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AIM:To evaluate corrective effect and stability of corneal morphology in patients with moderate to high myopia after 2a treatment of femtosecond laser assisted laser in situ keratomileusis(FS-LASIK)Xtra.METHODS:Retrospective case-control study. A total of 30 cases(58 eyes)Patients with moderate to high myopia combined with astigmatism who planned to undergo refractive surgery in our hospital from August 2019 to August 2020 were included, and different types of surgery were performed respectively based on the relevant index of keratoconus screening in the preoperative corneal topography. They were divided into FS-LASIK group and Xtra group, with 15 cases(29 eyes)in each group. Uncorrected visual acuity(UCVA), best corrected visual acuity(BCVA), spherical equivalent(SE)and the corneal curvature of the anterior and posterior surfaces of different diameters(3, 5 and 7 mm)measured by Sirius three-dimensional corneal topography were observed preoperatively and 3 mo, 1 and 2 a postoperatively.RESULTS: The UCVA of the two groups of patients at different time points after surgery was significantly increased compared with preoperatively(both P<0.01), and there was no difference in UCVA and SE between the two groups(P>0.05). After 2 a postoperatively, residual astigmatism was -0.25-0 D in 25 eyes(86%)of the FS-LASIK Xtra group and 24 eyes(83%)of the FS-LASIK group. The actual corrected SE and expected corrected SE of both groups were positively correlated(both P<0.05). There were differences in corneal curvature on the surface of different diameter areas(3, 5, and 7 mm)between the two groups at 3 mo, 1, and 2 a postoperatively compared with preoperatively. After 1 and 2 a postoperatively, the corneal posterior surface curvature of the FS-LASIK Xtra group with corneal diameter of 3 and 5 mm was higher than that of the FS-LASIK group(P<0.05).CONCLUSIONS:FS-LASIK Xtra has good safety, efficacy and predictability in correcting patients with moderate to high myopia.
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ObjectiveTo assess the repeatability （intra-operator variability） and reproducibility （inter-operator variability） of a new partial coherence interferometry （PCI）-based ocular biometer， Myopia Master， and its agreement with IOL Master 500 for measuring axial length （AL） and corneal curvature （K） in children aged 8-12 years. MethodsThe same operator measured school children with the Myopia Master and the IOL Master 500 in random order to assess agreement. Additionally， some of these children received measurements from another operator using the Myopia Master to assess repeatability and reproducibility. AL， flat keratometry （Kf）， steep keratometry （Ks）， mean keratometry （Km）， J0 and J45 were analyzed. The repeatability and reproducibility were assessed by the within-subject standard deviation （Sw）， test-retest repeatability （TRT）， coefficient of variation （CoV） and intra-class correlation coefficient （ICC）. The agreement between the Myopia Master and the IOL Master 500 was assessed by Bland-Altman plots and 95% limits of agreement （LoA）. ResultsBoth repeatability and reproducibility of the Myopia Master were high for AL measurements （Sw=0.02 mm， ICC=0.999； Sw=0.04 mm， ICC=0.998）， but moderate for K measurements （Sw range， 0.04 to 0.12 D， ICC range， 0.861 to 0.991； Sw range， 0.06 to 0.20 D， ICC range， 0.835 to 0.992）. There were significant mean differences between the Myopia Master and the IOL Master 500 in measurements of AL （-0.01±0.04） mm， Kf （-0.09 ± 0.15） D， Ks （-0.47±0.40） D， and Km （-0.28±0.23） D， J0 （0.18±0.20） D and J45 （-0.01±0.12） D. ConclusionsThe Myopia Master provided high repeatability and reproducibility for AL measurements in schoolchildren with myopia， but the Myopia Master and the IOL Master 500 cannot be used interchangeably in measuring AL and K.
