Early and complete vitrectomy versus tap and inject in acute post cataract surgery endophthalmitis presenting with hand motion vision; a quasi-experimental study

Background Based on endophthalmitis vitrectomy study, intravitreal injection of antibiotics is preferred for initial management of cases of acute post cataract surgery endophthalmitis (APCE) with presenting vision of hand motions (HM). This study aimed to compare outcomes of early and complete vitrectomy (VIT) and vitreous tap and antibiotic injection (T&I) in cases of APCE presented with vision of HM. Methods In this prospective study, cases of APCE with vision of HM between 2018 and 2020 were enrolled. According to the time of presentation, the patients were arranged into two groups (VIT vs. T&I). Demographic data, elapsed time to developing endophthalmitis, past medical history, microbiology results, complications, and final visual acuity were recorded and analyzed. Results Seventy-six eyes of 76 patients were enrolled. Fifty-three eyes underwent T&I and twenty-three were arranged into the VIT group. Past medical history of 34.2% of patients was significant for diabetes mellitus. There was a statistically significant lower logMAR in VIT group compared to T&I group (diff = 0.14, 95% CI: 0.04 to 0.24, P-value = 0.007). The comparison of the diabetic and non-diabetic patients in both groups showed that the visual outcome was better in non-diabetic cases compared to the diabetic subjects. There was no statistically significant difference between the diabetic and non-diabetic groups regarding the superiority of procedure. Conclusion Based on our results, we could recommend that it’s maybe better to do early and complete vitrectomy as the initial management of APCE with the vision of HM. Past medical history of diabetes mellitus is not a determining factor for choosing initial management between vitrectomy and antibiotic injection.

Neuronal circuits integrating visual motion information in Drosophila

The detection of visual motion enables sophisticated animal navigation, and studies in flies have provided profound insights into the cellular and circuit basis of this neural computation. The fly's directionally selective T4 and T5 neurons respectively encode ON and OFF motion. Their axons terminate in one of four retinotopic layers in the lobula plate, where each layer encodes one of four cardinal directions of motion. While the input circuitry of the directionally selective neurons has been studied in detail, the synaptic connectivity of circuits integrating T4/T5 motion signals is largely unknown. Here we report a 3D electron microscopy reconstruction, wherein we comprehensively identified T4/T5's synaptic partners in the lobula plate, revealing a diverse set of new cell types and attributing new connectivity patterns to known cell types. Our reconstruction explains how the ON and OFF motion pathways converge. T4 and T5 cells that project to the same layer, connect to common synaptic partners symmetrically, that is with similar weights, and also comprise a core motif together with bilayer interneurons, detailing the circuit basis for computing motion opponency. We discovered pathways that likely encode new directions of motion by integrating vertical and horizontal motion signals from upstream T4/T5 neurons. Finally, we identify substantial projections into the lobula, extending the known motion pathways and suggesting that directionally selective signals shape feature detection there. The circuits we describe enrich the anatomical basis for experimental and computations analyses of motion vision and bring us closer to understanding complete sensory-motor pathways.

Synergy of color and motion vision for detecting approaching objects in Drosophila

Color and motion are used by many species to identify salient moving objects. They are processed largely independently, but color contributes to motion processing in humans, for example, enabling moving colored objects to be detected when their luminance matches the background. Here, we demonstrate an unexpected, additional contribution of color to motion vision in Drosophila. We show that behavioral ON-motion responses are more sensitive to UV than for OFF-motion, and we identify cellular pathways connecting UV-sensitive R7 photoreceptors to ON and OFF-motion-sensitive T4 and T5 cells, using neurogenetics and calcium imaging. Remarkably, the synergy of color and motion vision enhances the detection of approaching UV discs, but not green discs with the same chromatic contrast, and we show how this generalizes for visual systems with ON and OFF pathways. Our results provide a computational and circuit basis for how color enhances motion vision to favor the detection of saliently colored objects.

