Centre for Eye Research Australia (CERA) - Research Publications
Now showing items 1-12 of 25
The impact of diabetic retinopathy on quality of life: qualitative findings from an item bank development project
PURPOSE: Assessing the efficacy of treatment modalities for diabetic retinopathy (DR) from the patient's perspective is restricted due to a lack of a comprehensive patient-reported outcome measure. We are developing a DR-specific quality of life (QoL) item bank, and we report here on the qualitative results from the first phase of this project. METHODS: Eight focus groups and 18 semi-structured interviews were conducted with 57 patients with DR. The sessions were transcribed verbatim and iteratively analysed using the constant comparative method and NVIVO software. RESULTS: Participants had a median age of 58 years (range 27-83 years). Twenty-seven (47%) participants had proliferative DR in the better eye, and 14 (25%) had clinically significant macular oedema. Nine QoL domains were identified, namely visual symptoms, ocular surface symptoms, vision-related activity limitation, mobility, emotional well-being, health concerns, convenience, social, and economic. Participants described many vision-related activity limitations, particularly under challenging lighting conditions; however, socioemotional issues were equally important. Participants felt frustrated due to their visual restrictions, concerned about further vision loss and had difficulty coping with this uncertainty. Restrictions on driving were pervasive, affecting transport, social life, relationships, responsibilities, work and independence. CONCLUSIONS: Patients with DR experience many socioemotional issues in addition to vision-related activity limitations. Data from this study will be used to generate data for a DR-specific QoL item bank.
The Prevalence of Self-Reported Diabetes in the Australian National Eye Health Survey
(PUBLIC LIBRARY SCIENCE, 2017-01-03)
OBJECTIVE: To present the prevalence of self-reported diabetes in Indigenous and non-Indigenous participants in the National Eye Health Survey. RESEARCH DESIGN AND METHODS: 3098 non-Indigenous Australians aged 50-98 years and 1738 Indigenous Australians aged 40-92 years were examined in 30 randomly selected sites, stratified by remoteness. A history of diabetes was obtained using an interviewer-administered questionnaire. RESULTS: 13.91% (431/3098) of non-Indigenous Australians and 37.11% (645/1738) of Indigenous Australians had self-reported diabetes. The age-adjusted prevalence of self-reported diabetes for non-Indigenous and Indigenous Australians was 11.49% and 43.77%, respectively (p <0.001). The prevalence of self-reported diabetes increased markedly with age (OR = 1.04 per year, p = 0.017). Indigenous Australians living in very remote areas were more likely to have self-reported diabetes than those in major city areas (OR = 1.61, p = 0.038). CONCLUSIONS: The prevalence of self-reported diabetes in Australia was high, with the prevalence being almost 4 times higher in Indigenous Australians compared with non-Indigenous Australians. With the prevalence of diabetes likely to increase, the results of this national survey may inform future policy, planning and funding allocation to assist in controlling the diabetes epidemic.
Prevalence of signs of trachoma, ocular Chlamydia trachomatis infection and antibodies to Pgp3 in residents of Kiritimati Island, Kiribati
(PUBLIC LIBRARY SCIENCE, 2017-09-01)
OBJECTIVE: In some Pacific Island countries, such as Solomon Islands and Fiji, active trachoma is common, but ocular Chlamydia trachomatis (Ct) infection and trachomatous trichiasis (TT) are rare. On Tarawa, the most populous Kiribati island, both the active trachoma sign "trachomatous inflammation-follicular" (TF) and TT are present at prevalences warranting intervention. We sought to estimate prevalences of TF, TT, ocular Ct infection, and anti-Ct antibodies on Kiritimati Island, Kiribati, to assess local relationships between these parameters, and to help determine the need for interventions against trachoma on Kiribati islands other than Tarawa. METHODS: As part of the Global Trachoma Mapping Project (GTMP), on Kiritimati, we examined 406 children aged 1-9 years for active trachoma. We collected conjunctival swabs (for droplet digital PCR against Ct plasmid targets) from 1-9-year-olds with active trachoma, and a systematic selection of 1-9-year-olds without active trachoma. We collected dried blood spots (for anti-Pgp3 ELISA) from all 1-9-year-old children. We also examined 416 adults aged ≥15 years for TT. Prevalence of TF and TT was adjusted for age (TF) or age and gender (TT) in five-year age bands. RESULTS: The age-adjusted prevalence of TF in 1-9-year-olds was 28% (95% confidence interval [CI]: 24-35). The age- and gender-adjusted prevalence of TT in those aged ≥15 years was 0.2% (95% CI: 0.1-0.3%). Twenty-six (13.5%) of 193 swabs from children without active trachoma, and 58 (49.2%) of 118 swabs from children with active trachoma were positive for Ct DNA. Two hundred and ten (53%) of 397 children had anti-Pgp3 antibodies. Both infection (p<0.0001) and seropositivity (p<0.0001) were strongly associated with active trachoma. In 1-9-year-olds, the prevalence of anti-Pgp3 antibodies rose steeply with age. CONCLUSION: Trachoma presents a public health problem on Kiritimati, where the high prevalence of ocular Ct infection and rapid increase in seropositivity with age suggest intense Ct transmission amongst young children. Interventions are required here to prevent future blindness.
