Background: To evaluate a fully automated vascular density (VD), skeletal density (SD) and fractal dimension (FD) method for the longitudinal analysis of retinal vein occlusion (RVO) eyes using projection-resolved optical coherence tomography angiography (OCTA) images and to evaluate the association between these quantitative variables and the visual prognosis in RVO eyes.
Methods: Retrospective longitudinal observational case series. Patients presenting with RVO to Creteil University Eye Clinic between October 2014 and December 2018 and healthy controls were retrospectively evaluated. Group 1 consisted of central RVO (CRVO) eyes, group 2 consisted of eyes with branch RVO (BRVO) and group 3 of healthy control eyes. OCTA acquisitions (AngioVue RTVue XR Avanti, Optovue, Inc., Freemont, CA) were performed at baseline and last follow up visit. VD, SD, and FD analysis were computed on OCTA superficial and deep vascular complex (SVC, DVC) images at baseline and final follow up using an automated algorithm. Logistic regression was performed to find if and which variable (VD, SD, FD) was predictive for the visual outcome.
Results: Forty-one eyes, of which 21 consecutive eyes of 20 RVO patients (13 CRVO in group 1, 8 BRVO in group 2), and 20 eyes of 20 healthy controls were included. At the level of SVC, VD and FD were significantly lower in RVO eyes compared to controls (P<0.0001 and P=0.0008 respectively). Best-corrected visual acuity (BCVA) at last follow-up visit was associated with baseline VD (P=0.013), FD (P=0.016), and SD (P=0.01) at the level of the SVC, as well as with baseline FD at the DVC level (P=0.046).
Conclusions: Baseline VD, SD, and FD are associated with the visual outcome in RVO eyes. These parameters seem valuable biomarkers and may help improve the evaluation and management of RVO patients.
Abstract: Navigation technology in ophthalmology, colloquially called “eye-tracking”, has been applied to various areas of eye care. This approach encompasses motion-based navigation technology in both ophthalmic imaging and treatment. For instance, modern imaging instruments use a real-time eye-tracking system, which helps to reduce motion artefacts and increase signal-to-noise ratio in imaging acquisition such as optical coherence tomography (OCT), microperimetry, and fluorescence and color imaging. Navigation in ophthalmic surgery has been firstly applied in laser vision corrective surgery and spread to involve navigated retinal photocoagulation, and positioning guidance of intraocular lenses (IOL) during cataract surgery. It has emerged as one of the most reliable representatives of technology as it continues to transform surgical interventions into safer, more standardized, and more predictable procedures with better outcomes. Eye-tracking is essential in refractive surgery with excimer laser ablation. Using this technology for cataract surgery in patients with high preoperative astigmatism has produced better therapeutic outcomes. Navigated retinal laser has proven to be safer and more accurate compared to the use of conventional slit lamp lasers. Eye-tracking has also been used in imaging diagnostics, where it is essential for proper alignment of captured zones of interest and accurate follow-up imaging. This technology is not routinely discussed in the ophthalmic literature even though it has been truly impactful in our clinical practice and represents a small revolution in ophthalmology.
Perception is the ability to see, hear, or become aware of external stimuli through the senses. Visual stimuli are electromagnetic waves that interact with the eye and elicit a sensation. Sensations, indeed, imply the detection, resolution, and recognition of objects and images, and their accuracy depends on the integrity of the visual system. In clinical practice, evaluating the integrity of the visual system relies greatly on the assessment of visual acuity, that is to say on the capacity to identify a signal. Visual acuity, indeed, is of utmost importance for diagnosing and monitoring ophthalmological diseases. Visual acuity is a function that detects the presence of a stimulation (a signal) and resolves its detail(s). This is the case of a symbol like “E”: the stimulus is detected, then it is resolved as three horizontal bars and a vertical bar. In fact, within the clinical setting visual acuity is usually measured with alphanumeric symbols and is a three-step process that involves not only detection and resolution, but, due to the semantic content of letters and numbers, their recognition. Along with subjective (psychophysical) procedures, objective methods that do not require the active participation of the observer have been proposed to estimate visual acuity in non-collaborating subjects, malingerers, or toddlers. This paper aims to explain the psychophysical rationale underlying the measurement of visual acuity and revise the most common procedures used for its assessment.
Backgrounds: To assess changes in anterior segment biometry during accommodation using a swept source anterior segment optical coherence tomography (SS-OCT). Methods: One hundred-forty participants were consecutively recruited in the current study. Each participant underwent SS-OCT scanning at 0 and -3 diopter (D) accommodative stress after refractive compensation, and ocular parameters including anterior chamber depth (ACD), anterior and posterior lens curvature, lens thickness (LT) and lens diameter were recorded. Anterior segment length (ASL) was defined as ACD plus LT. Lens central point (LCP) was defined as ACD plus half of the LT. The accommodative response was calculated as changes in total optical power during accommodation. Results: Compared to non-accommodative status, ACD (2.952±0.402 vs. 2.904±0.382 mm, P<0.001), anterior (10.771±1.801 vs. 10.086±1.571 mm, P<0.001) and posterior lens curvature (5.894±0.435 vs. 5.767±0.420 mm, P<0.001), lens diameter (9.829±0.338 vs. 9.695±0.358 mm, P<0.001) and LCP (4.925±0.274 vs. 4.900±0.259 mm, P=0.010) tended to decreased and LT thickened (9.829±0.338 vs. 9.695±0.358 mm, P<0.001), while ASL (6.903±0.279 vs. 6.898±0.268 mm, P=0.568) did not change significantly during accommodation. Younger age (β=0.029, 95% CI: 0.020 to 0.038, P<0.001) and larger anterior lens curvature (β=-0.071, 95% CI: -0.138 to -0.003, P=0.040) were associated with accommodation induced greater steeping amplitude of anterior lens curvature. The optical eye power at 0 and -3 D accommodative stress was 62.486±2.284 and 63.274±2.290 D, respectively (P<0.001). Age was an independent factor of accommodative response (β=-0.027, 95% CI: -0.038 to -0.016, P<0.001). Conclusions: During -3 D accommodative stress, the anterior and posterior lens curvature steepened, followed by thickened LT, fronted LCP and shallowed ACD. The accommodative response of -3 D stimulus is age-dependent.
Background: Continuous and primary in vitro cultures are largely used to study cellular mechanisms occurring in several pathologic-like or pathological conditions. Continuous cell lines allow to perform long-lasting experiments since they do not undergo senescence.
Methods: The immortalized Moorfields/Institute of Ophtalmology-Müller 1 (MIO-M1) cell type represents a valuable model to analyze the mechanistic pathways characterizing Müller glial cells, both in health and in disease. MIO-M1 can be used to dissect the response of these glial cells following treatments which mimic pathological condition. For instance, MIO-M1 are useful to study the response of this cell type to stress condition as the case of oxidative stress (OS) (cultured with hydrogen peroxide), pathological neovascularization (cultured with VEGF), hypoxic or hyperoxic condition (cultured in low or high oxygen chamber). On the other hand, primary cultures allow to specifically analyze cellular responses without the interference of the whole organ, although the experimental treatment is performed in vivo. Primary Müller cells can be used to perform electrophysiological analyses of different cell sites.
Discussion: We describe how to manage MIO-M1 cells and how to analyze their response to different stress conditions; moreover, we report how to isolate and identify primary Müller cells and how to perform patch clamp and single cell recordings on them.