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AIM: To compare and observe the accuracy of five intraocular lens(IOL)power calculation formulas in patients with cataracts who have previously undergone corneal refractive surgery.METHODS: Prospective case series study. A total of 23 cataract patients(34 eyes)with a history of myopic corneal refractive surgery at Jinan Mingshui Eye Hospital from September 2021 to March 2023 were collected, including 1 eye treated with photorefractive keratectomy(PRK)and 22 patients(33 eyes)treated with laser-assisted in situ keratomileusis(LASIK). Preoperative ocular biometry was performed using the IOL Master 700, while corneal true net refractive power(TNP)was measured via Pentacam analyzer. Anterior segment optical coherence tomography(OCT)was used to assesse net corneal power(NCP), posterior corneal refractive power, and central corneal thickness(CCT). The Shammas, Haigis-L, Potvin-Hill Pentacam, OCT, and Barrett True K formulas were utilized for IOL power calculations, with the optimal power selected accordingly. At 1 mo postoperatively, actual refractive outcomes were determined through subjective refraction, based on objective optometry results. The refractive prediction error(RPE)and refractive absolute error(RAE)of each formula were calculated and compared, and the percentage of eyes with RAE ≤0.5 D and ≤1.0 D was counted.RESULTS: No significant statistical difference was found in the RPE of the five formulas when compared to zero(all P>0.05), nor were there significant differences in RPE and RAE among the formulas(F=0.554, P=0.696; H=4.402, P=0.354). The RAE was within ≤0.5 D for 26 eyes(76%)using the Potvin-Hill Pentacam formula and for 24 eyes(71%)using the Barrett True K formula, with both formulas achieving an RAE within ≤1.0D in 33 eyes(97%).CONCLUSIONS: The Barrett True K and Potvin-Hill Pentacam formulas demonstrated high predictive accuracy for IOL power calculations in post-corneal refractive surgery cataract patients. Given the variability in corneal refractive power among these patients, further research on IOL power calculation is warranted. Clinically, it is advisable to consider a range of formulas for optimal outcomes.
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Objective@#To explore the pattern of change of axial length/curvatrue radius ratio (AL/CR) and associated factors in primary and secondary school students in Yunnan, so as to provide scientific basis and prospective guidance for early myopia intervention and control.@*Methods@#A total of 685 students from grades 2 to 3 and grade 7 in 2 cities/counties in Yunnan Province were selected by multi stage stratified random cluster sampling method in 2020. All the participants were followed up twice with questionnaire of myopia related factors, uncorrected distance visual acuity, and refractive parameter measurement from October,2021 and March,2023,respectivelty. The distribution and change of AL/CR in different classes and groups were analyzed, and the influencing factos of AL/CR cumulative progression were explored using generalized linear model.@*Results@#AL/CR ratio in primary school students was (2.95±0.09) at baseline, increased to (2.99±0.11) at the first follow up and (3.04±0.12) at the second follow up. AL/CR ratio in middle school students(3.08±0.13) at baseline, increased to (3.12±0.15) at the first follow up and (3.15±0.14) at the second follow up. The generalized linear model showed that after controlling for environmental factors, ethnicity ( β =-0.017) , cumulative progression of the SE ( β =-0.027) influenced the changes of AL/CR ratio among the primary school students, whereas the changes of AL/CR ratio were associated with baseline AL ( β =-0.005), baseline corneal curvatrue radius ( β =0.032) and cumulative progression of SE( β =-0.035) among middle school students ( P <0.05).@*Conclusions@#The AL/CR ratio of primary and secondary school students in Yunnan can be used to judge different refractive status types, but its variation is not only related to SE progression, but also affected by different ethnic groups and baseline ocular biological parameters. so the value of AL/CR application in assessing the progression of myopia needs to be further confirmed.
