To evaluate the relationship between refractive error, circadian phase, and melatonin with consideration of prior light exposure, physical activity, and sleep. METHODS. Healthy young myopic (spherical equivalent refraction [SER] ≤−0.50DS) and emmetropic adults underwent noncycloplegic autorefraction and axial length (AL) measures. Objective measurements of light exposure, physical activity, and sleep were captured across 7 days by wrist-worn Actiwatch-2 devices. Questionnaires assessed sleep quality and chronotype. Hourly evening saliva sampling during a dim-light melatonin onset (DLMO) protocol evaluated circadian phase, and both morning serum and saliva samples were collected. Liquid chromatography/mass spectrometry quantified melatonin. RESULTS. Subjects (n = 51) were aged 21.4 (interquartile range, 20.1−24.0) years. Melatonin was significantly higher in the myopic group at every evening time point and with both morning serum and saliva sampling (P ≤ 0.001 for all). DLMO-derived circadian phase did not differ between groups (P = 0.98). Multiple linear regression analysis demonstrated significant associations between serum melatonin and SER (B =-.34, β =-.42, P = 0.001), moderate activity (B = .009, β = .32, P = 0.01), and mesopic illumination (B =-.007, β =-.29, P = 0.02), F(3, 46) = 7.23, P < 0.001, R 2 = 0.32, R 2 adjusted = .28. Myopes spent significantly more time exposed to "indoor" photopic illumination (3 to ≤1000 lux; P = 0.05), but "indoor" photopic illumination was not associated with SER, AL, or melatonin, and neither sleep, physical activity, nor any other light exposure metric differed significantly between groups (P > 0.05 for all). CONCLUSIONS. While circadian phase is aligned in adult myopes and emmetropes, myopia is associated with both elevated serum and salivary melatonin levels. Prospective studies are required to ascertain whether elevated melatonin levels occur before, during, or after myopia development.

Often patients presenting to casualty with symptomatic PVD have two fundal examinations, separated by 5 or 6 weeks. As the frequency of retinal breaks developing in the 6 weeks after symptomatic PVD is unclear, the aim of this prospective study was to determine the frequency of retinal breaks in patients with symptomatic PVD 1 and 6 weeks after presentation, with the same vitreo-retinal fellow examining at each visit. Materials and methodsPatients who presented to the eye casualty with symptoms of PVD were examined by senior house officers or specialist registrar trainees. Slit-lamp biomicroscopy with a 78 D lens, Eye (1999) 13,237-240

Myopia was associated with smaller areas of CUVAF indicative of less cumulative ultraviolet-B exposure. These findings suggest that CUVAF measures are a useful, non-invasive biomarker of the time spent outdoors in adults in northern hemisphere populations.

CUVAF area and intensity were not associated with clinical measures of dry eye. Greater CUVAF area and intensity were associated with wearing sunglasses less frequently and spending more time outdoors. If sunglass wear is accounted for, CUVAF may be a useful biomarker of time spent outdoors in future myopia studies.

The use of enlarged breath shields has been suggested as part of a wide range of infection control measures implemented during the COVID-19 pandemic. Breath shields have long been a standard feature of slit lamps and act as a physical barrier between the examiner and subject but there is an absence of evidence on their effectiveness in reducing droplet transmission and respiratory infections.SARS-CoV-2 shares many of the features of other respiratory viruses including SARS-CoV-1 and is thought to be commonly spread though respiratory droplets (>5 μm) and fomites [1]. Fomites are formed either from droplets settling on surfaces or through direct contamination from touching mucosal surfaces. Smaller aerosolised droplet nuclei (≤5 μm) can travel further and remain in air longer. They have been shown to carry viable virus particles in experimental conditions [2] but are not thought to be a common mode of transmission of COVID-19 [1]. The risk of transmission from tears is also thought to be low [3].We sought to examine the efficacy of facemasks and standard and augmented slit lamp breath shields using a breathing simulator. These have been described previously and generally comprise of a particle source, commonly a nebuliser attached to a bellows or air tank and a particle detector which can consist of a laser particle counter [4] or an impinger from which viral particles can be sampled from air, cultured in cells and detected as plaques [5]. Direct visual inspection of sprayed dye droplets has also been described as a way to test eye protection [6,7]. We experimented using nebulised fluorescein 2% but were unable to capture sufficient dye to determine the patterns of droplet distribution.We used a mouthpiece nebuliser (Galemed Corp, Taiwan) containing 5 ml of 0.9% saline as our particle source and attached it to a 500 ml paediatric bag valve mask that was manually compressed 12 times per minute to simulate normal adult tidal breathing. The device produces a range of particles from 1 to 25 μm with median mass aerodynamic diameter of 3.8 μm. We used a Met One A2400 optical particle counter (Hach Co, Loveland, CO) operating at a flow rate of one cubic foot per minute to detect particles that reached the eyepiece over a 1-min period. This was initially performed without any shielding, and then repeated with the standard (11 × 11 × 0.2 cm) and augmented (45 × 44 × 0.2 cm) acrylic shields attached to the slit lamp objective lens (Fig. 1). We then tested the effect of placing a fluid resistant surgical facemask (BARRIER 4313, Mölnlycke Healthcare, Sweden) over the nebuliser mouthpiece alone and in combination with the large shield. The slit lamp arm was offset to 60°throughout and each barrier was tested five times. Linear regression was used to determine the effect of shield type and particle size on particle count. All analyses were performed using Stata v14.With no shield in place, the mean log particle count was 3.59 (95% CI: 3.48-3.70). There was a significant reduction to 3.01 (95% CI: 2.90-3.13, p < 0.01) with the s...