The Comparative Study On Contrast Visual Acuity Of Aspheric Intraocular Lens Eyes

Background and ObjectivePhacoemulsification and intraocular lens implantation is an effective way in the treatment of cataract ,the phacoemulsification can remove the opacity lens and implant an intraocular lens(IOL) to restore patients'vision .so the intraocular lens we elected is very important, patients'visual quality dependent on it to a large extent. To ensure the safety of operation, the intraocular lens implanted must have a good biocompatibility and refractive properties. Since 1949, the first doctor Ridley' who applied the first artificial lens to his patient in the world, despite the intraocular lens materials and design continue to improve, until now some problems still exist. With the socio-economic development and the continuous progress of human society, the cataract extraction of traditional surgery turn into the refractive surgery.patients have higher requirements on visual quality . looking comfortably and clearly is becoming more and more important, we know the traditional intraocular lens can help patients restore eyesight, but because of the optical surface'spherical design ,patients can easily get poor night vision, low contrast sensitivity , glare, and undergo other issues. With the continuous progress in research, it was recognized that the human eye aberrations can cause those phenomenon, so more and more ophthalmologists started to pay attention to the human eye aberration. In recent years, With the wave aberration technology'development and the combination with artificial lens design, the new concept on aspheric intraocular lens appeared .Aspheric intraocular lens which is wave-front designed to correct aberrations of the human eye , now many clinical studies show that aspherical intraocular lens can offset the corneal spherical aberration and make patients have better night vision ,Contrast sensitivity,and it can also reduce glare, However,aspheric intraocular lens have vast varieties, their design concept is also different. Germany Acri Tec company's AcriSmart 36A aspheric intraocular lens'material is acrylic, a hydrophobic surface, single-piece designed, diameter of optical surface is 6.0 mm, total diameter is 11.0 mm, thin edge, As a shorter time to market, the clinical study was relatively small.we did the research based on AcriSmart 36A aspheric intraocular lens and traditional intraocular lens to compare and evaluate the safety and effectiveness of AcriSmart 36A aspheric intraocular lens in the treatment of senile cataract.and Conduct the choice of aspheric intraocular lens. MethodsAfter the ophthalmological exam were completed, 50 patients were divided into two groups randomly and 50 eyes of 50 patients undergo phacoemulsification.One group were implanted with the Acri Smart 36A aspheric IOL , the other group with ACR6D SE spheric IOL, Three months postoperatively,the contrast visual acuity of two groups were measured in dark and high bright background in different contrast level by using multi-functional visual acuity tester. At the same time pupil diameter of two groups were measured and a Visual quality survey was made for the two groups.Statistical analysis was performed and p 0.05 was considered statistically significant.Result1,Contrast level'impact on visual acuityIn the same background, tow groups'visual acuity gradually decreased with the contrast level going down.At the same contrast level,visual acuity in bright background of tow groups'were both better than in dark background.2,The comparison of BCVA between tow groups21 patients with Acri Smart 36A get the BCVA over 0.8,20 patients with ACR6D SE get the BCVA over 0.8, The difference of BCVA was'nt statistically significan.3,The contrast acuity comparison between tow groupsPatients with Acri Smart 36A Aspheric IOLs had better visual acuity in low contrast level (10% and 5%)in dark backgroun(25cd/m2) than those with ACR6D SE spheric IOLs, the differentce was statistically significant(p<0.05),but in the bright background (255cd/m2)the difference was'nt statistically significan at any contrast level(100%,25%,10%,5%).4,The pupil diameter comparison between tow groups Three months later ,the pupil diameter of ACR6D SE group is 4.23±1.30mm, the pupil diameter of Acri Smart 36A group is 4.28±1.29mm, the pupil diameter did'nt show statistically significant difference between tow groups.5,Comparison of visual symptomsVisual quality survey show the average score is 72 for the ACR6D SE group,and 81 for Acri Smart 36A group. Two case with ACR6D SE complaint about glare, but there is no statistically difference between tow groups.Conclusion1,The implantation of Acri Smart 36A aspheric intraocular lens in the treatment of senile cataract is safe and effective。2,The Acri Smart 36A aspheric IOL can improve patients'contrast sensitivity and low contrast visual acuity in dark background when compared with ACR6D SE spheric IOL.3,In high bright background the two different IOL had no difference in improving visual quality in any contrast level and the BCVA of two groups show no statistically difference.