Effect of femtosecond laser-assisted steepest-meridian clear corneal incisions on preexisting corneal regular astigmatism at the time of cataract surgery

AIM:To investigate the clinical efficacy and safety of femtosecond laser-assisted steepest-meridian clear corneal incisions for correcting preexisting corneal astigmatism performed at the time of cataract surgery.METHODS:This prospective case series study comprised consecutive age-related cataract patients with corneal regular astigmatism(range:+0.75 to+2.50 D)who had femtosecond laser-assisted steepest-meridian clear corneal incisions(single or paired).Corneal astigmatism was performed with the Pentacam preoperatively and 3 mo postoperatively.Total corneal astigmatism and steepestmeridian measured in the 3-mm central zone were used to guide the location,size and number of clear corneal incision.The vector analysis of astigmatic change was performed using the Alpins method.RESULTS:Totally 138 eyes of 138 patients were included.The mean preoperative corneal astigmatism was 1.31±0.41 D,and was significantly reduced to 0.69±0.34 D(equivalent to difference vector)after surgery(P<0.01).The surgically-induced astigmatism was 1.02±0.54 D.The correction index(ratio of target induced astigmatism and surgically-induced astigmatism:0.72±0.36)as well as the magnitude of error(difference between surgically-induced astigmatism and target induced astigmatism:-0.29±0.51)represented a slight under correction.For angle of error,the arithmetic mean was 1.11±13.70,indicating no significant systematic alignment errors.CONCLUSION:Femtosecond-assisted steepest-meridian clear corneal incision is a fast,customizable,adjustable,precise,and safe technique for the reduction of low to moderate corneal astigmatism during cataract surgery.

Pivot concept: achieving a good-quality capsulorrhexis through a 2.2 mm or less clear corneal incision by using standard capsulorhexis forceps

Dear Editor,I am Dr.Hung-Yuan Lin,from the Universal Eye Center,Taiwan,China.I write to present one of the crucial techniques that enables easy maneuverability for ophthalmologists who perform the conventional method,which requires a corneal incision of 2.75-3.0 mm in width shifted to microincision phacoemulsification that only requires a corneal incision of1.8-2.2 mm in width.In 2014 APACRS survey and trends,we noted there are nearly40%of cataract surgery with 2.8 mm clear corneal incision（CCI）.

Optimal incision sites to reduce corneal aberration variations after small incision phacoemulsification cataract surgery

AIM： To analyze the effect of steep meridian small incision phacoemulsification cataract surgery on anterior,posterior and total corneal wavefront aberration.· METHODS： Steep meridian small incision phacoemulsification cataract surgery was performed in age-related cataract patients which were divided into three groups according to the incision site： 12 o＇clock, 9o＇clock and between 9 and 12 o＇clock（BENT） incision groups. The preoperative and 3-month postoperative root mean square（RMS） values of anterior, posterior and total corneal wavefront aberration including coma,spherical aberration, and total higher-order aberrations（HOAs）, were measured by Pentacam scheimpflug imaging. The mean preoperative and postoperative corneal wavefront aberrations were documented.·RESULTS： Total corneal aberration and total lower-order aberrations decreased significantly in three groups after operation. RMS value of total HOAs decreased significantly postoperatively in the 12 o＇clock incision group（P 〈0.001）. Corneal spherical aberration was statistically significantly lower after steep meridian small incision phacoemulsification cataract surgery in BENT incision group（P 〈0.05） and Pearson correlation analysisindicated that spherical aberration changes had no significant relationship with total astigmatism changes in all three corneal incision location.·CONCLUSION： Corneal incision of phacoemulsification cataract surgery can affect corneal wavefront aberration.The 12 o＇clock corneal incision eliminated more HOAs and the spherical aberrations decreased in BENT incision group obviously when we selected steep meridian small incision. Cataract lens replacement using wavefront-corrected intraocular lens combined with optimized corneal incision site would improve ocular aberration results.

Dr.Father Waclaw Szuniewicz,a forgotten pioneer in refractive surgery and his work in China

Father Waclaw Szuniewicz(1891-1963) was a skilled ophthalmic surgeon, missionary, and teacher. For several years he worked in China, afterwards in the United States and in Brazil. The aim of the paper is to present the unanalyzed issues of Szuniewicz’s research regarding corneal refractive surgery. Szuniewicz performed experiments on changing the corneal curvature with anterior, posterior and full-thickness incisions. The results of modifying the anterior and posterior corneal curvature were satisfactory, however, diminished significantly within months after surgery. Corneal band resections were superior in terms of efficacy, however, such an intervention commonly led to complications in animal studies. Szuniewicz’s work was not published during his life. Nevertheless, as a result of strong impact of his personality and ideas, he is frequently considered as a pioneer of corneal refractive surgery.

Femtosecond laser cataract surgery

Femtosecond laser(FSL)cataract surgery is in its infancy but is rapidly gaining popularity due to the improved consistency and predictability for corneal incisions and anterior capsulorhexis.It enables subsequently less phacoemulsification energy and time to be employed,which has gains in terms of reduced corneal oedema.In addition,the FSL allows better circularity of the anterior capsulotomy,capsule overlap,intraocular lens(IOL)placement and centration of the IOL.These advantages have resulted in improved visual and refractive outcomes in the short term.Complication rates are low which reduce with surgeon experience.This review article focuses on the Alcon LenSx system.