Julie M. Schallhorn

Optical coherence tomography of clear corneal incisions for cataract surgery

PURPOSE: To study the architecture of clear corneal incisions for phacoemulsification cataract surgery using optical coherence tomography (OCT). SETTING: Doheny Eye Institute and Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA. METHODS: This prospective study comprised 20 eyes of 20 patients 1 month after cataract surgery performed by 1 of 2 experienced surgeons. Temporal clear corneal single‐plane incisions were made with 3.0 mm metal keratomes. Each eye was scanned before and 1 month after surgery with a prototype high‐speed anterior segment OCT system (Carl Zeiss Meditec, Inc.). The OCT scans were repeated 3 times during the same visit. The length of the corneal incision, thickness of the cornea, and position of the incision (distance from external wound edge to scleral spur) were measured using a computer caliper. The angle of the incision relative to the corneal surface was then calculated. RESULTS: The mean corneal incision length was 1.81 mm ± 0.27 (SD), the mean corneal thickness at the incision was 747 ± 67μm, and the mean distance between the incision and the scleral spur was 1.46 ± 0.24 mm. The mean angle of the incision was 26.8 ± 5.5 degrees. The measurements were repeatable to within ±0.072 mm (pooled standard deviation) for the incision length, ±11 μm for the corneal thickness, and ±0.042 mm for the position of the incision. CONCLUSIONS: Optical coherence tomography allowed excellent evaluation of corneal incisions in cataract surgery postoperatively. Measurements of wound dimensions using OCT were highly repeatable.

Factors that Influence Intraocular Pressure Changes after Myopic and Hyperopic LASIK and Photorefractive Keratectomy: A Large Population Study

PURPOSE To describe the factors that influence the measured intraocular pressure (IOP) change and to develop a predictive model after myopic and hyperopic LASIK and photorefractive keratectomy (PRK) in a large population. DESIGN Retrospective, observational case series. PARTICIPANTS Patients undergoing primary PRK or LASIK with a refractive target of emmetropia between January 1, 2008, and October 5, 2011. METHODS The Optical Express database was queried for all subjects. Data were extracted on procedure specifics, preoperative central corneal thickness (CCT), IOP (using noncontact tonometry), manifest refraction, average keratometry, age, gender, and postoperative IOP at 1 week, 1 month, and 3 months. A linear mixed methods model was used for data analysis. MAIN OUTCOME MEASURES Change in IOP from preoperatively to 1 month postoperatively. RESULTS A total of 174 666 eyes of 91 204 patients were analyzed. Hyperopic corrections experienced a smaller IOP decrease than myopic corrections for both PRK and LASIK (P<0.0001). Patients who underwent LASIK had a 0.94 mmHg (95% confidence interval [CI], 0.89-0.98) greater IOP decrease than patients who underwent PRK (P<0.0001), reflecting the effect of the lamellar flap. The decrease in IOP was linearly related to preoperative manifest spherical equivalent (MSE) for myopic PRK and LASIK (P<0.0001), weakly correlated with preoperative MSE after hyperopic LASIK, and not related to preoperative MSE after hyperopic PRK. The single greatest predictor of IOP change was preoperative IOP across all corrections. By using the available data, a model was constructed to predict postoperative IOP change at 1 month; this was able to explain 42% of the IOP change after myopic LASIK, 34% of the change after myopic PRK, 25% of the change after hyperopic LASIK, and 16% of the change after hyperopic PRK. CONCLUSIONS Myopic procedures lower measured IOP more than hyperopic procedures; this decrease was proportional to the amount of refractive error corrected. Independent of the refractive correction, the creation of the lamellar LASIK flap decreased measured IOP by 0.94 mmHg. A best-fit model for IOP change was developed that may allow better interpretation of post-laser vision correction IOP values.

Quantification and Patterns of Endothelial Cell Loss Due to Eye Bank Preparation and Injector Method in Descemet Membrane Endothelial Keratoplasty Tissues.

