ABSTRACT
Background Accurate measurement of corneal refractive parameters plays an important role in the diagnosis of eye diseases,design of refractive surgery and calculation of intraocular lens (IOL) power.Ophtha TOP is a new IOL calculator,so it is necessary to evaluate the repeatability and accuracy of Ophtha TOP in measuring corneal refractive parameters.Objective This study was to evaluate the repeatability of Ophtha TOP in measuring corneal refractive status in normal eyes and determine the agreement of the measuring outcomes between Ophtha TOP and Pentacam in pre-surgery cataract eyes.Methods A reliability evaluation method of diagnosis test was performed from September 2013 to October 2014.Sixty eyes of healthy volunteers aged (30.83 ±8.66) years old were examined in Tianjin Eye Hospital with Ophtha TOP for more than 5 times to evaluate the stability in measuring corneal refractive parameters.Corneal refractive parameters were measured by both Ophtha TOP and Pentacam for more than twice in 30 pre-surgery cataract eyes to assess the agreement with Pentacam.Keratometry and astigmatism parameters were recorded,including the flattest meridian (Kf),steepest meridian (Ks),mean keratometry (Km) and the astigmatism at J0 and J45.Intra-class correlation coefficients (ICC),repeatability (2.77Sw) and coefficient of variation (CoVs) were used to assess the stability of Ophtha TOP,and Bland-Altman graphs were adopted to value the consistency of measuring outcomes between Ophtha TOP and Pentacam.This study complied with Helsinki declaration,and written informed consent was obtained from each patient prior to any medical examination.Results The ICC of Ks,Kf,Km,J0 and J45 by Ophtha TOP were all ≥0.90,and 2.77Sw were all ≤0.36,The CoVs of Kf,Ks,Km by Ophtha TOP were all ≤0.30.The measuring values of Kf,Ks and Km were significantly higher in the Ophtha TOP than those in the Pentacam,with the mean differences (0.18±0.28) D,(0.24±0.29) D and (0.21± 0.26) D,respectively(t =3.48,4.50,4.49,all at P=0.00).The mean difference of the J0 was (0.07±0.21) D and that of the J45 was (-0.02±0.18)D between Ophtha TOP and Pentacam,showing insignificant differences between them (both at P＞0.05).Bland-Altman graphs revealed that the 95％ limit of agreement (LoA) of Kf,Ks and Km between the two methods was-0.37 D to 0.73 D,-0.33 D to 0.81 D and-0.30 D to 0.72 D,respectively,and that of J0 and J45 was-0.34 D to 0.48 D and-0.37 D to 0.33 D,respectively.Conclusions Ophtha TOP shows an excellent repeatability.Compared with Pentacam,Ophtha TOP presents a good consistence for measurement of the corneal astigmatism and moderate consistence for corneal curvature.
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Background Corneal refractive surgery has significant effects on corneal biomechanical properties.However,there are few study on large scale population with corneal biomechanical properties in the myopic population before corneal refractive surgery.Objective This study was to evaluate the change of corneal biomechanical properties and influence factors in myopic eyes using ocular response analyzer (ORA).Methods A prospective cohort study was carried out in Beijing Tongren Eye Center from April 2010 to January 2011.Corneal hysteresis (CH) and corneal resistance factor (CRF) were detected using ORA in 1 792 eyes of 896 myopic subjects who were going to receive corneal refractive surgery under the informed consent.According to different spherical equivalent (SE) the eyes were grouped into-0.25-＜-3.0 D group,-3.0-＜-6.0 D group,-6.0-＜-9.0 D group,-9.0-＜-12.0 D group,-12.0-＜-15.0 D group and ≥-15.0 D group and according to different central corneal thickness (CCT),the eyes were grouped into ＜500 μm group,500-＜550 μm group,550-＜600 μm group and≥600 μm group.The CH value and CRF value in different SE groups or different CCT groups were compared,and the factors influencing CH and CRF were analyzed by Pearson correlation analysis.Results The mean CH and CRF value were (9.84±1.52)mmHg (1 mmHg =0.133 kPa) and (10.46±1.71) mmHg,respectively in the myopic eyes.The CH values were (10.35±1.53),(10.07±1.55),(9.81±1.46),(9.71±1.59),(9.35±1.55) and (9.23±1.28) mmHg in the-0.25-＜-3.0 D group,-3.0-＜-6.0 D group,-6.0-＜-9.0 D group,-9.0-＜-12.0 D group,-12.0-＜-15.0 D group and ≥-15.0 D group,respectively,showing a significant difference among the groups (F=20.69,P＜0.01),and the CH values in the-6.0-＜-9.0 D group,-9.0-＜-12.0 D group,-12.0-＜-15.0 D group and ≥-15.0 D group were significantly lower than those