Optic nerve analysis in COVID‐19 patients Burgos‐Blasco, Barbara; Güemes‐Villahoz, Noemi; Donate‐Lopez, Juan ...
Journal of medical virology,
January 2021, Letnik:
93, Številka:
1
Journal Article
Importance
To provide a normative vessel density (VD) database for the macula through swept‐source optical coherence tomography angiography (OCTA) and to assess the main determinants of this ...measurement.
Background
In contrast with dye angiography, the recently introduced OCTA technique allows for the non‐invasive measurement of retinal and choroidal VD metrics.
Design
Cross‐sectional study.
Participants
The right eyes of 346 healthy subjects were studied. In 105 subjects both eyes were imaged.
Methods
Foveal and parafoveal macular VD measurements were obtained in the retinal superficial capillary plexus (SCP), deep capillary plexus (DCP), and in the choriocapillaris (CC) layer. Also recorded were age, sex, axial length (AL), foveal and choroidal thickness (CT).
Main Outcome Measures
Normative database and determinants of macular VD measured by OCTA.
Results
Mean participant age was 38.3 ± 20.1 years (mean ± SD) (range 5‐83). Foveal VDs in the different plexuses were: SCP 22.1% ± 5.0% (7.3‐35.1), DCP 19.9% ± 6.3% (6.9‐51.2) and CC: 52.8% ± 4.3% (40.2‐62.1). Parafoveal VDs ranged from 45.4% ± 3.7% to 51.8% ± 4.6%. Positive correlation was observed between foveal VD and foveal thickness (R = .327), as well as between parafoveal DCP VD and CT (R = .250;P ≤ .006), while correlation with age was negative in the SCP and CC (R = −.283;P < .001). No associations were detected between macular VD and sex or AL (P ≥ .05).
Conclusion and Relevance
Macular VD showed wide individual variation, was positively correlated with foveal thickness and with CT, negatively correlated with age, and showed no correlation with AL or sex.
The formation of filtration blebs is the main drainage mechanism for reducing intraocular pressure after traditional incisional glaucoma surgery such as trabeculectomy and non‐penetrating deep ...sclerotomy. Early and short‐lasting blebs may also occur after canaloplasty. Bleb formation also plays an important role after the implantation of glaucoma drainage devices, including Minimally Invasive Glaucoma Surgery devices. Anterior segment optical coherence tomography (AS‐OCT) is a rapid and non‐invasive high‐resolution imaging technique that has evolved in recent years to become a routine examination. Anterior segment optical coherence tomography (AS‐OCT) provides key information in the assessment and follow‐up of glaucoma surgery, especially in the assessment of filtration blebs. Thus, bleb morphology can be qualitatively classified into diffuse, cystic, encapsulated and flattened, and AS‐OCT imaging can also provide several quantitative parameters of the bleb, such as total bleb height, bleb fluid‐filled cavity height, bleb wall thickness, number of microcysts and trabeculectomy opening size. These parameters could have an impact on clinical management during follow‐up because they may predict the success or failure of the surgery in the early and late postoperative periods. Additionally, they may also guide the procedures used to increase filtration and reduce intraocular pressure, such as bleb needling and laser suture lysis.
Purpose
To examine ciliary muscle (CM) dimensions in vivo by swept‐source optical coherence tomography (SS‐OCT) in a large healthy population. To assess the reproducibility of CM measurements and ...correlations with different parameters.
Methods
In this cross‐sectional study, the following CM measurements were made in 495 eyes of 495 subjects in the temporal and nasal quadrants: length (CML), area (CMA) and thickness at distances of 1000 μm (CMT1), 2000 μm (CMT2) and 3000 μm (CMT3) from the scleral spur using the SS‐OCT DRI‐Triton® (Topcon, Tokyo, Japan). These dimensions were then assessed for correlations with the factors age, gender, refractive error, anterior chamber angle (ACA) and intraocular pressure (IOP). The reproducibility of CM measurements was determined in 85 of the participants.