Purpose: To evaluate endothelial cell damage after eye bank preparation and passage through 1 of 2 different injectors for Descemet membrane endothelial keratoplasty grafts. Methods: Eighteen Descemet membrane endothelial keratoplasty grafts were prepared by Lions VisionGift with the standard partial prepeel technique and placement of an S-stamp for orientation. The grafts were randomly assigned to injection with either a glass-modified Jones tube injector (Gunther Weiss Scientific Glass) or a closed-system intraocular lens injector (Viscoject 2.2; Medicel). After injection, the grafts were stained with the vital fluorescent dye Calcein AM and digitally imaged. The percentage of cell loss was calculated by measuring the area of nonfluorescent pixels and dividing it by the total graft area pixels. Results: Grafts injected using the modified Jones tube injector had an overall cell loss of 27% ± 5% [95% confidence interval, 21%–35%]. Grafts injected using the closed-system intraocular lens injector had a cell loss of 32% ± 8% (95% confidence interval, 21%–45%). This difference was not statistically significant (P = 0.3). Several damage patterns including damage due to S-stamp placement were observed, but they did not correlate with injector type. Conclusions: In this in vitro study, there was no difference in the cell loss associated with the injector method. Grafts in both groups sustained significant cell loss and displayed evidence of graft preparation and S-stamp placement. Improvement in graft preparation and injection methods may improve cell retention.

A National Survey of Practice Patterns: Temporal Artery Biopsy

OBJECTIVE To assess current clinical practice patterns for temporal artery biopsy (TAB) among clinicians in establishing the diagnosis of giant cell arteritis. DESIGN A survey was sent via e-mail using the Survey Monkey website (www.surveymonkey.com; accessed January 24, 2013). The survey initially was sent in July 2010 and continued through October 2010. PARTICIPANTS The survey was sent via e-mail to the members and affiliates of the American Society of Ophthalmic Plastic and Reconstructive Surgery, the North American Neuro-Ophthalmology Society, and the American College of Rheumatology. METHODS Data from the survey were collected via Survey Monkey and data analysis was performed using the Fisher exact test and Wilcoxon rank-sum test. MAIN OUTCOME MEASURES Response to the survey questions on primary unilateral versus bilateral biopsy, performing second-side biopsy if first side results were negative, and the duration for which biopsy findings are reliable after initiating immunosuppressive therapy. RESULTS The self-described primary subspecialty of the 1074 respondents was as follows: oculoplastic surgery (n = 127), neuro-ophthalmology (n = 119), rheumatology (n = 799), and other (n = 28). Overall, 66% of respondents advocated initial unilateral TAB, 18% advocated bilateral biopsy in all cases, and 16% recommended either unilateral or bilateral TAB depending on the degree of clinical suspicion. Rheumatologists were 4.5 times more likely to advocate initial bilateral biopsy than neuro-ophthalmologists or oculoplastic surgeons (P<0.0001, Fisher exact test). Most respondents believed that biopsy results were accurate for more than 14 days. These results were not affected by stratification of years in practice by the Kruskal-Wallis rank-sum test. CONCLUSIONS Temporal artery biopsy practices vary greatly among treating physicians. This lack of consensus underscores the need for a systematic assessment of varying practice patterns. FINANCIAL DISCLOSURE(S) The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Differentiating Keratoconus and Corneal Warpage by Analyzing Focal Change Patterns in Corneal Topography, Pachymetry, and Epithelial Thickness Maps.

Purpose To differentiate between keratoconus and contact lens-related corneal warpage by combining focal change patterns in anterior corneal topography, pachymetry, and epithelial thickness maps. Methods Pachymetry and epithelial thickness maps of normal, keratoconus, and warpage, and forme fruste keratoconus (FFK) eyes were obtained from a Fourier-domain optical coherence tomography (OCT). Epithelial pattern standard deviation (PSD) was calculated and combined with two novel indices, the Warpage Index and the Anterior Ectasia Index, to differentiate between normal, keratoconus, and warpage eyes. The values of the three parameters were compared between groups. Results The study included 22 normal, 31 keratoconic, 11 warpage, and 8 FFK eyes. The epithelial PSD was normal (< 0.041) for 100% normal eyes and abnormal (> 0.041) for 100% of keratoconic eyes, 81.8% of warpage eyes, and 87.5% of FFK eyes. The Anterior Ectasia Index of normal eyes (1.66 ± 0.74) was significantly lower than that for the keratoconus eyes (17.5 ± 7.17), the warpage eyes (2.98 ± 1.69), and the FFK eyes (6.95 ± 5.86). The Warpage Index was positive in all warpage eyes and negative for all keratoconic and FFK eyes except three wearing rigid gas-permeable contact lens. Conclusions The epithelial PSD can distinguish normal from keratoconus or warpage, but does not distinguish between these two conditions. The Anterior Ectasia Index is abnormal in keratoconus but not warpage. The Warpage Index is positive for warpage and negative for keratoconus, except in cases where keratoconus and warpage coexist. Together, the three parameters are strong tripartite discriminators of normal, keratoconus, and warpage.

Patient-reported outcomes 5 years after laser in situ keratomileusis.

