Sumitra S. Khandelwal

Corneal cross-linking

Since its inception in the late 1990s, corneal cross-linking has grown from an interesting concept to a primary treatment for corneal ectatic disease worldwide. Using a combination of ultraviolet-A light and a chromophore (vitamin B2, riboflavin), the cornea can be stiffened, usually with a single application, and progressive thinning diseases such as keratoconus arrested. Despite being in clinical use for many years, some of the underlying processes, such as the role of oxygen and the optimal treatment times, are still being worked out. More than a treatment technique, corneal cross-links represent a physiological principle of connective tissue, which may explain the enormous versatility of the method. We highlight the history of corneal cross-linking, the scientific underpinnings of current techniques, evolving clinical treatment parameters, and the use of cross-linking in combination with refractive surgery and for the treatment of infectious keratitis.

Current and future applications of corneal cross-linking.

Purpose of review To review current concepts and future directions of corneal cross-linking (CXL) as a treatment for keratoconus, ectasia after refractive surgery and infectious keratitis. Recent findings Several important laboratory and clinical studies have established the safety and success of corneal cross-linking for the treatment of keratoconus and other corneal ectasias. Recently, additional studies have analyzed new directions and controversies in corneal cross-linking, exploring new indications, comparing new techniques and analyzing results of new protocols. Summary The results of bench and clinical research are providing the foundation to allow for protocol modifications of the standard cross-linking protocols and expansion of cross-linking concepts for techniques such as accelerated cross-linking, epithelium-sparing protocols and measurement of progression and success.

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.

Intraocular lens alignment methods.

Purpose of review This article reviews current concepts in intraocular lens alignment strategies to maximize intraocular lens (IOL) positioning. Recent findings A variety of strategies has been developed to maximize toric IOL position, including preoperative calculators to determine the appropriate IOL power and orientation, intraoperative alignment devices, and postoperative software to determine if IOL rotation would be beneficial for refractive outcomes. Summary The combination of using multiple toric IOL calculators and intraoperative alignment devices has improved toric IOL outcomes. The relationship of the posterior corneal power and its effect on outcomes remains to be fully elucidated. Postoperative IOL rotation may be necessary even when the IOL is aligned as planned because of surgically induced astigmatism.

Indications and outcomes of resident-performed cataract surgery requiring return to the operating room

Purpose To identify the clinical and operative factors predicting reoperation within 30 days of resident‐performed cataract surgery and correlate them with 1‐year visual outcomes. Setting Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas, USA. Design Retrospective cohort study. Methods The study assessed patients who had resident‐performed cataract surgery between 2005 and 2013 and required return to the operating room for a second surgery on the same eye within 30 days. Preoperative and intraoperative risk factors were assessed. Outcome measures included corrected distance visual acuity (CDVA) at 1 year. Results A review of 6644 resident‐performed cataract surgeries showed that 54 eyes (0.85%) of 54 patients required a return to the operating room within 30 days. The reoperation rate was higher in the first half of the academic year (1.18%) than in the second half (0.55%) (P = .004). The mean CDVA 1 year postoperatively was 20/40, with a loss of lines of vision in 4 eyes. The mean operative time was 59.23 minutes ± 35.05 (SD). A longer intraoperative time was predictive of a worse visual outcome (P < .01). Conclusions Despite the need for reoperation within 30 days, most patients achieved improved visual acuity. The reoperation rate was significantly lower in the second half of the academic year. Increased operation times correlated with worse visual acuity independent of other variables. Financial Disclosure None of the authors has a financial or proprietary interest in any material or method mentioned.

Outcomes of anterior chamber intraocular lenses placed by surgeons in training.

