ABSTRACT
@#AIM: To observe the changes of the development of the anterior segment in children after the treatment of laser photocoagulation(LP)for retinopathy of prematurity(ROP)by corneal topographic. <p>METHODS: In this retrospective case study, 25 children(50 eyes)as ROP group and 23 children(46 eyes)born at term as control group had participated in the study. The best corrected visual acuity(BCVA)was examined in both groups, and converted to LogMAR vision when statistical analysis was performed. The observation indicators of the Sirius anterior segment analysis system in the study were as follows: the horizontal iris diameter(HVID), corneal radius of the thinnest point, the thinnest point of the cornea, the maximum curvature of the cornea, the maximum radius of cornea curvature, central corneal thickness(CCT), corneal volume(CV), anterior chamber depth(ACD), anterior chamber volume and the anterior chamber angle.<p>RESULTS: The HVID, the thinnest point of the cornea, ACD, and the anterior chamber volume in ROP group were smaller than that in the control group(all <i>P</i><0.05). The CV and the anterior chamber angle in ROP group were smaller than that in the control group, but there was no significant difference between the two groups(all <i>P</i>>0.05). The BCVA was significantly better in the control group than that in the ROP group(0.07±0.10 <i>vs</i> 0.24±0.25, <i>P</i><0.05). <p>CONCLUSION: The development of eye anterior ganglion tissues of the ROP group had changed with steeper cornea, shallower anterior chamber, smaller angle of the anterior chamber and poor BCVA. All of the changes above might make it easier for the development of refractive errors and glaucoma.
ABSTRACT
Keratoplasty, which is cornea transplant surgery, is one of the treatment methods for patients with turbidity or keratitis. Recently, keratoplasty using a surgical robot was studied to increase precision. In this study, the effect of surgical factors on the deformation and curvature of the cornea were analyzed in order to improve the accuracy of keratoplasty and derive the optimal surgical factors using finite element method (FEM). Suturing tension and depth were selected as surgical factors. An FEM model, a constitutive equation, and boundary conditions were determined using experiments and reference data. Suturing tension significantly impacted deformation and curvature change, and suturing depth affected the position of the thread-cornea contact point. Both factors have a significant impact on a focal point in the retina and the patient's visual acuity after keratoplasty.
Subject(s)
Humans , Cornea , Corneal Transplantation , Finite Element Analysis , Keratitis , Methods , Retina , Visual AcuityABSTRACT
Objective To establish a conventional intraocular lens (IOL) calculation formula which is applicable to eyeballs with abnormal data and laser in situ keratomileusis (LASIK) postoperative eyes.Methods A case-series study was adopted.According to the classical optical theory,a normal IOL implanted eye has the following characteristics:when light is refracted by cornea and arrives on the IOL plane,the value of refractive power (F1) + IOL refractive power (F2) =the value of refractive power which is suitable for vitreous body depth (F3).Thereafter,a mathematical model was built on the basis of theory,experience,and regression analysis data after IOL implantation surgeries.Furthermore,based on the new LASIK postoperative cornea curvature modified formula,the two kinds of IOL calculation programs of conventional and LASIK postoperative eyes were established.The test data was collected from 644 patients who had undergone the cataract extractions and IOL implantation surgeries (600 physiological cornea eyes,7 radial keratotomy [RK] eyes and 37 LASIK postoperative eyes) at the Affiliated Drum Tower Hospital of Nanjing University Medical School.Through the analysis of these data,the new formulas were examined.Results With IOL refractive power of 607 eyes (including 7 RK postoperative eyes),the average error of XLQ formula (the tentative name of the established formula in this study)was 0.1 D,and the 95％ limits of agreement range was-1.1 to + 1.2 D.The error range of IOL refractive power predicted by XLQ,SRK-T and Haigis formulas was-2.21 to +2.25 D,-5.10 to +5.63 D and-3.00 to +3.18 D,respectively,the absolute average error of IOL refractive power predicted by the three formulas was (0.43 ± 0.28),(0.74 ± 0.53) and (0.79 ± 0.49) D,respectively.Compared with SRK-T and Haigis formulas,the average error of IOL refractive power predicted by XLQ formula was Lower,with significant differences between them (both at P =0.000).The error value of IOL refractive power predicted by XLQ formula had no statistical correlations with axial length (AL),keratometry (K) and A constant respectively (all at P＞0.05),while the error value predicted by SRK-T and Haigis formulas had statistical correlations with AL,K and A constant,respectively (all at P＜0.05).Thirty-seven patients who had conducted LASIK for myopia (and whose IOL refractive power value were predicted by XLQ formula) had been undergone the postoperative examination.Comparing the predicted and actual value,the error range of IOL refractive power was-0.52 to +1.18 D,and the absolute average error was (0.49±0.26)D.Conclusions The conventional mode of the XLQ formula established in this study can be used in the cases with broad values of axial length,corneal curvature and A constant,as well as various types of physiological cornea and RK postoperative eyes;the dedicated mode is suitable for LASIK postoperative eyes of myopia.