Role of advanced technology in the detection of sight-threatening eye disease in a UK community setting.

Background/aims: To determine the performance of combinations of structural and functional screening tests in detecting sight-threatening eye disease in a cohort of elderly subjects recruited from primary care. Methods: 505 subjects aged ≥60 years underwent frequency doubling technology (FDT) perimetry, iVue optical coherence tomography (iWellness and peripapillary retinal nerve fibre layer (RNFL) scans) and intraocular pressure with the Ocular Response Analyzer, all performed by an ophthalmic technician. The reference standard was a full ophthalmic examination by an experienced clinician who was masked to the index test results. Subjects were classified as presence or absence of sight-threatening eye disease (clinically significant cataract, primary open-angle glaucoma, intermediate or advanced age-related macular degeneration and significant diabetic retinopathy). Univariate and multivariate logistic regression analyses were used to determine the association between abnormal screening test results and the presence of sight-threatening eye disease. Results: 171 subjects (33.8%) had one or more sight-threatening eye diseases. The multivariate analysis found significant associations with any of the target conditions for visual acuity of <6/12, an abnormal FDT and peripapillary RNFL thickness outside the 99% normal limit. The sensitivity of this optimised screening panel was 61.3% (95% CI 53.5 to 68.7), with a specificity of 78.8% (95% CI 74.0 to 83.1), a positive predictive value of 59.5% (95% CI 53.7 to 65.2) and an overall diagnostic accuracy of 72.9% (95% CI 68.8 to 76.8). Conclusions: A subset of screening tests may provide an accurate and efficient means of population screening for significant eye disease in the elderly. This study provides useful preliminary data to inform the development of further larger, multicentre screening studies to validate this screening panel

Multiple and Multidimensional life transitions in the context of life-limiting health conditions:Longitudinal study focussing on perspectives of Young Adults, Families and Professionals

Background: There is a dearth of literature that investigates life transitions of young adults (YAs) with life-limiting conditions, families and professionals. The scant literature that is available has methodological limitations, including not listening to the voice of YAs, collecting data retrospectively, at one time point, from one group’s perspective and single case studies. The aim of this study was to address the gaps found in our literature review and provide a clearer understanding of the multiple and multi-dimensional life transitions experienced by YAs and significant others, over a period of time. Methods: This qualitative study used a longitudinal design and data were collected using semi-structured interviews over a 6-month period at 3 time points. Participants included 12 YAs with life-limiting conditions and their nominated significant others (10 family members and 11 professionals). Data were analysed using a thematic analysis approach. Results: Life transitions of YA and significant others are complex; they experience multiple and multi-dimensional transitions across several domains. The findings challenge the notion that all life transitions are triggered by health transitions of YAs, and has highlighted environmental factors (attitudinal and systemic) that can be changed to facilitate smoother transitions in various aspects of their lives. Conclusions: This study makes a unique and significant contribution to literature. It provides evidence and rich narratives for policy makers and service providers to change policies and practices that are in line with the needs of YAs with life-limiting conditions as they transition to adulthood. Families and professionals have specific training needs that have not yet been met fully

Predictive value of screening tests for sight-threatening eye disease in a UK population

Background/Aims To determine the performance of combinations of structural and functional screening tests in detecting sight-threatening eye disease in a cohort of elderly subjects recruited from primary care Methods 505 subjects ≥ 60 years underwent: Frequency Doubling Technology (FDT) perimetry; iVue OCT (iWellness® and peripapillary retinal nerve fibre layer (RNFL) scans); IOP with the Ocular Response Analyzer (ORA), all performed by an ophthalmic technician. The reference standard was a full ophthalmic examination by an experienced clinician who was masked to the index test results. Subjects were classified as presence or absence of sight-threatening eye disease (clinically significant cataract, primary open angle glaucoma, intermediate or advanced AMD and significant diabetic retinopathy). Univariate and multivariate logistic regression was used to determine the association between abnormal screening test results and the presence of sight-threatening eye disease. Results 171 subjects (33.8%) had one or more sight-threatening eye disease(s). The multivariate analysis found significant associations with any of the target conditions for visual acuity < 6/12, an abnormal FDT and peripapillary RNFL thickness outside the 99% normal limit. The sensitivity of this optimised screening panel was 61.3% (95% CI 53.5-68.7); specificity 78.8% (CI 74.0-83.1), positive predictive value 59.5% (CI 53.7-65.2) and an overall diagnostic accuracy of 72.9% (CI 68.8-76.8). Conclusion A subset of screening tests may provide an accurate and efficient means of population screening for significant eye disease in the elderly. This study provides useful preliminary data to inform the development of further larger, multicentre screening studies to validate this screening panel

