| Part I Evaluate the optical quality of young patients with myopia by usingthe Double-pass Optical Quality Analysis SystemObjective: Evaluate the optical quality of young patients with myopia by using the Double-pass Optical Quality Analysis System(OQASTM II) to establish a new range of reference values, further to provide evidence for the diagnosis and evaluation of myopia in young patients in clinical.Methods:It was a case-control study. The subjects of this study were 342 young patients from our hospital(October 2013 to December 2013). Basing on the spherical equivalent(SE) diopter, patients were divided into three groups: low myopia group, moderate myopia group, and high myopia group. Optical quality measurements for a 4.0mm pupil were performed using the OQASTM II. The following parameters were analyzed: the objective scatter index(OSI), the modulation transfer function cutoff frequency(MTF cutoff), the Strehl ratio(SR), the visual acuity(VA) at 100%, 20%, and 9% contrasts and the amplitude of accommodation(AMP).Results:1The normal limits of the optical quality parameters were: OSI,MTF cutoff,SR,VA100%,VA20%,VA9%,AMP:0.48 ~ 0.68,36.54 ~ 40.20,0.22 ~0.25,1.22 ~ 1.34,1.25 ~ 1.41,1.32 ~ 1.49,1.18 ~ 1.47 in low myopia, respectively; 0.61 ~ 0.76,34.55 ~ 37.07,0.21 ~ 0.22,1.15 ~ 1.24,1.16 ~1.26,1.20 ~ 1.30,1.28 ~ 1.48 in moderate myopia respectively;1.39 ~2.20,28.40~31.99,0.17~0.19,0.95~1.07,0.92~1.05,0.92~1.05,1.62~1.88 in high myopia, respectively; as the parameter values increase the visual quality of myopia decrease, while the OSI and AMP values increase.2.The OSI was negatively correlated with MTF cutoff and SR values with statistical significance(r=-0.65,-0.5, P<0.05, for both). While the correlation between age and OSI did not show difference( r=0.045 P=0.24>0.05).Conclusions:This study revealed the normal range of reference values of OQASTM II under different refractive status. Our study could provide evidence for establishing reference values, evaluating the visual quality of patients under different refractive status and discriminating healthy from early abnormal eyes. Part II Clinical comparison of visual quality after wavefront guided SBKby using objective and subjective detection methodObjective:Compare the wavefront-guided sub-Bowman keratomileusis,(SBK) postoperative visual quality with the sensitivity,wavefront analyzer and OQASTM II to provide a basis for doctors to select better visual quality evaluation method.Methods:The subjects of this study were 196 young patients with wavefront aberration guided SBK operation from the excimer myopic treatment center in our hospital(July 2013 to July 2014). Basing on the spherical equivalent(SE) diopter, patients were divided into three groups: low myopia group(SE≤-3.00D), moderate myopia group(-3.00D<SE≤-6.00D), and high myopia group(SE>-6.00D), respectively, for the three groups preoperative best corrected visual acuity and postoperative uncorrected visual acuity, refraction, contrast sensitivity, wavefront aberrations(total high order aberration, spherical aberration, coma, trefoil aberration RMS(RMS)), OQASTM II(the modulation transfer function cutoff frequency(MTF cutoff),the objective scatter index(OSI),the Strehl ratio(SR),the visual acuity(VA) at 100%, 20%, and 9% contrasts and other indicators were compared. Patients were evaluated at 1 week, 1 month and 3 months postoperatively. Using statistical software(version 13.0) to take comparative study.Results:1 VisionPreoperative best corrected visual acuity and 1 week, 1 month and 3 months postoperative uncorrected visual acuity were: 1.01±0.04, 1.05±0.16, 1.19±0.17,1.22±0.19 in low myopia, respectively; 1.01±0.03, 1.11±0.16, 1.13±0.17,1.17±0.17 in moderate myopia, respectively; 1.00±0.03, 1.02±0.17, 1.05±0.15,1.14±0.17 in high myopia, respectively; 3m postoperative uncorrected visual acuity compared with the preoperative best corrected visual acuity was improved in the three groups, and the difference was statistically significant(P<0.05).2 Postoperative refractionThe there groups hold stable