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1,051 result(s) for "Retina - radiation effects"
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Influence of Ranibizumab versus laser photocoagulation on radiation retinopathy (RadiRet) - a prospective randomized controlled trial
PurposeTo demonstrate superiority of intravitreal ranibizumab 0.5 mg compared to focal and peripheral laser treatment in patients with radiation retinopathy for choroidal melanoma.MethodsInclusion criteria were as follows: patients with radiation retinopathy and visual acuity impairment due to radiation maculopathy accessible for laser therapy, age ≥ 18 years, and BCVA less than 20/32. The main objective was to study the change in best-corrected visual acuity (BCVA) over 6 months from ranibizumab 0.5 mg (experimental) compared to focal laser of the macula and panretinal laser treatment of the ischemic retina (control) in patients with radiation retinopathy in choroidal melanoma. The secondary objectives of the radiation retinopathy study were to compare functional and anatomical results between ranibizumab and laser group over 12 months and to measure the frequency of vitreous hemorrhage and rubeosis iridis.ResultsThe intention-to-treat analysis included 31 patients assigned to ranibizumab (n = 15) or laser treatment (n = 16). In terms of BCVA at month 6, ranibizumab was superior to laser treatment, with an advantage of 0.14 logMAR, 95% CI 0.01 to 0.25, p = 0.030. The positive effect of ranibizumab disappeared after treatment was discontinued. Similar results without statistically significant difference were found with respect to macular thickness. In both groups, no change was observed at month 6 in the size of ischemia in the macula or periphery compared to baseline. There was 1 case of vitreous hemorrhage in the laser group and no case of rubeosis iridis over time.ConclusionsThis study showed a statistically significant improvement in visual acuity and clear superiority of ranibizumab compared to laser treatment up to 26 weeks, but this effect disappeared at week 52 after completion of intravitreal treatment. Ranibizumab and PRP are considered equivalent in terms of the non-appearance of proliferative radiation retinopathy during the study.Trial registrationEudraCT Number: 2011-004463-69
Short-term effects of sunlight exposure on fundus blood flow perfusion in children: a randomised controlled trial
AimTo evaluate the short-term effects of different sunlight exposure on fundus blood flow perfusion (BFP) after near work.MethodsIn this parallel randomised controlled trial, 81 students aged 7–15 with spherical equivalent refraction between −2.00 and +3.00 diopters were randomly assigned to either a low-illuminance (4k lux) group (N=40) or high-illuminance (10k lux) (N=41). Following 1 hour indoor reading, participants had sunlight exposure matching their group’s intensity for 15 minutes. BFPs in the superficial retina, deep retina and choroid were measured at four time points: pre-reading, post-reading, 5th-minute and 15th-minute sunlight exposure.ResultsWithin the initial 5 minutes of sunlight exposure, the 10k lux group showed a tendency for decreased BFP, particularly in the choroid (superficial retina: −0.2, 95% CI −0.9 to 0.5; deep retina: −0.1, 95% CI −0.6 to 0.4; choroid: −0.4, 95% CI −0.8 to 0.0), while the 4k lux group exhibited an increase (superficial retina: 0.7, 95% CI 0.1 to 1.3; deep retina: 0.3, 95% CI −0.2 to 0.8; choroid: 0.1, 95% CI −0.2 to 0.5). From 5 to 15 minutes, BFP decreased in both groups. At the 5th-minute mark, the 10k lux group exhibited a greater decrease in choroid (10k −0.4 vs 4k 0.1, p=0.051). No significant difference was observed after 15 minutes of exposure.ConclusionHigher illuminance sunlight exposure can restore fundus BFP more rapidly than lower; however, duration remains pivotal. To prevent myopia, continuous sunlight exposure for over 15 minutes is recommended to aid in reinstating the fundus BFP increased by near work.Trial registration number NCT05594732.
