Ametropia and the accommodative response

To investigate the influence of Ametropia on the lag of accommodation, and to compare the accommodative stimulus-response functions of Myopes, Emmetropes and Hyperopes in uncorrected conditions and in conditions of fully corrected Ametropia. One hundred young adults were classified as Early-Onset Myopes [n = 38], Emmetropes [n = 37] and Hyperopes [n = 25]. Each subject had no ocular abnormalities and was subjectively refracted to attain the Corrected-Ametropia-Most-Plus [CAMP] spectacle prescription. The lag of accommodation was assessed under binocular viewing conditions with the Nott Dynamic Retinoscopy Method. Each subject was assessed for accommodative lag without and with the CAMP spectacle prescription, for target distances of 66cm, 50cm and 33cm. In uncorrected conditions at all three target distances, there was an accommodative lead in Myopia which differed significantly [P < 0.05, Kruskal Wallis Multiple Comparison Test] from the accommodative lag in Emmetropia and Hyperopia [which were both identical]. In corrected conditions, accommodative lag was identical between groups at all three distances [P > 0.05, Single-Factor ANOVA]. Except in Uncorrected versus Corrected early-Onset Myopia [P < 0.05, Welch-Corrected Unpaired T-Test], the Average Accommodative Stimulus-Response Gradient did not vary significantly within and between groups in conditions of Uncorrected Ametropia / Emmetropia [p > 0.05, Welch-Corrected Unpaired T-Test for Myopia vs. Emmetropia and for Myopia vs. Hyperopia; p > 0.05, Unpaired T-Test], and in conditions of Corrected Ametropia / Emmetropia [P > 0.05, Unpaired T-Test for Myopia vs. Emmetropia and for Myopia vs. Hyperopia; P > 0.05, Welch-Corrected T-Test for Emmetropia vs. Hyperopia]. The presence and/or correction of refractive errors do not significantly influence the accommodative stimulus-response function. In fully corrected stable Ametropia, the lag of accommodation does not differ significantly between Early-Onset Myopia, Emmetropia and Low- to -Moderate Hyperopia

Congenital color vision defects in Saudi Arabia

One previous study [1980] reported a lower prevalence rate of congenital color vision defects in Saudi Arabian males [4.7%] compared with Caucasian males [8%]. This study aimed to re-evaluate the findings of those studies to take into account recent migration and urbanizatiom trends in Saudi Arabia. Six hundred adult male subjects divided equally between two cities [Riyadh and Qaseem] in the Central Region of Saudi Arabia were assessed for color vision using the Ishihara plates. The prevalence of congenuital color vision defects was found to be 7.2% in Saudi Arabian males, varying from 8.3% in the Riyadh Area to 6% the Qaseem Area. These results indicate a higher prevalence a of congenital color vision defects in Saudi Arabian males than previously thought, and we suggest that this is due to recent and on going migration and urbanization trends in Saudi Arabia