Resonant generation of propagating second-harmonic spin waves in nano-waveguides

Generation of second-harmonic waves is one of the universal nonlinear phenomena that have found numerous technical applications in many modern technologies, in particular, in photonics. This phenomenon also has great potential in the field of magnonics, which considers the use of spin waves in magnetic nanostructures to implement wave-based signal processing and computing. However, due to the strong frequency dependence of the phase velocity of spin waves, resonant phase-matched generation of second-harmonic spin waves has not yet been achieved in practice. Here, we show experimentally that such a process can be realized using a combination of different modes of nano-sized spin-wave waveguides based on low-damping magnetic insulators. We demonstrate that our approach enables efficient spatially-extended energy transfer between interacting waves, which can be controlled by the intensity of the initial wave and the static magnetic field.

Focus on reuse: reducing waste associated with topical preoperative antiseptics

PURPOSE

To outline the environmental and financial costs associated with single-use topical antiseptic (5% povidone-iodine [PVI] solution) in the ophthalmology theatre setting and explore potential methods of repurposing topical antiseptics.

SETTING

Large tertiary referral center (Flinders Medical Centre, Adelaide, Australia).

DESIGN

Single-center prospective observational study.

METHODS

Dedicated containers placed in the ophthalmology theatre of the participating institution were used to collect the number of disposed PVI bottles over the 3-week study period. Descriptive statistics were employed to determine the associated packaging bottle weight, mean unused quantity (mL) and cost of the single-use topical PVI solution and costs of unused antiseptic.

RESULTS

The total amount of waste generated from the use of single-use PVI bottles during the surveillance period was 10.823 kg, of which 21.9% was preventable; 72% of unused PVI by weight were discarded during the study period, equating to approximately $21 857.60 in wasted pharmaceutical content per year. 100% of the discarded PVI was successfully redirected and reused at a local wildlife rescue organisation and diverted from landfill.

CONCLUSIONS

This study has demonstrated that the utilization of single-use topical preoperative PVI preparations is associated with significant financial, pharmaceutical and environmental waste. Future studies examining the recyclability of single-use PVI bottles and investigating systematic strategies to recycle and repurpose this waste are required.

Fundus fluorescein angiography imaging of retinopathy of prematurity in infants: A review

Fluorescein angiography in retinopathy of prematurity is increasingly utilized over the past decade. The development of ultra-wide-field imaging combined with fluorescein angiography has allowed improved visualization of the peripheral retinal vasculature. Patient cooperation in the pediatric population is particularly challenging, but hand-held digital retinal photography has shown promise and can visualize the infant retina without the need for anesthesia and intravenous access. Many features of retinopathy of prematurity and its response to laser and anti-VEGF treatment can be either exclusively or better visualized on fluorescein angiography compared to indirect ophthalmoscopy or color fundus photography. Disease treatment is gradually shifting from laser photocoagulation to intravitreal anti-VEGF agents, the latter being associated with late-onset vision-threatening sequelae. The role of fluorescein angiography in retinopathy of prematurity monitoring will continue to increase with the longer follow-up required and different clinical behavior seen with anti-VEGF treatment. We highlight the utility, safety, and importance of fluorescein angiography in the diagnosis, treatment, and follow-up of retinopathy of prematurity.

Swept-Source OCT Mid-Peripheral Retinal Irregularity in Retinal Detachment and Posterior Vitreous Detachment Eyes

Irregularities in retinal shape have been shown to correlate with axial length, a major risk factor for retinal detachment. To further investigate this association, a comparison was performed of the swept-source optical coherence tomography (SS OCT) peripheral retinal shape of eyes that had either a posterior vitreous detachment (PVD) or vitrectomy for retinal detachment. The objective was to identify a biomarker that can be tested as a predictor for retinal detachment. Eyes with a PVD (N = 88), treated retinal detachment (N = 67), or retinal tear (N = 53) were recruited between July 2020 and January 2022 from hospital retinal clinics in South Australia. The mid-peripheral retina was imaged in four quadrants with SS OCT. The features explored were patient age, eye axial length, and retinal shape irregularity quantified in the frequency domain. A discriminant analysis classifier to identify retinal detachment eyes was trained with two-thirds and tested with one-third of the sample. Retinal detachment eyes had greater irregularity than PVD eyes. A classifier trained using shape features from the superior and temporal retina had a specificity of 84% and a sensitivity of 48%. Models incorporating axial length were less successful, suggesting peripheral retinal irregularity is a better biomarker for retinal detachment than axial length. Mid-peripheral retinal irregularity can identify eyes that have experienced a retinal detachment.

Retinal Shape-Based Classification of Retinal Detachment and Posterior Vitreous Detachment Eyes

INTRODUCTION

Retinal detachment is a sight-threatening emergency, with more than half of those affected suffering permanent visual impairment. A diagnostic test to identify eyes at risk before vision is threatened would enable exploration of prophylactic treatment. This report presents the use of irregularities in retinal shape, quantified from optical coherence tomography (OCT) images, as a biomarker for retinal detachment.

