Arturo Ramirez-Miranda

Repeatability, reproducibility, and agreement between three different Scheimpflug systems in measuring corneal and anterior segment biometry.

PURPOSE To assess the reliability of three different Scheimpflug systems and their agreement. METHODS Eighty-four eyes of 42 patients were examined with three Scheimpflug devices: the Galilei G2 Dual Scheimpflug Analyzer (Ziemer Ophthalmic Systems AG, Port, Switzerland), Pentacam HR system (Oculus Optikgerate GmbH, Wetzlar, Germany), and Sirius 3D imaging system (Costruzione Strumenti Oftalmici, Florence, Italy). The central corneal thickness, maximum anterior and posterior corneal elevation, anterior radius of curvature, total higher-order aberrations, and anterior chamber depth were evaluated. Repeatability and re-producibility were evaluated using coefficients of variation and intraclass correlation coefficients. Interdevice agreement was assessed by Bland-Altman comparison analysis. RESULTS The three Scheimpflug systems had excellent repeatability for central corneal thickness, anterior radius of curvature, and anterior chamber depth (coefficients of variation being less than 1%). Repeatability for anterior and posterior corneal evaluation was good for the Pentacam HR and Galilei G2 (coefficients of variation < 10%) and excellent for the Sirius 3D (coefficients of variation = 0). Reproducibility was excellent in the three devices, (intraclass correlation coefficient of more than 0.9). Interdevice agreement was excellent (P > .05) for anterior radius of curvature, central corneal thickness, and anterior chamber depth, but was poor (P < .05) for corneal elevation and higher-order aberrations. CONCLUSIONS Reliability was good to excellent in the three devices for all measured variables. Interdevice agreement analysis suggests that measurements for anterior radius of curvature, central corneal thickness, and anterior chamber depth, but not for maximum anterior and posterior corneal elevation and total higher-order aberrations, from the Sirius 3D and Galilei G2 can be interchangeable with the Pentacam HR.

Autologous simple limbal epithelial transplantation for unilateral limbal stem cell deficiency: multicentre results

Purpose To report outcomes of autologous simple limbal epithelial transplantation (SLET) performed for unilateral limbal stem cell deficiency (LSCD) at multiple centres worldwide. Methods In this retrospective, multicentre, interventional case series, records of patients who had undergone autologous SLET for unilateral LSCD, with a minimum of 6 months of follow-up, were reviewed. The primary outcome measure was clinical success, defined as a completely epithelised, avascular corneal surface. Kaplan–Meier survival curves were constructed and survival probability was calculated. A Cox proportional hazards analysis was done to assess association of preoperative characteristics with risk of failure. Secondary outcome measures included the percentage of eyes achieving visual acuity of 20/200 or better, percentage of eyes gaining two or more Snellen lines and complications encountered. Results 68 eyes of 68 patients underwent autologous SLET, performed across eight centres in three countries. Clinical success was achieved in 57 cases (83.8%). With a median follow-up of 12 months, survival probability exceeded 80%. Presence of symblepharon (HR 5.8) and simultaneous keratoplasty (HR 10.8) were found to be significantly associated with a risk of failure. 44 eyes (64.7%) achieved a visual acuity of 20/200 or better, and 44 eyes (64.7%) gained two or more Snellen lines. Focal recurrences of pannus were noted in 21 eyes (36.8%) with clinical success. Conclusion Autologous SLET is an effective and safe modality for treatment of unilateral LSCD. Clinical success rates and visual acuity improvement are equal to or better than those reported with earlier techniques.

Refractive Lenticule Extraction Complications.

Purpose: To report the complications associated with refractive lenticule extraction (ReLEx) in its 2 modalities: femtosecond lenticule extraction (FLEx) and small incision lenticule extraction (SMILE). Methods: In this retrospective review of a consecutive clinical case series, all patients who had a complicated ReLex FLEx or ReLEx SMILE procedure at the Cornea and External Disease Department at the Instituto de Oftalmologia Fundacion Conde de Valenciana, Mexico City, Mexico, were included. Demographic characteristics, type of complication, and final refraction and visual outcomes were recorded. Results: Our study comprised 94 eyes in the FLEx group and 160 eyes in the SMILE group with a mean follow-up period of 36 months. In the FLEx group, 15 eyes (18.3%) presented surgery-related complications, including suction loss, black spots, bubbles in the interface, and lenticule misdissection. In the SMILE group, 43 eyes (26.9%) had complications, including an epithelial defect (the most frequent), suction loss, opaque bubble layer, cap rupture, and lenticule rupture. Conclusions: Although ReLEx complications can occur, most of them are related to inexperience and have a favorable resolution with no lasting effect on the patients final visual acuity.