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AIM: To investigate the effect of different preoperative corneal curvature on the size of optical deformation area after femtosecond laser small incision lens extraction(SMILE).METHODS:A prospective study was conducted on 108 consecutive patients who underwent SMILE surgery in our hospital from February 2021 to January 2022. Considering the association between both eyes, only the left eye of each patient was studied. According to the average anterior corneal surface curvature in preoperative, the patients were divided into three groups: Km<42.0D group(n=30), Km>47.0D group(n=26)and conventional corneal curvature group(n=52)with 42.0D≤Km≤47.0D. All patients underwent standardized SMILE surgery, and the laser ablation diameter was 6.5mm. The diameters of optical deformation areas in the three groups were compared at 6mo after operation.RESULTS:There was no significant difference in preoperative data among the three groups except for the mean curvature of the anterior corneal surface(all P>0.05), and there was no significant difference in uncorrected distance visual acuity(UDVA)and subjective refraction at 6mo after operation(all P>0.05). The diameters of the optical deformation zone in the Km<42.0D group, Km>47.0D group and the conventional corneal curvature group were 6.54±0.14, 6.32±0.13, 6.45±0.15mm respectively(F=19.238, P<0.05). The optical area diameter of the group with flat corneal curvature was larger than that of the group with conventional corneal curvature and the group with steeper corneal curvature(P<0.05). The diameter of optical zone in the conventional curvature group was larger than that in the Km>47.0D group(P<0.05).CONCLUSION: When the preset laser cutting diameter is the same, the steeper the corneal curvature before operation, the smaller the diameter of the optical deformation area after operation.
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AIM: To explore Bland-Altman analysis of corneal curvature and astigmatism measured by new swept-source optical coherence tomography(SS-OCT)and Scheimpflug anterior segment analyzer in patients with age-related cataract.METHODS: A total of 177 patients(282 eyes)with age-related cataract admitted to the hospital between January and December 2021 were enrolled. The steep-axis curvature(Ks), flat-axis curvature(Kf), mean corneal curvature(Km), corneal astigmatism and astigmatism axis of anterior corneal surface, posterior surface and the whole cornea were measured by SS-OCT and Scheimpflug anterior segment analyzer respectively. All parameters were detected by paired sample t-test, intra-group repeatability test, Pearson correlation and Bland-Altman consistency analysis.RESULTS: There was no significant difference in Ks, Kf and Km of anterior corneal surface measured by SS-OCT and Scheimpflug anterior segment analyzer(P&#x003E;0.05). Ks, Kf and Km of posterior corneal surface and whole cornea measured by Scheimpflug anterior segment analyzer were all greater than those measured by SS-OCT(P&#x003C;0.05). There was no significant difference in astigmatism and axial values of anterior corneal surface, posterior surface and whole cornea measured by SS-OCT and Scheimpflug anterior segment analyzer(P&#x003E;0.05). The intraclass correlation coefficient(ICC)of all parameters was greater than 0.88, indicating a good intra-group repeatability. Ks, Kf, Km, astigmatism and axis of anterior corneal surface, posterior surface and whole cornea measured by SS-OCT were positively correlated with those measured by Scheimpflug anterior segment analyzer(P&#x003C;0.05). Bland-Altman consistency analysis showed that Ks, Kf, Km, corneal astigmatism and axis of anterior corneal surface, posterior surface and whole cornea measured by SS-OCT were highly consistent with those measured by Scheimpflug anterior segment analyzer(P&#x003C;0.05).CONCLUSION: The corneal curvature and astigmatism parameters measured by new SS-OCT are highly consistent with those measured by Scheimpflug anterior segment analyzer, which can be applied in the diagnosis of corneal curvature and astigmatism in patients with age-related cataract.
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AIM: To evaluate the effect of preoperative degrees of myopic astigmatism and anterior corneal curvature on the functional optical zone(FOZ)after transepithelial photorefractive keratectomy(TransPRK).METHODS: Retrospective study was conducted on 78 patients(130 eyes)with myopia and myopic astigmatism who underwent TransPRK, and they were divided into control group(cylinder 0D), moderate astigmatism group(-0.50～-2.00D)and high astigmatism group(>-2.00～<-6.00D). The FOZ was measured and compared among the three groups 6mo after operation. The correlations between attempted correction, anterior corneal curvature, corneal aberrations, Q value, and the FOZ were analyzed.RESULTS: At 6mo after operation, the mean FOZ was 5.16±0.12mm in the control group, 5.29±0.23mm in the moderate astigmatism group, and 5.49±0.23mm in the high astigmatism group(P<0.001), and the FOZ of the high astigmatism group was significantly higher than moderate astigmatism and control group(P<0.05, P<0.001); Pearson correlation analysis showed that the changes in spherical equivalent, total corneal higher-order aberrations(HOAs), coma, and spherical aberration were all negatively correlated with FOZ(all P<0.05); and FOZ positively correlated with changes in the steep curvature(K2), mean curvature(Km), corneal astigmatism, and Q value(all P<0.01). Multiple linear regression analysis showed that there was still positive correlation between preoperative K2 and FOZ after adjusting for other risk factors(P<0.001).CONCLUSION: Patients with high astigmatism can obtain a larger FOZ and less induced coma after TransPRK. A larger FOZ can be achieved in eyes with steeper keratometry.