Results
Mean age was 41.4 ± 17.5 years (range 5–83). The following means were recorded as follows: CML = 4.57 ± 0.73 mm (range 2.16–6.97), CMA = 1.35 ± 0.31 mm2 (2.04–5.45), CMT1 = 558 ± 98 μm (299–891), CMT2 = 366 ± 100 μm (89–629) and CMT3 = 210 ± 75 μm (36–655). Negative correlation was detected between CML/CMA and age (R = −0.516/R = −0.404; p < 0.001) and refractive error (R = −0.519/R = −0.538; p < 0.001). No gender differences were observed (p ≥ 0.150). Both CML and CMA were correlated with ACA (R = 0.498 and 0.546; p < 0.001) and slightly with IOP (R = −0.175; p < 0.001). The reproducibility of the CM measurements was excellent (intraclass correlation coefficient ≥0.878).
Conclusions
Swept‐source optical coherence tomography is a valid tool for in vivo CM measurements. Our data indicate a larger CM in myopes and its diminishing size with age.
To predict and compare the hypotensive efficacy of three minimally-invasive glaucoma surgery (MIGS) implants through a numerical model. Post-implant hypotensive efficacy was evaluated by using a ...numerical model and a computational fluid dynamics simulation. Three different devices were compared: the XEN 45 stent (tube diameter, 45 mum), the XEN 63 stent (63 mum) and the PreserFlo microshunt (70 mum). The influence of the filtration bleb pressure (Bp) and tube diameter, length, and position within the anterior chamber (AC) on intraocular pressure (IOP) were evaluated. Using baseline IOPs of 25, 30 and 50 mmHg, respectively, the corresponding computed post-implant IOPs for each device were as follows: XEN 45: 17 mmHg (29% decrease), 19 mmHg (45%) and 20 mmHg (59%) respectively; XEN 63: 13 mmHg (48%), 13 mmHg (62%), and 13 mmHg (73%); PreserFlo: 12 mmHg (59%), 13 mmHg (73%) and 13 mmHg (73%). At a baseline IOP of 35 mmHg with an increase in the outflow resistance within the Bp from 5 to 17 mmHg, the hypotensive efficacy for each device was reduced as follows: XEN45: 54% to 37%; XEN 63: 74% to 46%; and PreserFlo: 75% to 47%. The length and the position of the tube in the AC had only a minimal (non-significant) effect on IOP (<0.1 mmHg). This hydrodynamic/numerical model showed that implant diameter and bleb pressure are the two most pertinent determinants of hypotensive efficacy. In distinction, tube length and position in the AC do not significantly influence IOP.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The main aim of glaucoma treatment is to reduce the intraocular pressure (IOP). One of the most common surgical treatments of glaucoma is the implantation of a glaucoma drainage device to drain the ...aqueous humor from the anterior chamber to a filtration bleb, where the aqueous humor is absorbed. In some cases, the excess of drainage causes ocular hypotony, which constitutes a sight-threatening complication. To prevent hypotony after this intervention, surgeons frequently introduce a suture into the device tube, which increases the hydraulic resistance of the tube and, therefore, the IOP. This study aims to provide an analytical model to correct hypotony following implantation surgery of a glaucoma drainage device, which may help glaucoma surgeons decide on hypotony treatment. The results indicate that the IOP after implanting a cylindrical tube around 300 μm in diameter is essentially the same as that built up in the filtering bleb and can hardly be controlled by introducing a straight suture unless the suture diameter is slightly lower than that of the tube. On the contrary, when the tube diameter is smaller than, for example, 100 μm, significant reductions of the IOP can be obtained by introducing a thin suture into the tube.
