VN May 2022

Vetnews | Mei 2022 35 The following procedures are performed during data collection: a) Schirmer Tear Test – measures the aqueous component of the precorneal tear film (13) b)Tonometry – estimates intraocular pressure (IOP) (13) (14) c) Keratometry – measures corneal curvature (refraction) (15) d)Slit Lamp Biomicroscopy – allows detailed examination of globe and adnexa (13) e) Fluorescein Dye Test – excellent tool to identify corneal ulceration (13) f) Ocular Ultrasonography and Biometry – measurement of intraocular structures (13)(16) Figure 2 illustrates the typical ultrasound image obtained with a13MHz linear ultrasound probe. Several animals examined had small thorns in their corneas. Incredibly, virtually no inflammation of the cornea was observed in these animals, and focal cataracts were associated with thorns that penetrated the lens. Very little lenticular and posterior segment pathology has been observed thus far. The desperate plight these animals are facing is heart-breaking. I feel that any information that may improve our management of them, hopefully, ensure their survival, is critical to obtain. v REFERENCES 1. Radcliffe RW, Morkel P vdB. Rhinoceroses. In: Zoo Animal and Wildlife Immobilization and Anesthesia. 2014. p. 731–71. 2. Kipling R. Just so stories. 2016. 3. IUCN. Diceros bicornis: Emslie, R.: The IUCN Red List of Threatened Species 2020: e.T6557A152728945 [Internet]. International Union for Conservation of Nature; 2020 [cited 2021 Feb 9]. Available from: https://www.iucnredlist.org/species/6557/152728945 4. IUCN. Ceratotherium simum: Emslie, R.: The IUCN Red List of Threatened Species 2020: e.T4185A45813880 [Internet]. International Union for Conservation of Nature; 2020 [cited 2021 Feb 9]. Available from: https://www.iucnredlist.org/species/4185/45813880 5. Howland HC, Rowland M, Murphy CJ. Refractive state of the rhinoceros. Vision Res. 1993 Dec;33(18):2649–51. 6. Pettigrew JD, Manger PR. Retinal ganglion cell density of the black rhinoceros ( Diceros bicornis ): Calculating visual resolution. Vis Neurosci. 2008 Mar;25(2):215–20. 7. Coimbra JP, Manger PR. Retinal ganglion cell topography and spatial resolving power in the white rhinoceros ( Ceratotherium simum ): Vision in the white rhinoceros. J Comp Neurol. 2017 Aug 1;525(11):2484–98. 8. Horowitz IH, Dubielzig RR, Botero-Anug AM, Lucio-Forster A, Bowman DD, Rosenzweig AB, et al. Conjunctival habronemiasis in a square-lipped rhinoceros ( Ceratotherium simum ). Vet Ophthalmol. 2016 Mar;19(2):161– 6. 9. Esson DW, Wellehan JFX, Lafortune M, Valverde A, Citino SB. Surgical management of a malacic corneal ulcer in a greater one-horned Asian rhinoceros (Rhinoceros unicornis) using a free island tarsoconjunctival graft. Vet Ophthalmol. 2006 Jan;9(1):65–9. 10. Gandolf AR, Willis MA, Blumer ES, Atkinson MW. Melting corneal ulcer management in a greater one-horned rhinoceros (Rhinoceros unicornis). J ZooWildl Med. 2000 Mar;31(1):112–7. 11. Prole J. Removal of a Prolapsed Eyeball in aWild Black Rhinoceros. Vet Rec. 1965 Feb 6;77(6):156–7. 12. Kretzschmar P, RS, Schaffer N. Eyedisorders in captive Sumatran rhinoceros (Dicerorhinus sumatrensis harrissoni) in Sabah, Malaysia. 2009. 13. Featherstone HJ, Heinrich CL. The Eye Examination and Diagnostic Procedures. In: Veterinary Ophthalmology. Fifth. Wiley; 2013. p. 533–613. 14. Ofri R, Raz D, Shvartsman E, Horowitz IH, Kass PH. Intraocular pressure and tear production in five herbivorous wildlife species. Vet Rec. 2002 Aug;151(9):265–8. 15. Ramakrishnan R, Naik A. Comparison of Manual Keratometer with Autokeratometer. Biosci Biotechnol Res Asia. 2014 Apr 30;11(1):339–41. 16. Dietrich UM. Diagnostic Ultrasonography. In: Veterinary Ophthalmology. Fifth. Wiley; 2013. p. 669–83. Regulars I Ophthalmology Column Figure 2 Ultrasound image obtained during data collection: 1)Axial globe length 2)Anterior chamber depth 3)Axial lens thickness 4)Posterior segment depth