Morphological Biomarkers Related to Visual Acuity in Patients With Radiation Retinopathy Treated With Intravitreal Ranibizumab
Background and Objective: Our objective was to monitor variables via spectral-domain optical coherence tomography (SD-OCT) and identify the most relevant biomarkers related to best-corrected visual acuity (BCVA) in radiation retinopathy (RR). Patients and Methods: A post-hoc analysis of the two-year Ranibizumab for Radiation Retinopathy (RRR) trial analyzed vision and OCT parameters including intraretinal fluid, ellipsoid zone (EZ) disruption, retinal pigment epithelium atrophy, hard exudates, retinal hemorrhage, retinal neovascularization, and subfoveal fluid. BCVA and SD-OCT parameters were evaluated by univariate analysis and a mixed-effects model. Results: Forty eyes from the RRR trial were included. Intraretinal cyst vertical size (week 24: P = 0.032; week 48: P = 0.021), neovascularization (week 48: P = 0.028; week 72: P = 0.025), and EZ disruption (week 72: P = 0.029; week 104: P = 0.019) were the clinical parameters most relevant to BCVA by univariate analysis in at least two time points. The mixed-effects model confirmed the relevance of intraretinal cyst vertical size (P = 0.001) and neovascularization (P = 0.001) but not EZ disruption (P = 0.119) over the course of the study. Conclusions: This study characterizes the course of visual loss in RR by identifying intraretinal cyst vertical size, neovascularization, and EZ disruption as biomarkers of poor BCVA over a span of two years. Larger multicenter studies are needed to confirm these findings. [Ophthalmic Surg Lasers Imaging Retina 2024;55:255–262.]
Short-term effectiveness and safety of photobiomodulation on low-to-moderate myopia
To find and assess the effectiveness and safety of short-term Photobiomodulation (PBM) treatment in children with low-to-moderate myopia. Children with low-to-moderate myopia were recruited and divided into PBM or control groups based on whether they received PBM treatment. The PBM group underwent a three-month treatment with a 650 nm low-energy semiconductor laser, while the control group did not receive any therapeutic intervention. At the end of the trial, the changes in spherical equivalent refractive (SER) and axial length (AL) before and after treatment were compared between the PBM group and the control group to evaluate the effectiveness of PBM in preventing myopia. The best corrected visual acuity (BCVA), nerve fiber layer thickness (RNFLT), ganglion cell layer thickness (GCLT), central point retinal thickness (CPRT), 3-mm subfield central retinal thickness (3 mm-CRT), superficial retinal vascular density (SCP), and central choroid thickness (CCT) were self-compared to assess the safety of PBM. A total of 57 subjects were prospectively followed from October 2020 to September 2021, comprising 28 participants (56 eyes) in the PBM group and 29 participants (58 eyes) in the control group. After three months of treatment, the AL decreased by 0.07 ± 0.11 mm, and the SER decreased by -0.12 ± 0.39 D in the PBM group. However, both SER and AL increased in the control group. Furthermore, there were statistically significant differences between the PBM and control groups (p < 0.01). The BCVA, RNFLT, GCLT, CPRT, and 3 mm-CRT remained almost unchanged in the PBM group; The SCP decreased from 0.37 ± 0.03 to 0.35 ± 0.02 in the PBM group with a statistically significant difference before and after treatment (p = 0.045). The CCT increased from 255 ± 41 µm to 274 ± 29 µm in the PBM group without any significant difference before and after treatment. The administration of PBM significantly suppresses the elevation of AL and SER following a three-month duration. No significant adverse effects were observed on visual function and retinal morphology. Trial Registration: This study is registered at https://clinicaltrials.gov/ (registration number: NCT04604405).
Safety and acceptability of an organic light-emitting diode sleep mask as a potential therapy for retinal disease
Purpose The purpose of the study was to study the effect of an organic light-emitting diode sleep mask on daytime alertness, wellbeing, and retinal structure/function in healthy volunteers and in diabetic macular oedema (DMO). Patients and methods Healthy volunteers in two groups, 18–30 yrs (A), 50–70 yrs (B) and people with DMO (C) wore masks (504 nm wavelength; 80 cd/m 2 luminance; ≤8 h) nightly for 3 months followed by a 1-month recovery period. Changes from baseline were measured for (means): psychomotor vigilance task (PVT) (number of lapses (NL), response time (RT)), sleep, depression, psychological wellbeing (PW), visual acuity, contrast sensitivity, colour, electrophysiology, microperimetry, and retinal thickness on OCT. Results Of 60 participants, 16 (27%) withdrew, 8 (13%) before month 1, due to sleep disturbances and mask intolerance. About 36/55 (65%) who continued beyond month 1 reported ≥1 adverse event. At month 3 mean PVT worsened in Group A (RT (7.65%, P <0.001), NL (43.3%, P =0.005)) and mean PW worsened in all groups (A 28.0%, P =0.01, B 21.2%, P =0.03, C 12.8%, P <0.05). No other clinically significant safety signal was detected. Cysts reduced/resolved in the OCT subfield of maximal pathology in 67% Group C eyes. Thinning was greater at 3 and 4 months for greater baseline thickness (central subfield P <0.001, maximal P <0.05). Conclusion Sleep masks showed no major safety signal apart from a small impairment of daytime alertness and a moderate effect on wellbeing. Masks were acceptable apart from in some healthy participants. Preliminary data suggest a beneficial effect on retinal thickness in DMO. This novel therapeutic approach is ready for large clinical trials.
