AIM:To evaluate the effects of polarized and nonpolarized sunglasses on visual functions,including distance and near visual acuity,phoria,stereopsis and contrast sensitivity across five spatial frequencies(1.5,3,6,12,...AIM:To evaluate the effects of polarized and nonpolarized sunglasses on visual functions,including distance and near visual acuity,phoria,stereopsis and contrast sensitivity across five spatial frequencies(1.5,3,6,12,18 cycles/degree).METHODS:A before-after study was conducted on 45 emmetropic students from Shahid Beheshti University of Medical Sciences.Visual acuity,contrast sensitivity,stereopsis and phoria were measured under three conditions:without sunglasses,with non-polarized sunglasses and with polarized sunglasses.Tests were conducted under controlled glare conditions to simulate outdoor environments.RESULTS:A total of 45 participants were evaluated,comprising 17 males(37.8%)and 28 females(62.2%).The mean age was 21.67±2.31y(range 18-27y).The mean of distance and near visual acuity in all three conditions were equal to 0.00 logMAR.Contrast sensitivity generally decreased slightly with the use of non-polarized sunglasses compared to the no-sunglasses condition.The mean stereopsis with polarized sunglasses was 101.33±56.139 arc sec,which was worse than the no-sunglasses condition(94.33±46.632 arc sec)and better than the non-polarized sunglasses condition(105.67±58.965 arc sec),although these changes were not significant.In the phoria parameter,distance phoria appeared more affected than near phoria.CONCLUSION:Polarized and non-polarized sunglasses do not significantly affect visual acuity,stereopsis,or phoria under controlled glare conditions.Slight changes in contrast sensitivity are noted,but they are not statistically significant.展开更多
Background: The sunglass standards are not strictly implemented in many countries except Aus-tralia. The purpose of the study was to evaluate the optical properties of unbranded sunglasses for light transmittance. Met...Background: The sunglass standards are not strictly implemented in many countries except Aus-tralia. The purpose of the study was to evaluate the optical properties of unbranded sunglasses for light transmittance. Methods: Unbranded sunglasses with no information about their specifications were included. They were allocated to two groups based on their prices;the ones > 25 US$ (Group A) and the cheaper ones (Group B). Their transmittance spectrum was measured between 190 nm and 900 nm using a double beam scanning spectrophotometer. The European standard for sunglasses was used to evaluate their compliance regarding ultraviolet radiation (UVR) transmittance and minimum requirement for wearing when driving. Results: Thirty-eight sunglasses (Group A = 20 and Group B = 18) were evaluated. Four sunglasses in each group were non-compliant. Percentage transmittance of visible light was <8% in five sunglasses of Group A and in three of Group B, so these were not appropriate to wear when driving. Totally six sunglasses of Group A and five of Group B were non-compliant and/or inappropriate to wear when driving. Conclusions: Based on our findings about their UVR protection and visible light transmittance %, eye care professionals must warn people against the use of unbranded sunglasses without any information about their specifications.展开更多
文摘AIM:To evaluate the effects of polarized and nonpolarized sunglasses on visual functions,including distance and near visual acuity,phoria,stereopsis and contrast sensitivity across five spatial frequencies(1.5,3,6,12,18 cycles/degree).METHODS:A before-after study was conducted on 45 emmetropic students from Shahid Beheshti University of Medical Sciences.Visual acuity,contrast sensitivity,stereopsis and phoria were measured under three conditions:without sunglasses,with non-polarized sunglasses and with polarized sunglasses.Tests were conducted under controlled glare conditions to simulate outdoor environments.RESULTS:A total of 45 participants were evaluated,comprising 17 males(37.8%)and 28 females(62.2%).The mean age was 21.67±2.31y(range 18-27y).The mean of distance and near visual acuity in all three conditions were equal to 0.00 logMAR.Contrast sensitivity generally decreased slightly with the use of non-polarized sunglasses compared to the no-sunglasses condition.The mean stereopsis with polarized sunglasses was 101.33±56.139 arc sec,which was worse than the no-sunglasses condition(94.33±46.632 arc sec)and better than the non-polarized sunglasses condition(105.67±58.965 arc sec),although these changes were not significant.In the phoria parameter,distance phoria appeared more affected than near phoria.CONCLUSION:Polarized and non-polarized sunglasses do not significantly affect visual acuity,stereopsis,or phoria under controlled glare conditions.Slight changes in contrast sensitivity are noted,but they are not statistically significant.
文摘Background: The sunglass standards are not strictly implemented in many countries except Aus-tralia. The purpose of the study was to evaluate the optical properties of unbranded sunglasses for light transmittance. Methods: Unbranded sunglasses with no information about their specifications were included. They were allocated to two groups based on their prices;the ones > 25 US$ (Group A) and the cheaper ones (Group B). Their transmittance spectrum was measured between 190 nm and 900 nm using a double beam scanning spectrophotometer. The European standard for sunglasses was used to evaluate their compliance regarding ultraviolet radiation (UVR) transmittance and minimum requirement for wearing when driving. Results: Thirty-eight sunglasses (Group A = 20 and Group B = 18) were evaluated. Four sunglasses in each group were non-compliant. Percentage transmittance of visible light was <8% in five sunglasses of Group A and in three of Group B, so these were not appropriate to wear when driving. Totally six sunglasses of Group A and five of Group B were non-compliant and/or inappropriate to wear when driving. Conclusions: Based on our findings about their UVR protection and visible light transmittance %, eye care professionals must warn people against the use of unbranded sunglasses without any information about their specifications.
