Belgian ECVO Panel

Cataract: any hereditary or non-hereditary, congenital or acquired, non-physiological opacity of the lens and/or its capsule. The defect may result in blindness if complete and bilateral. All bilateral or unilateral cataracts and especially cortical cataracts are known and presumed hereditary eye diseases except in cases known to be associated with trauma, other causes of ocular inflammation, metabolic disease, nutritional deficiencies, persistent pupillary membrane, persistent hyaloid artery or old age. DNA-tests for specific breeds are available.

Collie Eye Anomaly (CEA): known hereditary congenital eye disease;a congenital syndrome of ocular anomalies mainly in Collie breeds affecting the choroid and sclera and indirectly the retina and optic disc. It is characterized by bilateral and often symmetrical defects including choroidal hypoplasia (CH, CRD)with or without coloboma, retinal detachment and intraocular hemorrhage. Vision varies with the degree to which an individual is affected and may be minimally compromised to having severe visual impairment or blindness. DNA-tests for choroidal hypoplasia in specific breeds are available.

Corneal dystrophy: presumed hereditary eye disease; non-inflammatory corneal opacity in one or more of the corneal layers (epithelium, stroma, endothelium). It is usually bilateral but not always symmetrical. The onset in one eye may precede the other.

Corneal dystrophy, endothelial: abnormal loss of the inner lining (endothelium) of the cornea causing progressive fluid retention (edema) leading to increased corneal thickness, keratitis, corneal clouding and decreased vision

Corneal dystrophy, epithelial / stromal: non- inflammatory corneal opacity (white to grey with crystalline appearance) in one or more of the corneal layers. Often associated with deposits of cholesterol and other lipids (or fats) within the cornea

Distichiasis: presumed hereditary eye disease; single or multiple hairs (cilia) from an abnormally located hair follicle in the eyelid margin, usually growing from or in between the Meibomian glands, and arising from the Meibomian duct openings, which may cause ocular irritation. The defect is due to abnormal differentiation of a tarsal gland. Distichiasis usually occurs at an early age ( 1-2 years), but may occur any time in life

Ectopic cilia: presumed hereditary eye disease; single or multiple hairs (cilia) from an abnormally located hair follicle in the eyelid margin,usually growing from or in between the Meibomian glandsemerging through the eyelid conjunctiva. Ectopic cilia occur more frequently in younger dogs. They generally cause severe discomfort and corneal disease

Ectropion: presumed hereditary eye disease; a conformational defect resulting in eversion (rolling-out) of the margin of the eyelids, which may cause ocular problems due to exposure. In the hereditary forms, it is likely that ectropion is influenced by several genes (polygenic), defining the skin and other structures which make up the eyelids, the amount and weight of skin covering the head and face, the orbital contents and the conformation of the skull. Secondary, non-hereditary ectropion may also occur, for example due to iatrogenic, trauma or scarring Ectropion with macroblepharon:presumed hereditary eye disease; ectropion associated with an excessively large lid fissure and laxity of the canthal structures. Central lower lid ectropion is often associated with entropion of the adjacent lid. This causes severe ocular irritation.

Entropion: presumed hereditary eye disease;a conformational defect resulting in “in-rolling” of one or both of the margins of the eyelids which may cause ocular irritation. It is likely that entropion is influenced by several genes (polygenic), defining the skin and other structures which make up the eyelids, the amount and weight of the skin  covering the head and face, the orbital contents and the conformation of the skull. Secondary, non-hereditary entropion may also occur, for example due to trauma, severe enophthalmos, loss of orbital fat, etc.

Fibrae latae: presumed hereditary eye disease, pectinate ligament fibres with either a confluent (broad) base and shortened thin insertions at the cornea or formation of thick fibres (< 5 fibres)

Lamina (LA): presumed hereditary eye disease,pectinate ligament fibres form plates or sheets of continuous tissue (>5 fibres), with or without flow holes

Lens luxation (primary): known hereditary eye disease; partial (subluxation) or complete displacement of the lens from the normal anatomic site, in the fossa patellaris, behind the pupil. Lens luxation may result in elevated intraocular pressure (glaucoma) causing vision impairment or blindness. DNA-tests for specific breeds are available.

