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【Objective】 To investigate the influencing factors of surgically induced astigmatism (SIA) in phacoemulsification. 【Methods】 Cataract phacoemulsification was performed in 69 patients with regular corneal astigmatism from December 2021 to March 2022. SIA of the anterior corneal surface, posterior corneal surface and simulated keratometry (SimK) in the diameter range of 3 mm, 5 mm and 7 mm centered at the apex of the cornea was observed. Pearson correlation analysis was used to analyze SIA with age, axial length (AL), anterior chamber depth (ACD), white-to-white (WTW), and central corneal thickness (CCT). Multiple linear regression was used to analyze the influencing factors of SIA. 【Results】 The mean age of the 69 patients was (63.25±14.74) years old, and 28 (40.58%) were male. The analysis found that the |SIA| of SimK was negatively correlated with WTW (r=-0.265, P=0.028), the |SIA| of 3 mm, 5 mm, 7 mm anterior surface was negatively correlated with WTW (r=-0.320, P=0.007; r=-0.337, P=0.005; r=-0.287, P=0.017), and the |SIA| of 3 mm, 5 mm, 7 mm posterior surface was negatively correlated with AL (r=-0.390, P=0.001; r=-0.352, P=0.003; r=-0.317, P=0.008). Multiple regression analysis showed that WTW was negatively correlated with |SIA| of SimK, 3 mm, 5 mm, 7 mm anterior surface and 3 mm posterior surface (B=-0.261, P=0.047; B=-0.387, P=0.016; B=-0.323, P=0.009; B=-0.297, P=0.041; B=-0.085, P=0.049). WTW was positively correlated with XSIA of 3 mm anterior surface, YSIA of 5 mm, and 7 mm anterior surface (B=0.347, P=0.040; B=0.318, P=0.034; B=0.403, P=0.010). AL was negatively correlated with |SIA| on the posterior surface of 3 mm and 5 mm (B=-0.023, P=0.021; B=-0.034, P=0.030). 【Conclusion】 During cataract surgery, the effect of ocular biological parameters such as axial length and corneal diameter on SIA should be considered.
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Background: An understanding of the location, number, direction and size of nutrient foramina in long bones isvery important clinically, especially in orthopaedic surgical procedures such as fracture repair, bone grafting,vascularized bone microsurgery, intramedullary reaming and plating,as well as in medico legal cases. An accurateknowledge of the location of the nutrient foramina in long bones should help prevent intraoperative injuries inorthopaedic, as well as in plastic and reconstructive surgery.Aims & Objectives: The aim of our study is to observe the variations in number, location, direction and size of thenutrient foramina of Dried Human Femur.Materials and Methods: The study comprised 200 dry normal adult femur bones of unknown sex obtained fromthe Department of Anatomy of various medical colleges of Telangana, India.Results: The total number of nutrient foramina obtained in 200 femurs was 326. 82 bones had single nutrientforamen (41%), 111 bones had double nutrient foramina (55.5%), 6 bones had triple nutrient foramina (3%), andonly 1 bone 4 nutrient foramina (0.5%) and none of the bones showed zero foramen. The size of nutrient foraminawere also noted in 200 bones, 60 bones presented small sized foramina (18%), 130 bones presented with mediumsized foramina (40%), and rest of 136 bones presented with large sized foramina (42%). The nutrient foraminaobeyed the general rule that is, directed away from the growing end of the bone. Among 326 nutrient foramina149 were located on posterior surface (46%), about 126 foramina were located on medial surface (38.50%), 38were located on the lateral surface (12%), and the remaining 12 were located on the popliteal surface (6%), andnone on the anterior surface.Conclusion: Knowledge of the localization and number of the nutrient foramina is useful in certain surgicalprocedures such as bone grafting and microsurgical vascularized bone transplantation, to preserve the circulationintact and for open reduction surgeries.