The validity of self-report of eye diseases in participants with vision loss in the National Eye Health Survey
(NATURE PUBLISHING GROUP, 2017-08-18)
We assessed the validity and reliability of self-report of eye disease in participants with unilateral vision loss (presenting visual acuity worse than 6/12 in the worse eye and equal to or better than 6/12 in the better eye) or bilateral vision loss (presenting visual acuity worse than 6/12 in the better eye) in Australia's National Eye Health Survey. In total, 1738 Indigenous Australians and 3098 non-Indigenous Australians were sampled from 30 sites. Participants underwent a questionnaire and self-reported their eye disease histories. A clinical examination identified whether participants had cataract, age-related macular degeneration, diabetic retinopathy and glaucoma. For those identified as having unilateral or bilateral vision loss (438 Indigenous Australians and 709 non-Indigenous Australians), self-reports were compared with examination results using validity and reliability measures. Reliability was poor for all four diseases (Kappa 0.06 to 0.37). Measures of validity of self-report were variable, with generally high specificities (93.7% to 99.2%) in all diseases except for cataract (63.9 to 73.1%) and low sensitivities for all diseases (7.6% in Indigenous Australians with diabetic retinopathy to 44.1% of non-Indigenous Australians with cataract). This study suggests that self-report is an unreliable population-based research tool for identifying eye disease in those with vision loss.
Altered biometal homeostasis is associated with CLN6 mRNA loss in mouse neuronal ceroid lipofuscinosis
(COMPANY OF BIOLOGISTS LTD, 2013-06-15)
Neuronal ceroid lipofuscinoses, the most common fatal childhood neurodegenerative illnesses, share many features with more prevalent neurodegenerative diseases. Neuronal ceroid lipofuscinoses are caused by mutations in CLN genes. CLN6 encodes a transmembrane endoplasmic reticulum protein with no known function. We characterized the behavioural phenotype of spontaneous mutant mice modeling CLN6 disease, and demonstrate progressive motor and visual decline and reduced lifespan in these mice, consistent with symptoms observed in neuronal ceroid lipofuscinosis patients. Alterations to biometal homeostasis are known to play a critical role in pathology in Alzheimer's, Parkinson's, Huntington's and motor neuron diseases. We have previously shown accumulation of the biometals, zinc, copper, manganese and cobalt, in CLN6 Merino and South Hampshire sheep at the age of symptom onset. Here we determine the physiological and disease-associated expression of CLN6, demonstrating regional CLN6 transcript loss, and concurrent accumulation of the same biometals in the CNS and the heart of presymptomatic CLN6 mice. Furthermore, increased expression of the ER/Golgi-localized cation transporter protein, Zip7, was detected in cerebellar Purkinje cells and whole brain fractions. Purkinje cells not only control motor function, an early symptomatic change in the CLN6 mice, but also display prominent neuropathological changes in mouse models and patients with different forms of neuronal ceroid lipofuscinoses. Whole brain fractionation analysis revealed biometal accumulation in fractions expressing markers for ER, Golgi, endosomes and lysosomes of CLN6 brains. These data are consistent with a link between CLN6 expression and biometal homeostasis in CLN6 disease, and provide further support for altered cation transporter regulation as a key factor in neurodegeneration.
Emerging ocular biomarkers of Alzheimer disease
Interest in reliable biomarkers of Alzheimer disease, the leading cause of dementia, has been fuelled by challenges in diagnosing the disease and monitoring disease progression as well as the response to therapy. A range of ocular manifestations of Alzheimer disease, including retinal and lens amyloid-beta accumulation, retinal nerve fiber layer loss, and retinal vascular changes, have been proposed as potential biomarkers of the disease. Herein, we examine the evidence regarding the potential value of these ocular biomarkers of Alzheimer disease.