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Epithelial basement membrane dystrophy(EBMD)is a common anterior corneal dystrophy with hidden and easily missed clinical manifestations. Patients usually complain of mild blurred vision or foreign body sensation, or occasional pain at night or immediately after opening the eyelid in the morning. Slit-lamp examination revealed irregular, amorphous corneal surfaces, fingerprint-like linear lesions, and punctate or bubble-like lesions. EBMD has a significant impact on preoperative biometrics and intraocular lens power calculation, which can lead to inaccurate measurement and postoperative refractive accident, and cataract surgeons must be aware of this. This article reviews recent research and conference reports on the impact of EBMD on cataract surgery, as a reference for refractive cataract surgeons, thus improving the preoperative diagnosis and detection rate, so as to provide the optimal treatment plan for patients.
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Objective:To investigate an accurate and quantitative method to measure the eyeball morphological parameters of guinea pigs through a method that combines programmed digital techniques and mathematical geometric principles.Methods:Twenty-two three-week-old clean-grade male tricolor guinea pigs were selected and sacrificed by anesthesia overdose.Eyeballs were enucleated.The horizontal and sagittal images of the eyeball were taken with the high-speed photographic model of 13 million pixels macro meter, and the pictures were imported into pycharm programming software.Using the pre-written analysis program of Python 3.9, the conversion coefficient between the photo pixel and the actual length was obtained by a scale, and then the corneal surface was fitted by arc fitting and conic curve fitting.The results of arc fitting were converted to calculate the corneal radius of curvature.The corneal eccentricity was calculated according to the general conic equation (Ax 2+ Bxy+ Cy 2+ Dx+ Ey+ F=0). The corneal asphericity was evaluated by curve fitting between the central 3-mm and the whole cornea.The use and care of the animals complied with Regulations for the Administration of Affairs Concerning Experimental Animals by State Science and Technology Commission.The study protocol was approved by the Ethics Committee of Shanghai Public Health Clinical Center (No.2022-A009-01). Results:The digital method of Python programming can show the corneal contour of guinea pigs completely and clearly.In the transverse plane, there was no significant difference in the corneal curvature measurements among the digital fitting in central 3-mm cornea, digital fitting in whole cornea and curvature meter ( F=1.693, P=0.190). In the sagittal plane, there was a significant difference in the corneal curvature measurements among the three methods ( F=3.500, P=0.030), and the corneal curvature measurements of the whole cornea measured by the curvature meter were significantly greater than those measured by the digital fitting ( P<0.05). There was no statistical significance in the measurements of corneal curvature radius among the three methods in the transverse plane and the sagittal plane ( F=1.817, P=0.170; F=2.050, P=0.133). The horizontal and sagittal corneal eccentricity measured by digital fitting in central 3-mm cornea were 0.55±0.15 and 0.53±0.17, which were lower than 0.66±0.10 and 0.64±0.14 measured by digital fitting in whole cornea, and the differences were statistically significant ( t=-4.860, -5.210; both at P<0.01). Conclusions:It is feasible to use Python programming digital method to measure the corneal curvature and eccentricity of guinea pigs.
