Eric J. Kim

Scleral-fixated capsular tension rings and segments for ectopia lentis in children.

PURPOSE To report the short-term outcomes and complications of implantation of scleral-fixated capsular tension rings and/or capsular tension segments with intraocular lenses (IOL) in pediatric patients with ectopia lentis. DESIGN Retrospective, observational case series. METHODS Thirteen consecutive pediatric patients (19 eyes) underwent placement of in-the-bag IOL with either a Cionni modified capsular tension ring or a capsular tension segment in conjunction with a conventional capsular tension ring between January 1, 2009 and March 30, 2013 by 3 anterior segment surgeons at a single academic center. The scleral fixation suture was 9-0 polypropylene in 16 eyes and CV-8 Gore-Tex (expanded polytetrafluoroethylene) in 3 eyes. Outcome measures included change in corrected distance visual acuity (CDVA) and complications. RESULTS The mean age was 10.2 years ± 4.8 (SD) and the median follow-up, 23.4 months. A Cionni modified capsular tension ring was implanted in 5 eyes and a capsular tension segment with an unsutured capsular tension ring was implanted in 12 eyes. In 2 eyes, capsular tension segment alone was placed. The mean CDVA at the final follow-up (0.10 ± 0.11 logMAR, 18 eyes) was significantly better than preoperatively (0.58 ± 0.26 logMAR, 15 eyes) (P < .001). The CDVA at the final follow-up was 20/40 or better in 18 eyes (94.7%). All IOLs were well centered. Posterior capsule opacification developed in 11 eyes (57.9%), 9 eyes (47.4%) required neodymium-yttrium-aluminum-garnet capsulotomy, and 3 eyes (15.8%) required pars plana vitrectomy and posterior capsulotomy. Other complications included broken suture (5.3%) (9-0 polypropylene at CTR eyelet, repaired with CV-8 Gore-Tex), conjunctival dehiscence (5.3%), suture exposure (5.3%) (trans-scleral 9-0 polypropylene), and vitreous strand at inferior paracentesis (5.3%). CONCLUSIONS Implantation of in-the-bag IOL with either a Cionni modified capsular tension ring or a capsular tension segment in conjunction with a conventional capsular tension ring appears to be a safe and effective technique for visual rehabilitation in pediatric ectopia lentis.

Accuracy of toric intraocular lens axis alignment using a 3-dimensional computer-guided visualization system

Purpose To evaluate the accuracy of toric intraocular lens (IOL) alignment in femtosecond laser–assisted cataract surgery using the Truevision 3‐dimensional (3‐D) computer‐guided visualization system compared with a manual marking method. Setting Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. Design Retrospective comparative case series. Methods Preoperatively, all patients had corneal topography measurements with a color light‐emitting diode topographer. The 3‐D system used the anterior keratometry values to create an optimized plan for the toric IOL alignment. Intrastromal marks were created by the femtosecond laser at the intended toric meridian, guided by manual ink marks placed at the 3 o’clock and 9 o’clock limbus with the patient sitting upright. Intraoperatively, the 3‐D system was used to align the IOL and measure the angular position of the femtosecond marks relative to the IOL meridian. Three weeks postoperatively, the manifest refraction, corrected distance visual acuity, and toric IOL alignment were recorded. Results The mean 3‐D imaging error was −0.58 degrees ± 3.90 (SD) (range −9 to 5 degrees), and the mean manual ink error was −0.27 ± 3.65 degrees (range −8 to 5 degrees); neither was statistically significantly different from zero (P = .28 and P = .76, respectively). The mean absolute errors were 2.96 ± 2.54 degrees and 2.88 ± 2.18 degrees, respectively. Conclusion The 3‐D computer‐guided system and manual marking combined with femtosecond laser marks were similar in accuracy for toric alignment. Financial Disclosures Dr. Wang received research support from Ziemer USA, Inc. Dr. Weikert is a consultant to Ziemer USA, Inc. Dr. Koch is a consultant to Alcon Laboratories, Inc., and Abbott Medical Optics, Inc., and received research support from Ziemer USA, Inc., i‐Optics Corp, and Truevision Systems. None of the other authors has a financial or proprietary interest in any material or method mentioned.

