The Night Visual Quality And Related Factors Of Myopes Before And After LASIK Surgery

Purpose:To evaluate the visual quality especially the night visual quality changes between the low and moderate myopes and the high myopes under photopic and mesopic conditions before and after LASIK surgery using the subjective questionnaire and the objective tests.Then further analyze and approach the related factors that affect night visual quality,then propose a series of precautions and managements.Methods:The low and moderate myopes and the high myopes were randomly select,dividing into two groups with each contain 38 persons.All the patients were examined and treated under the regular clinical LASIK standards and guidance by one surgeon with the same set of Technolas 217z Excimer Laser.To record the basic information of the patients and then carried out the subjective and objective examination at the point of pre-operation,post-operation 1month and 3 months.The subjective examination mainly refers to questionnaires which recording the night visual disturbances.The objective examination contains contrast sensitivity function by CGT- 1000 and MesotestⅡb,corneal K,Q value by Orbscan corneal topography,pupil diameter by pupilometry and so on.Preoperative and postoperative parameters in and between the two groups were compared as well as linear correlations between the parameters were studied.Chose the patients who have night vision disturbances or decreased contrast sensitivity function under mesopic condition as the experimental group,the patients who haven't as the controlled group,using logistic regression analysis to screening the risk factors of decreased night visual quality.Results:There is an increase in night vision complaints after surgery in both groups.The frequency and severity of night vision complaints in the high myopes group outweigh the other group both before and after surgery.The CSF of the high myopes group is worse than that of the low and moderate myopes group both before and after surgery(P＜0.05).The self-contrast in two group shows that while there is a significant difference in CSF between pre-and post-operation in the high myopes,no significant difference is found in the low and moderate myopes.The logistic regression analysis show that the difference between optical zone and pupil diameter,pre-operative diopter,the method of ablation,age and so on are related to the night vision quality.Conclusion:Before the surgery,the visual quality of the low and moderate myopes group is better than that of the high myopes group.After the surgery,the visual quality were both worser than that ofpre-operation in two groups,even worser in the high myopes.There was a tendency of recovery in every index,but still needs longer follow-up.Night vision quality can be affected by multiple factors,of which the difference between optical zone and pupil diameter,pre-operative diopter and the method of ablation are the most important factors.