Age-related macular degeneration (AMD) is the leading cause of irreversible central vision loss in patients over the age of 65 years in industrialized countries. Epidemiologic studies suggest that ...high dietary fat intake is a risk factor for the development and progression of both vascular and retinal disease. These, and other associations, suggest a hypothesis linking elevated cholesterol and AMD progression. It follows, therefore, that cholesterol-lowering medications, such as statins, may influence the onset and progression of AMD. However, the findings have been inconclusive as to whether statins play a role in AMD. Due to the significant public health implications of a potential inhibitory effect of statins on the onset and progression of AMD, it is important to continually evaluate emerging findings germane to this question.
To use the pupillary light reflex and polysomnography to evaluate the function of intrinsically photosensitive retinal ganglion cells (ipRGCs) and to correlate this function with structural damage in ...glaucoma.
Cross-sectional study.
A study was conducted on both eyes of 45 participants (32 patients with glaucoma and 13 healthy subjects).
For the pupillary reflex evaluation, patients were tested in the dark using a Ganzfeld system (RETIport; Roland Consult, Brandenburg, Germany); pupil diameter was measured with an eye tracker system. To preferentially stimulate ipRGCs, we used a 1-second 470-nm flash with a luminance of 250 cd/m(2). To stimulate different retinal photoreceptors, we used a 1-second 640-nm flash with a luminance of 250 cd/m(2). All of the subjects underwent polysomnography. Subjects underwent standard automated perimetry and optical coherence tomography (Cirrus HD-OCT; Carl Zeiss Meditec Inc, Dublin, CA).
Correlations between ipRGC activity, as measured by the pupillary light reflex, and polysomnography parameters, and correlations between retinal nerve fiber layer (RNFL) thickness and the pupillary light reflex and polysomnography parameters.
The mean patient ages in the healthy and glaucoma groups were 56.8±7.8 years and 61.5±11.6 years, respectively (P = 0.174). Patients with glaucoma had significantly lower average total sleep time, sleep efficiency, and minimum oxyhemoglobin saturation compared with the healthy subjects (P = 0.008, P = 0.002, and P = 0.028, respectively). Patients with glaucoma had significantly higher arousal durations after falling asleep and more periodic limb movements (P = 0.002 and P = 0.045, respectively). There was an inverse correlation between the rapid eye movement latency and the peak of the pupillary response to the blue flash (P = 0.004). The total arousals were inversely correlated with the sustained blue flash response (P = 0.029). The RNFL thickness was associated with the peak and sustained responses to the blue flash (P < 0.001 for both comparisons); however, RNFL thickness was only associated with the mean oxygen desaturation index among the polysomnography parameters (P = 0.023).
This study demonstrated that decreased ipRGC function caused by glaucoma affected pupillary response and sleep quality.
Patients with glaucoma showed to have higher daytime sleepiness measured by Epworth sleepiness scale. In addition, this symptom was associated with pupillary reflex and polysomnography parameters. ...These ipRGC functions might be impaired in patients with glaucoma, leading to worse quality of life.
One of the major yet little recognized challenges in robotic vitreoretinal surgery is the matter of tool forces applied to the sclera. Tissue safety, coordinated tool use and interactions between ...tool tip and shaft forces are little studied. The introduction of robotic assist has further diminished the surgeon's ability to perceive scleral forces. Microsurgical tools capable of measuring such small forces integrated with robot-manipulators may therefore improve functionality and safety by providing sclera force feedback to the surgeon. In this paper, using a force-sensing tool, we have conducted robot-assisted eye manipulation experiments to evaluate the utility of providing scleral force feedback. The work assesses 1) passive audio feedback and 2) active haptic feedback and evaluates the impact of these feedbacks on scleral forces in excess of a boundary. The results show that in presence of passive or active feedback, the duration of experiment increases, while the duration for which scleral forces exceed a safe threshold decreases.
To evaluate the effects of sildenafil on the autonomic nervous system in patients with severe obstructive sleep apnea.
Thirteen male patients with severe obstructive sleep apnea (mean age 43±10 years ...with a mean body mass index of 26.7±1.9 kg/m2) received a single 50-mg dose of sildenafil or a placebo at bedtime. All-night polysomnography and heart rate variability were recorded. Frequency domain analysis of heart rate variability was performed for the central five-minute sample of the longest uninterrupted interval of slow wave and rapid eye movement sleep, as well as for one-minute samples during apnea and during slow wave and rapid eye movement sleep after resumption of respiration.
