PURPOSE. To describe a standardized flood-illuminated adaptive optics (AO) imaging protocol suitable for the clinical setting and to assess sampling methods for measuring cone density.METHODS. Cone density was calculated following three measurement protocols: 50 3 50-lm sampling window values every 0.58 along the horizontal and vertical meridians (fixed-interval method), the mean density of expanding 0.58-wide arcuate areas in the nasal, temporal, superior, and inferior quadrants (arcuate mean method), and the peak cone density of a 50 3 50-lm sampling window within expanding arcuate areas near the meridian (peak density method). Repeated imaging was performed in nine subjects to determine intersession repeatability of cone density. RESULTS.Cone density montages could be created for 67 of the 74 subjects. Image quality was determined to be adequate for automated cone counting for 35 (52%) of the 67 subjects. We found that cone density varied with different sampling methods and regions tested. In the nasal and temporal quadrants, peak density most closely resembled histological data, whereas the arcuate mean and fixed-interval methods tended to underestimate the density compared with histological data. However, in the inferior and superior quadrants, arcuate mean and fixed-interval methods most closely matched histological data, whereas the peak density method overestimated cone density compared with histological data. Intersession repeatability testing showed that repeatability was greatest when sampling by arcuate mean and lowest when sampling by fixed interval. CONCLUSIONS.We show that different methods of sampling can significantly affect cone density measurements. Therefore, care must be taken when interpreting cone density results, even in a normal population.
The purpose of this study was to correlate features on flood-illuminated adaptive optics (AO) images with color fundus, fundus autofluorescence (FAF) and spectral domain optical coherence tomography (SD-OCT) images in patients with retinitis pigmentosa (RP). We imaged 39 subjects diagnosed with RP using the rtx1™ flood-illuminated AO camera from Imagine Eyes (Orsay, France). We observed a correlation between hyper-autofluoresence changes on FAF, disruption of the interdigitation zone (IZ) on SD-OCT and loss of reflective cone profiles on AO. Four main patterns of cone-reflectivity were seen on AO: presumed healthy cone mosaics, hypo-reflective blurred cone-like structures, higher frequency disorganized hyper-reflective spots, and lower frequency hypo-reflective spots. These regions were correlated to progressive phases of cone photoreceptor degeneration observed using SD-OCT and FAF. These results help provide interpretation of en face images obtained by flood-illuminated AO in subjects with RP. However, significant ambiguity remains as to what truly constitutes a cone, especially in areas of degeneration. With further refinements in technology, flood illuminated AO imaging has the potential to provide rapid, standardized, longitudinal and lower cost imaging in patients with retinal degeneration.
Purpose To determine prevalence of burnout in ophthalmology residents in the United States using the Maslach Burnout Inventory—Human Services Survey and to identify factors associated with burnout and wellness. Methods Anonymous survey distributed to residents via residency program directors. Results Ninety-one programs out of 113 (80.5%) confirmed survey distribution. Of 267 included respondents, 23 (8.6%) met criteria for high burnout, and 169 (63.3%) met criteria for at least one aspect of burnout. Longer work hours, longer hours spent on call, higher number of consults seen on call, fewer hours of sleep on call, and not meeting recommended physical activity minimums were associated with higher emotional exhaustion. Most common factors cited to improve wellness included physical activity, nurturing relationships, and co-resident support, whereas most commonly cited factors that contributed to burnout included sleep deprivation, call, and workload. Conclusion Burnout in ophthalmology residents is common, occurring at similar rates as reported in residencies of other specialties.
PURPOSE To test for the ability of different MRI modalities to discriminate the time course of damage and regeneration in a model of acute, toxin-induced muscle damage. MATERIALS AND METHODS We analyzed the time course of tissue and cellular changes in mouse lower limb musculature following localized injection of myotoxin by T2, magnetization transfer (MT) and diffusion weighted MRI. We also used T1 weighted imaging to measure leg muscle volume. In addition, post-mortem histological analysis of toxin-injected muscles was compared to uninjected controls. RESULTS The damages detected by the MRI modalities are transient and recover within 3 weeks. Muscle water diffusivity and edema measured by leg volume increased within the first hours after injection of the toxin. The rate constant for volume increase was 0.65 ± 0.11 hr−1, larger than the increase in T2 (0.045 ± 0.013 hr−1) and change in MT ratio (0.028 ± 0.021 hr−1). During repair phase, the rate constants were much smaller: 0.022 ± 0.004 hr−1, 0.013 ± 0.0019 hr−1 and 0.0042 ± 0.0016 hr−1 for volume, T2 and MT ratio, respectively. Histological analyses confirmed the underlying cellular changes that matched the progression of MR images. CONCLUSION The kinetics of change in the MRI measurements during the progression of damage and repair shows MRI modalities can be used to distinguish these processes.
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