Purpose To assess vision‐related, quality‐of‐life outcomes 5 years after laser in situ keratomileusis (LASIK) and determine factors predictive of patient satisfaction. Setting Optical Express, Glasgow, Scotland. Design Retrospective case series. Methods Data from patients who had attended a clinical examination 5 years after LASIK were analyzed. All treatments were performed using the Visx Star S4 IR excimer laser. Patient‐reported satisfaction, the effect of eyesight on various activities, visual phenomena, and ocular discomfort were evaluated 5 years postoperatively. Multivariate regression analysis was performed to determine factors affecting patient satisfaction. Results The study comprised 2530 patients (4937 eyes) who had LASIK. The mean age at the time of surgery was 42.4 years ± 12.5 (SD), and the preoperative manifest spherical equivalent ranged from −11.0 diopters (D) to +4.88 D. Five years postoperatively, 79.3% of eyes were within ±0.50 D of emmetropia and 77.7% of eyes achieved monocular uncorrected distance visual acuity (UDVA) and 90.6% of eyes achieved binocular UDVA of 20/20 or better. Of the patients, 91.0% said they were satisfied with their vision and 94.9% did not wear distance correction. Less than 2.0% of patients noticed visual phenomena, even with spectacle correction. Major predictors of patient satisfaction 5 years postoperatively were postoperative binocular UDVA (37.6% variance explained by regression model), visual phenomena (relative contribution of 15.0%), preoperative and postoperative sphere and their interactions (11.6%), and eyesight‐related difficulties with various activities such as night driving, outdoor activities, and reading (10.2%). Conclusion Patient‐reported quality‐of‐life and satisfaction rates remained high 5 years after LASIK. Uncorrected vision was the strongest predictor of satisfaction. Financial Disclosure Dr. S.C. Schallhorn is a consultant to Abbott Medical Optics, Inc., Zeiss Meditec AG, and Autofocus Inc. and a global medical director for Optical Express. No other author has a financial or proprietary interest in any material or method mentioned.

Energy Setting and Visual Outcomes in SMILE: A Retrospective Cohort Study

PURPOSE To assess the independent effect of energy setting on postoperative uncorrected distance visual acuity (UDVA) in small incision lenticule extraction (SMILE) and further investigate an optimal energy setting for the 4.5-μm spot-track-distance, which is in wide clinical use. METHODS A total of 1,130 eyes were included in a retrospective cohort study from Tianjin Eye Hospital, Tianjin Medical University from April 2015 to July 2016. Energy settings and baseline characteristics were recorded and 3-month UDVA was tested by a nurse blinded to the energy settings used. Multiple regression analysis and generalized estimating equations were used to take into account the correlation between the measurements from two eyes. RESULTS The 3-month UDVA (mean ± standard deviation) of 125 to 160 nJ (by 5-nJ increments) was 1.39 ± 0.19, 1.40 ± 0.32, 1.33 ± 0.27, 1.36 ± 0.27, 1.34 ± 0.25, 1.29 ± 0.19, 1.36 ± 0.27, and 1.19 ± 0.22, respectively. Energy was significantly associated with postoperative logMAR UDVA in different models and the regression coefficient (β) was robust (β = 0.01, 95% confidence interval = 0.00 to 0.01). The regression coefficient β (0.01, 95% confidence interval = 0.00 to 0.02, P = .0029) of energy (125 to 150 nJ, by 5-nJ increments) on 4.5-μm spot-track-distance was still associated with the logMAR UDVA when adjusted for sex, age, myopia, astigmatism, mean keratometry, central corneal thickness, preoperative logMAR CDVA, and side spot-track-distance. CONCLUSIONS The lower end of the energy studied was associated with a better postoperative UDVA in this population. The spot-track-distance of 4.5 μm with 125 nJ energy was the optimal combination within this range. [J Refract Surg. 2018;34(1):11-16.].

Distinguishing between contact lens warpage and ectasia: Usefulness of optical coherence tomography epithelial thickness mapping