METHODS

OCT images were taken from posterior and mid-peripheral retina of 264 individuals [97 after a posterior vitreous detachment (PVD), 99 after vitrectomy for retinal detachment and 68 after laser for a retinal tear]. Diagnoses were taken from history, examination and OCT. Retinal irregularity was quantified in the frequency domain, and the distribution of irregularity across the regions of the eye was explored to identify features exhibiting the greatest difference between retinal detachment and PVD eyes. Two of these features plus axial length were used to train a quadratic discriminant analysis classifier. Classifier performance was assessed by its sensitivity and specificity in identifying retinal detachment eyes and visualised with a receiver operating characteristic (ROC) curve.

RESULTS

Validation set specificity was 84% (44/52 PVD eyes correctly labelled) and sensitivity 35% (23/64 retinal detachment eyes identified, p = 0.02). Area under the ROC curve was 0.75 (95% confidence intervals 0.58-0.85). Retinal detachment eyes were significantly more irregular than PVD eyes in the superior retina (0.70 mm versus 0.49 mm, p < 0.05) and supero-temporal retina (1.12 mm versus 0.80 mm, p < 0.05). Lower sensitivity (16/68, 24%) was seen for eyes with a retinal tear without detachment, that were intermediate in size between retinal detachment and PVD eyes. Axial length on its own was a poor classifier. Neither irregularity nor classification were affected by surgery for retinal detachment or the development of PVD.

CONCLUSIONS

The classifier identified 1/3 of retinal detachment eyes in this sample. In future work, these features can be evaluated as a test for retinal detachment prior to PVD.

Bilateral intermediate uveitis following treatment with paclitaxel in a patient with invasive ductal carcinoma of the breast

BACKGROUND

To report a case of bilateral intermediate uveitis without cystoid macular edema secondary to paclitaxel therapy, and its successful management with oral corticosteroids.

CASE PRESENTATION

A 66-year-old female developed bilateral intermediate uveitis with reduced best corrected visual acuity to 20/40 right and 20/200 left, following 12 cycles of paclitaxel therapy for breast carcinoma. Optical coherence tomography demonstrated no cystoid macular edema in either eye, and fundus fluorescein angiography showed localized retinal vascular leakage. Resolution of uveitis and improvement of visual acuity followed treatment with oral prednisolone for two months. Fourteen months after presentation, right and left visual acuities had returned to 20/32 and 20/40, respectively, and there was no recurrence of the uveitis.

CONCLUSIONS

This is the first reported case of bilateral intermediate uveitis in a patient treated with paclitaxel. Drug-induced uveitis should be considered in patients with visual symptoms in the setting of taxane chemotherapy, and oral corticosteroids are a safe and effective treatment.

Genome-wide association studies for diabetic macular edema and proliferative diabetic retinopathy

Background

Diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR) are sight-threatening complications of diabetes mellitus and leading causes of adult-onset blindness worldwide. Genetic risk factors for diabetic retinopathy (DR) have been described previously, but have been difficult to replicate between studies, which have often used composite phenotypes and been conducted in different populations. This study aims to identify genetic risk factors for DME and PDR as separate complications in Australians of European descent with type 2 diabetes.

Methods

Caucasian Australians with type 2 diabetes were evaluated in a genome-wide association study (GWAS) to compare 270 DME cases and 176 PDR cases with 435 non-retinopathy controls. All participants were genotyped by SNP array and after data cleaning, cases were compared to controls using logistic regression adjusting for relevant covariates.

Results

The top ranked SNP for DME was rs1990145 (p = 4.10 × 10^− 6, OR = 2.02 95%CI [1.50, 2.72]) on chromosome 2. The top-ranked SNP for PDR was rs918519 (p = 3.87 × 10^− 6, OR = 0.35 95%CI [0.22, 0.54]) on chromosome 5. A trend towards association was also detected at two SNPs reported in the only other reported GWAS of DR in Caucasians; rs12267418 near MALRD1 (p = 0.008) in the DME cohort and rs16999051 in the diabetes gene PCSK2 (p = 0.007) in the PDR cohort.

Conclusion

This study has identified loci of interest for DME and PDR, two common ocular complications of diabetes. These findings require replication in other Caucasian cohorts with type 2 diabetes and larger cohorts will be required to identify genetic loci with statistical confidence. There is considerable overlap in the patient cohorts with each retinopathy subtype, complicating the search for genes that contribute to PDR and DME biology.

Electronic supplementary material

The online version of this article (10.1186/s12881-018-0587-8) contains supplementary material, which is available to authorized users.

Visual outcomes following vitrectomy for diabetic retinopathy amongst Indigenous and non-Indigenous Australians in South Australia and the Northern Territory

IMPORTANCE

Visual outcomes following diabetic vitrectomy have not previously been studied in an Australian population.

