| The Pentacam anterior segment analysis system can objectively and quantitatively analyze all anterior segment data from the anterior surface of the cornea to the posterior surface of the lens.It is easy to operate and can quantitatively observe the anterior segment changes before and after phacoemulsification.Purpose: This study used the Pentacam anterior segment analysis system to measure the dynamic changes of important parameters of the anterior segment of the cataract in different periods of conventional cataract surgery,especially the changes of posterior corneal surface power and posterior surface astigmatism,and statistical analysis.Postoperative anterior segment recovery is beneficial to guide the surgical approach,postoperative dynamic observation,postoperative treatment plan and prognosis,and provide reference for clinical practice.Method:Clinically,from December 2017 to December 2018,100 eyes of 83 patients with cataract and phacoemulsification combined with intraocular lens implantation were enrolled in our hospital.There were 32 males and 32 females,aged(65.15±8.66)years old.Exclude corneal diseases,ocular trauma,corneal bandages,fundus diseases,glaucoma,etc.All patients were treated with Pentacam to measure corneal refractive power、corneal astigmatism、astigmatic axial position、central corneal thickness、corneal volume、anterior chamber depth before surgery、naked eyesight and best corrected visual acuity.Statistical analysis was performed on the data using SPSS 21.0 statistical software.Results:1.The flat meridian power of the anterior surface of the cornea and the average refractive power of the anterior surface of the cornea decreased at 1 week and 1 month after surgery,and the difference was statistically significant(P<0.05).The postoperative 3months and preoperative phase were no statistical difference(P>0.05).The steep meridian refractive power of the anterior surface of the cornea at 1 week after surgery was significantly smaller than that of the preoperative,and the difference was statistically significant(P<0.05).There was no significant difference at 1 month after operation and 3months after operation(P>0.05).2.The results of this study found that the posterior corneal refractive power values were generally distributed in(-6—-7)D.The absolute value of posterior corneal refractive power(flatness,steepness,mean)was significantly greater at 1 week postoperatively and 1 month postoperatively than before surgery.There was a statisticaldifference(P<0.05).There was no significant difference between the preoperative level and 3 months after surgery(P>0.05).3.The total corneal refractive power(flatness,steepness,mean)at 1 week after surgery was significantly higher than that before surgery,and the difference was statistically significant(P<0.05).There was no significant difference between the 3months after operation and the preoperative phase(P<0.05).4.The anterior surface astigmatism increased by 0.25 D at 1 week after operation,and the difference was statistically significant(P<0.05).There was no statistical difference between preoperative and 1 month after operation and 3 months after operation(P >0.05).The absolute value of astigmatism on the posterior surface of the cornea increased by 0.10 D at 1 week after operation,and the difference was statistically significant(P<0.05).There was no significant difference between the 3 months and the preoperative period(P>0.05).Corneal total astigmatism increased by 0.30 D 1 week after surgery,and there was no significant difference between the 3 months and the preoperative period(P>0.05).5.The astigmatic axial position of the anterior surface of the cornea was(89.61±40.69)°,of which 63% were WTR.The astigmatism axis of the posterior corneal surface was(87.68±56.14)°,of which 42% were ATR.The average axial astigmatism of the cornea before surgery was(90.89±49.73)°,of which 51% were WTR.The astigmatism on the anterior surface of the cornea is dominated by WTR before the age of60.After the age of 60,it changes to the ATR.The astigmatism on the posterior surface of the cornea is dominated by ATR before the age of 60.After 60 years of age,the ATR begins to drift toward the WTR.Total corneal astigmatism is dominated by WTR before the age of 60,but after 60 years of age,ATR and oblique astigmatism begin to increase.Analysis of variance by randomized block showed that there was no significant difference between the astigmatism axis of anterior surface of the cornea 、 the posterior corneal surface and the total astigmatism of the cornea before and after operation(P>0.05).6.The depth of the anterior chamber was deeper at 1 week after surgery、1 month after surgery and 3 months after surgery.The differences were statistically significant(P<0.05).7.The corneal volume was increased at 1 week、1 month after surgery and 3 months after surgery.The difference was statistically significant(P<0.05).There was no significant difference between the 3 months after operation and the 1 month after operation(P>0.05).8.Central corneal thickness increased at 1 week after surgery and 1 month after surgery.There was a statistically significant difference between preoperative and 1 week postoperatively、1 month postoperatively(P<0.05).There was no significant difference between the 3 months and the preoperative period(P>0.05).9.The best corrected visual acuity improved at 1 week、1 month after surgery and 3months after surgery.There was a statistically significant difference between preoperative and 1 week postoperatively、1 month postoperatively(P<0.05).There was no significant difference between the 1 month postoperatively and the 3 months postoperatively(P>0.05).10.There was a significant positive correlation between preoperative corneal volume and central corneal thickness(P<0.05).11.There was a significant positive correlation between corneal total astigmatism and anterior corneal astigmatism(P<0.05).This correlation was moderate.There was a significant negatively correlated between corneal total astigmatism and posterior surface of the cornea(P=0.05).This