Purpose To evaluate risk factors and outcomes of unplanned, primary anterior chamber intraocular lenses (AC IOLs) placed by surgeons in training. Setting Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas, USA. Design Retrospective case series. Methods Cataract surgeries performed primarily by a resident surgeon that resulted in an unplanned AC IOL were included. Cases that had concomitant retinal surgery were excluded. Preoperative data gathered included corrected distance visual acuity (CDVA), intraocular pressure (IOP), and ocular comorbid conditions. Operative times and complications requiring an AC IOL were assessed. Postoperative CDVA, IOP, corneal edema, persistent intraocular inflammation, macular edema, and need for additional surgery were analyzed for the first postoperative year. Results Twenty‐two eyes were included. The mean preoperative CDVA was 1.24 logMAR ± 0.92 SD and the mean preoperative IOP was 17.55 ± 3.88 mm Hg. The mean operative time was 103 ± 30 minutes. The most common operative complications necessitating an AC IOL were 7 (32%) capsule tears with vitreous prolapse requiring anterior vitrectomy and 7 (32%) capsule tears, zonular dehiscence, and vitreous prolapse requiring anterior vitrectomy. By the first postoperative year, the mean visual acuity was 0.40 ± 0.58 logMAR and the IOP was 15.05 ± 6.01 mm Hg. The most common complications 1 year postoperatively included persistent macular edema (23%) and need for additional surgery (18%). Conclusion This group of patients who received unplanned primary AC IOLs by surgeons in training had improved visual acuity and well‐controlled IOP 1 year postoperatively. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Preoperative Prediction of the Optimal Toric Intraocular Lens Alignment Meridian

PURPOSE To determine whether any of three keratometry devices is superior to the others in predicting the ideal toric intraocular lens (IOL) alignment meridian. METHODS A retrospective review was performed to identify patients who underwent cataract phacoemulsification with toric IOL implantation from November 2014 to November 2016 at a single academic institution. For each patient, corneal measurements were performed with an optical low-coherence reflectometer/autokeratometer (OLCR), a dual Scheimpflug/Placido analyzer, and a color light-emitting diode (LED) topographer. Postoperatively, the ideal toric IOL alignment meridian that would have resulted in the least amount of residual astigmatism was determined using the online Berdhal & Hardten Toric Results Analyzer (BHTRA). To determine the prediction error, this ideal alignment meridian was compared to the corneal meridian with the highest refractive power, as provided by the three devices. RESULTS Fifty-six eyes of 56 patients were included in the study. The mean absolute errors in the toric IOL alignment meridians of the color LED topographer, dual Scheimpflug/Placido analyzer, and OLCR were 5.2° ± 5.2°, 7.6° ± 5.7°, and 5.4° ± 5.1°, respectively. There was no significant difference in the ability of each device to predict the ideal alignment meridian as determined by the BHTRA. CONCLUSIONS The color LED topographer, dual Scheimpflug/Placido analyzer, and OLCR may all be used to preoperatively determine the best alignment meridian for toric IOL placement. Surgeons should use their best judgment in determining which device to use in preoperative planning for individual patients. [J Refract Surg. 2018;34(8):515-520.].

Phacoemulsification of the rock-hard dense nuclear cataract: Options and recommendations

We describe the essential steps in the successful phacoemulsification of the rock-hard, dense cataract. Appropriate and directed preoperative history, physical examination, and diagnostics allow the surgeon to select the best incision, anesthesia, and intended surgical technique for a given dense nuclear challenge. Hard nucleus-specific approaches for hydrodissection, pupil management, and zonular protection then allow the surgeon to approach the rock-hard nucleus with maximum safety. Dense nuclear dismantling options are then discussed in detail along with fluidic and power modulation considerations. Various specific phacoemusification machine settings for rock-hard cataracts from the authors representing several different phaco systems are then presented. The combination of these steps and considerations allow a more successful dense cataract removal and potential restoration of vision for patients. This paper represents the collective experience and advice of the Challenging and Complex Cataract Surgery Subcommittee.

Sequential traumatic corneal open globe rupture in a patient with osteogenesis imperfecta type I

Purpose To report a case of sequential open globe rupture in a young patient with osteogenesis imperfecta type I following minor accidental blunt injury. This represented the patients sole clinical manifestation of connective tissue disease, leading to a diagnosis of osteogenesis imperfecta type I at the age of 12 years old. Observations A 12-year-old male presented with right eye pain following accidental blunt trauma at school while wearing protective lenses. One year ago, he required surgical repair of a left open globe following blunt trauma during a middle school basketball game. His exam was significant for a full-thickness corneal laceration, necessitating open globe repair of his right eye, which was remarkably difficult given the poor tissue constitution of the cornea and sclera. He was referred to a genetics specialist, where he was found to have a pathogenic heterozygous splice site variant in the COL1A1 gene, consistent with osteogenesis imperfecta type I. Conclusions and importance Connective tissue disease should be considered in any case of open globe rupture following minor trauma, even in the absence of other clinical manifestations of the disease. The surgical management of these patients is particularly challenging due to the fragility of the connective tissue. Early diagnosis of connective tissue disease is important to preserve visual acuity and prevent further damage to the eyes.