Ophthalmic parameters in adult lowland paca (Cuniculus paca) raised in captivity Camila P. Balthazar da Silveira, Tiago B. Lima, Roberta M. Crivelaro, Luciana C. C. de Lacerda, Ivan R. M. P adua, Roberta Renzo, Alexandre A. F. de Barros Sobrinho, Fabr  ıcio S. Oliveira, Marcela Aldrovani and Jos e L. Laus Department of Veterinary Clinic and Surgery, College of Agricultural and Veterinarian Sciences, S~ ao Paulo State University, Jaboticabal, SP, Brazil Address communications to: J. L. Laus Tel.: +55 16 3209-2631-538 Fax: +55 16 3203-1226 e-mail: jllaus@fcav.unesp.br Abstract Objective To investigate the ophthalmic parameters of lowland pacas, including the anatomic features, tear production, intraocular pressure, central corneal thickness, and morphology of the corneal endothelium. Animals studied Thirteen adult, anesthetized Cuniculus paca. Procedure Eyes were evaluated using slit-lamp biomicroscopy, the Schirmer tear test I, digital applanation tonometry, binocular indirect ophthalmoscopy, and noncontact specular microscopy. Results The biomicroscopy findings showed blue/brown pigmented bulbar conjuncti- vae, well-developed cilia (only in the upper eyelid margin), superior and inferior lacri- mal puncta, brown irides, round pupils, and vestiges of the nictitating membrane. The results of the Schirmer tear test I revealed (mean Æ SD) a lacrimation rate of 4.10 Æ 0.44 mm/min. The intraocular pressure was 6.34 Æ 0.43 mmHg. Central cor- neal thickness measured by specular microscopy was 0.35 Æ 0.01 mm. The mean val- ues of density, hexagonality, and the area of the endothelial cells were 2083.15 Æ 42.47 cells/mm 2 , 67.07 Æ 3.30%, and 486.30 Æ 9.56 lm 2 , respectively. Conclusions The ocular parameters defined in this study may be used for reference in future studies and might also contribute to therapeutic approaches appropriate to this species. Key Words: eye, feral, lowland pacas, rodent, species conservation, wild animal INTRODUCTION Lowland pacas (Cuniculus paca) belong to the order Rodentia and family Cuniculidae. They are the second lar- gest rodents in Latin America and are only smaller than capybaras (Hydrochaeris hydrochaeris). 1 Individuals of this species exhibit aquatic and nocturnal habits and are largely found in Central and South America, including in all Brazilian territories. 2,3 Although they live in mangroves, forests near water streams, and deciduous and semi-decid- uous forests, tropical humid forests are the preferred habi- tats of lowland pacas. 4 They have a generalist diet based on fruits and seeds available in the environment. 5 Cuniculus paca has been employed as an experimental model in studies on the morphophysiology of the cardio- vascular 6 system and on the masculine and feminine uro- genital systems. 7,8 Several studies have been performed to understand the anatomical characteristics of lowland pacas by radiography of the teeth 9 and of the axial 10 and appen- dicular 11 skeleton. However, normal ophthalmic examina- tion and many ocular parameters have not yet been described in this species. Due to the lack of knowledge about ocular morphophysiological parameters of Cuniculus paca, treatment and diagnosis of ophthalmic affections in this species is based on normative data established for other species of rodents, such as the capybara, 12 black- tailed prairie dogs (Cynomys ludovicianus), 13 chinchillas (Chinchilla lanigera), 14,15 guinea pigs (Cavia porcellus), 16 and Syrian Hamsters (Mesocricetus auratus), 17 even though extrapolation between species is not always appropriate. The purpose of this study was to characterize an oph- thalmic examination and report normative data for certain ophthalmic parameters of C. paca. Data referring to tear production, anatomic features, intraocular pressure (IOP), and corneal endothelium were evaluated using the Schir- mer tear test (STT I), slit-lamp biomicroscopy, digital © 2017 American College of Veterinary Ophthalmologists Veterinary Ophthalmology (2017) 1–6 DOI:10.1111/vop.12476