Bilateral retrobulbar optic neuropathy in the setting of interferon alpha-2a therapy.

The development of biopharmaceutical agents, including the interferons (IFN), offers new treatment options for a wide range of medical conditions. Such advancements, however, have not come without risk to patients. Optic neuropathy in the setting of IFN therapy has been previously documented and is usually attributed to anterior ischaemic optic neuropathy; however, the pathophysiology remains poorly understood. Retrobulbar optic neuropathy associated with IFN treatment has not been described in the medical literature to date. We report the case of a 38-year-old Caucasian female with refractory acute myeloid leukaemia who developed painless bilateral blurred vision within 2 weeks of commencing a course of IFN alpha-2a. Extensive clinical workup demonstrated bilateral retrobulbar optic neuropathy. We report the clinical evaluation of this first documented case and discuss the possible aetiologies of her presentation

Incidence and clinical predictors of ocular candidiasis in patients with Candida fungemia.

Purpose. The aim of this study is to determine the incidence and the predictors of ocular candidiasis among patient with Candida fungemia. Methods. We retrospectively reviewed the charts of all patients diagnosed with candidemia at the University of Kansas Medical Center during February 2000-March 2010. Data regarding patients' demographics, clinical characteristics, laboratory results, and ophthalmology examination findings were collected. Results. A total of 283 patients with candidemia were enrolled. The mean age (± standard deviation) was 55 ± 18 years; 66% were male. The most commonly isolated Candida species were C. albicans (54%), C. parapsilosis (20%), C. glabrata (13%), and C. tropicalis (8%). Only 144 (51%) patients were evaluated by ophthalmology; however, the proportion of patients who were formally evaluated by an ophthalmologist increased during the study period (9%in 2000 up to 73%in 2010; P < 0.0001). Evidence of ocular candidiasis was present in 18 (12.5%) patients. Visual symptoms were reported by 5 of 18 (28%) patients. In multivariable analysis, no predictors of ocular candidiasis were identified. Conclusions. The incidence of ocular candidiasis among patients with fungemia remains elevated. Most patients are asymptomatic and therefore all patients with candidemia should undergo fundoscopic examination to rule out ocular involvement

An overview of optometrists' diabetic retinopathy practice patterns - a cross-sectional survey

PURPOSE: Contemporary eye care increasingly recommends the use of advanced retinal imaging technology. Anecdotal evidence suggests that this equipment is widely available in primary eye care settings; however, knowledge regarding how optometrists use this equipment in the context of diabetic retinopathy (DR) is limited. This study aimed to obtain a current overview of optometrists' clinical practice behaviours in the detection, screening, diagnosis and management of patients with diabetes. METHODS: A cross-sectional survey was designed to evaluate optometrists' self-reported clinical practice patterns and perceptions, as well as the availability and impact of retinal imaging equipment specific to DR and diabetic macular oedema (DMO) on optometrists' clinical practice. The survey invited participation from all optometrists practising in Australia. RESULTS: One hundred and sixty-seven optometrists participated. Optometrists' self-reported confidence in assessing DR and DMO was high. Optometrists' referral patterns considered the severity of DR and DMO before initiating referral to secondary ophthalmology care. Nearly all optometrists (98.8%) indicated that they had some form of retinal imaging equipment available to them in clinical practice. An optical coherence tomography (OCT) device was available to 75.5% of optometrists. A significant association between having an OCT device in the practice and higher self-reported confidence levels in the assessment of DMO was found. CONCLUSIONS: Many optometrists are well equipped with sophisticated retinal imaging technology for the provision of high-quality eye care. Enhancing optometric training and education programmes can maximise the community benefit of access to this equipment and improve delivery of eye care in the community

Mapping the human parafoveal vascular network to understand flow variability in capillaries

