to the type of night light.without parentheses % of patients. In parentheses number of patients. Type of night lights No light Light Total number of patients Patients Emmetropic Myopic Hyperopic Astigmatic 59 (1594) 56 (384) P< (322) 56 (62) P< (1978) 6 (156) 8 (57) P< (46) 10 (11) P<0.5 6 (213) 30 (810) 31 (213) P< (185) 25 (28) P< (1023) 5 (131) 5 (32) P< (22) 9 (10) P< (163) Table 2. Prevalence of refractive errors in relation to the type of room light.without parentheses % of patients. In parentheses number of patients. Type of room Living room Dining room Child's room Parents bedroom Kitchen Bathroom Total number of patients Patients Emmetropic Myopic Hyperopic Astigmatic 59 (1955) 63 (23) P< (1934) 59 (44) P< (1952) 59 (26) P< (1956) 58 (22) P< (1853) 52 (125) P< (1914) 56 (64) P< (1978) 6 (212) 3 (1) P< (208) 7 (5) P< (210) 7 (3) P< (212) 3 (1) P< (195) 7 (18) P< (207) 5 (6) P< (213) 30 (1013) 28 (10) P< (1003) 27 (20) P< (1010) 29 (13) P< (1013) 26 (10) P< (938) 35 (85) P< (987) 32 (36) P< (1023) 5 (161) 6 (2) P< (158) 7 (5) P< (161) 5 (2) P< (158) 13 (5) P< (150) 6 (13) P< (155) 7 (8) P< (163) astigmatism is most likely linked with the influence of light emitted by lamps on corneal and anterior chamber growth. Perhaps a particular function is also played in this process by the ciliary ganglion and ciliary muscle [17,19]. On the other hand, the phenomenon of the more frequent occurrence of emmetropia when lamps were used in the kitchen is hard to explain, and requires further investigation. CONCLUSIONS Disturbance of the daily light/dark cycle during the time period when refraction is developing may disrupt emmetropization and lead to refractive errors. Acknowledgments We would like to thank Professor R. A. Stone from the Department of Ophthalmology, University of Pennsylvania School of Medicine, Philadelphia, U.S.A, for his critical review of the manuscript, and A. Pechmann for help in data collection. REFERENCES: 1. Quinn GE, Shin CH, Maguire M et al: Myopia and ambient lighting at night. Nature, 1999; 399: Loman J, Quinn GE, Kamoun L et al: Darkness and nearwork: myopia and its progression in third-year law students. Ophthalmology, 2002; 109: Gwiazda J, Ong E, Held R et al: Myopia in children is not associated with night-time lighting in infancy. In: Thorn F, Troilo D, Gwiazda J (eds.): Myopia Proceedings of the VIII International Conference on Myopia. Boston, July 7 9, Conference on Myopia 2000 Inc, Boston, 2000: Mutti DO, Jones LA, Irvin BC et al: Nursery lighting is not associated with myopia. In: Thorn F, Troilo D, Gwiazda J (eds.): Myopia Proceedings of the VIII International Conference on Myopia. Boston, July 7 9, Conference on Myopia 2000 Inc, Boston, 2000: Saw S-M, Wu H-M, Hong C-Yet al: Myopia and night lighting in children in Singapore. Br J Ophthalmol, 2001; 85: Sugimoto R, Kuwayama Y, Stone RA: Myopia and night-time light exposure in Japanese schoolchildren. Invest Ophthalmol Vis Sci, 2001; Suppl 42: S Czepita D, Pechmann A, Mojsa A: Role of ambient night-time lighting in the hyperopia and myopia development. Proceedings of the XIII Congress of the European Society of Ophthalmology, Istanbul, June 3 7, 2001: Czepita D: The role of light in the pathogenesis of refractive errors (in Polish with English abstract). Klin Oczna, 2002; 104: Czepita D: Myopia epidemiology, pathogenesis, present and coming possibilities of treatment. Case Rep Clin Prac Rev, 2002; 3: Koraszewska-Matuszewska B, Illg W: The value of ophthalmological mass examinations in school-children (in Polish with English abstract). Klin Oczna, 1972; 42: Mikulski T: Dynamics of anomalies of refraction (in Polish with English abstract). Klin Oczna, 1972; 42: CR170

4 Med Sci Monit, 2004; 10(4): CR Czepita D et al Light and refractive errors 12. Muszyƒska-Lachota I, Czepita D, uczyƒska V, Wysiecki P: Prevalence of refractive errors among 7 and 8 year old children in the West Pomeranian region (in Polish with English abstract). Ann Acad Med Stetin, in press 13. Ogielska E, Czerek-Jaguczaƒska H, Pacyƒska J: The problem of refraction anomalies in school children and students (in Polish with English abstract). Klin Oczna, 1967; 37: Zadnik K, Mutti DO: Incidence and distribution of refractive anomalies. In: WJ Benjamin, IM Borish (eds.) Borish s clinical refraction. W.B. Saunders Company, Philadelphia, 1998, Hung GK, Ciuffreda KJ: Differential retinal-defocus magnitude during eye growth provides the appropriate direction signal. Med Sci Monit, 2000; 6: Lauber JK, Shutze JV, McGinnis J: Effects of exposure to continuous light on the eye of the growing chick. Proc Soc Exp Biol Med, 1961; 106: Li T, Howland HC: Modulation of constant light effects on the eye by ciliary ganglionectomy and optic nerve section. Vision Res, 2000; 40: Boelen MK, Cottriall CL: Nightlights affect diurnal cycling of dopamine release and the rate of emmetropisation. Invest Ophthalmol Vis Sci, 2000; Suppl 41: S LeÊnik H, Poborc-Godlewska J: The relationship between ciliary muscle fatigue and the type of artificial light used to illuminate the area of visual work. Pol J Occup Med Env Health, 1993; 6: CR CR171

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