Study Contrast Seneitivity Of Laser In Situ Keratomileusis For High Myopia

Backgroud and ObjectiveLaser in situ keratomileusis for myopic with safety and effectiveness,has become the first choice today refractive surgery surgical cornea.Howevercorneal refractive surgery to correct refractive error correction also changed the original corneal normal form,what could cause the postoperatives visual quality declining.Some patients will appear some symptoms of the visual quality drop down,such as contrast sensitivity declining,glare,and halo and poor eyesight night.With patients discontented on visual quality of postoperative,clinical doctors gradually realized the importance of studying on contrast sensitivity and the necessity,especially contrast sensitivity in the dark environment,because contrast sensitivity is the important human visual function evaluation index,and it changes earlier than vision,fundus and vision,so it can accuratly and timely reflect the changes of visual function of surgery,still can make accurate evaluation of operation methods and operative effects.Although there are study reported about contrast sensitivity at home and abroad.but for laser in situ keratomileusis for high myopia with postoperative mesopic contrast sensitivity researches are less,and the results are endless and same.We collected 66 cases (129 eyes) of preoperative equivalent spherical mirrors for (-6.00～-12.75) D and had prospectie study, to explore clinical effect of the high myopia human after laser in situ keratomileusis,and compared the changes of contrast sensitivity with other sensitive parameters such as preoperative dioptre,pupil diameter, diameter of surgery ablation light area,gender,age,glare of relevancy.MethodsFrom May 2010 to August 2010,66 cases 129 eyes with high myopia in our hospital excimer laser treatment center were received laser in situ keratomileusis, prospectie study.At preoperative and postoperative 1,3 and 6 months,we bested the best corrected visual acuity and photorefractive for all patients,and used CSV-1000E contrast sensitivity tester for checking dark environment contrast sensitivity,we compared the changes of contrast sensitivity with other sensitive parameters such as preoperative dioptre,pupil diameter,diameter of surgery ablation area, gender, age, glare of relevancy.The data were analyzed by SPSS17.0 statistical software,contrast sensitivity changed with single factor analysis of variance (ANOVA),various correlation analysis with Pearson,every times of contrast sensitivity with or without glare with paired-t test,P< 0.05 as considered the standard of significant differences.Results1. Postoperative six months,95 eyes(73.60%) uncorrected visual acuity reached or exceeded 1.0,effective index is 0.996,safety index is 1.052,122 eyes (94.57%) spherical equivalent within±1.00 D,97 eyes (75.19%) spherical equivalent within±0.50 D.2. Postoperative one month, low frequency (3c/d),middle spatial frequencies (6, 12c/d) and high frequencies (18c/d) contrast sensitivity are obviously decline, postoperative six months low frequency contrast sensitivity can be recovered to preoperative levels (no statistically significant difference, P> 0.05),but middle and high contrast sensitivity not be recovered to preoperative levels (statistically significant difference,P< 0.05).3. Preoperative dioptre is negatively correlated with preoperative and postoperative contrast sensitivity,especially the contrast sensitivity of high and middle spatial frequency;The diameter of surgery ablation is positively correlated with postoperative contrast sensitivity,especially low and middle frequency contrast sensitivity in the scotopia;Each period of photopic and mesopic with glare contrast sensitivity lower than without glare contrast sensitivity,all spatial frequencies are statistically significant difference (P< 0.05).4. Contrast sensitivity is irrelevanted with gender, age, pupil diameter and et al.Conclusions1. Laser in situ keratomileusis for high myopia,at postoperative one month in dark environment each frequency band of four states contrast sensitivity had been decreased, postoperative six months,the low frequency contrast sensitivity has been restored to preoperative level;but middle and high frequencies not be recovered to preoperative levels.2. In Dark environment of postoperative contrast sensitivity is negatively correlated with preoperative diopter and positively correlated with glare.