Comparison of navigated laser and conventional single-spot laser system for induced pain during panretinal photocoagulation
To compare the panretinal photocoagulation (PRP)–induced pain response between novel navigated laser (Navilas) and conventional single-spot laser. The eyes were randomly assigned to Navilas or conventional laser. Contralateral eyes underwent PRP with the other system with 30 min resting interval. Pulse duration was 100 ms in conventional laser and 30 ms or 100 ms in Navilas and power setting was enough to create gray-white light burn on both devices. Pain response was evaluated by verbal scale (VS) (0–4) and visual analog scale (VAS) (0–10) after each PRP application. The mean age of 70 patients (140 eyes) was 62.52 ± 9.49 years. Mean power and spot numbers for Navilas and conventional laser were 291.9 ± 85.3 mW vs 368.4 ± 72.0 mW, and 375.4 ± 108.4 vs 374.2 ± 105.0 ( p < 0.001 and p = 0.53, respectively). Pain scores for Navilas and conventional laser were 1.19 ± 0.73 and 1.99 ± 0.84 for VS and 2.41 ± 1.65 and 4.74 ± 2.17 for VAS ( p < 0.001 and p < 0.001). More comfortable PRP is achieved with Navilas system in comparison with conventional single-spot laser system. However, small number of patients treated with same pulse duration and different contact lenses used for two systems should be taken into consideration. Besides, we did not report comparative clinical efficiency of either laser system.
Inhibition decorrelates visual feature representations in the inner retina
The retina extracts visual features for transmission to the brain. Different types of bipolar cell split the photoreceptor input into parallel channels and provide the excitatory drive for downstream visual circuits. Mouse bipolar cell types have been described at great anatomical and genetic detail, but a similarly deep understanding of their functional diversity is lacking. Here, by imaging light-driven glutamate release from more than 13,000 bipolar cell axon terminals in the intact retina, we show that bipolar cell functional diversity is generated by the interplay of dendritic excitatory inputs and axonal inhibitory inputs. The resulting centre and surround components of bipolar cell receptive fields interact to decorrelate bipolar cell output in the spatial and temporal domains. Our findings highlight the importance of inhibitory circuits in generating functionally diverse excitatory pathways and suggest that decorrelation of parallel visual pathways begins as early as the second synapse of the mouse visual system. The functional diversity of bipolar cells, which split visual inputs into different excitatory channels within the retina, arises from centre–surround interactions in their receptive fields that tune both spatial and temporal signalling. Representation of visual features in the retina Visual features such as edges or motion are extracted by the retina for transmission to the brain. This is made possible by bipolar cells, which split photoreceptor input into separate channels, owing to their neuroanatomical and molecular diversity. By imaging 13,000 bipolar cells in the mouse retina, Tom Baden and colleagues now describe the excitatory and inhibitory inputs that allow for the vast functional diversity of bipolar cells. The results suggest that the centre and surround receptive-field interactions, which are classically associated with spatial contrast, also serve to tune temporal signalling.