PURPOSE To distinguish between corneal ectasia and contact lens-related warpage by characteristic patterns on corneal topography and optical coherence tomography (OCT) epithelial thickness maps. SETTING Casey Eye Institute, Portland, Oregon, USA. DESIGN Prospective and retrospective case series. METHODS Axial and mean power maps were obtained on corneal topography systems. Epithelial thickness maps were generated using RTVue OCT. A sector divider was applied to all maps. The locations of the minimum epithelial thickness, maximum epithelial thickness, maximum axial power, and maximum mean power were determined based on sector averages. Agreement was defined as the extremums occurring in the same or adjacent sectors. RESULTS Twenty-one eyes with keratoconus, 6 eyes with forme fruste keratoconus (better eye of asymmetric keratoconus), and 15 eyes with contact lens-related warpage were identified. The keratoconus and forme fruste keratoconus eyes had coincident topographic steepening with epithelial thinning. The locations of minimum epithelial thickness and maximum axial power agreed in 90% of the keratoconic eyes, while the minimum epithelial thickness and maximum mean power agreed in 95% of them. Conversely, the warpage eyes had coincident topographic steepening with epithelial thickening and normal pachymetry maps. The locations of maximum epithelial thickness and maximum axial power agreed in 93% of the warpage eyes, while the maximum epithelial thickness and maximum mean power agreed in all warpage eyes. CONCLUSION Results show that epithelial thickness maps and corneal topographic maps are powerful synergistic tools in evaluating eyes with abnormal topography and can help differentiate between keratoconus and nonectatic conditions.

Outcomes and complications of excimer laser surgery in patients with collagen vascular and other immune-mediated inflammatory diseases

Purpose To assess refractive and visual outcomes and postoperative complications in a large number of patients with well‐controlled collagen vascular and other immune‐mediated inflammatory diseases. Setting Optical Express, Glasgow, United Kingdom. Design Retrospective case series. Methods The files were reviewed of patients who had collagen vascular and other immune‐mediated inflammatory diseases and who had excimer laser surgery between 2008 and 2015. In all cases, the disease was well controlled with no flare or symptoms for a minimum of 6 months preoperatively. Results The study comprised 622 patients (1224 eyes) with 1 of the following underlying diseases: rheumatoid arthritis (50.6% of patients), systemic lupus erythematosus (19.5%), psoriatic arthritis (10.5%), sarcoidosis (10.0%), ankylosing spondylitis (6.4%), multiple sclerosis (1.9%), or scleroderma (1.1%). Laser in situ keratomileusis (LASIK) was performed in 1114 eyes (91.0%) and photorefractive keratectomy (PRK) in 110 eyes (9.0%). The mean follow‐up was 10.9 months. The preoperative spherical equivalent ranged between −10.13 diopters (D) and +4.13 D (LASIK) and −9.50 D and +4.00 D (PRK). Postoperatively, 81.8% LASIK eyes and 82.3% PRK eyes were within ±0.50 D. The uncorrected distance visual acuity was 20/20 or better in 76.8% and 73.4%, respectively. Complications were mostly those that would be expected after excimer laser surgery in a population of patients without disease with the exception of 1 peripheral flap melt that responded to treatment with topical steroids. Conclusion Excimer laser surgery can be safely performed in patients with well‐controlled collagen vascular or other immune‐mediated inflammatory disease. Financial Disclosure Dr. S.C. Schallhorn is a consultant to Abbott Medical Optics, Inc., Acufocus, Inc., and Carl Zeiss Meditec AG, and a global medical director for Optical Express. No other author has a financial or proprietary interest in any material or method mentioned.

Outcomes of excimer laser enhancements in pseudophakic patients with multifocal intraocular lens

Purpose The aim of this study was to assess visual and refractive outcomes of laser vision correction (LVC) to correct residual refraction after multifocal intraocular lens (IOL) implantation. Patients and methods In this retrospective study, 782 eyes that underwent LVC to correct unintended ametropia after multifocal IOL implantation were evaluated. Of all multifocal lenses implanted during primary procedure, 98.7% were refractive and 1.3% had a diffractive design. All eyes were treated with VISX STAR S4 IR excimer laser using a convectional ablation profile. Refractive outcomes, visual acuities, patient satisfaction, and quality of life were evaluated at the last available visit. Results The mean time between enhancement and last visit was 6.3±4.4 months. Manifest spherical equivalent changed from −0.02±0.83 D (−3.38 D to +2.25 D) pre-enhancement to 0.00±0.34 D (−1.38 D to +1.25 D) post-enhancement. At the last follow-up, the percentage of eyes within 0.50 D and 1.00 D of emmetropia was 90.4% and 99.5%, respectively. Of all eyes, 74.9% achieved monocular uncorrected distance visual acuity 20/20 or better. The mean corrected distance visual acuity remained the same before (−0.04±0.06 logMAR [logarithm of the minimum angle of resolution]) and after LVC procedure (−0.04±0.07 logMAR; P=0.70). There was a slight improvement in visual phenomena (starburst, halo, glare, ghosting/double vision) following the enhancement. No sight-threatening complications related to LVC occurred in this study. Conclusion LVC in pseudophakic patients with multifocal IOL was safe, effective, and predictable in a large cohort of patients.