Search

We present light curves and flares from a 7 day, multiwavelength observational campaign of AU Mic, a young and active dM1e star with exoplanets and a debris disk. We report on 73 unique flares between the X-ray to optical data. We use high-time-resolution near-UV (NUV) photometry and soft X-ray (SXR) data from the X-ray Multi-Mirror Mission to study the empirical Neupert effect, which correlates the gradual and impulsive phase flaring emissions. We find that 65% (30 of 46) flares do not follow the Neupert effect, which is 3 times more excursions than seen in solar flares, and propose a four-part Neupert effect classification (Neupert, quasi-Neupert, non-Neupert types I and II) to explain the multiwavelength responses. While the SXR emission generally lags behind the NUV as expected from the chromospheric evaporation flare models, the Neupert effect is more prevalent in larger, more impulsive flares. Preliminary flaring rate analysis with X-ray and U -band data suggests that previously estimated energy ratios hold for a collection of flares observed over the same time period, but not necessarily for an individual, multiwavelength flare. These results imply that one model cannot explain all stellar flares and care should be taken when extrapolating between wavelength regimes. Future work will expand wavelength coverage using radio data to constrain the nonthermal empirical and theoretical Neupert effects to better refine models and bridge the gap between stellar and solar flare physics.

Purpose: To present a case of inadvertent retinal toxicity induced by a standard dose of subconjunctival cefuroxime after epiretinal membrane surgery. Narrative review of cefuroxime overdose or toxicity after intraocular surgery was carried out to describe characteristics of cefuroxime toxicity and their relationship to visual outcome. Observations: A 64-year-old man underwent pars plana vitrectomy (PPV) with epiretinal membrane peel and received a standard dose of subconjunctival cefuroxime as endophthalmitis prophylaxis. At two weeks, visual acuity measured counting fingers, and fundus examination showed haemorrhages and cotton wool spots. Fluorescein angiography confirmed widespread ischaemia involving the macula. Subsequent litigation ruled that inadvertent cefuroxime toxicity after an accidental penetration of sclera was the likely aetiology. Conclusions and importance: In addition to inadvertent overdose due to dilution errors, accidental scleral penetration is another mechanism for drug toxicity following subconjunctival cefuroxime injection. Literature review revealed broadly different manifestations of cefuroxime retinal toxicity. This case highlights the need to consider severe cefuroxime toxicity in patients presenting with unexplained post-PPV visual loss.

Abstract The following is a response to the recent review article by Girsang and colleagues (Int J Retina Vitreous. 2020;6:46), who describe concept and application of relaxing radial retinectomy for retinal detachment with advanced proliferative vitreoretinopathy. We discuss the distribution of the retinal nerve fiber layer, an aspect not touched on by the authors, and the importance of its consideration in determining visual field outcomes when performing retinectomy. Moreover, we share our clinical experience with both radial and circumferential retinectomy and discuss scenarios where the combination of both is more effective.