Optic neuritis is associated with rarefaction of the superficial and deep retinal vessels. Alterations of the choriocapillaries might be linked to disease activity in MS.

ABSTRACT.Purpose: Intravitreal injections are used extensively to treat retinal diseases. Performing an intravitreal injection increases intraocular volume by the amount of fluid brought into the eye. Whether this influences intraocular pressure (IOP) was investigated here. Methods: A biomechanical model relying on 3-dimensional elasticity theory was developed to determine the short-term effect of volume changes on IOP. We calculated the effect for intravitreal injections of 0.1 ml in myopic, emmetropic and hyperopic eyes. Our calculations were compared with IOP measurements obtained immediately after intravitreal injection of 4 mg triamcinolone in 0.1 ml solution (IVTA) in 22 patients. Shortly after the measurement had been taken, IOP was reduced by paracentesis. Results: Immediately after IVTA, measured IOP was elevated by a mean of 40.6 ± 12.1 mmHg compared with initial pressure (p < 0.001). Measured and calculated IOP were comparable. Eyes with shorter axial length had higher IOP immediately after the injection (p < 0.05). Conclusions: The effect of injected volumes on IOP can be calculated with a biomechanical model. Our results show that paracentesis might be recommended when injecting 0.1 ml of a substance to avoid a short-term increase in IOP. As intravitreal injections are mostly applied in diseases that are due to vascular compromise, it might be prudent not to impair perfusion in those eyes, even for short periods of time.

ABSTRACT.Purpose: To evaluate the efficacy of intravitreal dexamethasone implants in eyes with cystoid macular oedema (CME) secondary to branch retinal vein occlusion (BRVO) or central retinal vein occlusion (CRVO) in the clinical everyday practice, examine the effects of early retreatment and compare the results with the GENEVA study. Methods: The charts of 102 patients (102 eyes) with CME secondary to BRVO (n = 54) or CRVO (n = 48) treated with Ozurdex at 8 centres were retrospectively reviewed. The patients were examined monthly over a 24-week period. Slit-lamp biomicroscopy, measurement of best-corrected visual acuity (BCVA) and measurement of the central retinal thickness (CRT) with spectral-domain optical coherence tomography (SD-OCT) were performed at baseline and at every follow-up examination. The mean CRT at baseline was 740 ± 351 lm and it decreased to 419 ± 315 lm after 4 weeks, 352 ± 261 lm after 8 weeks, 455 ± 251 lm after 12 weeks, 497 ± 280 lm after 16 weeks, 468 ± 301 lm after 20 weeks and 395 ± 234 lm after 24 weeks. The BCVA improvement was statistically significantly better (p < 0.05) compared with baseline in both groups at every follow-up visit. The mean CRT maintained significantly better when compared with baseline in both groups at all follow-up visits. Early reinjection was indicated in BRVO in 40.7% after 17.5 ± 4.2 weeks and in CRVO in 50% after 17.68 ± 4.2. Six eyes (11%) with BRVO received a sectorial laser photocoagulation at a mean interval of 22 ± 5.0 weeks. Seven eyes (15%) with CRVO received a panretinal laser photocoagulation after a mean interval of 18 ± 7.0 weeks. The BCVA improvement and the mean CRT reduction were statistically significant (p < 0.05) compared with baseline in both groups at every follow-up visit. Conclusions: Dexamethasone intravitreal implant resulted in a significant improvement of the BCVA and reduction of CME in patients with BRVO or CRVO. Early retreatment after 16 weeks instead of 24 weeks, like in the GENEVA study, was indicated in 50% to stabilize the improved functional and anatomical results.

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Abstract-This paper introduces the design and development of a new robotic system to assist surgeons performing ophthalmic surgeries. The robot itself is very compact and similar to an average human hand in size. Its primary application is intraocular micromanipulation in order to overcome the existing challenges in treatment of diseases like Retinal Vein Occlusion (RVO). The novel hybrid mechanism designed for this robot allows microscale motions and is stable in the presence of vibrations common in operation room (OR). The robotic system can be easily integrated into standard operation rooms and does not require modification of conventional surgical tools. This compact microsurgical system is suitable for mounting on the patient's head and thereby, solves the problem of patient motion. The compatibility of the robotic system with a real world surgical setup was evaluated and confirmed in this work.

Subretinal injection is a delicate and complex microsurgery. The main surgical difficulties come from the surgeon's hand tremor, dexterous motion, and insufficient visual feedback. In order to begin addressing these challenges, this article presents a robot system for subretinal insertion integrated with intraoperative optical coherence tomography (OCT). The surgical workflow using this system consists of two main parts. The first part is the manual robot control, which aims the target before approaching the retinal surface, while considering the remote center of motion (RCM) constraint. When the injection area has been located precisely, needle is inserted into retina. To ensure surgical safety, needle insertion depth is estimated using OCT images on a continuous basis. A soft RCM control method is designed and integrated for the controller of our hybrid parallel-serial surgical robot. Safety and accuracy performance evaluation with a 15-ms control loop shows that the worst-case RCM deviation error is within 1 mm. Experimental results demonstrated that the proposed system has the ability to improve surgical outcomes by surgeons overcoming their physical limitations in order to enable a better dexterous motion, and furthermore enhancing their visual feedback for a better intraocular perception.

In the clinical routine Ozurdex treatment has proven to be a therapy method with minimal side effects. In Ozurdex administration intraocular pressure elevation was observed as the most common side effect; however, this generally did not require surgical intervention. Caution is advised in patients with an anterior chamber lens and iridectomy. Macular holes as a rare complication might result from vitreous traction during the administration process. In summary, even in the clinical routine application of Ozurdex the complication rate was not higher than in registration studies.

PurposeTo investigate changes in the area of the foveal avascular zone (FAZ) in patients with retinal vascular disease.Patients and methodsThis retrospective, consecutive study examined 53 eyes of 53 patients with macular edema due to branch retinal vein occlusion in 25 patients (47.2%) and nonproliferative diabetic retinopathy in 28 patients (52.8%). The macular edema was treated with an intravitreal injection of 0.05 mL equal to 1.25 mg bevacizumab. Before and 6–8 weeks after the injection, best corrected visual acuity, slit lamp biomicroscopy of the anterior segment and fundus, optical coherence tomography, and fluorescein angiography were conducted. The FAZ was manually circumscribed on early-phase angiography images and the area of the FAZ was measured.ResultsThe preoperative overall mean FAZ area was 0.327 ± 0.126 mm2 (median 0.310 mm2). At the control consultation, the overall mean area was significantly larger (0.422 ± 0.259 mm2; median 0.380 mm2; P < 0.001). In the nonproliferative diabetic retinopathy subpopulation, the mean area was 0.361 ± 0.129 mm2 (median 0.330 mm2) before bevacizumab application and 0.434 mm2 at the follow-up visit (mean increase 0.071 mm2/19.7%). In the branch retinal vein occlusion group, the baseline FAZ area was 0.290 ± 0.115 mm2 and 0.407 ± 0.350 mm2 at follow-up (median 0.330 mm2; mean increase 0.117 mm2/40.3%). No cases of severe operation-associated complications were observed.ConclusionThe results confirm the safety of intravitreal bevacizumab injection in patients with macular edema due to nonproliferative diabetic retinopathy and branch retinal vein occlusion. The enlargement of the FAZ could be equivalent to an increase in retinal ischemia. These results may be transient; a potential vascular risk, however, when applying antivascular endothelial growth factor therapy in eyes with preexistent vascular disease must be considered.