To determine the efficacy and safety of the Ologen collagen matrix adjunctive to Ahmed valve surgery. A randomized prospective multicentre clinical trial involving 58 patients that were followed for ...one year. Conventional surgery with Ahmed valve was performed in 31 eyes (Control group/CG) and in 27 Ologen (Ologen group/OG) was placed over the valve's plate. Baseline data: age, corneal thickness, intraocular pressure(IOP) and antiglaucoma medications.Postoperative data (days 1, 7 and months 1, 3, 6 and 12): IOP, antiglaucoma medications, visual acuity and complications were recorded. Frequency of hypertensive phase, complete and qualified success and survival rate were studied. No differences were found between CG and OG in the baseline data. The only difference between groups was a significantly lower IOP at day 1. No other differences were found in the follow-up between groups. Hypertensive phase (56%CG and 55%OG, p = 0,947), complete success 28,6%CG and 30,4%OG (p = 0,88) and qualified success 96,4% and 95,9%(p = 0,794). Survival rates at 1 year were 76,7%(CG) and 69,2%(OG)(p = 0,531). 38,7% of patients in the CG suffered some complication during follow-up and 61,5% in OG(p = 0,086). Ologen does not increase safety or efficacy in Ahmed valve surgery at one-year follow-up. This is the first study that shows no benefit of Ologen adjunctive to this surgery.
Purpose
To measure the Schlemm's canal (SC) in vivo by Fourier‐domain optical coherence tomography (FD‐OCT) in a Caucasian paediatric population.
Methods
Participants of this cross‐sectional study ...were 290 healthy children. In the right eye of each child, SC cross‐sectional diameter and area measurements were made with the FD‐OCT instrument RTVue® (Optovue Inc, Fremont, CA, USA) in the nasal and temporal quadrants. These SC variables were then assessed for correlation with the factors age, gender, refractive error, anterior chamber angle and trabecular meshwork (TM) metrics. Finally, the reproducibility of the SC measurements was assessed in 30 of the participants.
Results
Mean participant age was 10.7 ± 3.4 years (range 3–18). SC diameters could be measured in both quadrants in 70.6% and 70.4% of subjects, respectively. Mean SC diameters were similar (p = 0.125) for the temporal and nasal quadrants: 266.7 ± 84.1 μm (range 131–509) and 273.2 ± 77.3 μm (range 124–486), respectively. Mean SC areas were also similar (p = 0.167) for the two quadrants: 9975 ± 3514 μm2 (range 4000–23 000) versus 9688 ± 3297 μm2 (range 3000–24 000). No differences were detected in SC measurements according to gender, refractive error or angle and TM measurements (R ≤ 0.116; p ≥ 0.125). The exception was age which was directly correlated with SC size (p ≤ 0.041). The reproducibility of the SC measurements was excellent (intraclass correlation coefficients ≥0.936).
Conclusion
FD‐OCT allows the identification of the SC in children. Our data indicate an increase in SC size produced with age.
To compare aqueous humour (AH) dynamics in the presence of a precrystalline (Implantable Collamer Lens®; ICL) or iris-fixed (Artiflex®) phakic intraocular lens (PIOL).
By computational fluid dynamics ...simulation, AH flow was modelled through a peripheral iridotomy (PI) or central lens hole (both 360 μm) in the presence of an Artiflex or ICL lens, respectively. The impacts of AH flow were then determined in terms of wall shear stress (WSS) produced on the endothelium or crystalline lens. Effects were also modelled for different scenarios of pupil diameter (PD 3.5 or 5.5 mm), ICL vault (100, 350, 800 μm) and number of Artiflex iridotomies (1 or 2) and location (12 or 6 o'clock).
For a PD of 3.5 mm, AH volumes flowing from the posterior to the anterior chamber were 37.6% of total flow through the lens hole (ICL) and 84.2% through PI (Artiflex). For an enlarged PD (5.5 mm), corresponding values were 10.3% and 81.9% respectively, so PI constitutes a very efficient way of evacuating AH. Central endothelial WSS in Pa was lower for the large vault ICL and the Artiflex (1-03 and 1.1-03 respectively) compared to the PIOL-free eye (1.6-03). Crystalline lens WSS was highest for the lowest vault ICL (1-04).
AH flow varied according to the presence of a precrystalline or iris-fixed intraocular lens. Endothelial WSS was lower for an implanted ICL with large vault and Artiflex than in the PIOL-free eye, while highest crystalline WSS was recorded for the lowest vault ICL.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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