Compared to the placebo, sildenafil was associated with an increase in the normalized high-frequency (HFnu) components and a decrease in the low/high-frequency components of the heart rate variability ratio (LF/HF) in slow wave sleep (p<0.01 for both). Differences in heart rate variability parameters between one-minute post-apnea and apnea samples (Δ = difference between resumption of respiration and apnea) were assessed. A trend toward a decreasing magnitude of ΔLF activity was observed during rapid eye movement sleep with sildenafil in comparison to placebo (p=0.046). Additionally, ΔLF/HF in SWS and rapid eye movement sleep was correlated with mean desaturation (sR = −0.72 and −0.51, respectively, p= 0.01 for both), and ΔHFnu in rapid eye movement sleep was correlated with mean desaturation (sR= 0.66, p= 0.02) and the desaturation index (sR= 0.58, p = 0.047).
The decrease in arousal response to apnea/hypopnea events along with the increase in HFnu components and decrease in LH/HF components of the heart rate variability ratio during slow wave sleep suggest that, in addition to worsening sleep apnea, sildenafil has potentially immediate cardiac effects in patients with severe obstructive sleep apnea.
Robot-assisted retinal surgery has become increasingly prevalent in recent years in part due to the potential for robots to help surgeons improve the safety of an immensely delicate and difficult set ...of tasks. The integration of robots into retinal surgery has resulted in diminished surgeon perception of tool-to-tissue interaction forces due to robot's stiffness. The tactile perception of these interaction forces (sclera force) has long been a crucial source of feedback for surgeons who rely on them to guide surgical maneuvers and to prevent damaging forces from being applied to the eye. This problem is exacerbated when there are unfavorable sclera forces originating from patient movements (dynamic eyeball manipulation) during surgery which may cause the sclera forces to increase even drastically. In this study we aim at evaluating the efficacy of providing warning auditory feedback based on the level of sclera force measured by force sensing instruments. The intent is to enhance safety during dynamic eye manipulations in robot-assisted retinal surgery. The disturbances caused by lateral movement of patient's head are simulated using a piezo-actuated linear stage. The Johns Hopkins Steady-Hand Eye Robot (SHER), is then used in a multi-user experiment. Twelve participants are asked to perform a mock retinal surgery by following painted vessels inside an eye phantom using a force sensing instrument while auditory feedback is provided. The results indicate that the users are able to handle the eye motion disturbances while maintaining the sclera forces within safe boundaries when audio feedback is provided.
Pars plana vitrectomy is a challenging, minimally invasive microsurgical procedure due to its intrinsic manoeuvres and physiological limits that constrain human capability. An important human ...limitation is physiological hand tremor, which can significantly increase the risk of iatrogenic retinal damage resulting from unintentional manoeuvres that affect anatomical and functional surgical outcomes. The limitations imposed by normal physiological tremor are more evident and challenging during 'micron-scale' manoeuvres such as epiretinal membrane and internal limiting membrane peeling, and delicate procedures requiring coordinated bimanual surgery such as tractional retinal detachment repair. Therefore, over the previous three decades, attention has turned to robot-assisted surgical devices to overcome these challenges. Several systems have been developed to improve microsurgical accuracy by cancelling hand tremor and facilitating faster, safer and more effective microsurgeries. By markedly reducing tremor, microsurgical precision is improved to a level beyond present human capabilities. In conclusion, robotics offers potential advantages over free-hand microsurgery as it is currently performed during ophthalmic surgery and opens the door to a new class of revolutionary microsurgical modalities. The skills transfer that is beyond human capabilities to robotic technology is a logical next step in microsurgical evolution.
Abstract The purpose of the study was to present a case of choroidal neovascularization (CNV) in unilateral acute idiopathic maculopathy (UAIM) associated with coxsackievirus B2. We present a case of ...UAIM with coxsackie B2 positive serology, presenting CNV as a complication. Follow-up multimodal retinal imaging was performed to characterize the macular abnormalities further. A 27-year-old woman complained of a sudden central visual field scotoma in her left eye (LE) 2 days before her presentation. The patient reported flu-like symptoms 2 weeks before her initial ophthalmic symptoms. Ophthalmologic examination and multimodal imaging were performed at the initial presentation and 2 months follow-up when CNV was detected. The patient underwent an intravitreous ranibizumab injection in the LE. After the injection, the optical coherence tomography was repeated and there was a partial decrement of the subretinal hyperreflective area, and visual acuity improved to 20/30. To the best of our knowledge, no previous reports were found linking coxsackie B2 infection with UAIM and CNV. The present case report demonstrates the importance of serial multimodal imaging to guarantee accurate diagnosis and effective therapy for patients with UAIM secondary to coxsackievirus infection, regardless of the virus variant involved.
PDF
