ABSTRACT
Objective To study the optical imaging quality of multifocal intraocular lens (IOL) following Nd∶YAG laser damage.Methods Three hydrophobic acrylate discs used to make multifocal IOL were placed in line,and the Nd∶YAG laser was used to emit the posterior surface,mid-plane and anterior surface of the discs by gradually increasing the emitting energy to determine the damaged threshold energy of various planes.Eight multifocal IOLs were divided into 2 groups.IOL damage models were established by emitting 12 points along 12 clocks on circle of 3.0 mm in diameter in the group 1 (IOLs NO.1,2,3,4) and 6 points with 1-clock interval on circle of 1.0 mm in diameter in the group 2 (IOLs NO.5,6,7,8) with Nd∶YAG laser.The modulation transfer function (MTF),line spread function (LSF) and United States air force (USAF) test target images of the IOLs were tested under the optical aperture at 2.0,3.0 and 4.5 mm.Results The damage thresholds of laser power were not significantly different among three hydrophobic acrylate discs (Fgroup =1.100,P =0.337),and the thresholds were significantly different among different planes in the discs (Fposition =195.279,P=0.000),with the highest damage threshold in the anterior surface and the lowest damage threshold in the mid-plane of the discs(all at P＜0.01).The shifts of far focus and near focus MTF curves,LSF curves and USAF target images of the IOLs under the 2.0,3.0 and 4.5 mm optical aperture after laser damage were in coincidence with those before laser damage both in group 1 and group 2.The glare phenomenon of the USAF target image was observed at near focus under the 4.5 mm optical aperture both before and after laser damage.Conclusions Multifocal IOL is vulnerable to injury when the laser beam focuses on the midplane,and the anterior surface of IOL can tolerate certain degree of damage.In standard model eye,the MTF curves,LSF curves and USAF target images of multifocal IOL was not impacted by laser induced spots injuries under different pupil diameters.
ABSTRACT
Objective:To determine whether implantation of an intraocular lens(IOL) with a modified prolate anterior surface results in reduced spherical aberration and improved contrast sensitivity after cataract surgery.Methods: Consecutively 72 eyes were selected from 53 senile cataract patients who had received phacoemulsification and IOL implantation in Peking University Eye Center.Each was randomly assigned to receive Tecnis Z9001 IOL or Sensar AR40e(both made by AMO).Three months after operation,the eyes underwent several tests including visual acuity,optometry and wavefront aberration examination.Mesopic contrast sensitivity test was measured with ROLAND BA-4 Contrastometer.Results: The eyes treated with Tecnis Z9001 had significantly less spherical aberration.The eyes treated with Tecnis IOL got lower C12 coefficient and RMS4 than those with Sensar AR40e(P value
ABSTRACT
Objective: To observe the pathological changes of the lens and anterior lens capsule of the patients with familial congenital aniridia, and discuss the histopathological etiology of the fragility of the anterior capsule and the significance of surgical project. Methods: Anterior lens capsules and lens specimens were obtained from aniridic patients during cataract surgery. The intraoperative behavior of each capsule was noted, after which the specimens were submitted for histopathologic evaluation and electron microscope examination. Results: The anterior lens capsule was extremely fragile and remarkably thin. Degenerative changes(degeneration, necrosis, loss) of the lens epithelium and discontinuity of the lens epithelium were found in some specimens. Proliferation and double layer of the epithelial cells in some area of the specimens can be seen also. Ply structure of the anterior capsule became thin or disappeared. Conclusion: Degenerative or proliferative changes of the lens epithelial cells were associated with the thinness and extreme intraperative fragility of the anterior lens capsules in familial aniridia with cataract. Greater awareness of anterior capsule fragility in some aniridic patients with cataract may reduce the risk of capsule complications and lead to safer surgical outcomes.