MRI-based quantification of ophthalmic changes in healthy volunteers during acute 15° head-down tilt as an analogue to microgravity

Spaceflight is known to cause ophthalmic changes in a condition known as spaceflight-associated neuro-ocular syndrome (SANS). It is hypothesized that SANS is caused by cephalad fluid shifts and potentially mild elevation of intracranial pressure (ICP) in microgravity. Head-down tilt (HDT) studies are a ground-based spaceflight analogue to create cephalad fluid shifts. Here, we developed non-invasive magnetic resonance imaging (MRI)-based techniques to quantify ophthalmic structural changes under acute 15° HDT. We specifically quantified: (i) change in optic nerve sheath (ONS) and optic nerve (ON) cross-sectional area, (ii) change in ON deviation, an indicator of ON tortuosity, (iii) change in vitreous chamber depth, and (iv) an estimated ONS Young's modulus. Under acute HDT, ONS cross-sectional area increased by 4.04 mm 2 (95% CI 2.88–5.21 mm 2 , p < 0. 000), while ON cross-sectional area remained nearly unchanged (95% CI −0.12 to 0.43 mm 2 , p = 0.271). ON deviation increased under HDT by 0.20 mm (95% CI 0.08–0.33 mm, p = 0.002). Vitreous chamber depth decreased under HDT by −0.11 mm (95% CI −0.21 to −0.03 mm, p = 0.009). ONS Young's modulus was estimated to be 85.0 kPa. We observed a significant effect of sex and BMI on ONS parameters, of interest since they are known risk factors for idiopathic intracranial hypertension. The tools developed herein will be useful for future analyses of ON changes in various conditions.

Ocular surface disorders in dogs and cats submitted to dissociative anesthesia in elective orchiectomy procedure

The present study aims to verify whether dogs and cats submitted to dissociative anesthesia for elective orchiectomy may present alterations in the tear production and consequent lesions on the ocular surface. For this purpose, 40 animals, 22 cats and 18 dogs, underwent an ophthalmic semiotechnique composed of the evaluation of anterior and posterior chambers, fundscopy, Schirmer's tear test (TLS) and fluorescein test. Subsequently, they underwent dissociative anesthesia, associating ketamine with diazepam or midazolam. Immediately at the end of the procedure, the fluorescein and TLS test was repeated. After 24 hours, a new ophthalmic evaluation was performed to compare the results obtained. There were no ophthalmic changes. With the use of diazepam, TLS remained within the normal range with a median of 19 mm / min, with a mean and standard deviation of 19.27 ± 3.01 mm / min for dogs and a median of 18 mm / min, with a mean and standard deviation of 19.05 ± 2.81 mm / min for cats. When using midazolam, the TLS of the dogs had a median of 19 mm / min, with a mean and standard deviation of 18.84 ± 2.69 mm / min and of the cats, they had a median of 18 mm / min with a mean and standard deviation of 18.37 ± 2.32 mm / min. The results found suggest that the use of dissociative anesthesia for short procedures does not significantly alter the tear production, nor does it cause eye injuries.

COMPLICATIONS IN LOCAL ANESTHESIA: WHAT ARE THEY? AND WHAT IS THE PERSPECTIVE FOR THE FUTURE? LITERATURE REVIEW

BACKGROUND: The present work is a review of the literature on the main complications related to local anesthetics and brings what the articles indicate about the incidences of the future. OBJECTIVE: To deal with the main documented complications and, using the available information, draw a picture of future complications. METHOD: The basic information was found in searches in the PubMed, MEDLINE, SciELO and Google Scholar databases. RESULT: Complications found were: Injection pain, needle breaking, trismus, hematoma, infection, edema, necrosis, allergies, intoxication, methemoglobinemia, ophthalmic changes, paraesthesia and complications modulated by systemic changes. The authors conclude that the next few years may have an increase in the impact of complications.

Severe Corneal Edema in a Dog Naturally Infected by Leishmania spp.

Background: Visceral leishmaniasis (VL) is an infectious disease caused by the protozoan Leishmania infantum that is transmitted to dogs and humans by sandflies. The incidence of eye injuries in VL is high. They occur in 20 to 81% of infected dogs and include blepharitis, granulomatous conjunctivitis, scleritis, keratitis, anterior uveitis, keratoconjunctivitis sicca, and secondary glaucoma. However, some dogs present only the clinical signs of eye damage. The main objective of this manuscript is to report a case of anterior uveitis with severe corneal edema in a dog with VL that underwent clinical and surgical ophthalmic treatments after miltefosine therapy.Case: An 8-month-old, intact male Labrador Retriever with brown fur presented with pruritus, diffuse desquamation, and conjunctival hyperemia on physical evaluation. On the basis of an ophthalmic examination, nodular conjunctivitis and uveitis were diagnosed in both eyes. Moreover, laboratory examination results showed hyperproteinemia, increased serum alkaline phosphatase activity, and positive reactions to immunochromatographic tests for VL. Clinical treatment was instituted from the moment of diagnosis, when miltefosine and allopurinol were prescribed. At the end of treatment, based on laboratory examination results, only allopurinol was prescribed at a lower dose than initially prescribed for treatment continuation. Topical medications (prednisolone eye drops and sodium hyaluronate) were recommended for the ophthalmic changes. One week after the start of topical treatment, the dog showed an improvement in eye inflammation but still had bilateral corneal edema. A hyperosmotic agent was prescribed to improve edema, and a surgical procedure was recommended if there was no improvement. The physician opted for the surgical procedure in one of the eyes that had not shown significant improvement after the clinical treatment.Discussion: VL is a zoonosis, and the domestic dog is the main reservoir. These animals often have dermatological conditions, and the ophthalmic changes observed can be unilateral or bilateral, with more than one change in the same eye. Lymphoplasmacytic or granulomatous anterior uveitis is the most prevalent change, as the uvea and conjunctiva are important lymphoid areas of the eye; this also explains the high incidence of uveitis and conjunctivitis in dogs with VL. In uveitis, corneal edema is driven by endothelial cell damage induced by prostaglandins, which interfere with the function of the endothelial pump and interrupt the normal dehydrated state of the cornea. Severe corneal edema can result in the formation of fluid-filled multifocal bubbles in the corneal stroma—a condition called bullous keratopathy. These bubbles accumulate under or inside the corneal epithelium, and they can burst spontaneously, leading to corneal erosions or ulcerations. Drug therapy with hyperosmotic agents could, in principle, reduce the formation of bubbles. Surgical options to decrease edema and blistering include a permanent conjunctival graft or thermokeratoplasty. Thermokeratoplasty induces the formation of superficial scars in the corneal stroma, applying multiple cauterization foci to the stroma exposed in the areas of bullous keratopathy and epithelial ulceration. In conclusion, the surgical therapeutic choice results in better visual quality in patients who do not respond well to clinical treatment.