refraction in 3 months. The postoperative refraction within±0.75 D were 90% of patients(72eyes), 94% of patients(190eyes), 85% of patients(104eyes), in low myopia, moderate myopia and high myopia, respectively; within ±0.50 D were 83% of patients(66eyes), 81% of patients(164eyes), 72% of patients(88eyes) in low myopia, moderate myopia and high myopia, respectively. There was no significant difference(P>0.05) among the three groups.3 Contrast sensitivityThe contrast sensitivity(contrast sensitivity, CS) and glare contrast sensitivity(glare contrast sensitivity, GS)of the three groups with different spatial frequency compared with preoperation were increased,the visual quality were improved. The low myopia group: In addition to the low frequency(1.5c/d,3c/d) increasing was not statistically significant, the other three spatial frequency of CS in 1m and GS in 1w increasing were statistically significant(P<0.05) after surgery.The moderate group:The difference of CS at 3c/d 6c/d and 12 c/d spatial frequency in 1w was statistically significant(P<0.05), CS at 1.5c/d and 18c/d spatial frequency in 1m was statistically significant(P<0.05), GS at all spatial frequency in 1w was statistically significant(P<0.05). The high group: The difference of CS at 6c/d and 12 c/d spatial frequency in 1m was statistically significant(P<0.05), GS at all spatial frequency in 1m was statistically significant(P<0.05).4 Wavefront aberrationThe RMSh and SA were increased in three groups after surgery, the difference was statistically significant(P<0.05). The Coma was higher than preoperation in three groups,the difference was not statistically significant(P>0.05). The trefoil was lower than preoperation in three groups, the difference was not statistically significant(P>0.05).5 Double-pass Optical Quality Analysis System(OQASTM II)When the three groups of patients in 1w the MTF cutoff,SR, VA100%, VA20% and VA9% values decreased slightly,then gradually rose to 3m when the level is higher than preoperative. The OSI values in 1w was increased after surgery, it can increased earlier and more accurately reflect the quality of the slight visual changes. MTF cutoff: When the three groups of patients in 1w the MTF cutoff values decreased slightly, then gradually rose to 3m when the level is higher than preoperative. MTF cutoff in 3m compared with the preoperative was improved in moderate myopia group, and the difference was statistically significant(P<0.05). The difference in 1m and 3m show statistically significant in high myopia group(P<0.05). SR: When the three groups of patients in 1w the MTF cutoff values decreased slightly, then gradually rose to 3m when the level is higher than preoperative, but the difference was not statistically significant.OSI: The OSI values of three groups in 1w were higher than preoperative and the difference show statistically significant(P<0.05). The difference in 1m and 3m were not statistically significant. VA100%,VA20% and VA9%: When the three groups of patients in 1w the MTF cutoff values decreased slightly, then gradually rose to 3m when the level is higher than preoperative. The difference of VA100% and VA20% in 1m and 3m show statistically significant in moderate and high myopia group(P<0.05).Conclusions:1 Wavefront-guided SBK operation has good visual acuity, refractive stability, high visual quality.2 Three visual quality methods in assessment of wavefront guided SBK visual quality show: Contrast sensitivity increases after operation, wavefront aberration values RMSh SA and Coma are higher than preoperation,Trefoil are lower than preoperation. The OQASTM II parameters displayed in 1w compared with the preoperative visual quality decreased, then gradually rose to 3m when the level is higher than preoperative.3 By comparing the visual quality of the three detection methods, the OQASTM II parameters may reflect abnormal early visual quality, high sensitivity, visual quality evaluation method is superior contrast sensitivity and wavefront aberration. |
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