Clinicopathologic Findings of Congenital Megalocornea in Three Blue-Throated Conures (Pyrrhura cruentata).

Congenital megalocornea should be considered differential for presumed glaucoma in birds.

This case series describes the first documented occurrence of congenital megalocornea in three genetically related juvenile blue-throated conures (Pyrrhura cruentata). All three birds presented with bilateral blindness and corneal enlargement as the predominant ocular feature. Comprehensive diagnostic evaluation included physical and ophthalmic examinations, ocular ultrasound biomicroscopy (UBM), and Micro-CT imaging. UBM revealed globoid cornea, enlarged anterior chamber, and anterior lens displacement in some cases. Initial misdiagnosis of congenital glaucoma with buphthalmos was made. Treatment included chemical cycloablation in the left eye for size reduction and enucleation in one bird due to severe corneal ulceration. Ocular histopathology confirmed megalocornea with secondary ulcerative keratitis, stromal attenuation, fibrosis, and discontinuous Descemet's membrane. Two birds were euthanized shortly after presentation due to systemic health concerns, while one survived 8 years before dying of suspected cardiac pathology. This report establishes megalocornea as an important differential diagnosis for avian buphthalmos and congenital ocular enlargement.

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