Three Kind Of Instrument Survey Cornea Curvature Uses In The Artificial Lens Diopter Computation The Variance Analysis

Objective:With the cataract phacoemulsification and intraocular lens implantation in patients becoming more perfect, has not only a sight restoring cataract surgery, but also a refractive surgery, postoperative refractive status became concerned about the patients and ophthalmologists consistent pursuit of biological, therefore accurate preoperative measure-ment of intraocular lens and the choice of surgical procedure is very important, and became the focus of this year. As the cataract surgery technology improvement and development, surgically induced refractive errors are gradually reduced, accurate preoperative biometric and refractive intraocular lens calculation accuracy has also become crucial factors. Many hospitals still use manual keratometer to measure the cornea's curvature, with the development of medical devices in recent years has emerged a variety of instruments measuring corneal curvature. This experiment manual keratometer, automatic computer optometry curvature and corneal topography instrument three different instruments to measure corneal curvature for intraocular lens calculation of the difference in refraction analysis to understand the three instruments measured before cataract surgery refractive intraocular lens to provide K value of accuracy. And analysis of three kinds of measuring instruments to measure corneal curvature corneal refractive curvature of the feasibility of calculating intraocular lens.Methods:Randomly selected from August 2009 to October 2009 at the Second Affiliated Hospital of Dalian Medical University Eye Hospital for cataract surgery were 60 eyes of 44 patients, aged 55-82 years, mean age (65±6.7) years old, men and women not limited to, side by side in addition to the history of corneal disease and eye surgery patients into the group. And each patient must be carried out measurements of these three instruments. Manual keratometry measurement technique for 3 eyes, will check the income of the 90°and 180°of corneal refractive power after adding the average value of corneal curvature as the corneal refractive power by checking the average. Automatic keratometry test 3 times, automatically record the two vertical axis of corneal curvature, and axial astigmatism. Eye surgery using corneal topography on photo 3 times, select the best image, select the central 3mm SimK and MinK within the sum of the average value of checks as proceeds of corneal topography and mean refractive astigmatism axis, A measurement of axial length with ultra for 6 times, take average. A super machine containing a variety of common SRK II formula, A is a constant, simply enter the machine in the corneal curvature can print out the results of intraocular lens power calculation. IOL diopter value of all this machine are calculated and printed, and then analyzed statistically. Kinds of measuring instruments to measure corneal curvature and corneal curvature calculating the feasibility of artificial lens refraction.Results:Three Methods for Measurement of corneal horizontal axis near the measured refraction of the statistical results showed that:the instrument measuring the differences were not statistically significant (P> 0.05); three kinds of methods in the cornea vertical axis close to the measured refraction of the statistics The results showed that:the instrument measuring the differences were not statistically significant (P> 0.05); three methods was measured corneal axial results, three instruments of corneal axial differences mean a larger range distributed in 9.8412°-15.5889°between the statistical test, P value> 0.05, indicating that three kinds of instruments detect the difference was not statistically significant. But the real work, as corneal topography of the objective factors are many, and the manual keratometer and the repeatability is good, so clinical use more manual keratometer to measure the astigmatism of intraocular lens axial, clinical that the use of Artificial corneal curvature measuring astigmatism crystal axial reliable; by the three methods was measured corneal curvature and the calculated intraocular lens refraction results show that:the three instruments of the corneal curvature and the calculated intraocular lens refraction fluctuations in scope than small, distributed in 18.8266D-19. 1024D between the three instruments of intraocular lens calculation of the differences were not statistically significant, P> 0.05.Conclusion:Automatic keratometry and corneal topography measurement curvature, although with different advantages and disadvantages, but cataract and intraocular lens surgery in the majority only need to know when the optical area of central corneal curvature, the three kinds of corneal curvature in both can be used in refractive intraocular lens calculation, and the data is accurate and reliable. If implantation of intraocular lens and astigmatism axial, since the corneal topography of the objective factors are many, and the manual keratometer the repeatability is good, so more clinical use of artificial keratometer to measure the astigmatism of intraocular lens axial. For those who had corneal flat, steep or need accurate measurement of the refractive status, then the recommended corneal topography.