BACKGROUND

This analysis aimed to determine the rate of, and factors associated with visual success following diabetic vitrectomy performed for Indigenous and non-Indigenous Australians, and investigate factors predisposing to early progression to diabetic retinopathy (DR) requiring vitrectomy.

DESIGN

Retrospective, population-based audit.

PARTICIPANTS

All patients undergoing vitrectomy for the complications of DR in South Australia (SA) and the Northern Territory (NT) between 2007 and 2011.

METHODS

Medical records were audited and data collected, including demographics, diabetic history, past treatment for DR, indication for vitrectomy and visual acuity pre and postoperatively.

MAIN OUTCOME MEASURES

Visual success (gain of ≥15 ETDRS letters) at 6 and 12 months, postoperatively.

RESULTS

A total of 495 diabetic vitrectomies, for 404 eyes of 335 patients were performed in SA and NT between 2007 and 2011. 77 (23%) patients requiring diabetic vitrectomy were Indigenous Australians. 87% of patients undergoing diabetic vitrectomy had stable or improved vision at 1 year, postoperatively. There was no significant difference between indigenous and non-indigenous eyes achieving visual success (P = 0.929). Timely preoperative laser treatment (P = 0.03) and preoperative visual acuity (P = 0.01) were the predominant factors associated with visual success.

CONCLUSIONS AND RELEVANCE

Indigenous patients are just as likely to have improved vision following diabetic vitrectomy as non-Indigenous Australians. However, the small subset of indigenous patients with blind eyes prior to vitrectomy are significantly less likely to improve from surgery. The underlying factors associated with poor outcomes in this group requires further exploration.

Genome-wide association study for sight-threatening diabetic retinopathy reveals association with genetic variation near the GRB2 gene

AIMS/HYPOTHESIS

Diabetic retinopathy is a serious complication of diabetes mellitus and can lead to blindness. A genetic component, in addition to traditional risk factors, has been well described although strong genetic factors have not yet been identified. Here, we aimed to identify novel genetic risk factors for sight-threatening diabetic retinopathy using a genome-wide association study.

METHODS

Retinopathy was assessed in white Australians with type 2 diabetes mellitus. Genome-wide association analysis was conducted for comparison of cases of sight-threatening diabetic retinopathy (n = 336) with diabetic controls with no retinopathy (n = 508). Top ranking single nucleotide polymorphisms were typed in a type 2 diabetes replication cohort, a type 1 diabetes cohort and an Indian type 2 cohort. A mouse model of proliferative retinopathy was used to assess differential expression of the nearby candidate gene GRB2 by immunohistochemistry and quantitative western blot.

RESULTS

The top ranked variant was rs3805931 with p = 2.66 × 10(-7), but no association was found in the replication cohort. Only rs9896052 (p = 6.55 × 10(-5)) was associated with sight-threatening diabetic retinopathy in both the type 2 (p = 0.035) and the type 1 (p = 0.041) replication cohorts, as well as in the Indian cohort (p = 0.016). The study-wide meta-analysis reached genome-wide significance (p = 4.15 × 10(-8)). The GRB2 gene is located downstream of this variant and a mouse model of retinopathy showed increased GRB2 expression in the retina.

CONCLUSIONS/INTERPRETATION

Genetic variation near GRB2 on chromosome 17q25.1 is associated with sight-threatening diabetic retinopathy. Several genes in this region are promising candidates and in particular GRB2 is upregulated during retinal stress and neovascularisation.

Delayed onset panuveitis following intravitreal aflibercept injection

Aflibercept has been listed on the Australian Pharmaceutical Benefit Scheme for the past year for neovascular age-related macular degeneration. Since that time there have not been any reports of delayed onset panuveitis. We present two cases of anterior and posterior uveitis that have occurred 4 weeks or more after first intravitreal injection of aflibercept. Both patients had received other vascular endothelial growth factor inhibitors prior to aflibercept administration without signs of inflammation and both cases had sterile endophthalmitis. On resolution of the inflammation the patients were recommenced on ranibizumab without further incident.

Review of the prevalence of diabetic retinopathy in Indigenous Australians

The purpose of this review is to compare the prevalence of diabetic retinopathy (DR) between Indigenous and non-Indigenous Australians with Diabetes Mellitus (DM). Australian DR prevalence data from 6 Indigenous studies (n = 2865) and 5 non-Indigenous studies (n = 9801) conducted between 1985 and 2013 were included for analysis. Estimated prevalence of any DR among Indigenous Australians with DM was 23.4% compared with 28.9% for non-Indigenous Australians (χ(2)  = 26.9, P < 0.001). In studies performed after 1990, a significantly higher rate of diabetic macular edema was found in Indigenous compared with non-Indigenous Australians with DM (7.6% versus 4.9%, χ(2)  = 6.67, P = 0.01). Although there are limitations in comparing these studies, one explanation for the observed data could be a model in which Indigenous Australians are relatively resistant to early stage DR, but with a subset progressing to sight threatening DR due to individual genetic and environmental susceptibility factors coupled with poor glycemic control.