The Dark Focus of Accommodation in Swedish Myopes

Abstract: The dark focus is a resting state of accommodation, which occurs when there are not enough stimuli for the eye to focus on. This means that the eye becomes more myopic and some people notice a blur for example at night time, more known as night myopia. In this study the dark focus in Swedish myopes is measured and any difference between early and late onset myopes is investigated. Method: The dominant eye of 56 myopes was first measured with static retinoscopy, using a distant target, and then with near retinoscopy, with the retinoscope beam as the target. The full working distance of 2.00 D was subtracted in both methods and the values were compared. The difference, if any, was the dark focus. Results: The mean value of dark focus was 0.53 D ± 0.26 for the entire group. The mean value for early onset myopes was 0.56 D ± 0.29 and for late onset myopes the mean value was 0.47 D ± 0.21. This showed no significant difference (p-value = 0.18). No significant correlation between amount of refractive error and dark focus was found. Conclusion: The Swedish myopes in this study have a smaller mean value of dark focus than mean values found in other studies using the same technique and the previous findings that early and late onset myopes differ in mean values of dark focus is not applied to this study.