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Purpose: To investigate the impact of different?thickness scleral lenses (SLs) on corneal thickness, curvature, and fluid reservoir thickness in keratoconic eyes. Methods: Schiempflug imaging and AS?OCT was captured before and immediately following 6 h of SL wear. Different?thickness lenses were used while keeping the other parameters the same. The timing of the measurement for day 1 and day 2 was matched to allow for the control of the confounding influence of diurnal variation. Results: Immediately after 6 h of lens wear, no statistically significant difference (P > 0.05) was noted in corneal edema in any region and quadrants between thin? and thick?lens wearers. The calculated percentage of corneal edema was also within the range of overnight closed eye physiological swelling. Pentacam measured higher central corneal thickness compared to AS?OCT in both baselines and after 6 h of lens wear. The current investigation reported minimal but not statistically significant (P > 0.05) flattening in anterior and steepening in posterior curvature parameters in both thin and thick SLs. The mean reduction in the fluid reservoir thickness was 80.00 ± 3.99 and 79.36 ± 3.84 microns after 6 h of thin? and thick?lens wear, respectively, which was not statistically significant (P > 0.05). A statistically significant positive correlation (r = 0.67, P = 0.02) was found between lens thickness and change in anterior steep k with thick?lens wear. Conclusion: Central lens thickness of 200–400 ?m did not cause any significant change in corneal curvature and fluid reservoir thickness and did not induce clinically significant corneal edema after short?term SL wear.
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Purpose: To primarily compare surgically induced astigmatism (SIA), total and posterior corneal curvature, pachymetry, and their stabilization after 2.2 and 2.8 mm clear corneal incision in phacoemulsification. Methods: A randomized, prospective interventional study of 130 patients (130 eyes) of either sex having senile cataract (>40 years) divided randomly into two groups. The patients underwent uncomplicated phacoemulsification surgery with foldable intraocular lens implantation using 2.2 mm (group 1) and 2.8 mm incisions (group 2). The patients were evaluated preoperatively and followed?up at first, third, and sixth weeks. Results: Mean SIA was less in group 1 at all the follow?up visits which was not statistically significant (P value – 0.507 (at week 1), 0.626 (at week 3), and 0.312 (at week 6). Mean SIA decreased from week 1 to week 6 in both the groups. Both the groups showed an increase in SIA with the increase in the hardness of cataract. Posterior keratometry (k1 and k2) showed statistically significant steepening in the first postoperative week, followed by gradual flattening which continued till the sixth week postoperatively. Posterior astigmatism increased in both the groups at week 1 (not statistically significant). Thereafter, it decreases and does not change significantly after 3 weeks. Pachymetry increased significantly (P value < 0.001 in both the groups) in the first week in both the groups and thereafter stabilizing at 3 weeks. Conclusion: Reducing the incision size does not result in any significant reduction in SIA. We observed that the posterior corneal curvature majorly stabilized by 3 weeks, but some stabilization continued till 6 weeks.
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AIM: To investigate the influencing factors of disequilibrium refractive development in children aged 6-12 years old.METHODS: A total of 607 children with a mean age of 8.2±1.8 years old from two primary schools in Binhai New Area of Tianjin in December 2019 were selected by cluster sampling for optical biometry measurement(axial length and equivalent corneal power), cycloplegia refractive examination and questionnaire survey.RESULTS: The childrens'spherical equivalent was -0.11±1.63D, binocular spherical equivalent difference was -0.08±0.64D and absolute value of spherical equivalent difference was 0.41±0.49D. There were 56 children with anisometropia and 551 children without anisometropia. There was no difference in the absolute value of binocular corneal power difference between anisometropia and non-anisometropia group(0.30±0.34D vs 0.27±0.24D, P=0.430). But the absolute value of axial difference was significantly different(0.67±0.39mm vs 0.13±0.13mm, P=0.005). Multivariate linear regression analysis showed that weekly usage time of phones/computers, weekly close work hours, weekly visual fatigue times and habitual reading distance were the influencing factors of refractive imbalance development(the absolute value of binocular spherical equivalent difference). Habitual reading distance and handedness in writing are the influencing factors of the developmental bias of refractive imbalance(binocular spherical equivalent difference).CONCLUSION: Children aged 6-12 years old who spend more time on phones/computers, and have prolonged close work, more times of visual fatigue and close habitual reading distance may increase the degree of refractive imbalance. Children with right-handed handwriting and severe left or right head deviation have a deeper degree of myopia in the right eye than in the left eye.