Macroblepharon: presumed hereditary eye disease; an exceptionally large palpebral fissure. Macroblepharon in conjunction with laxity of the lateralcanthal structures may lead to lower lid ectropionin combination with lateral entropion and upper lid entropion and trichiasis. This may in severe cases sometimes result in diamond-shaped eyes. Either of these conditions may lead to conditions associated with corneal exposure

Micropapilla: small optic disc which is not associated with vision impairment. May not be differentiated from hypoplastic papilla/ optic disc on a routine, dilated ECVO-eye examination

Optic nerve hypoplasia: see and use hypoplastic papilla/ optic disc

Pectinate ligament: thin, filamentous fibres radiating from the base of the iris and inserting into the inner surface of the cornea as the entrance of the aqueous drainage system

Pectinate ligament abnormality (PLA): presumed hereditary eye disease; characterized by an abnormal pectinate ligament that can be divided into 2 predominant types:

1. Fibrae latae

2. Lamina

Diagnosis is by gonioscopy (picture)

Persistent hyperplastic tunica vasculosa lentis/ persistent hyperplastic primary vitreous (PHTVL/PHPV): known orpresumed hereditary, congenital eye disease which results from failure of regression of the embryologic vascular network, surrounding the developing lens and primary vitreous. The latter fails to regress within the first 2-3 weeks after birth. The defect is currently graded in 6 levels of severity, in which grade 1 is characterized by uni- or bilateral small, yellow to brown dots mainly centrally, retrolentally on the posterior capsule of the lens. These are stationary and do not affect vision. The more severe forms (2-6) usually occur bilaterally and cause visual impairment or blindness. Known hereditary e.g. in the Dobermann and the Staffordshire Bull terrier

Persistent pupillary membrane (PPM): presumed hereditary congenital eye diseasein which blood vessel remnants of the embryological vascular network in the anterior chamber of the eye fail to regress which normally occurs during the first 4 to 5 weeks of life.These remnants may be found on the surface of the iris at the colarette, the lens capsule or against the corneal endothelium or strands may bridge from iris to iris, iris to cornea, iris to lens, with or without sheets of tissue in the anterior chamber. The last three forms pose the greatest threat to vision and, when

severe, vision impairment may occur.

Retinal degeneration/Progressive Retinal Atrophy (PRA): known hereditary eye disease; a group of bilateral, hereditary dysplastic and /or degenerative diseases of the photoreceptors primarily, progressing to blindness in both eyes simultaneously. The onset of the blindness depends on the affected breed and the type of process (dysplasia and/or degeneration). The photoreceptor abnormalities can be detected by an electroretinogram (not part of a routine ECVO Scheme eye examination) before there are detectable fundus changes observed by ophthalmoscopy. These funduscopic changes consist in the early disease of a change in reflectivity with greyish discoloration mainly in the periphery and midperiphery in the tapetal area of the fundus accompanied by slight vascular attenuation.With progression of the disease there are more generalized changes with hyperreflectivity of the tapetal fundus, depigmentation and uneven pigment distribution in the non-tapetal fundus, severe vascular attenuation and a pale optic disc. There are multiple genetic types of PRA including different forms of rod-cone dysplasia and degeneration (rcd1-4) and progressive rod cone degeneration (prcd). DNA-tests for specific forms and breeds are available.

Retinal dysplasia: presumed hereditary eye disease; abnormal development of the retina with ophthalmoscopic changes observed early in life, characterized by neuroretinal folding (s), rosettes and partial or total retinal detachment; non-progressive and generally recognized to have three forms: (multi)focal, geographic and total

- Retinal dysplasia- (multi)focal: seen ophthalmoscopically as linear (vermiform), triangular, curved or curvilinear foci of retinal folding that may be single or multiple. When seen in puppies this condition may partially or completely resolve with maturity. Its significance to vision is unknown. The two other forms of retinal dysplasia (geographic and complete) which are known to be hereditary in some breeds and, in their most severe form, may cause blindness. The genetic relationship between folds and more severe forms of retinal dysplasia is undetermined

- Retinal dysplasia- geographical: any irregularly, horseshoe- or bladder-like shaped area of abnormal retinal development, most often in the central part of the tapetal area of the fundus, in close association with the dorsal retinal vasculature, containing both areas of thinning and areas of elevation representing focal retinal detachment and areas of retinal disorganization. This form may be associated with vision impairment

- Retinal dysplasia- total: severe retinal disorganization associated with total separation (detachment) of the retina.

The geographic and total forms of retinal dysplasia are associated with partial or complete vision impairment or

blindness and can be diagnosed already in puppies. Retinal dysplasia is known to be hereditary in many breeds. The

genetic relationship between the three forms of the disease is not known for all breeds

Trichiasis: presumed hereditary eye disease or acquired abnormality of deviated hairs on a normal place around the lid fissure, irritating the conjunctiva, the free lid margin of the opposite lid and/or the conjunctiva and/or the globe. Predominantly on the nasal folds or on the lateral part of the superior eyelid edge