Effect of Myopia and Glare on Mesopic Contrast Sensitivity

Effect of Myopia and Glare on Mesopic Contrast Sensitivity

Aim: The aim of the study is to evaluate the simultaneous effect of mild myopia and glare on contrast sensitivity under mesopic conditions corresponding to the conditions of night driving.

Material and Methods: The study included 22 volunteers (11 women and 11 men) aged between 20 and 42 years (mean age 26.5 years, standard deviation 5.2 years) with normal or corrected to normal binocular and monocular vision acuity and normal healthy eyes. The study was designed as a prospective study. After adaptation to mesopic conditions, three series of contrast sensitivity measurements (with fully corrected refractive error, with induced myopia -0.50 D and -1.0 D) were performed in random order using the Mesotest II device. In each series, measurements were performed with and without glare. All measurements were performed twice, and their average was considered as the result. The effect of induced myopia and glare was assessed using the analysis of variance method for repeated measures.

Results: Significant effects of myopia (p < 0.001) and glare (p < 0.001) on mesopic contrast sensitivity were proven, with contrast sensitivity decreasing with increasing myopia or in the presence of glare. A significant interaction of these factors (p < 0.001) was also found, which was manifested by an increased effect of glare in the presence of refractive error. The impact of glare increased with the size of the refractive error. In the absence of myopia, the effect of glare was minimal if any.

Conclusion: Mesopic contrast sensitivity is significantly affected by both the level of uncorrected myopia and the presence of glare. The significant effect of glare is observed especially in the presence of myopia, which enhances its impact. Therefore, emphasis should be placed on well-defined refractive correction in individuals who need quality vision under mesopic conditions (typically drivers). To prevent the undesirable effect of glare, it is also appropriate to consider correction of possible night myopia in these subjects.

Keywords:

contrast sensitivity – contrast – mesopic lighting conditions – glare – uncorrected myopia – Mesotest II