Influences of Flap Shape and Hinge Angle on Opaque Bubble Layer Formation in Femtosecond Laser-Assisted LASIK Surgery.

PURPOSE: To evaluate the effects of different flap shapes and hinge angles on opaque bubble layer (OBL) formation using a femtosecond laser for flap creation in LASIK surgery. METHODS: This retrospective study evaluated 138 eyes of 73 patients who underwent femtosecond laser-assisted LASIK with a 150-kHz IntraLase femtosecond laser (Abbott Medical Optics, Inc., Santa Ana, CA) for myopic astigmatism and compared differences between different flap shapes and hinge angles on OBL formation. The surgical procedures were videotaped, and the patterns and sizes of the OBLs seen during surgery were analyzed. Preoperative and postoperative data including patient demographics, refractive status, keratometry, central corneal thickness, and intraoperative data (flap size and pocket parameters) were recorded. The eyes were divided into four groups based on the corneal flap shape (elliptical versus round) and hinge angle (50° versus 60°). RESULTS: The preoperative demographic data, mean spherical errors, cylindrical power, and central corneal thickness were not significantly different among the groups. Of the 138 eyes, 107 (77%) developed an OBL covering a mean area of 13.8% ± 12.6% in each case. This area was significantly smaller in the elliptical flap with 60° hinge angle group (P < .05). CONCLUSIONS: An oval-shaped flap with a larger hinge angle tended to result in less OBL formation in femtosecond laser-assisted LASIK. [J Refract Surg. 2017;33(3):178-182.].

Risk of skin cancer in patients with pterygium: a nationwide population-based cohort study in Taiwan.

This study investigated the association between pterygium and skin cancer linking to ultraviolet (UV) radiation using claims data from 1997-2010, obtained from the Taiwan National Health Insurance Research Database. The study included 19,701 patients with pterygium and 78,804 sex- and age-frequency-matched comparison subjects. Multivariate Cox regression analyses were performed to assess the relationship between pterygium and risk of skin cancer by the end of 2010. The incidence rates of malignant melanoma (MM) and nonmelanoma skin cancer (NMSC) in two cohorts and adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) of the diseases were measured. Results showed that the incidences of MM and NMSC were both higher in the pterygium cohort than in the comparison cohort (5.5 vs 3.2 and 32.3 vs 15.0 per 100,000 person years, respectively). After adjusting for age, sex, UV index, occupation, and the other comorbidities, pterygium remained a significant predictor of NMSC (hazard ratio [HR], 1.64; 95% confidence interval [CI], 1.11-2.42), but not MM (HR, 1.46; 95% CI, 0.59-3.65). These results suggest that pterygium patients are associated with an increased risk of NMSC, but not significant for MM.

Infrared-based third and second harmonic generation imaging of cornea.

The cornea functions as an optical lens and plays an important role in vision. For corneal diagnosis and treatment such as refractive surgery, a microscopic imaging system with a 3-D cellular resolution and retinal safety is strongly desired. Recently, confocal and multiphoton microscopies have been applied to corneal imaging with visible to near-infrared light sources. To increase retinal safety, an infrared light source is be needed. In this work, an infrared-based third and second harmonic generation microscopic study of mouse eyes is reported with approximately 700-mum penetrability and high cellular resolution. This study provides a critical reference for future development of infrared-based corneal imaging.

In vivo and ex vivo imaging of intra-tissue elastic fibers using third-harmonic-generation microscopy.

Elastin is an essential and widespread structural protein in charge of the integrity on tissues and organs. In this study, we demonstrate that elastin is a major origin of the third-harmonic-generation (THG) contrast under Cr:forsterite laser excitation operating at 1230nm, with selective visualization inside many tissues such as lung tissues and arteries. In vivo imaging of the nude mouse elastic cartilage beneath the hypodermis by epi- THG microscopy keeps the high resolution and contrast in all three dimensions. Combined with second-harmonic-generation microscopy, THG microscopy exhibits the ability to show the extraordinary proliferation of elastic fibers for the ophthalmic disease of pterygium and the capability of distinguishable visualization from collagen.