correlation was small.12.The mean refractive power of the posterior corneal surface,the depth of the anterior chamber,the best corrected visual acuity at 1 month postoperatively,and the total corneal astigmatism at 3 months after surgery were not significantly different between the intraocular lens 920 H and ZCB00(P>0.05).13.There was a significant positive correlation between the refractive power of the anterior surface of the cornea and the total refractive power of the cornea.There was a significant negative correlation between the total refractive power of the cornea and the refractive power of the posterior surface of the cornea,and a significant positive correlation with the absolute value of the refractive power of the posterior surface of the cornea.The influence of the refractive power of the anterior surface of the cornea on the total refractive power of the cornea was 74.6%.The effect of posterior corneal refractive power on total corneal refractive power was 23.1%.Conclusion:1.The change of refractive power of the anterior surface of the cornea caused by cataract surgery mainly occurred within 1 month after operation.It showed that the cornea became flattened and the refractive power of the anterior surface of the cornea decreased within 1 week after operation.The refractive power of the anterior surface of the cornea gradually increased after 1 week.The surface refractive power was close to the preoperative level at 3 months after surgery and began to become stable and no longer changed.2.The results of this study found that the posterior corneal refractive power values were generally distributed in(-6—-7)D.The results of this study found that the values of posterior corneal surface power before and after surgery were generally distributed in(-6-7)D.The change of refractive power on the posterior surface of the cornea occurred mainly within 3 months after cataract surgery.The general manifestation was that the posterior corneal surface became steeper and the posterior surface of the cornea increased significantly.After that,it gradually decreased to the preoperative period.3 months aftersurgery were achieved preoperative levels.3.The change of corneal total refractive power occurred within 3 months after cataract surgery.The general manifestation of corneal total refractive power began to increase in the early postoperative period,reached the highest level 1 week after surgery,and then gradually decreased to the preoperative period.At 3 months after cataract surgery,total corneal refractive power returned to preoperative levels.4.The anterior surface of the cornea、astigmatism of the posterior cornea and total astigmatism of the cornea were significantly increased at 1 week after operation,but the astigmatism of the anterior surface of the cornea was stable after 1 month.The posterior corneal surface astigmatism and total corneal astigmatism were stable at 3 months after surgery.The average astigmatism in the stable phase was not much different from that before surgery.5.The anterior surface of the cornea in cataract patients is mainly WTR,and the astigmatism on the posterior surface of the cornea is mainly caused by ATR.The proportion of WTR in the total corneal astigmatism before surgery is large.With age,astigmatism of the anterior surface of the cornea and total astigmatism of the cornea drift from the WTR to ATR,and the astigmatism of the posterior surface of the cornea drifts from the ATR to WTR.Corneal astigmatism axis has no significant change after cataract surgery.6.Cataract surgery can deepen the anterior chamber.The depth of the anterior chamber increased by 1.45 mm 1 week after surgery,and the depth of the anterior chamber was stable 1 week after surgery.7.The corneal volume became significantly larger within 1 week after cataract surgery,and the difference was significant.After that,the corneal volume gradually decreased,and it was stable 1 month after operation.The central corneal thickness was the thickest within 1 week after cataract surgery,and then gradually thinned,reaching the preoperative level by 3 months after surgery.The period of cataract surgery with the greatest influence on central corneal thickness and corneal volume was 1 week after operation,which may be related to the heavier corneal edema within 1 week after surgery.After the corneal edema was relieved,the central corneal thickness began to become thinner and stable.8.The best corrected visual acuity reached a steady state 1 month after surgery and did not change until 3 months after surgery.If there is corneal astigmatism,it is recommended that the period of optician is 1 month after cataract surgery.9.There was a significant positive correlation between preoperative corneal volume and central corneal thickness.10.The astigmatism on the anterior surface of the cornea and the astigmatism on theposterior surface of the cornea have an effect on the total astigmatism of the cornea.The effect of astigmatism on the posterior surface of the cornea on the total astigmatism of the cornea can not be ignored in cataract surgery.11.There are no differences between the two common aspherical single-focal intraocular lenses in improving vision,deepening the anterior chamber depth,and changing the refractive power of the posterior corneal surface.12.There is a significant positive correlation between corneal total refractive power and corneal anterior surface refractive power,and a significant positive correlation with the absolute value of corneal posterior surface refractive power.The influence of the refractive power of the anterior surface of the cornea on the total refractive power of the cornea was 74.6%,and the influence of the refractive power of the posterior corneal surface on the total refractive power of the cornea was 23.1%.13.The Pentacam three-dimensional anterior segment analysis system provides a reliable method for studying early anterior segment changes after cataract surgery,and provides a reference for clinical application. |
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