in the-6.0-＜-9.0 D group,-9.0-＜-12.0 D group (all at P＜0.01).There was no significant difference in the CRF values among different SE groups (F =0.65,P =0.49).CH and CRF values were increasing with the raise of CCT,with evidently differences among the CCT＜500 μm group,500 μm ≤ CCT＜550 μm group,550 μm≤ CCT＜600 μm group and CCT≥ 600 μm group (CH:F=110.99,P＜0.01;CRF:F =84.35,P＜0.01),and the CH and CRF values were significantly higher in the 550 μm ≤ CCT＜600 μm group and CCT ≥600 μm group than those in the CCT＜500 μm group (all at P＜0.01).CH showed a positive correlation with SE (r =0.24,P＜0.01),and no significant correlation between CRF and SE (r =0.03,P =0.20).The CH and CRF showed the positive correlations with the CCT (r=0.42,0.57,both at P＜0.01).In addition,CH and CRF values increased as the increases of SE,corneal curvature (CC) and CCT values,with the regression equation of CH =-7.87+0.08SE+0.16CC+0.02CCT (R2=0.26,P＜0.01) and CRF=-11.42+0.14CC+0.03CCT (R2=0.34,P＜0.01),respectively.The CH and CRF did not change with the age and gender in the subjects.Conclusions Corneal biomechanical properties including CH and CRF were positively correlated with CCT,CC and SE.
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Background The ultrasonography for silicone tamponade eye is a problem in diagnosis and treatment of eye diseases,especially for the calculation of intraocular lens (IOL) power.IOL Master is usually used to the biometric measurement of the silicone tamponade eye in well-equipped hospital,but it is still disabled in serious cataractous eyes.Corrective B or A-type ultrasound methods have been used for a fewer years,but these measured results are incomparable probably due to the difference of viscosity of silicone oils.Objective This study attempted to investigate the accuracy of B-type ultrasonography for ocular axial length (AL) measurement in silicone tamponade eyes.Methods The transmitting speed of ultrasonic wave in the silicone oil was determined by comparing the outcomes between balance solution mesuring and 5 500 mPas silicone oil,and a calculating formula for corrective ocular AL in 5 500 mPas silicone filled eyes was further established.Thirty-two eyes of 30 patients who received 5 500 mPas silicone oil tamponade due to complex retinal detachment were enrolled in Qingdao Hiser Medical Group from May 2012 to March 2014.The eyes were assigned to the AL＜26 mm group (18 eyes of 16 patients) and AL≥26 mm group (14 eyes of 14 patients).B-scan ultrasound and IOL Master were used to measure the AL before the removal of the silicone oil,and the Als were measured again using A-scan ultrasound and B-scan ultrasound 3 months after the removal of the silicone oil.The outcomes were compared and the correlations were evaluated among different measuring methods.The vitrous length values before and after removal of the oils,and the diopters before and after intraocular pressure (IOP) implantation were compared to varify the results of B-type sonography for 5 500 mPas silicone-tamponade eyes.Results The transmitting speed of sound wave in 5 500 mPas silicone oil was 1 023 m/second with the conversion factor 0.668 between silicon oil eyes and vitreous cavity,and the corrected formula for AL measurement was:the length form cornea apex to the posterior pole of lens or the center of the capsular membrane+ 0.668×the length form posterior pole of lens or the center of the capsular membrane to the macular area.No significnant differences were found in the AL values among the corrective-B scan,IOL Master method,postoperative Bscan method and A-scan method both in the AL＜26 mm group and the AL≥26 mm group (AL＜26 mm:F=0.108,P =0.955;AL ≥ 26 mm:F =0.011,P =0.998),and the AL values by corrective B-scan was significantly correlated with that by IOL Master,postoperative B-scan and A-scan,respectively (AL＜26 mm group:r =0.876,0.921,0.809,all at P＜0.01;AL ≥ 26 mm group:r =0.943,0.956,0.955,all at P＜0.01).The vitreous cavity depth was (20.78 ±2.13)mm by corrective B-scan in 1 day before the removal of silicone,and that in 3 months after removal of silicone was (20.89±2.16) mm,without statistical diference between them (t =0.795,P =0.219).The actual postoperative refraction in 16 eyes with IOL was (-1.25 ± 1.69) D,and preoperative refrection was (-1.50 ±0.00) D,the difference was not statistically significant (t =0.585,P =0.284).Conclusions The biometry of B-scan ultrasonography for silicone-tamponade eye is accurate and simple,with a good feasibility in clinical measurement.
