- Typically arise from the anterior surface of the iris in the region of the collarette and insert in a variety of locations including the anterior lens capsule and corneal endothelium.
- Cause : congenital failure of normal atrophy of embryonic vasculature of developing lens (tunica vasculosa lentis).
- Inherited in Basenji.
- Signs : usually no clinical problems may be associated with corneal opacities or cataract. Non-progressive.
- Diagnosis : distinguish from post-inflammatory synechiae.
- Treatment : usually none required.
- Prognosis : usually excellent.
At the severe end of the spectrum of anterior segment dysgenesis is Peters' Anomaly where the cornea and the lens fail to separate but this very rare in the dog and persistent pupillary membrane at the mild end of the spectrum is much more commonly seen.
- Pigment flecks visible on lens capsule.
- Very severe cases may suffer visual impairment.
- Synechiae - post-inflammatory adhesions generally arise from pupillary margin.
- Excellent: unless other abnormalities, eg microphthalmos, or extensive lens or corneal opacities.