Screening for Keratoconus in a High-Risk Adolescent Population.

PURPOSE: To estimate the prevalence of keratoconus (KC) in a majority-Emirati adolescent population and to demonstrate the feasibility of screening using a dual Scheimpflug and Placido imaging device. METHODS: Adolescent subjects from two secondary schools in Abu Dhabi, UAE underwent corneal imaging with the Galilei tomographer (Ziemer Ophthalmic Systems AG, Port, Switzerland). The prevalence of KC and KC suspects was determined using a combination of both subjective and objective criteria. Objective criteria included these KC indices: percent probability of keratoconus, inferior-superior index, asphericity asymmetry index, maximum keratometry and thinnest pachymetry. Subjective pattern analysis was performed by four experienced cornea specialists. Subjects were classified by each cornea specialist into three groups: normal, KC and KC suspect. The final classification was made by group reconciliation of cases where disagreement was present. Inter-observer agreement was assessed with the kappa statistic. RESULTS: A total of 839 eyes of 420 students between 10 and 19 years of age underwent corneal tomography. After the exclusion of 251 eyes due to insufficient scan quality based on internal instrument-derived standards, 588 eyes of 339 subjects were included in the analysis. The prevalence of KC and KC suspect was estimated to be 2.7% (95% CI [1.2%, 5.0%]) and 19.8% (95% CI [15.7%, 24.4%]), respectively. There was a strong inter-observer agreement between examiners' classification of the subjects' KC status (kappa = 0.84). CONCLUSION: KC is highly prevalent in Emirati adolescents. Screening secondary school students for keratoconus appears to be feasible and may be indicated in this population to improve early detection and intervention.

Association of Ramadan daytime fasting with ocular surface inflammation and dry eye.

PURPOSE: Despite the widespread practice of fasting, there are no studies looking at ocular surface inflammation, specifically matrix metalloproteinase 9 (MMP-9) testing, during fasting. In this prospective study, we wanted to evaluate the effect of Ramadan fasting on the level of tear film MMP-9 as well as other standard indicators of dry eye disease. METHODS: Forty healthy patients without history of ocular disease were tested before and toward the end of Ramadan. Each patient was assessed at each timepoint for tear film MMP-9 positivity as measured by a commercially available test (InflammaDry; Quidel Corp., San Diego, CA, USA) which detects MMP-9 levels of more than 40 ng/ml. Ocular surface disease index (OSDI) scores, tear breakup time (TBUT), Schirmer I test (S1T) and corneal fluorescein staining (CFS) were also evaluated at each timepoint. RESULTS: InflammaDry was positive in 10 patients (25%) prior to Ramadan and 21 patients (52.5%) during Ramadan fasting, and this change was statistically significant (p = 0.02). Mean TBUT decreased from 7 s prior to Ramadan to 5.3 s during Ramadan fasting, and this change was statistically significant (p = 0.01). OSDI, CFS and S1T did not show any statistically significant changes (p > 0.05 for all). CONCLUSION: Ramadan fasting has a significant impact on TBUT and ocular surface inflammation detected by Inflamma Dry testing. Patients who suffer from dry eye disease and those who develop symptoms during Ramadan are advised to consult with a physician before or during Ramadan fasting.

Biological and biomechanical responses to traditional epithelium-off and transepithelial riboflavin-UVA CXL techniques in rabbits.

