The Effects of Silicone Enclosure Colour on the Function of Optical Sensors.

The colour of the silicone enclosure of an implantable reflectance-based optical probe plays a critical role in sensor performance. Red-coloured probes that are highly reflective to near-infrared light have been found to increase photodetector power by a factor of 6 for wavelengths between 660 and 950 nm and triple the magnitude of measured cardiac pulsations compared to traditional black probes. The increase in photodetector power and cardiac pulsation magnitude is presumably due to increased spatial range resulting from a higher magnitude of superficial tissue scattering. Conversely, probes with highly absorbent colours such as black and blue result in more stable signals and are expected to have higher spatial resolution and depth of penetration.

Initial Management of Acute and Chronic Low Back Pain: Responses from Brief Interviews of Primary Care Providers.

Background: In April 2017, the American College of Physicians (ACP) published a clinical practice guideline for low back pain (LBP) recommending nonpharmacologic treatments as first-line therapy for acute, subacute, and chronic LBP. Objective: To assess primary care provider (PCP)-reported initial treatment recommendations for LBP following guideline release. Design: Cross-sectional structured interviews. Participants: Convenience sample of 72 PCPs from 3 community-based outpatient clinics in high- or low-income neighborhoods. Approach: PCPs were interviewed about their familiarity with the ACP guideline, and how they initially manage patients with acute/subacute and chronic LBP. Treatment responses were coded as patient education, nonpharmacologic, pharmacologic, or medical specialty referral. PCPs were also asked about their comfort referring patients to nonpharmacologic treatment providers, and about barriers to referring. Responses were assessed using content analysis. Differences in responses were assessed using descriptive statistics. Key results: Interviews were completed between December 2017 and March 2018. Of 72 participating PCPs (50% male; mean years of practice = 13.8), over three-fourths indicated being familiar with the ACP guideline (76%-87% at 3 clinics). For acute LBP, PCPs typically provided advice to stay active (81%) and pharmacologic management (97%; primarily nonsteroidal anti-inflammatory drugs). For chronic LBP, PCPs were more likely to recommend nonpharmacologic treatments than for acute LBP (85% vs. 0%, p < 0.001). The most common nonpharmacologic treatments recommended for chronic LBP were physical therapy (78%), chiropractic care (21%), massage therapy (18%), and acupuncture (17%) (each compared with 0% for acute LBP, all p < 0.001). The cost of nonpharmacologic treatments was perceived as a barrier. However, PCPs working in low-income neighborhood clinics were as likely to recommend nonpharmacologic approaches as those from a high-income neighborhood clinic. Conclusions: While most PCPs indicated they were familiar with the ACP guideline for LBP, nonpharmacologic treatments were not recommended for patients with acute symptoms. Further dissemination and implementation of the ACP guideline are needed.

Effects of collagen cross-linking on the keratoconus metabolic network.

PURPOSE: Keratoconus (KC) is a multifactorial, ectatic corneal disease. Metabolic changes in the corneal stroma with alterations in collagen fibril stability, oxidative stress, and urea cycle, have previously been reported as key players in KC pathobiology. Recently, corneal collagen cross-linking (CXL) has been introduced as a treatment that can address the progressive nature of KC. While the treatment has been successful in the early days, it is not without clinical ramifications. In this study, we investigated the alterations in KC metabolic profiles due to CXL. METHODS: Primary human corneal fibroblasts (HCFs) from healthy donors and human KC fibroblasts (HKCs) from KC donor patients were plated on transwell polycarbonate membranes and stimulated by a stable vitamin C. At 4 weeks, riboflavin was added to the cultures followed by UVA irradiation (365 nm). Using mass spectrometry, we measured the major differences in metabolites in HKCs compared to HCFs pre- and post CXL. RESULT: The analysis of 276 metabolites in HCFs and HKCs revealed that the most affected metabolites due to CXL were glutathione disulfide, ascorbic acid, proline, and lysine. A significant decrease in the pro-inflammatory biomarkers (myo-inositol and histidine) was also observed. Furthermore, a significant downregulation of many amino acids, lactate levels, and other water-soluble metabolites was noted in HKCs following CXL. CONCLUSION: CXL is a KC treatment available to patients within certain criteria. Surprisingly, the cellular and molecular mechanisms are considerably understudied limiting our ability for more precise and targeted CXL treatments. In this study, for the first time, we report the effects of CXL on KC metabolism.

Femtosecond laser-assisted cataract surgery in complex cases.

PURPOSE: To describe the use of the femtosecond laser in complex cataract cases. SETTING: Department of Ophthalmology, University of Colorado, Aurora, Colorado, USA. DESIGN: Retrospective case series. METHODS: This was a single-center retrospective review of consecutive complex cataract surgery cases in which the Lensx femtosecond laser was used between October 2012 and February 2015. Complex cases were defined as white cataracts, dense brunescent cataracts, or cataracts in which zonulopathy was identified preoperatively. Outcome measures included an assessment of the capsulotomy, surgical complications, and postoperative corrected distance visual acuity (CDVA). RESULTS: Thirty-four eyes of 34 patients were included in this study; 27 had white cataract, 3 had dense brunescent cataract, and 6 had zonulopathy (2 of these also had white cataract). Three patients had an incomplete capsulotomy, and 3 had small radial tears in the anterior capsule. Four patients (11.7%) developed posterior capsule tears during phacoemulsification; 1 of these subsequently had pars plana vitrectomy for a retained lens fragment. Twenty-eight (97%) of 29 patients had a postoperative CDVA of 20/40 or better. Three patients were identified with comorbidities that limited postoperative CDVA. One patient developed postoperative cystoid macular edema. CONCLUSION: The femtosecond laser was useful in the surgical approach to patients with complex cataracts, especially for the creation of the capsulotomy. FINANCIAL DISCLOSURE: None of the authors has a financial or proprietary interest in any material or method mentioned.