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Objective:To observe the changes of corneal curvature and ocular surface after congenital ptosis.Methods:A total of 188 patients with congenital blepharoptosis were treated with frontal muscle flap suspension, levator eyelid muscle shortening and fixation, and levator aponeurosis according to different conditions. The postoperative correction effect, corneal curvature, and ocular surface changes were observed.Results:There was no significant difference in the good correction rate among the three methods ( P>0.05). The corneal curvature at 3 months after operation was lower than that before operation and 7 days after operation ( P<0.05). The fluorescein staining score at 7 days after operation was higher than that before operation and 3 months after operation ( F=2 910.05, P<0.05). The tear film rupture time at 7 days after operation was significantly shorter than that before operation and 3 months after operation ( F=758.12, P<0.05). There was no significant difference in tear secretion test before operation, 7 days after operation and 3 months after operation ( P>0.05). The conjunctival congestion score at 3 months after operation was lower than that at 7 days after operation, and the incidence of meibomian gland dysfunction and abnormal eyelash angle at 3 months after operation was lower than that at 7 days after operation ( t=113.56, χ 2=11.02, 11.46, P<0.05). 3 months after operation, the average diopters of 3 mm and 5 mm were higher than those before operation ( t=12.35, 15.19, P<0.05). Conclusions:Frontal muscle suspension, levator eyelid muscle shortening and fixation, and levator aponeurosis are effective in treating congenital blepharoptosis, and can effectively improve the ocular surface and corneal curvature. Clinically, the appropriate one can be selected according to the condition of the child correction method.
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Occult myopia refers to a special type of myopia, which is caused by the axial length beyond the normal range of children's normal age, and the corneal curvature is lower than the normal range of children with the normal age range of the vision. Because the vision of occult myopia children is within the normal range, it is easy to be ignored in myopia screening. Without timely myopia prevention and control, occult myopia is very easy to develop into dominant myopia, not only the visual development is seriously affected, but visual function will also produce irreversible changes. It is found that the axial length, corneal curvature, retina and chorioid of occult myopia are different from those of ordinary myopia. The change of these indicators can be used to assist the diagnosis and observe their development process. The purpose of this paper is to summarize the research progress at home and abroad on ocular axis length, corneal curvature, macular retinal thickness, macular choroidal thickness and other related factors in children with occult myopia, in order to provide references for related clinical research.
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@#AIM: To explore the postoperative axial length(AL)and corneal curvature(K)shift in high myopia silicone oil patients complicated cataract after silicone oil removal combined with cataract surgery as well as the relationship.<p>METHODS: From August 2020 to November 2020 in the Affiliated Eye Hospital of Nanchang University, 45 patients(48 eyes)with silicone oil eye complicated cataract were divided into 2 groups: 20 eyes of 20 patients(refraction ≥-6.00D and AL ≥26mm)in high myopia group and 28 eyes of 25 patients(refraction < -6.00D or AL <26mm)in non-high myopia group. Record the general information and IOL-Master measurement data AL and K, statistical analysis was performed. <p>RESULTS: There was no difference in preoperative and postoperative K value of two groups(all <i>P</i>>0.05). The AL of the patients in the high myopia group was 28.35±1.68mm after silicone oil removal combined with cataract surgery, which was shorter than 28.08±1.53mm before the operation(<i>P</i><0.001), yet not statistically significant in non-high myopia group(<i>P</i>>0.05). The median ΔAL of patients in the high myopia group was \〖-0.28(-0.44, -0.08)\〗 compared with the non-high myopia group \〖-0.06(-0.20, 0.15)\〗, which was statistically different(<i>P</i><0.05), but no significant difference in both ΔK(<i>P</i>>0.05). There was no correlation between |ΔAL| and |ΔK|, or and preoperative K values(<i>P</i>>0.05)in two groups. Preoperative AL was moderately positive correlated with |ΔAL| in the high myopia group(<i>r</i>=0.702, <i>P</i>=0.01), but not in the non-high myopia group(<i>P</i>>0.05).<p>CONCLUSION: There was no significant shift in K value of high myopia group with silicone oil eye complicated cataract after the silicone oil removal combined with cataract surgery. The longer preoperative AL in high myopia group, the more likely become shorter after surgery, meanwhile the longer AL, the greater AL shift.