Capillary flow is known to be non-homogenous between vessels and variable over time, for reasons that are poorly understood. The local properties of individual vessels have been shown to have limited explanatory power in this regard. This exploratory study investigates the association of network-level properties such as vessel depth, branch order, and distance from the feeding arteriole with capillary flow. Detailed network connectivity analysis was undertaken in 3 healthy young subjects using flood-illuminated adaptive optics retinal imaging, with axial depth of vessels determined via optical coherence tomography angiography. Forty-one out of 70 vessels studied were of terminal capillary type, i.e. fed from an arterial junction and drained by a venous junction. Approximately half of vessel junctions were amenable to fitting with a model of relative branch diameters, with only a few adhering to Murray's Law. A key parameter of the model (the junction exponent) was found to be inversely related to the average velocity (r = -0.59, p = 0.015) and trough velocity (r = -0.67, p = 0.004) in downstream vessels. Aspects of cellular flow, such as the minimum velocity, were also moderately correlated (r = 0.46, p = 0.009) with distance to the upstream feeding arteriole. Overall, this study shows that capillary network topology contributes significantly to the flow variability in retinal capillaries in human eyes. Understanding the heterogeneity in capillary flow is an important first step before pathological flow states can be properly understood. These results show that flow within capillary vessels is not affected by vessel depths but significantly influenced by the upstream feeder distance as well as the downstream vessel junction exponents, but there remains much to be uncovered regarding healthy capillary flow

Validation of an automated method for studying retinal capillary blood flow

Two major approaches for tracking cellular motion across a range of biological tissues are the manual labelling of cells, and automated analysis of spatiotemporal information represented in a kymograph. Here we compare these two approaches for the measurement of retinal capillary flow, a particularly noisy application due to the low intrinsic contrast of single red blood cells (erythrocytes). Image data were obtained using a flood-illuminated adaptive optics ophthalmoscope at 750 nm, allowing the acquisition of flow information over several cardiac cycles which provided key information in evaluating tracking accuracy. Our results show that in addition to being much faster, the automated method is more accurate in the face of rapid flow and reduced image contrast. This study represents the first validation of commonly used kymograph approaches to capillary flow analysis

The relationship between ON–OFF function and OCT structural and angiographic parameters in early diabetic retinal disease

PURPOSE: This study measured associations between ON and OFF functional indicators and structural optical coherence tomography (OCT) and OCT angiography (OCTA) markers in diabetic retinal disease. METHODS: Fifty-four participants with type 1 or type 2 diabetes (mean age = 34.1 years; range 18-60) and 48 age-matched controls (mean age = 35.4 years, range 18-59) underwent visual psychophysical testing, OCT and OCTA retinal imaging. Psychophysical tasks measuring (A) contrast increment and decrement sensitivity and (B) response times to increment and decrement targets were assessed as surrogate measures of ON and OFF retinal ganglion cell function. RESULTS: The group with diabetes had worse foveal contrast increment and decrement thresholds (p = 0.04) and were slower to search for increment and decrement targets relative to controls (p = 0.009). Individuals with diabetes had a less circular foveal avascular zone (FAZ) (p < 0.001) but did not differ from controls in foveal vessel density and FAZ area. Functional and structural outcome measures related to the peripheral retina were also comparable between those with and without diabetes. Functional responses to increments and decrements were not significantly correlated with FAZ circularity or vessel density in individuals with diabetes. CONCLUSIONS: Diabetic retinal disease results in impaired performance on measures of inferred ON and OFF pathway function in addition to vascular deficits measurable with OCTA. Future longitudinal studies may determine the temporal relationship between these deficits, and whether they predict future diabetic retinopathy

Improvements in allelic discrimination of microsatellite markers using denaturing polyacrylamide gel electrophoresis

Poor resolution, retarded progress of DNA through gels, and variable sizing of DNA fragments between and within gels hinder accurate genotyping of some simple sequence length polymorphism (SSLP) markers with the Perkin Elmer Applied Biosystems 377 Sequenator. These problems are similar to renaturation related problems observed in DNA sequencing gels. PCR products especially susceptible to these problems are shown to have higher melting temperatures (T(m)) than others. Gels containing increased concentrations of denaturants allow greater accuracy in allelic discrimination. This is especially beneficial where quantification is necessary