A preliminary trial to determine whether prevention of dark adaptation affects the course of early diabetic retinopathy
This study was designed to determine whether a new form of treatment of diabetic retinopathy (DR) was acceptable to patients and whether reduction in the maximal activity of rods in diabetes could affect the progress of DR. Methods In 12 patients, trans-lid retinal illumination of one eye was employed during sleep to prevent the depolarisation of rods and thus reduce their metabolic activity. Techniques A headband was used to place a source of chemical light over one eye, with its fellow as a control. Measurements Colour contrast thresholds were measured before and after a period of treatment in treated eyes, and the changes were compared to those in untreated fellow eyes, and areas of ‘dark retinal anomalies’ (microaneurysms, dot haemorrhages) were measured at the same time points. Results Patients found this intervention to be acceptable, and no adverse effects were noted. In the majority of cases, and for each outcome measure, the treated eyes improved relative to their fellows. The intervention significantly reduced the tritan thresholds in treated eyes relative to their fellows ( P =0.03), and the area of dark retinal anomalies decreased in treated eyes and increased in untreated eyes, with a similar probability. Conclusions The study showed that this intervention is safe. Although the study was not powered to study efficiacy, the results are promising and consistent with other reports that indicate the retina in DR is suffering from hypoxia; however, further trials should be undertaken.
NF1 mutation drives neuronal activity-dependent initiation of optic glioma
Neurons have recently emerged as essential cellular constituents of the tumour microenvironment, and their activity has been shown to increase the growth of a diverse number of solid tumours 1 . Although the role of neurons in tumour progression has previously been demonstrated 2 , the importance of neuronal activity to tumour initiation is less clear—particularly in the setting of cancer predisposition syndromes. Fifteen per cent of individuals with the neurofibromatosis 1 (NF1) cancer predisposition syndrome (in which tumours arise in close association with nerves) develop low-grade neoplasms of the optic pathway (known as optic pathway gliomas (OPGs)) during early childhood 3 , 4 , raising  the possibility that postnatal light-induced activity of the optic nerve drives tumour initiation. Here we use an authenticated mouse model of OPG driven by mutations in the neurofibromatosis 1 tumour suppressor gene ( Nf1 ) 5 to demonstrate that stimulation of optic nerve activity increases optic glioma growth, and that decreasing visual experience via light deprivation prevents tumour formation and maintenance. We show that the initiation of Nf1- driven OPGs ( Nf1- OPGs) depends on visual experience during a developmental period in which Nf1 -mutant mice are susceptible to tumorigenesis. Germline Nf1 mutation in retinal neurons results in aberrantly increased shedding of neuroligin 3 (NLGN3) within the optic nerve in response to retinal neuronal activity. Moreover, genetic Nlgn3 loss or pharmacological inhibition of NLGN3 shedding blocks the formation and progression of Nf1- OPGs. Collectively, our studies establish an obligate role for neuronal activity in the development of some types of brain tumours, elucidate a therapeutic strategy to reduce OPG incidence or mitigate tumour progression, and underscore the role of Nf1 mutation-mediated dysregulation of neuronal signalling pathways in mouse models of the NF1 cancer predisposition syndrome. Mouse models of NF1-associated optic pathway glioma show that tumour initiation and growth are driven by aberrantly high levels of NLGN3 shedding in the optic nerve in response to retinal neuron activity.
Retinal innervation tunes circuits that drive nonphotic entrainment to food
Daily changes in light and food availability are major time cues that influence circadian timing 1 . However, little is known about the circuits that integrate these time cues to drive a coherent circadian output 1 – 3 . Here we investigate whether retinal inputs modulate entrainment to nonphotic cues such as time-restricted feeding. Photic information is relayed to the suprachiasmatic nucleus (SCN)—the central circadian pacemaker—and the intergeniculate leaflet (IGL) through intrinsically photosensitive retinal ganglion cells (ipRGCs) 4 . We show that adult mice that lack ipRGCs from the early postnatal stages have impaired entrainment to time-restricted feeding, whereas ablation of ipRGCs at later stages had no effect. Innervation of ipRGCs at early postnatal stages influences IGL neurons that express neuropeptide Y (NPY) (hereafter, IGL NPY neurons), guiding the assembly of a functional IGL NPY –SCN circuit. Moreover, silencing IGL NPY neurons in adult mice mimicked the deficits that were induced by ablation of ipRGCs in the early postnatal stages, and acute inhibition of IGL NPY terminals in the SCN decreased food-anticipatory activity. Thus, innervation of ipRGCs in the early postnatal period tunes the IGL NPY –SCN circuit to allow entrainment to time-restricted feeding. Ablating retinal input at early postnatal stages—but not later time points—impaired entrainment to time-restricted feeding in adult mice, as did silencing intergeniculate-leaflet neurons that express neuropeptide Y and project to the central pacemaker