Aerial course stabilization is impaired in motion-blind flies

Visual motion detection is among the best understood neuronal computations. As extensively investigated in tethered flies, visual motion signals are assumed to be crucial to detect and counteract involuntary course deviations. During free flight, however, course changes are also signalled by other sensory systems. Therefore, it is yet unclear to what extent motion vision contributes to course control. To address this question, we genetically rendered flies motion-blind by blocking their primary motion-sensitive neurons and quantified their free-flight performance. We found that such flies have difficulties maintaining a straight flight trajectory, much like unimpaired flies in the dark. By unilateral wing clipping, we generated an asymmetry in propulsive force and tested the ability of flies to compensate for this perturbation. While wild-type flies showed a remarkable level of compensation, motion-blind animals exhibited pronounced circling behaviour. Our results therefore directly confirm that motion vision is necessary to fly straight under realistic conditions.

Spherical arena reveals optokinetic response tuning to stimulus location, size, and frequency across entire visual field of larval zebrafish

Many animals have large visual fields, and sensory circuits may sample those regions of visual space most relevant to behaviours such as gaze stabilisation and hunting. Despite this, relatively small displays are often used in vision neuroscience. To sample stimulus locations across most of the visual field, we built a spherical stimulus arena with 14,848 independently controllable LEDs. We measured the optokinetic response gain of immobilised zebrafish larvae to stimuli of different steradian size and visual field locations. We find that the two eyes are less yoked than previously thought and that spatial frequency tuning is similar across visual field positions. However, zebrafish react most strongly to lateral, nearly equatorial stimuli, consistent with previously reported spatial densities of red, green and blue photoreceptors. Upside-down experiments suggest further extra-retinal processing. Our results demonstrate that motion vision circuits in zebrafish are anisotropic, and preferentially monitor areas with putative behavioural relevance.

Two Patients with Atypical Choroidal Detachment

Serous choroidal detachment that is caused by rhegmatogenous retinal detachment (RRD) may present a significant diagnostic challenge as delayed recognition and repair of the underlying RRD can severely impact the final anatomical and visual outcome. We report 2 consecutive patients with atypical choroidal detachments who were later found to have underlying RRDs. A 71-year-old female presented with a 1-week history of painful vision loss and floaters in the left eye. Examination revealed choroidal detachments in the nasal and temporal periphery and an overlying retinal detachment with shifting subretinal fluid. However, no retinal breaks were identified. An extensive laboratory workup and imaging of the orbits were unrevealing. She was treated with 80 mg oral prednisone daily for 2 weeks with subsequent resolution of the choroidals but persistence of the retinal detachment. Similarly, a 52-year-old male presented with a 3-week history of flashes and floaters followed by painful vision loss in the left eye 1 day prior to presentation. He had hand motion vision OS and the intraocular pressure was undetectable by hand-held tonometry OS. Dense brunescent cataract prevented adequate viewing of the posterior pole. B-scan ultrasonography revealed a funnel retinal detachment, with homogenous choroidal echogenicities suggestive of hemorrhagic choroidal detachment. Extensive laboratory workup was unrevealing. The patient was started on 60 mg oral prednisone and re-evaluated every 2 days, but ultrasonography revealed persistence of the choroidal detachment after 1 week. The diagnosis of RRD with an associated choroidal detachment should be considered, even in the absence of an identifiable causative retinal break.

Aerial course stabilization is impaired in motion-blind flies

Visual motion detection is among the best understood neuronal computations. One assumed behavioural role is to detect self-motion and to counteract involuntary course deviations, extensively investigated in tethered walking or flying flies. In free flight, however, any deviation from a straight course is signalled by both the visual system as well as by proprioceptive mechanoreceptors called ‘halteres’, which are the equivalent of the vestibular system in vertebrates. Therefore, it is yet unclear to what extent motion vision contributes to course control, or whether straight flight is completely controlled by proprioceptive feedback from the halteres. To answer these questions, we genetically rendered flies motion-blind by blocking their primary motion-sensitive neurons and quantified their free-flight performance. We found that such flies have difficulties maintaining a straight flight trajectory, much like control flies in the dark. By unilateral wing clipping, we generated an asymmetry in propulsory force and tested the ability of flies to compensate for this perturbation. While wild-type flies showed a remarkable level of compensation, motion-blind animals exhibited pronounced circling behaviour. Our results therefore unequivocally demonstrate that motion vision is necessary to fly straight under realistic conditions.