Corneal deformation signal waveform analysis in keratoconic versus post-femtosecond laser in situ keratomileusis eyes after statistical correction for potentially confounding factors

PURPOSE: To evaluate and compare corneal biomechanical waveform parameters between keratoconic and post‐femtosecond laser in situ keratomileusis (LASIK). SETTING: Jules Stein Eye Institute, University of California, Los Angeles, California, USA. DESIGN: Comparative case series. METHODS: The Ocular Response Analyzer was used to obtain the corneal hysteresis (CH), corneal resistance factor (CRF), and 39 biomechanical waveform parameters in manifest keratoconic eyes and post‐femtosecond LASIK eyes. Univariate tests were used to assess the difference in each parameter between the 2 groups of eyes. After controlling for central corneal thickness (CCT) and age, a logistic regression model was used to select the parameters most useful in distinguishing between the 2 groups. RESULTS: After statistically controlling for the differences in CCT and age, 7 parameters were found to be the most useful in distinguishing between groups: aplhf (high frequency noise in the region between peaks [P1 and P2]; P<.0001), w2 (width of P2 at base; P=.001), dslop1 (down‐slope of P1 of wave; P<.0001), aindex (degree of “non‐monotonicity” of rising and falling edges of first peak of wave, P=.0007), uslope1 (upslope of the P1 of wave; P=.001), CH (P=.035), and P1area (area under P1 of wave; P=.006). The area under the receiver operating characteristic curve for the model using these parameters was 0.932. CONCLUSIONS: Differences in multiple biomechanical waveform parameters between the keratoconus and post‐LASIK groups suggests that waveform analysis may be useful to differentiate between healthy and diseased biomechanical conditions. Financial Disclosure: Dr. Hamilton has received honoraria from Reichert for educational lectures on corneal biomechanics. No author has a financial or proprietary interest in any material or method mentioned.

Trends in Microbiological and Antibiotic Sensitivity Patterns in Infectious Keratitis: 10-Year Experience in Mexico City.

Purpose: To report the distribution and trends in microbiological and antibiotic sensitivity patterns of infectious keratitis in a 10-year period at a reference center in Mexico City. Methods: In this retrospective observational case series, samples were obtained from corneas with a diagnosis of infectious keratitis from January 2002 to December 2011 at the Institute of Ophthalmology “Conde de Valenciana” in Mexico City. Results of cultures, stains, and specific sensitivity/resistance antibiograms for each microorganism were analyzed. Results: A total of 1638 consecutive corneal scrapings were analyzed. Pathogen was recovered in 616 samples (38%), with bacterial keratitis accounting for 544 of the positive cultures (88%). A nonsignificant increasing trend in gram-negative isolates (P = 0.11) was observed. The most commonly isolated pathogen was Staphylococcus epidermidis, and the most common gram-negative isolated species was Pseudomonas aeruginosa. Methicillin-resistant Staphylococcus aureus (MRSA) was present in 45% of the S. aureus isolates; meanwhile, 53.7% coagulase-negative Staphylococcus isolates were methicillin resistant (MRCNS). Pseudomonas aeruginosa resistance to ceftazidime increased from 15% in the first period to 74% for the last 5 years of the study (P = 0.01). The overall sensitivity for vancomycin of MRSA was 87.5%, whereas 99.6% of the MRCNS were sensitive. Conclusions: There was a nonsignificant increase in the recovered gram-positive and gram-negative microorganisms over time. We observed an increased resistance to methicillin in almost half of the MRSA and MRCNS isolates.

Comparison of Posterior Corneal Imaging Before and After LASIK Using Dual Rotating Scheimpflug and Scanning Slit-Beam Corneal Tomography Systems

PURPOSE To compare the maximum posterior elevation (MPE) measurements before and after LASIK using a dual rotating Scheimpflug (DRS) imaging system (Galilei, Ziemer Ophthalmic Systems, Port, Switzerland) and a scanning slit-beam (SSB) imaging system (Orbscan IIz, Bausch & Lomb, Rochester, NY). METHODS This retrospective study included 78 eyes from 78 patients who underwent myopic LASIK. Preoperative and postoperative data collected included anterior and posterior best-fit sphere radius and axial curvature readings, posterior central elevation (PCE), and MPE relative to a best-fit sphere using a 7.8-mm region of interest. Data were compared using paired t test analysis. RESULTS Mean preoperative PCE (5.06 ± 2.29 μm with the DRS system and 12.78 ± 6.90 μm with the SSB system) and MPE (4.87 ± 4 μm with the DRS system and 15.44 ± 9.78 μm with the SSB system) were statistically different (P < .001). Mean postoperative PCE (4.55 ± 2.34 μm with the DRS system and 20.59 ± 8.11 μm with the SSB system) and MPE (4.90 ± 3.35 μm with the DRS system and 24.95 ± 10.15 μm with the SSB system) were statistically different (P < .001). The difference between preoperative and postoperative MPE measurements by DRS was not statistically significant (P = .953), whereas the difference measured by SSB was statistically significant (P < .001). CONCLUSIONS The consistency of DRS measurements suggests that the posterior surface of the cornea does not change appreciably after keratorefractive surgery and is imaged more accurately using DRS compared with SSB. The DRS system affords confidence in interpreting data that are useful for discerning morphologic abnormalities of the cornea, both before and after keratorefractive surgery.

