Bouvier Glaucoma & the Iridocorneal Angle

Glaucoma is characterized by an elevation of intraocular pressure (IOP) which,
when sustained, causes intraocular damage resulting in blindness. The elevated
intraocular pressure occurs because the fluid cannot leave through the
iridocorneal angle. Diagnosis and classification of glaucoma requires
measurement of the IOP (tonometry) and examination of the iridocorneal angle
(gonioscopy). Neither of these tests is part of a routine screening exam for
certification.

In this breed, primary glaucoma is associated with narrowed iridocrorneal angles
and various degrees of congenital angle malformations varying from mild to
severe. Dysplastic pectinate ligaments and subsequent narrowed angles are
similar to those described in the Basset and American and English Cocker
Spaniels. The occurrence of glaucoma is related to the most severe abnormalities
of the pectinate ligaments. The relationship between glaucoma development and
the anomaly of the pectinate ligament is not clear.

B.	Persistent pupillary membranes (PPM) Persistent blood vessel remnants in the
anterior chamber of the eye which fail to regress normally during the first
three months of life. These strands may bridge from iris to iris, iris to
cornea, iris to lens, or form sheets of tissue in the anterior chamber. The last
three forms pose the greatest threat to vision and when severe, vision
impairment or blindness may occur.

C.	Cataract A partial or complete opacity of the lens and/or its capsule. In
cases where cataracts are complete and affect both eyes, blindness results. The
prudent approach is to assume cataracts to be hereditary except in cases known
to be associated with trauma, other causes of ocular inflammation, specific
metabolic diseases, persistent pupillary membrane, persistent hyaloid or
nutritional deficiencies. Cataracts may involve the lens completely (diffuse) or
in a localized region.

D.	Persistent hyperplastic primary vitreous (PHPV)/Persistent hyperplastic
tunica vasculosa lentis (PHTVL)

Persistent hyperplastic primary vitreous is a congenital defect resulting from
abnormalities in the development and regression of the hyaloid artery (the
primary vitreous) and the interaction of this blood vessel with the posterior
lens capsule/cortex during embryogenesis. This condition is often associated
with persistent hyperplastic tunica vasculosa lentis which results from failure
of regression of the embryologic vascular network which surrounds the developing
lens.

In the Bouvier des Flandres, the condition is associated with retinal dysplasia
and detachment, optic nerve hypoplasia, lenticonus, cataract and congenital
blindness.

References

1.	ACVO Genetics Committee, 1999 and/or Data from CERF All-Breeds Report, 1991-
1998.

2. Boeve' MH, Stades FC: Glaucoom bij hond en kat. Oversicht en retrospectieve
evaluatie van 421 patienten I.Pathobiologischeachtergronden, indeling en
raspredisposities. [Glaucoma in dogs and cats. Review and retrospective
evaluation of 421 patients I. Pathobiological background, classification and
breed predisposition]. Tijdschr Diergeneeskd 110: 219, 1985.

3.	van der Linde-Sipman JS: Dysplasia of the pectinate ligament and primary
glaucoma in the Bouvier des Flandres dog. Vet Pathol 24: 201, 1987.

4. Van Rensburg IBJ, Petrick S, Van der Lagt J, Smit M: Multiple inherited eye
anomalies including persistent hyperplastic tunica vasculosa lentis in the
Bouvier des Flandres. Prog Vet Comp Ophthal 2:143, 1992.