Non Tubular Intrascleral Simplified Gonioimplant for Glaucoma Surgery in Three Dogs - Pilot Report
H. D. Herrera
School of Veterinary Sciences, University of Buenos Aires, Buenos Aires, Argentina
Glaucoma is one of the most common causes of blindness in the adult dog because of the low response to therapy. Surgical treatments appear to be the most effective in reducing the intraocular pressure (IOP) to safe levels. Gonioimplants usually consisted of a device divided in two parts: a silicon tube which is introduced into the anterior chamber, joined to a foot plate (scleral explant) fixed to the sclera which collects the aqueous humor flowed through the tube. The purpose of this abstract is to communicate a new concept in glaucoma devices using a non tubular gonioimplant.
Materials and methods
Three female dogs, one Fox Terrier, one Shar Pei, and one crossbreed aging from 5 to 7-year-old were included. They presented closed angle primary glaucoma diagnosed by clinical signs and gonioscopy. The intraocular pressure ranged from 56 to 74 mm Hg in the operated eye at the first visit. The implant consisted of a silicon strip, 4 mm in width, which was fixed in a intrascleral position after a scleral flap, and placed into the anterior chamber through a limbal incision. 5 - Fluorouracil was used in the three cases in order to reduce the conjunctival fibrosis proliferation.
A postoperative follow up from 2 to 14 months could be made (Fox Terrier: 12 months, Shar Pei: 14 months and crossbreed: 2 months). There were no intraoperative complications in any case, the gonioimplant was well tolerated and healing occurred in a normal way. No complications due to material or shape of the implant were observed. The IOP remained lower than 15 mmHg in two cases (Fox Terrier and Shar Pei) but could not be controlled in the third case. Along the studied period those two cases showed clinical signs of vision (menace response and normal pupillary light reflexes). The Fox Terrier started to show an increase of IOP after one year and was re-operated but IOP could not be controlled at this time. The crossbreed dog maintained high IOP at the early postoperative and intravitreal injection of gentamicin was performed in order to control the pressure.
It is well known that the most important cause of failure of tubular gonioimplants is the obstruction of the tubing due to conjunctival fibrosis. By using this new concept of gonioimplants this common complication is attempted to be avoided. More cases will be necessary for further conclusions but the results obtained in these dogs are encouraging.
1. Herrera HD. Cirugía de glaucoma en el canino con implante de silicón simplificado. Resultados en 5 casos. Clín Vet Peq An 1995; 15(2): 90-97.
2. García GA, et al. Evaluation of valved and nonvalved gonioimplant in 83 eyes of 65 dogs with glaucoma. An Eye Res 1998; 17(1-2): 9-16.
3. Jégou JP, et al. Artificial meshwork (MESH), a new concept for the treatment of glaucoma in the dog. A pilot study of tolerance and efficacy (abstract). 31st Proc. Am. Coll. Vet. Ophthalmol., Montreal 2000.