Multifocal toric intraocular lens implantation for forme fruste and stable keratoconus.

PURPOSE To describe the results of multifocal toric intraocular lens implantation in two patients (one with forme fruste keratoconus and the other with frank but stable keratoconus). METHODS A 50-year-old woman with forme fruste keratoconus and positive family history of keratoconus and a 42-year-old man with frank keratoconus underwent corneal collagen cross-linking. Uncorrected distance visual acuity was 20/800 in the right eye and 20/400 in the left eye and 20/400 in the right eye and 20/100 in the left eye, respectively. Refractive lens exchange was performed using multifocal toric intraocular lenses in both cases. RESULTS After phacoemulsification, uncorrected distance visual acuity, corrected distance visual acuity, binocular uncorrected distance visual acuity was 20/25 and 20/30 in cases 1 and 2, respectively, and residual refraction was within 0.5 diopters of emmetropia in both cases. Patients were subjectively satisfied. CONCLUSIONS Presbyopic treatment options are scarce for patients with keratoconus and multifocal toric intraocular lenses may be useful in selected cases.

Minor ipsilateral simple limbal epithelial transplantation (mini-SLET) for pterygium treatment

We describe a novel surgical technique for pterygium removal taking advantage of the properties of amniotic membrane and limbal epithelial stem cells. A total of 10 eyes underwent pterygium excision with amniotic membrane coverage of the bare sclera and placement of pieces of limbal epithelium in a linear fashion in the affected limbal area covered by a second amniotic membrane using fibrin glue. After up to 8 months of follow-up, there were no signs of early recurrence or sight-threatening complications. The minor ipsilateral simple limbal epithelial transplantation technique for the treatment of pterygium requires less tissue than the conventional conjunctival autograft, leaving healthy conjunctiva if needed for another procedure in the future and offers the advantages of epithelial stem cells, which in the long term may reduce the rate of recurrence significantly.

Cicatricial changes in ocular pemphigus.

PurposeTo describe the clinical characteristics of ocular involvement in patients with pemphigus at an ophthalmological referral center.MethodsA retrospective review was conducted on patients with the immunopathological diagnosis of pemphigus examined between 1 January 2000 and 1 April 2010. Uncorrected distance visual acuity (UDVA), best corrected distance visual acuity (BCVA), ocular symptoms, and ocular surface inflammatory and scarring changes were assessed.ResultsA total of 15 patients were identified, with a mean age of 68.27±14.35 years, and 80% (n=12) were female. Extraocular involvement was reported in one patient. All of the eyes showed cicatricial changes in the conjunctiva. In all, 6 eyes (20%) were classified as stage I; 12 eyes (40%) as stage II; 10 eyes (33%) as stage III; and 2 eyes (7%) as stage IV. A statistically significant association was found between BCVA and the severity of ocular involvement. The mean BCVA logMAR was 1.66 (20/914), with a range from logMAR 0 (20/20) to logMAR 4 (NLP). Other ocular diseases were found in 8 (53.3%), systemic diseases in 10 (66.7%), and the use of pemphigus-inducing drugs in 10 patients (66.7%).ConclusionsThe present report represents the largest series of ocular involvement in pemphigus confirmed by immunopathology. The clinical manifestations varied from conjunctival hyperemia to corneal scarring and perforation. There was a strong association between scarring changes and low BCVA. Ocular and systemic diseases as well as the use of pemphigus-inducing drugs may predispose to ocular cicatricial changes observed in this series.

Limbal Lacuna: A Novel Limbal Structure Detected by In Vivo Laser Scanning Confocal Microscopy

Limbal lacuna is a novel limbal structure detected by in vivo laser scanning confocal microscopy in normal subjects and the unaffected limbus in sectoral limbal stem cell deficiency. This unique structure harbors normal limbal epithelial cells deep inside the limbal stroma and the palisades of the Vogt are absent in these subjects. This well-protected location could better shield limbal stem/progenitor cells from damage and might serve as an alternative niche for limbal stem/progenitor cells.