Amyloid precursor protein drives down-regulation of mitochondrial oxidative phosphorylation independent of amyloid beta
(NATURE PUBLISHING GROUP, 2017-08-29)
Amyloid precursor protein (APP) and its extracellular domain, soluble APP alpha (sAPPα) play important physiological and neuroprotective roles. However, rare forms of familial Alzheimer's disease are associated with mutations in APP that increase toxic amyloidogenic cleavage of APP and produce amyloid beta (Aβ) at the expense of sAPPα and other non-amyloidogenic fragments. Although mitochondrial dysfunction has become an established hallmark of neurotoxicity, the link between Aβ and mitochondrial function is unclear. In this study we investigated the effects of increased levels of neuronal APP or Aβ on mitochondrial metabolism and gene expression, in human SH-SY5Y neuroblastoma cells. Increased non-amyloidogenic processing of APP, but not Aβ, profoundly decreased respiration and enhanced glycolysis, while mitochondrial DNA (mtDNA) transcripts were decreased, without detrimental effects to cell growth. These effects cannot be ascribed to Aβ toxicity, since higher levels of endogenous Aβ in our models do not cause oxidative phosphorylation (OXPHOS) perturbations. Similarly, chemical inhibition of β-secretase decreased mitochondrial respiration, suggesting that non-amyloidogenic processing of APP may be responsible for mitochondrial changes. Our results have two important implications, the need for caution in the interpretation of mitochondrial perturbations in models where APP is overexpressed, and a potential role of sAPPα or other non-amyloid APP fragments as acute modulators of mitochondrial metabolism.
Progress in the clinical development and utilization of vision prostheses: an update
(DOVE MEDICAL PRESS LTD, 2016-01-01)
Vision prostheses, or "bionic eyes", are implantable medical bionic devices with the potential to restore rudimentary sight to people with profound vision loss or blindness. In the past two decades, this field has rapidly progressed, and there are now two commercially available retinal prostheses in the US and Europe, and a number of next-generation devices in development. This review provides an update on the development of these devices and a discussion on the future directions for the field.
A Tablet-Based Retinal Function Test in Neovascular Age-Related Macular Degeneration Eyes and At-Risk Fellow Eye
(ASSOC RESEARCH VISION OPHTHALMOLOGY INC, 2018-03-01)
Purpose: To determine the feasibility of a tablet-based application to detect changes in retinal sensitivity and correlations with underlying pathology in neovascular age-related macular degeneration (nAMD) eyes undergoing treatment and in at-risk fellow eyes. Method: Participants with nAMD in at least one eye were recruited, examined, and imaged using spectral-domain optical coherence tomography (SD-OCT). Retinal sensitivity was measured within the central 5° at 12 locations using a customized test delivered on an iPad. Test points were superimposed on SD-OCT locations to investigate structure/function relationships. Results: Included in the study were 53 nAMD eyes and 21 at-risk fellow eyes. In nAMD eyes, the mean retinal sensitivity was 24.1 ± 1.8 dB with reduced retinal sensitivity associated with the presence of atrophy (P < 0.01), retinal pigment epithelium (RPE) disruption (P < 0.01), and absent ellipsoid zone (EZ) (P < 0.01), but not with the presence of subretinal fluid (P = 0.94) nor intraretinal fluid (P = 0.52). In at-risk eyes, the average retinal sensitivity was 28.8 ± 0.6 dB, with reduced sensitivity significantly associated with the presence of drusen, atrophy, RPE disruption, and absent EZ (P < 0.01). Conclusion: The tablet-based test of retinal sensitivity was able to be performed by an elderly cohort with nAMD. The ability to correlate differences in sensitivity with pathology is encouraging when considering using the tablet devices as a home monitoring tool with remote surveillance. Dual pathology often present with retinal fluid confounded our ability to correlate fluid with sensitivity. Translational Relevance: These findings highlight the potential of tablet-based devices in performing visual function measures as a home monitoring tool with remote surveillance for the earlier detection of nAMD.
