© 2003 American College of Veterinary Ophthalmologists Veterinary Ophthalmology (2003) 6, 3, 255–263 Blackwell Publishing Ltd. Effects of low-intensity pulsed ultrasound on wound healing in corneas of dogs following keratoplasty F. A. M. Vicenti,* J. L. Laus,* J. M. Costa Neto,† I. C. Talieri,* C. F. Campos,* A. T. Jorge,* A. L. Ferreira‡ and A. P. Fantinatti* *Faculdade de Ciências Agrárias e Veterinárias, UNESP, Jaboticabal, São Paulo, Brazil, †Universidade Federal da Paraíba, UFPB, Patos, Paraíba, Brazil, ‡Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, USP, Ribeirão Preto, São Paulo, Brazil Abstract The effects of low-intensity pulsed ultrasound on wound healing were evaluated at the graft-cornea transition in dogs following lamellar keratoplasty using tunica vaginalis preserved in 98% glycerin. Twenty-one dogs were subdivided into three groups of seven animals. The first group ( W/ US) received daily treatment of low-intensity pulsed ultrasound (20 mW/cm 2 ) for 15 min for the first 10 days post surgery. The second group ( N/ US) was submitted to the same procedure but with the ultrasound apparatus turned off. The third group, the control (CO), underwent the surgical procedure only. The animals were clinically evaluated during the initial (1–15 days), intermediate (16 – 30 days) and late (31–120 days) postoperative period. The corneas were evaluated by light microscopy at 1, 3, 7, 15, 30, 60 and 120 days after surgery. Clinically, there were no differences which would promote an advantage to any of the treatments. Light microscopy, however, revealed more extensive vascularization and more advanced wound healing in the W/ US group, as well as a tendency towards early graft incorporation. Based on the present results, low-intensity pulsed ultrasound shows advantages, especially in situations where trophic support is a mandatory condition, facilitating better graft incorporation and rapid recovery of stromal organization. Key Words: corneal healing, dogs, keratoplasty, tunica vaginalis, ultrasound Address communications to: J. L. Laus Tel.: +55 21 16 32092626 Fax: +55 21 16 32025169 e-mail: jllaus@fcav.unesp.br INTRODUCTION Ultrasound can be defined as a form of mechanical energy with a frequency higher than the human audible limit, i.e. higher than 20 kHz. 1 Various physical modalities may be used as adjuvant therapy for the treatment of chronic injuries, including for example, hydrotherapy, electrostimu- lation, lasers, pressure and ultrasound. When applied cor- rectly, these modalities reduce treatment time and patient’s suffering by shortening the time of healing. 2 Therapeutic ultrasound, as well as other physical modali- ties, induces wound repair. The objectives of ultrasound treatment are the stimulation of fibroblasts and macro- phages, mastocyte degranulation, induction of angiogenesis, and reduction in the exudative (inflammatory) phase of wound healing and healing time. 3 Some authors have also reported the analgesic properties of therapeutic ultrasound. 4 The use of ultrasound for the stimulation of tissue repair has been studied since the middle of the last century. In 1968, the effect of ultrasound waves at intensities of 0.1– 8 W/cm 2 on the tissue regeneration of sheep ears was stud- ied, with the stimulating effect being more significant when lower intensities (0.1, 0.25, 0.5 and 1 W/cm 2 ) were used. 5 Based on these studies, numerous other investigations were conducted and the effects of low-intensity ultrasound on the regeneration of soft tissues were confirmed. Among them were studies on the effects of ultrasound on cutaneous ulcers, 6–9 skin, 10–13 tendon 14,15 and bone injuries. 16–20 With respect to its use in ophthalmology, the beneficial effects of ultrasound as an adjuvant in the treatment of infected wounds of the cornea, 21 suppurative corneal ulcers 22 and chemical burns of the eyes 23 have been reported. The physical mechanism by which ultrasound waves interact with cells, tissues, organs and live organisms are generally classified as thermal and nonthermal. 24 With the ultrasonic parameters optimized for therapeutic use, the local increase in temperature is minimal, indicating the pos- sibility of nonthermal mechanisms in the biologic actions of ultrasound. 8,25 The increase in temperature is zero or mini- mal when the ultrasound intensity is low or the system is