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@#AIM: To compare the differences and agreement in axial length(AL), anterior chamber depth(ACD)flat axial corneal curvature(K1)and steep axial corneal curvature(K2)measured by SW-9000 and IOL Master 500.<p>METHODS: Totally 258 eyes of 129 patients with ametropia were measured with SW-9000 and IOL Master 500. Among them, 159 eyes were low to moderate myopia(-0.75D≤ spherical equivalent <-6D)and 99 eyes were high myopia(spherical equivalent ≥-6D). Comparison between two devices were performed for AL, ACD, K1, and K2. The difference between two instruments were evaluated with a paired samples <i>t</i>-test. The correlation between the measurements was evaluated using Pearson correlation coefficients. The agreement between the devices was evaluated with Bland-Altman plots. <p>RESULTS: There was significant difference between SW-9000 and IOL Master 500 in measuring AL and ACD(all <i>P</i><0.01), but there was no significant difference between K1 and K2 in patients with low to moderate myopia. There was no significant difference in AL, ACD and K1 between SW-9000 and IOL Master 500(all <i>P</i>>0.05), but there was significant difference in K2(<i>P</i><0.05)in patients with high myopia. Pearson correlation analysis showed that AL, ACD, K1 and K2 of patients with low to moderate and high myopia were highly correlated(all <i>P</i><0.01). Bland-Altman consistency analysis showed that the two methods had good consistency in measuring AL in patients with low to moderate and high myopia, but poor consistency in measuring ACD, K1 and K2.<p>CONCLUSION: SW-9000 and IOL Master 500 have good consistency in measuring the AL of people with ametropia. The measurement of ACD and corneal curvature has poor consistency, and should be carefully selected in combination with clinical practice.
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@#AIM: To investigate the correlation of myopia severity(SE)with axial length(AL), intraocular pressure(IOP), central corneal thickness(CCT), anterior chamber depth(ACD), and mean keratometry(Km)in young myopia patients.<p>METHODS: In the retrospective study, we selected myopic patients who were diagnosed in Lanzhou Huaxia Eye Hospital from Mar. 2017 to Jul. 2019. They were divided into four myopia groups, A(mild), B(moderate), C(high), and D(hyper)based on the SE. We then measured and analyzed the correlation of the degree of myopia with AL, IOP, CCT, ACD, and Km. Differences between groups were analyzed by one-way analysis of variance. Relationships between the relevant factors were analyzed by Pearson correlation analysis.<p>RESULTS: The SE were(-2.38±0.49)D,(-4.60±0.82)D,(-7.40±1.08)D and(-11.58±1.23)D in the mild, moderate, high and hyper myopia groups respectively. The AL were(24.55±0.72)mm,(25.68±0.77)mm,(26.75±0.64)mm and(28.00±0.56)mm in the respective myopia groups. The IOP were(14.68±3.18)mmHg,(14.78±2.81)mmHg,(15.19±2.66)mmHg,(15.70±2.68)mmHg in the respective myopia groups. The ACD were(3.41±0.24)mm,(3.34±0.25)mm,(3.32±0.25)mm and(3.24±0.27)mm in the respective myopia groups. The Km were(42.96±1.22)D,(43.02±1.43)D,(43.29±1.47)D and(43.56±1.47)D in the respective myopia groups. There were no significant differences for CCT among the different groups. SE was significantly positive correlated to AL(<i>r</i>=0.851, <i>P</i><0.001), IOP(<i>r</i>=0.104, <i>P</i><0.001), CCT(<i>r</i>=0.066, <i>P</i><0.001)and Km(<i>r</i>=0.157, <i>P</i><0.001); SE was negative correlated to ACD(<i>r</i>=-0.129, <i>P</i><0.001).<p>CONCLUSION: In our study, there is a positive correlation between the progression of myopia and the increase in AL, IOP, CCT, and Km. There is a negative correlation between myopia and ACD.
