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Strabismus treatment in children: a model that allows bupivacaine injection of extraocular muscles

Grant number: 14/06807-6
Support type:Scholarships abroad - Research
Effective date (Start): July 01, 2014
Effective date (End): June 30, 2015
Field of knowledge:Health Sciences - Medicine
Principal Investigator:Iara Debert
Grantee:Iara Debert
Host: Joel Miller
Home Institution: Hospital das Clínicas da Faculdade de Medicina da USP (HCFMUSP). Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil
Local de pesquisa : Strabismus Research Foundation (SRF), United States  

Abstract

Over recent years, attention has been directed at developing less invasive procedures as alternatives to strabismus surgery. Eye muscle resection, a common surgical treatment for strabismus, sacrifices tissue to stretch the muscle, increasing its elastic force and compromising orbital mechanics. Bupivacaine injection into eye muscles, in contrast, offer the possibility of increasing contractile strength and elastic stiffness, as well as changing muscle length, without resecting tissue or compromising orbital mechanics. Bupivacaine injection is a minimally invasive treatment with long-term benefits that is a promising alternative to conventional strabismus surgery. Currently, it is performed only in adults because the injection is targeted using electromyography signals recorded by the tip of the injection needle from movement-activated muscles and is not compatible with sedation, when movement-related electrical activity cannot be recorded. As the largest population requiring treatment of strabismus comprises children, we sought to develop a way to inject bupivacaine accurately in children under narcosis. To guide needle placement during injection, our model will combine ultrasound with electrical stimulation.The experiment will be done in rabbits. The first stage of the research will involve ultrasonography to guide injection needle placement in the eye muscle. Several ultrasound frequencies will be tested to visualize the needle tip in the posterior orbit. The second stage will involve electrical stimulation performed under close observation of muscle contraction and consequent movement of the eye in the related direction. The institution where the research will be conducted has facilities for the design and construction of the eye muscle electrical stimulator and other devices that will be employed for developing and enhancing the injection technique. Safety and effectiveness of ultrasonography and electrical stimulation in guiding injection needle placement will be worked out based on optimal parameters of ultrasound frequency and power, electrical stimulation frequency and amplitude and duration of current pulses. For both stages, one eye of the animal will be treated, while the fellow eye will be left untreated. At the conclusion of the experiment animals will be sacrificed. Lens, retina and other ocular tissues will be examined clinically and histologically, and compared with those of untreated fellow eyes, for evidence of damage.Developing this project at Strabismus Research Foundation, a research center with advanced technology and local resources available for creating and manufacturing devices that will be used to develop the proposed model, is a unique opportunity to methodological update. My supervisors Dr. Alan Scott e Dr. Joel Miller are recognized for having revolutionized the understanding of the mechanisms of ocular motility disorders and the treatment of strabismus. They have been pioneers in the use of bupivacaine in the eye muscles and the significant work on bupivacaine treatment of strabismus has been done in their laboratories. Undertaking this research under their guidance will contribute to new strabismus treatment modalities. This is not only an important topic for scientific research, but also one with direct application in clinical ophthalmology. To participate in the development of this bold model that expands the treatment of strabismus with bupivacaine injection to the pediatric population is also a unique opportunity to conduct research that could revolutionize strabismus treatment. (AU)

Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
DEBERT, IARA; MILLER, JOEL M.; DANH, KENNETH K.; SCOTT, ALAN B. Pharmacologic injection treatment of comitant strabismus. JOURNAL OF AAPOS, v. 20, n. 2, p. 106-111, APR 2016. Web of Science Citations: 7.

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