Evaluation of visual stress symptoms in age-matched dyslexic, Meares-Irlen syndrome and normal adults

AIM： To examine the prevalence of dyslexia and Meares-Irlen syndrome（MIS） among female students and determine their level of visual stress in comparison with normal subjects.·METHODS： A random sample of 450 female medical students of King Saud University Riyadh（age range, 18-30y） responded to a wide range of questions designed to accomplish the aims of this study. The detailed questionnaire consisted of 54 questions with 12 questions enquiring on ocular history and demography of participants while 42 questions were on visual symptoms. Items were categorized into critical and non-critical questions（CQ and NCQ） and were rated on four point Likert scale. Based on the responses obtained, the subjects were grouped into normal（control）, dyslexic with or without MIS（Group 1） and subjects with MIS only（Group 2）. Responses were analysed as averages and mean scores were calculated and compared between groups using one way analysis of variance to evaluate total visual stress score（TVSS =NCQ ＋CQ）, critical and non-critical visual stress scores. The relationship between categorical variables such as age, handedness and condition were assessed with Chi-square test.·RESULTS： The completion rate was 97.6% and majority of the respondents（92%） were normal readers, 2%dyslexic and 6% had MIS. They were age-matched. More than half of the participants had visited an eye care practitioner in the last 2y. About 13% were recommendedeye exercises and one participant experienced pattern glare. Hand preference was not associated with any condition but Group 1 subjects（3/9, 33%） were significantly more likely to be diagnosed of lazy eye than Group 2（2/27, 7%） and control（27/414, 7%） subjects. The mean±SD of TVSS responses were 63±14 and it was 44±9for CQ and 19 ±5 for NCQ. Responses from all three variables were normally distributed but the CQ responses were on the average more positive（82%） in Group 2 and less positive（46%） in Group 1 than control. With NCQ,the responses were equally less positive in Group 1 and2 than control. Group 2 subjects showed significantly higher TVSS（P =0.002）, NCQ（P =0.006） and CQ（P =0.008）visual stress scores than control but no difference between Group 1 and control subjects, was observed for all scores（P 〉0.05, for all comparisons）.·CONCLUSION： The prevalence of dyslexia and MIS among Saudi female students was 2% and 6%,respectively. Critical questions performed best for assessing visual stress symptoms in dyslexic and MIS subjects. Generally, students with MIS were more sensitive to visual stress than normal students but dyslexics were more likely to present with a lazy eye than MIS and normal readers.

Smartphone use patterns and the impact on accommodation and convergence system of the eyes among Malaysian teenagers

AIM:To determine the smartphone use patterns and effects of smartphone use on accommodation and convergence system of the eyes among Malaysian teenagers.METHODS:A total of 62 participants aged between 13 and 17y were involved.A self-administered questionnaires containing 12 items was used to evaluate the smartphone usage patterns.This was followed by an eye examination,involving a battery of accommodation and convergence assessments before and after the smartphone use.The data analysis comprised descriptive statistics,paired t-test,and correlation coefficients.RESULTS:The use of smartphones is at a high level and at an optimal distance daily,with more than 6h a day watching video films,games,and completing school projects.Majority of the participants not reported eye strain factors and eye prescription changes with the use of digital devices.The use of a smartphone continuously for 30min was found to significantly decrease amplitude of accommodation,accommodative facility,and positive relative accommodation(P<0.001).Meanwhile,the lag of accommodation parameters and negative relative accommodation increased with the use of smartphones significantly(P<0.001).The near point of convergence(NPC)and distance and near negative fusional vergence decreased significantly(P<0.001).The NPC parameter was found to have a weak negative association with the frequency of smartphone use(R=-0.276,P<0.05).CONCLUSION:Frequent and continuous use of smartphones have increased visual stress and resulted in weakness of accommodation and vergence functions.Therefore,frequent break is mandatory when using a smartphone and appropriate visual hygiene,the 20-20-20 rule(every 20min,view something 20 feet away for 20s)are required during smartphone use to maintain visual function.