PURPOSE: To compare the biological effects of riboflavin-ultraviolet A (UVA) corneal cross-linking (CXL) performed with a traditional epithelium-off method to several transepithelial methods in a rabbit model. Preliminary experiments on biomechanical rigidity were also performed. METHODS: Four treatment groups were included: (1) standard epithelium-off, (2) tetracaine transepithelial, (3) benzal-konium chloride-ethylenediaminetetraacetic acid (BKC-EDTA) transepithelial, and (4) femtosecond laser-assisted transepithelial riboflavin-UVA CXL. Six eyes from each treatment group and the untreated control group were analyzed at 24 hours and 2 months after treatment in wound healing studies. The TUNEL assay was performed to detect the extent of stromal cell death. Optical density was measured with a Scheimpflug analyzer. The corneal stiffening effect was quantitated in three eyes from each group using optical coherence elastography performed 2 months after treatments. RESULTS: Twenty-four hours after CXL, stromal cell death extended full corneal thickness with both standard epithelium-off CXL and femtosecond laser-assisted CXL, but only approximately one-third stromal depth after BKC-EDTA transepithelial CXL. Negligible stromal cell death was detected with tetracaine transepithelial CXL. Cell death results were statistically different between the BKC-EDTA transepithelial CXL and standard epithelium-off CXL groups (P < .0001). Significant corneal opacity differences were noted. Standard epithelium-off CXL had the greatest density and tetracaine transepithelial CXL had the least density compared to the control group after treatment. As measured with optical coherence elastography, a trend toward greater mean stiffening was observed with BKC-EDTA transepithelial CXL than with epithelium-off CXL, femtosecond laser-assisted CXL, or tetracaine transepithelial CXL, but the result did not reach statistical significance. All of the CXL treatment groups exhibited significantly smaller variance of stiffness compared to the control group. CONCLUSION: In the rabbit model, BKC-EDTA transepithelial CXL produced less stromal cell death and less risk of endothelial cell damage than standard epithelium-off CXL or femtosecond laser-assisted CXL. Additional study is needed to determine whether biomechanical stiffness is significantly different between the epithelium-off CXL and transepithelial CXL groups.

Flap relift for retreatment after femtosecond laser-assisted LASIK.

PURPOSE: To analyze the results of LASIK retreatment performed by relifting the original femtosecond laser-created flap. METHODS: A retrospective analysis was performed on 1298 eyes from 688 patients treated with LASIK using the femtosecond laser to identify 88 consecutive eyes of 71 patients that underwent attempted flap lift to treat residual refractive error. The eyes were separated in groups in which the flap lift was possible or flap lift was not possible to investigate factors that could make flap lifting more difficult. The main factors evaluated were bed and side-cut energy and time between original surgery and retreatment. In addition, all retreated eyes were studied as a group to evaluate the refractive outcomes of flap lift retreatment. RESULTS: In 10 (11.3%) retreated eyes, flap lift was not possible without risk of flap injury due to strong healing of the original femtosecond laser interface. The group of eyes in which the flap could not be relifted had the attempted retreatment performed a longer time period after original LASIK (10.3±3.3 months) compared to the group in which the flap could be re-lifted (5.24±3.14 months) (P<.001). No significant differences were found between groups in any other parameters, including bed and side-cut energies. After retreatment, 82% of eyes achieved 20/20 or better uncorrected visual acuity. CONCLUSIONS: This study provides clinical evidence that flap lift retreatment after femtosecond laser-assisted LASIK achieves excellent clinical results and is significantly easier to perform in the first 6 to 8 months after primary LASIK.

Long-term potency, sterility, and stability of vancomycin, ceftazidime, and moxifloxacin for treatment of bacterial endophthalmitis.

PURPOSE: To determine the long-term potency, sterility, and stability of vancomycin, ceftazidime, and moxifloxacin prepared in single-use polypropylene syringes for intravitreal injection. METHODS: Experimental study. Vancomycin 1 mg/0.1 mL, ceftazidime 2 mg/0.1 mL, and moxifloxacin 160 µg/0.1 mL were compounded and prepared in 1-mL polypropylene syringes and stored at 4 °C, -20 °C, and -80 °C. Antibiotic potency, sterility, pH, osmolality, and concentration were tested at baseline and at 1, 2, 4, 8, 12, and 24 weeks after preparation. RESULTS: Potency, sterility, and stability were preserved for all 3 antibiotics at all temperatures out to 24 weeks, although there was a trend toward reduced potency at Week 24 for vancomycin and ceftazidime stored at 4°C. The largest zones of inhibition for Staphylococcus epidermidis and S. aureus were consistently demonstrated by moxifloxacin. CONCLUSION: Vancomycin, ceftazidime, and moxifloxacin prepared in single-use polypropylene syringes retain potency, sterility, and stability out to 24 weeks when stored at -20 °C or -80 °C. The results of this study may have important implications for the current management of endophthalmitis.

Formative evaluation to guide early deployment of an online content management tool for medical curriculum.

KM is a Web-accessible, comprehensive database that organizes course materials (at the level of full lectures, not just outlines or syllabi) from the Vanderbilt School of Medicine curriculum. KM uses natural language processing techniques to analyze educational documents for biomedical concepts. Lecture handouts and Microsoft PowerPoint presentations are indexed and available online for students, faculty and administrators to search for individual or interrelated concepts across the medical school curriculum.