Microphakia associated with lens luxation in the cat

Abstract

Congenital defects of the lens are rare in the cat. In this report, two unrelated Siamese kittens, a four-month-old male and a six-month-old female, with microphakia are presented. Abnormally small lenses were associated with elongation and rupture of the ciliary processes, leading to lens subluxations and subsequent anterior luxations. To the authors' knowledge, this condition has been reported only once previously.

Macrophakia in three cats

“…lens capsule thickness, size of the lens, changes of the lens fibers) was not obtained. This is similar to the already described cases of lens anomalies that were diagnosed by ophthalmic examination only, 1–3 with the exception of the case of keratolenticular dysgenesis 4 . This diagnosis was confirmed by histopathologic examination.…”

“…Congenital lens anomalies are uncommon in cats. Aphakia, 1 microphakia, 2,3 keratolenticular dysgenesis, 4 and congenital cataracts 5 have already been described. Macrophakia, an oversized lens, has not been reported previously in animals.…”

Primary lens instability in ten related cats: clinical and genetic considerations

“…Four cases of unrelated congenital bilateral lens dislocations associated with microphakia have been described in three Siamese cats and one domestic shorthair kitten. When dislocations were incomplete, elongated ciliary processes were found to be directly inserted all around the equator of the microphakic lenses (Aguirre and Bistner 1973, Molleda and others 1995). In canines, a case of congenital lens luxation associated with microphakia in a Brittany spaniel puppy revealed a lack of zonular fragments attached to the equator on scanning electron microscopy, suggesting a congenital aplasia of zonular fibres (Martin 1978).…”

“…An apparently primary zonular degeneration occurred in aged animals, but was infrequent (Olivero and others 1991). Microphakia with elongated ciliary processes and subsequent anterior lens luxation has been described in three unrelated Siamese cats and in a domestic shorthair cat (Aguirre and Bistner 1973, Molleda and others 1995). Barnett (1988) also reported two cases of lens dislocation in young Burmese cats, accompanied in one case by ciliary body abnormalities.…”

Feline glaucoma—a comprehensive review

“…McLellan, manuscript in process). It would appear from sporadic reports in the veterinary literature of glaucoma occurring secondary to uveitis, 37 and of primary microphakia with lens luxation, 23,38,39 in Siamese cats, that this disease may actually have existed in the Siamese cat breed in the USA and Europe for more than 50 years.…”