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@#AIM: To compare the differences of corneal curvature and astigmatism measured by Pentacam, IOL Master and iTrace of cataract patients.<p>METHODS:In this prospective clinical trial,68 cataract patients(82 eyes)received treatment at the ophthalmology department of our hospital. In the treatment process, used the IOL Master, Pentacam and iTrace to measure the patient's corneal curvature(K1, K2, Km)and astigmatism(J0, J45). The difference, correlation and consistence among three instruments were analysed. <p>RESULTS: Differences analysis showed that in the measurement of K1, K2, Km, there was no difference among Pentacam, IOL Master and iTrace(<i>P</i>>0.05). Pearson correlation analysis showed that K1, K2, Km were highly correlated among three instruments(|<i>r</i>|>0.5, <i>P</i><0.01). J0, J45 were moderately correlated between IOL Master and Pentacam, so as IOL Master and iTrace(0.3<|<i>r</i>|<0.5, <i>P</i><0.01). J0, J45 were weakly correlated between Pentacam and iTrace(0.1<|<i>r</i>|<0.3, <i>P</i><0.05). The Bland-Altman showed that the corneal curvature and astigmatism vectors examined by these three devices had non-comparable results.<p>CONCLUSION: K1, K2, Km, J0, J45 were correlated among the three devices, but the three devices all cannot directly interchanged, targeted selection is required for the measuring the corneal curvature and astigmatism by these three different instruments in the actual clinical process.
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@#<p style="text-align: justify;"><strong>Objective.</strong> To create an age-based formula to estimate the base curve needed for contact lens fitting using measured central corneal curvature (CCC) with a handheld auto keratometer from ophthalmologically normal infants.</p><p style="text-align: justify;"><strong>Methods.</strong> This is a prospective cross-sectional study involving 70 ophthalmologically normal full-term infants aged 0 to 12 months. The infants were divided into four groups: 0-3 months, >3-6 months, >6-9 months and >9-12 months. CCC was measured with a handheld auto keratometer and was used to compute for the base curve. Differences in CCC between the four groups were measured and linear regression models were used for formula creation.</p><p style="text-align: justify;"><strong>Results.</strong> The mean CCC was highest in group 1 at 45.5 ±2.4 diopters (D). These values slowly decreased as age increased. A formula predictive of the base curve based on the infants age was derived using linear regression analysis. It predicted that for every month increase in age, there is a 0.063 millimeter increase in the base curve (p<0.001).</p><p style="text-align: justify;"><strong>Conclusion.</strong> Infant CCC is highest at birth and gradually decreases as age increases. The formula can predict the base curve needed for contact lens fitting in infants without the need for a handheld autokeratometer.</p>
Subject(s)
Infant , Contact LensesABSTRACT
OBJECTIVES@#To investigate angle Kappa and diopter distribution in myopic patients and the changes of angle Kappa and corneal morphology after Sub-Bowman-Keratomileusis (SBK), and to analyze the effects of the surgery on corneal morphologic changes and the patients' near fixation characteristics.@*METHODS@#The clinical data of 134 myopic patients (268 eyes) undergoing SBK from August 2015 to August 2016 were retrospectively analyzed. Angle Kappa, corneal curvature in the central corneal region of 3 mm, and post-corneal Diff value were measured by Orbscan IIz Corneal Topography System before operation, 1 month and 6 months after operation. According to the values of angle Kappa before SBK, the patients were divided into 2 groups: the large K group (angle Kappa≥5°, 71 eyes) and the small K group (angle Kappa<5°, 197 eyes). Correlation analysis of the factors influencing angle Kappa at 6 months after operation was performed.@*RESULTS@#In the large K group, angle Kappa was (5.67±0.65)°, spherical equivalent was (-4.84±2.32) D, and angle Kappa was decreased after operation (both @*CONCLUSIONS@#The angle Kappa is decreased in low-moderate myopia patients with large angle Kappa, while is increased in high myopia patients with small angle Kappa after SBK. Myopia patients after SBK will look for the new balance of the binocular accommodation and vergence function for improving the comfort in the near-work situations.