Bilateral Convergent Strabismus with Exophthalmus in a Cow

Bilateral convergent strabismus with exophthalmus (BCSE) is a heritable eye defect prevalent in many cattle breeds and known worldwide. The defect is of relatively high incidence, particularly in Holstein and German Brown cattle (Distl and Gerst, 2000; Holmes and Young, 1957 and Power, 1987). Reports of BCSE among cattle in India are lacking. The present paper reports a case of bilateral convergent strabismus and exophthalmus in a 3-year-old Jersey-Brown Swiss crossbred high yielding cow. The owner reported that the strabismus was present since birth, which gradually progressed to the present condition. The owner could not notice any problem with vision. The cow had a moderately disoriented and insecure gait and handling was difficult. Examination revealed bilateral, symmetric rotation of eyeballs in an anterio-medial direction with severe latero-dorsal exophthalmus and epiphora. The cow was able to move the eyelids over the cornea. Cornea was moist and normal in appearance. Menace and pupilary light responses were normal. The optic axis was clear and transparent, along with a good fundic reflection. The axial length, measured using A-Scan ultrasonography, was 32.83 mm for the left eye (OS) and 33 mm for the right eye (OD). The rotation of eye balls was approximately 70 degrees anterio-medial, which could be rotated to central by traction on the dorso-lateral bulbar conjunctiva. The visible sclera of both eyes had dark brown pigmentation. The vision for each eye was good, but the visual field of the animal was considerably reduced. No further investigations were done, due to poor compliance of the owner, but he was