Repeatability of posterior and total corneal curvature measurements with a dual Scheimpflug–Placido tomographer

Purpose To evaluate the repeatability of the Galilei G4 dual Scheimpflug analyzer in measuring simulated keratometric, total, and posterior corneal curvature in normal and post‐refractive surgery eyes. Setting Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. Design Prospective evaluation of diagnostic technology. Methods A single observer performed 3 consecutive measurements in 1 eye of each subject. The following were evaluated in both eyes and in eyes that had previous myopic excimer‐laser surgery: (1) simulated keratometric corneal power and astigmatism, (2) total corneal power and astigmatism, and (3) posterior corneal power and astigmatism. Repeatability was assessed by calculating the within‐subject standard deviation (Sw), coefficient of variation (CoV), and intra‐class correlation coefficient (ICC). Results The study evaluated 41 normal eyes and 36 post‐refractive surgery eyes. In normal eyes, the Sw was 0.08 diopters (D), 0.10 D, and 0.03 D for simulated keratometric, total, and posterior corneal power, respectively. The CoV ranged from 0.16% to 0.40%, and the ICC was 0.992 or more (P < .001) for all corneal powers. In post‐refractive surgery eyes, the Sw was 0.09 D, 0.09 D, and 0.02 D for simulated keratometric, total, and posterior corneal power, respectively. The CoV ranged from 0.19% to 0.32%, and the ICC was 0.990 or more (P < .001) for all corneal powers. For posterior corneal astigmatism, the ICC was 0.814 and 0.886 for normal and post‐refractive surgery eyes, respectively. Conclusions In normal corneas and corneas that had undergone myopic excimer laser ablation, the dual Scheimpflug analyzer showed high intra‐observer repeatability for simulated keratometric, total, and posterior corneal power measurements and moderate repeatability for posterior corneal astigmatism. Financial Disclosure Drs. Koch, Weikert, and Wang received research support from Ziemer USA, Inc. No other author has a financial or proprietary interest in any material or method mentioned.

Lens Placement in the Absence of Capsular Support: Scleral-fixated Versus Iris-fixated IOL Versus ACIOL.

Cataract surgery is one of the most commonly performed surgical procedures in the United States, and the prevalence of cataracts is projected to further increase to 30 million by 2020. Ideally, the cataract is extracted and an intraocular lens (IOL) is implanted in the native capsular bag or ciliary sulcus in a single procedure. However, the absence of adequate capsular support necessitates alternative surgical approaches, which include scleral-fixation, iris-fixation, or placement in the anterior chamber angle. Although each method offers unique advantages and disadvantages regarding surgical complexity, operative duration, and complications, there is still no clear consensus on the optimal approach. Early closed-loop anterior chamber intraocular lenses (ACIOLs) were initially reported to have good short-term results, but were later found to be associated with several complications, including cystoid macular edema (CME), glaucoma, uveitis, hyphema, irreversible endothelial cell loss, and corneal decompensation. However, new and improved open-loop ACIOL designs have eliminated the vast majority of these complications. As an alternative, scleral and iris fixation methods were also developed. In 1976, uveal fixation sutures were first used to stabilize posterior chamber intraocular lenses (PCIOLs). In 1983, transsulcus suture fixation of a PCIOL to the sclera was first reported. Other techniques such as sutureless scleral fixation and iris claw IOLs soon followed.

Optimization of Toric IOL Calculation

Implantation of toric IOLs is a predictable method of treating corneal astigmatism and results in good visual and refractive outcomes. The ideal toric IOL candidate has regular and symmetric astigmatism, but patients with mild, stable irregular astigmatism may also benefit. Ignoring the effect of the posterior corneal astigmatism on the total corneal astigmatism leads to astigmatism prediction errors when implanting toric IOLs. It is preferable to leave patients with a slight amount of with-the-rule astigmatism to compensate for the against-the-rule shift that occurs with advancing age. The most important complication of toric IOLs is misalignment of the IOL, which can occur due to (1) inaccurate calculation of the ideal IOL alignment, (2) inaccurate alignment of the IOL during surgery, or (3) postoperative rotation of the IOL.

Using Vector Analysis to Calculate Surgically Induced Astigmatism and Refractive Change

1. Calculation of surgically induced astigmatism (SIA) is based on the summation of two obliquely crossed spherocylindrical lenses. 2. Astigmatism is a vector quantity, and SIA can be calculated if the pre- and postoperative astigmatism values are known. 3. Fourier analysis can be applied to represent spherocylinders as power vectors for the analysis of surgically induced refractive change (SIRC). 4. The SIRC can be calculated if the pre- and postoperative keratometric K readings are known. 5. With-the-wound and against-the-wound astigmatic change can be calculated by using the meridian of the incision as the reference meridian.