PHPV
Persistent Hyperplastic Primary Vitreous
Testing method
Slit-lamp biomicroscopic examination of the posterior lens capsule and retrolensal space following pupil dilation. The condition is graded 1 to 6 in the Dobermann using the Stades grading system. Grade 1 is not recorded as affected. In the Staffordshire Bull Terrier the presentation differs slightly from the Dobermann — posterior lens capsule changes are more variable and secondary cataracts are less frequent, but retrolensal fibrovascular plaques, posterior lenticonus, and persistent capsulopupillary vessels are common.
What is persistent hyperplastic primary vitreous?
Persistent hyperplastic primary vitreous (PHPV) is a congenital developmental condition in which the primary vitreous — a vascular structure present in the developing eye during gestation — fails to regress normally after birth. Remnants of this structure persist and can form fibrovascular tissue on the posterior lens capsule and in the space behind the lens, causing a range of lens and vitreous abnormalities.
The condition is bilateral in most affected dogs, though the severity may differ between the two eyes. The clinical appearance is variable — from minor pigment deposits on the posterior lens capsule in the mildest cases, to dense fibrovascular plaques, cataract, lens coloboma, intraocular haemorrhage, and severe visual impairment in the most severe cases.
Grading in the Dobermann
In the Dobermann, PHPV is graded on a scale of 1 to 6 using the system described by Stades:
Grade 1 is the mildest manifestation, consisting of capsular and retrolensal pigment dots with a minor posterior capsular cataract. Grade 1 is not considered an affected result under the BVA scheme.
Grade 2 involves a more intense central posterior capsular cataract with yellow-brown fibrous tissue on the posterior capsule and multiple pigment dots. Persistent pupillary membrane remnants may also be present.
Grade 3 involves visible hyaloid system vessels behind the lens, associated with Grade 2 abnormalities.
Grade 4 involves posterior lenticonus with associated Grade 2 changes.
Grade 5 is a combination of Grade 3 and Grade 4 abnormalities.
Grade 6 is the most severe form, combining features of other grades with additional abnormalities such as lens coloboma, microphakia, microphthalmos, and intraocular haemorrhage.
Presentation in the Staffordshire Bull Terrier
In the Staffordshire Bull Terrier, PHPV typically presents as a fibrovascular pigmented plaque on the posterior lens capsule, often bilateral. Associated findings include posterior lenticonus, lens colobomata, intralenticular haemorrhage, secondary cataracts, and persistent capsulopupillary and hyaloid vessels. Unlike the Dobermann, the posterior lens capsule itself is often normal, and secondary cataracts are less frequent, though retinal folds and rosettes are more widespread.
As in the Dobermann, Grade 1 is not considered an affected result under the scheme in the Staffordshire Bull Terrier.
Breeds affected
PHPV is certified under the BVA scheme in the Dobermann and the Staffordshire Bull Terrier.
What the examination involves
The examination requires pupil dilation to allow thorough assessment of the posterior lens capsule and retrolental space by slit-lamp biomicroscopy. Both eyes must be examined. The examination is performed as part of the routine BVA eye examination at the standard fee.