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Background Pentacam anterior segment analysis system (Pentacam) is more accurate in the quantitative evaluation of ocular anterior segment in primary angle-closure glaucoma (PACG) eyes than slit lamp microscope and ultrasound biomicroscope (UBM).However,its accuracy in the earlier stage of PACG before and after YAG laser peripheral iridotomy (LPI) is not fully elucidated.Objective This study was to assess the effect of YAG LPI in PACG patients with Pentacam.Methods A prospective self-controlled study was performed.Thirtyfive fellow eyes (pre-clinical stage of PACG) of acute PACG and 35 fellow eyes of chronic PACG were included in the Second Hospital of Hebei Medical University from July,2012 to December,2013.YAG LPI was performed on the eyes,and the parameters of ocular anterior segment including central anterior chamber depth (ACD),anterior chamber volume (ACV) and peripheral anterior chamber angle (ACA) were measured and compared by Pentacam before and 1 day,7 days,28 days after operation.This study was approved by the Ethic Committee of the Second Hospital of Hebei Medical University and informed consent was obtained from all subjects.Results In pre-clinical stage of PACG eyes,the postoperative ACD and ACV values were increased in comparison with preoperation,showing significant differences among various time points (ACD:F =6.783,P =0.004;ACV:F =19.090,P =0.000),and no significant difference was found in ACA among different time points (F =0.153,P =0.928).In the fellow eyes of chronic PACG,the postoperative ACD and ACV values were larger than those of preoperation,with significant differences among various time points (ACD:F =21.576,P =0.000;ACV:F =47.506,P =0.000),and no significant difference was found in ACA among different time points (F=0.581,P=0.629).The change values of ACD and ACV were (0.064±0.022) mm and (27.840±4.963) mm3 in the eyes of pre-clinical stage of PACG,and those in the fellow eyes of chronic PACG were (0.047-± 0.020) mm and (21.000 ± 3.278) mm3,showing significant differences between the two groups (ACD:t=2.783,P=0.008;ACV:t=5.749,P=0.000).Conclusions Pentacam allows easy,fast,automatic and non-contact quantification and three-dimension image of the anterior chamber parameters before and after YAG LPI in pre-clinical stage of PACG eyes and fellow eyes of chronic PACG.The ACD deepens and ACV increases after LPI in glaucomous eyes,especially in the pre-clinical stage of PACG eyes.
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Background Tear hyperosmosis is considered to be one of the core mechanisms of dry eye.The measurement of tear osmolarity is important in the clinical diagnosis of dry eye.However,relevant study is lack in Chinese population.Objective The aim was to investigate the relation of tear osmolarity and pathogenesis of dry eye and evaluate the diagnosis value of tear hyperosmosis in dry eye.Methods Sixty-one consecutive dry eye patients were enrolled in Affiliated Eye Hospital of Wenzhou Medical University from May to August in 2011,including 30 mild and moderate dry eyes and 31 severe dry eyes,and 30 normal volunteers with matched age and gender were collected simultaneously under the informed consent.The visual acuity,Ocular Surface Disease Index (OSDI) questionnaire,osmotic pressure of tear,tear film breakup time (TFBUT),corneal fluorescein staining,conjunctival lissamine green staining,Shirmer Ⅰ test (S Ⅰ t) without anesthesia and meibomian function were examined in turn in the subjects,and lateral eyes with higher tear osmotic pressure were analyzed.The differences in above indexes among the different groups were statistically compared,and the correlations between the osmotic pressure of tear and clinical parameters were assessed.Results The osmotic pressure of tear was (326.46 ±22.66) mOsm/L in the dry eye group,which was significantly higher than (296.60± 10.81) mOsm/L in the normal control group (P＜0.05),and the OSDI scores,TFBUT,corneal fluorescine scores,conjunctival staining scores and S Ⅰ t values in the dry eye group were remarkably elevated in comparison with the normal control group (all at P＜0.05).The osmotic pressure of tear was (341.90 ± 21.15) mOsm/L in the severe dry eye group,which was significantly higher than (310.50±8.99) mOsm/L in the mild and moderate group (P＜0.017).The area under the curve for tear osmolarity in the dry eye group was 0.916,and cutoff value of sensitivity and specificity in dry eye diagnosis was 308 mOsm/L,with the sensitivity value 0.79 and specificity 1.00.The significant correlations were found between the osmotic pressure of tear and OSDI scores,corneal fluorescine scores,conjunctival staining scores and S Ⅰ t outcomes (r=0.338,0.407,0.246,-0.461,all at P＜0.05).However,the osmotic pressure of tear was not correlated with TFBUT (r=-0.113,P＞0.05).Conclusions Tears osmotic pressure might be a useful indicator for the diagnosis of dry eye and assessment of severity.A combined application of tear osmolarity measurement with other relevant indexes can improve the diagnostic value.