Minimally invasive curved-micro-drainer (CMD) capable of innocuous drainage of subretinal fluid for the treatment of retinal detachment

Oblique injection depth correction by a two parallel OCT sensor guided handheld SMART injector

We present a SMART injector with two parallel common-path optical coherence tomography fibers to enable angle measurements and injection depth corrections for oblique subretinal injection. The two optical fibers are attached to opposite sides of a 33 G needle with known offsets and designed to pass through a 23 G trocar that has an inner diameter of 0.65 mm. By attaching a SMART system to a rotational stage, the measured angles are calibrated for minimal error from reference angles. A commercial eye model was used to evaluate the control performance, and injection experiments were performed on a phantom made of agarose gel and a porcine eye.

The Effect of Hematocrit and Nanoparticles Diameter on Hemodynamic Parameters and Drug Delivery in Abdominal Aortic Aneurysm with Consideration of Blood Pulsatile Flow

BACKGROUND AND OBJECTIVE

The present article has simulated to investigate the efficient hemodynamic parameters, the drug persistence, and drug distribution on an abdominal aortic aneurysm.

METHODS

Blood as a non-Newtonian fluid enters the artery acting as a real pulse waveform; its behavior is dependent on hematocrit and strain rate. In this simulation of computational fluid dynamic, magnetic nanoparticles of iron oxide which were in advance coated with the drug, are injected into the artery during a cardiac cycle. A two-phase model was applied to investigate the distribution of these carriers.

RESULTS

The results are presented for different hematocrits and the nanoparticle diameter. It is observed that hematocrit significantly affects drug persistence, so that lower hematocrit incites more accumulation of the drug in the dilatation part of the artery. The better drug accumulation is noticed, at the higher wall shear stress. Although no considerable impact on the flow pattern and wall shear stress was found with various nanoparticle diameters, the smaller size of the nanoparticles results in a greater amount of drug augmentation in the aneurysm wall output.

CONCLUSIONS

At the higher hematocrit levels, the blood resistance to drug delivery increases throughout the artery. Also, the drug accumulates less on the aneurysm wall and stays longer on the aneurysm wall. On the contrary, the drug accumulates more by decreasing hematocrit level and stays shorter on the aneurysm wall. Moreover, the maximum drug concentration is observed at the lowest hematocrit level and nanoparticle diameter; also, the diameter of nanoparticles imposes no significant effect on the vorticity and wall shear stress. It is seen that the increment of the hematocrit level reduces the strength of vorticity and increases the amount of wall shear stress in the dilatation segment of the artery. The shear stress at three points of the dilatation wall is extreme, where the maximum density of nanoparticles occurs.

Novel transscleral sutureless subretinal fluid drainage using a 25-gauge trocar-cannula with a self-closing valve in patients with advanced Coats disease

AIM

To assess surgical outcomes of a novel method of transscleral drainage of subretinal fluid using a 25-gauge trocar-cannula with a self-closing valve (DTV) in patients with severe exudative retinal detachment (ERD) in Coats disease.

METHODS

Retrospective consecutive cases of 20 patients (20 eyes) of severe ERD due to Coats disease (stage 3B) in total 156 Coats patients between June 2015 and April 2019 were included in this study. The participants were aged 1 to 10y with a mean age of 3.50±1.79y. The mean follow-up time were 11.9mo. Subretinal fluid was drained transsclerally using a novel method of DTV. The height of the retinal detachment and the regression of abnormal vessels including telangiectasias and aneurysms were observed. Complications including vitreoretinal fibrosis, tractional retinal detachments (TRD), endophthalmitis, retinal holes, and hemorrhages were evaluated.

RESULTS

Following surgeries, the patients showed the replacement of ERD and regression of telangiectatic retinal vessels observed with binocular indirect ophthalmoscopy. Six patients received retinal cryotherapies and 12 patients received laser photocoagulations following first external subretinal fluid drainage using DTV. All patients underwent intravitreal anti-vascular endothelial growth factor therapies to induce residual subretinal fluid absorption. During follow-ups, 8 patients underwent a second drainage operation, 17 patients received retinal laser photocoagulations and 7 patients received cryotherapies. Vitreoretinal fibrosis was found in 7 patients and 6 patients underwent micro-invasive vitrectomies during the follow-up period. Severe TRD, iatrogenic retinal holes, and hemorrhages were not found.

CONCLUSION

The authors present a new therapeutic approach that successfully drains subretinal fluid in advanced stage 3B Coats disease with severe ERD. This is a simple, safe and less invasive approach when compared with traditional managements. However, it should be strictly selected for patients with high bullous ERD close to the central axis of the eye in order to avoid the complication of retinal holes.