Functional and structural changes in a canine model of hereditary primary angle-closure glaucoma.
OBJECTIVE
To characterize functional and structural changes in a canine model of hereditary primary angle-closure glaucoma.


METHODS
Intraocular pressure (IOP) was evaluated with tonometry in a colony of glaucomatous dogs at 8, 15, 18, 20, and 30 months of age. Retinal function was evaluated using electroretinography (scotopic, photopic, and pattern). Examination of anterior segment structures was performed using gonioscopy and high-frequency ultrasonography (HFU).


RESULTS
A gradual rise in IOP was observed with an increase in age: 8 months, 14 mm Hg (median value); 15 months, 15.5 mm Hg; 18 months, 17.5 mm Hg; 20 months, 24 mm Hg; 30 months, 36 mm Hg. Provocative testing with mydriatic agents (tropicamide and atropine 1%) caused significant increases in IOP (35% and 50%, respectively). HFU analysis showed complete collapse of iridocorneal angles by 20 months of age. Scotopic and photopic ERG analysis did not reveal significant deficits, but pattern ERG analysis showed significantly reduced amplitudes in glaucomatous dogs (glaucoma, 3.5 +/- 0.4 muV; control, 6.2 +/- 0.3 muV; P = 0.004; Student's t-test). Histologic analysis revealed collapse of the iridocorneal angle, posterior bowing of the lamina cribrosa, swelling and loss of large retinal ganglion cells, increased glial reactivity, and increased thickening of the lamina cribrosa.


CONCLUSIONS
Canine hereditary angle-closure glaucoma is characterized by a progressive increase in intraocular pressure, loss of optic nerve function, and retinal ganglion cell loss.
Grozdanic
Sinisa D
SD
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa 50011, USA. sgrozdan@iastate.edu
Kecova
Helga
H
Harper
Matthew M
MM
Nilaweera
Wijitha
W
Kuehn
Markus H
MH
Kardon
Randy H
RH
D000818:Animals; D000869:Anterior Eye Segment / Q000000981:diagnostic imaging / Q000473:pathology*; D004195:Disease Models, Animal; D004283:Dog Diseases / Q000235:genetics / Q000503:physiopathology*; D004285:Dogs; D004596:Electroretinography; D015785:Eye Diseases, Hereditary / Q000235:genetics / Q000503:physiopathology / Q000662:veterinary*; D015812:Glaucoma, Angle-Closure / Q000235:genetics / Q000503:physiopathology / Q000662:veterinary*; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006068:Gonioscopy; D007124:Immunoenzyme Techniques; D007429:Intraocular Pressure; D009901:Optic Nerve Diseases / Q000235:genetics / Q000503:physiopathology / Q000662:veterinary; D012165:Retinal Ganglion Cells / Q000473:pathology*; D014065:Tonometry, Ocular; D014463:Ultrasonography
D005904:Glial Fibrillary Acidic Protein