Quantitative Analysis of the Ellipsoid Zone Intensity in Phenotypic Variations of Intermediate Age-Related Macular Degeneration
(ASSOC RESEARCH VISION OPHTHALMOLOGY INC, 2017-04-01)
Purpose: Reduction of the ellipsoid zone (EZ) intensity has been reported in eyes with age-related macular degeneration (AMD). This study determined whether overall EZ intensity, in retinal locations undisturbed by pathologic features, is associated with the presence of clinical features, which are known important phenotypic risk factors for disease progression, large drusen, reticular pseudodrusen (RPD), and pigmentary abnormalities. Methods: A horizontal B-scan through the foveola on spectral-domain optical coherence tomography (SD-OCT) was performed in both eyes of 75 participants with bilateral intermediate AMD and 10 age-similar control participants. Eyes with AMD were classified as per the presence of large drusen, RPD, and hyperpigmentary changes. The relative EZ intensity profile, up to an eccentricity of 3400 μm, was averaged over seven 1000-μm retinal segments. The association between relative EZ intensity profile over seven retinal segments and AMD pathologic features was analyzed. Results: The average relative EZ intensities were significantly reduced in eyes with intermediate AMD compared to normal eyes (P ≤ 0.025) and with increasing age (P ≤ 0.020). On multivariate analyses, only the presence of hyperpigmentary changes and increasing age were significantly associated with reduced overall relative intensities (P ≤ 0.024), but not the presence of large drusen or RPD (P ≥ 0.115). Conclusions: The presence of hyperpigmentary change in the macula in association with large drusen, not large drusen alone, nor large drusen with RPD, was significantly associated with a generalised reduction in EZ intensity. Quantitative assessment of the relative EZ intensity may serve as an effective biomarker of disease severity and progression.
Retinal Changes in an ATP-Induced Model of Retinal Degeneration
(FRONTIERS MEDIA SA, 2016-04-29)
In rodents and felines, intravitreal administration of adenosine triphosphate (ATP) has been shown to induce photoreceptor death providing a tractable model of retinal degeneration in these species. This study investigated the long term effects of photoreceptor loss in an ATP induced feline model of retinal degeneration. Six normal sighted felines were unilaterally blinded using intravitreal ATP injections and assessed using electroretinography (ERG) and optical coherence tomography (OCT). At 30 h (n = 3) or 12 weeks (n = 3) post-injection, the animals were euthanized and the eyes enucleated. Retinae were sectioned and labeled using immunohistochemistry for markers of cell death, neural remodeling and gliosis. Ongoing cell death and retinal degeneration was observed in the outer retina at both 30 h and 12 weeks following unilateral ATP injection. Markers of mid to late-stage retinal remodeling such as cell displacement and aberrant neurite growth were observed in the inner retina at 12 weeks post-injection. Ganglion cells appeared to remain intact in ATP injected eyes. Müller cell gliosis was observed throughout the inner and outer retina, in some parts completely enveloping and/or displacing the surviving neural tissue. Our data suggests that the ATP injected feline retina continues to undergo progressive retinal degeneration and exhibits abnormalities consistent with a description of retinal remodeling commonly seen in other models of retinal degeneration. These findings validate the use of intravitreal ATP injection in feline as a large animal model of retinal degeneration which may aid in development of therapies aiming to restore visual function after photoreceptor degeneration.
Genetically low vitamin D concentrations and myopic refractive error: a Mendelian randomization study
(OXFORD UNIV PRESS, 2017-12-01)
Background: Myopia prevalence has increased in the past 20 years, with many studies linking the increase to reduced time spent outdoors. A number of recent observational studies have shown an inverse association between vitamin D [25(OH)D] serum levels and myopia. However, in such studies it is difficult to separate the effects of time outdoors and vitamin D levels. In this work we use Mendelian randomization (MR) to assess if genetically determined 25(OH)D levels contribute to the degree of myopia. Methods: We performed MR using results from a meta-analysis of refractive error (RE) genome-wide association study (GWAS) that included 37 382 and 8 376 adult participants of European and Asian ancestry, respectively, published by the Consortium for Refractive Error And Myopia (CREAM). We used single nucleotide polymorphisms (SNPs) in the DHCR7, CYP2R1, GC and CYP24A1 genes with known effects on 25(OH)D concentration as instrumental variables (IV). We estimated the effect of 25(OH)D on myopia level using a Wald-type ratio estimator based on the effect estimates from the CREAM GWAS. Results: Using the combined effect attributed to the four SNPs, the estimate for the effect of 25(OH)D on refractive error was -0.02 [95% confidence interval (CI) -0.09, 0.04] dioptres (D) per 10 nmol/l increase in 25(OH)D concentration in Caucasians and 0.01 (95% CI -0.17, 0.19) D per 10 nmol/l increase in Asians. Conclusions: The tight confidence intervals on our estimates suggest the true contribution of vitamin D levels to degree of myopia is very small and indistinguishable from zero. Previous findings from observational studies linking vitamin D levels to myopia were likely attributable to the effects of confounding by time spent outdoors.