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@#AIM:To investigate the distribution of corneal spherical aberration in age-related cataract.<p>METHODS: Retrospective study. Totally 217 cases of age related cataract(217 eyes)were collected in the Central Hospital of Kaifeng from August 2017 to August 2018. Patients were divided into 3 groups according to age: 50-60 years(63 eyes)in group Ⅰ, 61-70 years(107 eyes)in group Ⅱ, 71-80 years(47 eyes)in group Ⅲ. Pentacam anterior segment analysis was used to measure the anterior and posterior corneal K-readings. The corneal spherical aberration of anterior, posterior and total were calculated on an area of 6mm diameter by Zernike analysis and a descriptive study was used.<p>RESULTS:The Mean±SD of total corneal spherical aberration was 0.311±0.098μm for all the patients. Statically significant were found for the anterior and total corneal spherical aberration(<i>F</i>=34.434, 32.896; <i>P</i><0.05). The anterior, posterior corneal K-readings and posterior corneal spherical aberration had no correlation with age(<i>r</i>=0.040, 0.066, 0.097, <i>P</i>>0.05). The anterior and total corneal spherical aberration were positively correlated with age(<i>r</i>=0.506, 0.509, <i>P</i><0.05).<p>CONCLUSION:The total corneal spherical aberration in age-related cataract was slightly higher than that before. The anterior and total corneal spherical aberration increased with age, and then the posterior corneal spherical aberration was not.
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AIM:To contrast analysis of postoperative variation of corneal posterior surface heights after Femtosecond LASlK ( FS - LASlK ) and small incision lenticule extraction ( SMlLE) for high myopia. ●METHODS: Sixty-seven cases of high myopic patients (132 eyes) operated with laser corneal refractive in our hospital from May to Dec. in 2015 (-6. 00D≤spherical equivalent degree≤-10. 00D) were selected and divided into FS-LASlK group and SMlLE group. The thickness of corneal flaps at FS-LASlK and the thickness of map at SMlLE were designed to be 110μm. Corneal posterior surface heights were examined by Pentacam at preoperation, postoperative 3 and 6mo after FS-LASlK and SMlLE operation. Surface height changes after preoperative, postoperative 3 and 6mo were compared by measuring Pentacam corneal analysis system. ●RESULTS: Six months after operation, the FS-LASlK posterior corneal surface height was 6. 47 ± 1. 65mm, significantly higher than 5. 20 ± 1. 32mm before operation. SMlLE posterior corneal surface height was 6. 40 ± 1. 33mm, significantly higher than 5. 18 ± 1. 25mm before operation, the differences were statistically significant( P0. 05). ●CONCLUSION:After FS-LASlK and SMlLE, the corneal posterior surface is protrusive. FS - LASlK is slightly obvious than SMlLE in early period. The stability of the posterior surface is better after SMlLE.
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Para convertir las mediciones obtenidas de la superficie corneal a un valor dióptrico, el keratómetro de Bausch & Lomb Optical Company utiliza la fórmula (n n)/ R y asume un índice n de 1,3375 (diferente al índice real de la córnea de 1,376). Este valor ficticio incluye una compensación para contrarrestar el pequeño pero significativo poder negativo de la superficie posterior de la córnea. Esto permite hacer la lectura directamente tanto del radio de curvatura como del poder dióptrico de la córnea.
To convert the measurements obtained from the corneal surface into dioptric value, the B&L keratometer uses the general lens formula (n-n/R) and assumes an n of 1,3375 (compared to the actual corneal refractive index of n=1,376). This is afictional value, which includes an allowance for the small, yet significant, negative power of the posterior corneal surface.
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Cornea , RefractometryABSTRACT
Objective To investigate the corneal posterior surface topography characteristics of keratoconus at early stages applying the Pentacam anterior segment analysis system. Methods The present study included 43 eyes of 43 patients with keratoconus at the subclinical stage (group A), 40 eyes of 40 suspected keratoconus patients (group B), and 143 normal eyes of 143 controls (group C). Based on an examination of the Pentacam anterior segment analysis system of each subject, a series of data, including the posterior surface refractive power, the posterior surface elevation were collected. The differences among the three groups, the correlation among indices, and the area under the receiver operating characteristic (ROC) curves were analyzed. Results The mean values of the posterior surface maximum refractive power in 3 groups were -6.2 D, Q=0.5;-5.6 D, Q=0.3;and -5.5 D, Q=0.3, respectively. The mean values of the posterior surface maximum elevation were 23 μm, Q=14;11 μm, Q=8.5;and 7 μm, Q=6, respectively. The posterior surface maximum refractive power and maximum elevation among three groups were statistically different. The area under ROC (AUR) of posterior maximum refractive power and the AUR of posterior maximum elevation were greater than that of other indices in the diagnosis of early keratoconus. Conclusions Based on the results from the Pentacam anterior segment analysis system, the changes of the posterior surface refractive power and elevation are important characteristics of early keratoconus.