Unilateral cranial defect bone reconstruction utilising 3D design and manufacturing

A cranial contour defect can occur when bone is removed following direct trauma, removal of a tumor or for surgical access to the brain. These defects impair function (protection) and aesthetic contour and require a design strategy for reconstructing the defect. In principle, if the defect is unilateral (one side) then designing a form to restore the contour could be assisted by attaining a mirror image of the undamaged side of the skull. As an alternative to mirroring the undamaged skull an interpolated surface could also be generated for repairing this cranial defect. A case with a unilateral left temporal bone defect was considered for this study. A cranioplasty reconstruction was to be performed to restore the bone contour. The patient's Computed Tomography (CT) scan (1 mm slice thickness) was saved in the raw file format Digital Imaging and Communication in Medicine (DICOM). The DICOM data was converted to a standard tessellation file (stl.) using MIMICS software (Materialise V24. Belgium). The stl. file of the skull was used to generate a 3D design of the implant using Computer-aided Design/ Computer-aided Manufacturing (CAD/CAM) software. The design was used to 3D print a base template, which could finally be used to fabricate the physical implant to restore the defect. This case explored the two techniques of mirroring and interpolation for repairing a cranial defect. A comparison of the two techniques was performed. Feedback from the surgeon suggested that interpolation provided a digitally accurate implant surface comparable to a mirrored implant

Use of polyethylene glycol coatings for optical fibre humidity sensing

Humidity induced change in the refractive index and thickness of the polyethylene glycol (PEG) coatings are in situ investigated for a range from 10 to 95%, using an optical waveguide spectroscopic technique. It is experimentally demonstrated that, upon humidity change, the optical and swelling characteristics of the PEG coatings can be employed to build a plastic fibre optic humidity sensor. The sensing mechanism is based on the humidity induced change in the refractive index of the PEG film, which is directly coated onto a polished segment of a plastic optical fibre with dip-coating method. It is observed that PEG, which is a highly hydrophilic material, shows no monotonic linear response to humidity but gives different characteristics for various ranges of humidity levels both in index of refraction and in thickness. It undergoes a physical phase change from a semi-crystal line structure to a gel one at around 80% relative humidity. At this phase change point, a drastic decrease occurs in the index of refraction as well as a drastic increase in the swelling of the PEG film. In addition, PEG coatings are hydrogenated in a vacuum chamber. It is observed that the hydrogen has a preventing effect on the humidity induced phase change in PEG coatings. Finally, the possibility of using PEG coatings in construction of a real plastic fibre optic humidity sensor is discussed. (C) 2008 The Optical Society of Japan

Optimizing cranial implant and fixture design using different materials in cranioplasty

Cranial implants are used to secure intracranial structures, reconstruct the skull contour, normalise cerebral hemodynamic, and repair cranial defects. Larger bone defects require intervention for repair from an implant made from autologous bone or other material. To repair such defects using implants, materials necessitate biocompatibility with the natural bone. Patient Specific Implants (PSI) are designed to repair specific cranial defects following standard procedures for implant design, fabrication and cranioplasty. Autologous bone, bone cement comprising HydroxyApatite (HA), Poly methyl methacrylate (PMMA), Medical Grade Titanium Alloy (Ti-6Al-4V) and Polyether-ether-ketone (PEEK), are widely used to fabricate PSI for repairing different types of bone defects. To optimize a PSI for shape, size and weight, it is essential to design the implant using 3D modelling and fabrication techniques. Effective attachment of an implant material with a defective skull is also influenced by the joints and fixture arrangements at the interface, these fixtures can be of various types, materials and have different joining procedures. In this study, a comparative analysis of different cranial implant materials (Autologous Bone, PMMA, PEEK and Ti-6Al-4V) attached to a defective skull with Ti-6Al-4V and PEEK fixture plates has been performed, using Finite Element Analysis (FEA). Two types of fixture designs were used as Square 'X' and Linear shapes, which were fixed along the interface between implant and the skull. Four fixture plates were fixed symmetrically along the boundary for maximising stability. The findings suggested that all the implant materials were able to sustain extreme boundary conditions such as external loads of 1780N and IntraCranial Pressure (ICP) of 15mmHg without failures. PEEK implants exhibited 13.5 % to 35% lower von Mises stresses in comparison to autologous bone implants and Square 'X' fixture design provided higher stress relieving results in comparison to Linear fixtures by nearly 18.4% for Ti-6Al-4V fixture material and 10.9% for PEEK fixture material, thereby, encouraging PEEK as an alternative to conventional cranial implant and fixture materials