Use of Rebound Tonometry as a Diagnostic Tool to Diagnose Glaucoma in the Captive California Sea Lion
IAAAM 2009
Johanna C. Mejia1,2; Elizabeth M. Hoffman3; Carmen M.H. Colitz4,5; Skip W. Jack1; Lora Ballweber6; Maya Rodriguez2; Michael S. Renner2; Todd Schmitt7; Leslie M. Dalton8; Steve Osborn8; Scott A. Gearhart9; Lara A. Croft9; Christopher Dold9; Allison D. Tuttle10; Tracy A. Romano10; Connie L. Clemons-Chevis11
1Mississippi State University College of Veterinary Medicine, Mississippi State, MS, USA; 2Miami Seaquarium, Miami, FL, USA; 3CPT, Veterinary Corps, US Army, U.S. Navy Marine Mammal Program, SPAWAR Systems Center, San Diego, CA, USA; 4Aquatic Animal Eye Care, Jupiter, FL, USA; 5Animal Eye Specialty Clinic, West Palm Beach, FL, USA; 6Colorado State University College of Veterinary Medicine, Fort Collins, CO, USA; 7Seaworld California, San Diego, CA, USA; 8Seaworld Texas, San Antonio, TX, USA; 9Seaworld Florida, Orlando, FL, USA; 10Mystic Aquarium and Institute for Exploration, Mystic, CT, USA; 11Institute for Marine Mammal Studies, Gulfport, MS, USA

Abstract

Purpose

One of the most common medical problems seen in the California sea lion (Zalophus californianus) is ocular disease. Glaucoma is a disease that has not been evaluated extensively in the sea lion. Observing clinical signs and measuring intraocular pressures (IOP) is critical for early diagnosis. The objective of this project is to measure IOP in clinically normal captive sea lions without ocular pathology to establish a normal range.

Methods

The TonoVet® (Webster Veterinary) was selected to be used in the study. The TonoVet® uses a new non-invasive, rebound method to estimate IOP. An electrical magnetic tonometer probe comes into contact with and rebounds from the corneal surface to estimate an IOP. In order to record an accurate IOP, six measurements were taken and averaged resulting with the mean value. A complete ophthalmic examination has been performed on all sea lions by a veterinary ophthalmologist.

Results

Currently, there are twenty sea lions in the study with no clinical ocular pathology. Overall mean in 39 healthy eyes was 32.8 mmHg with a SD +/- 3.2 at a 95% CI of 26.4 to 39.1.

Conclusion

We have established a normal baseline range for IOP values in captive sea lions without ocular pathology. This range is higher than the generally accepted range using other tonometers (e.g., Tono-Pen Vet®). This is likely due to the increased thickness of the pinniped cornea as well as the different mechanism of the instrument itself. This range will provide a comparative measurement when evaluating a diseased eye. By measuring the IOP regularly in juvenile sea lions, veterinarians will be able to determine when IOP's begin to change so that medical management can be started prior to loss of vision.

Acknowledgements

The authors would like to give a special thank you to Mississippi State University College of Veterinary Medicine for the instrumentation and initial funding of this Masters study and the Institute for Marine Mammal Studies of Gulfport for providing the startup venue and guidance for the project. Additional thanks to Webster Veterinary for helping to provide the tonometer probes. A note of appreciation is given to the members of my Masters committee: Dr. Skip Jack, Dr. Lora Ballweber and Dr. Carmen Colitz for their support and encouragement throughout this study. A special thanks to the trainers (Tim Hoffland, Marci Romagnoli, and Shannon Huyser) and Dr. Connie Chevis for having an open mind to train this behavior for the first time. This research would not be possible without the help and skills of all of the staff, doctors, trainers, and animals of the following places: in Florida (SeaWorld®, Miami Seaquarium®, Dolphin Research Center, Theater of the Sea, Dolphins Plus, and Gulf World Marine Park), in New York (New York Aquarium and Atlantis Marine World®), Institute for Marine Mammal Studies, Gulfport, MS, US Navy Marine Mammal Program, CA, SeaWorld®, San Antonio, SeaWorld®, CA, Six Flags® Great Adventure and Wild Safari, NJ, Six Flags® Discovery Kingdom, CA, Mystic Aquarium & Institute for Exploration, CT, MaritimeAquarium, CT, Audubon Zoo, Louisiana, New England Aquarium, MA, Atlantis,Paradise Island, BahamasTM, Dolphin Island, Dominican Republic, ZooMarine®, Italy, and Dolphin Discovery, Mexico.

References

1.  Colitz C.M.H, M. Renner, T. Schmitt, L. Dalton, S. Osborne, B. Chittick, T. Reidarson, S.J. Dugan, and J. McBain. 2006. Incidence of lens disease in captive pinnipeds. Vet Ophthalmol 9(6): 423.

2.  Gulland F.M.D., M. Haulena, and L. Dierauf. 2001. Seals and sea lions. In: L.A. Dierauf and F.M.D. Gulland (eds). CRC Handbook of Marine Mammal Medicine: Health, Disease, and Rehabilitation, 2nd ed., CRC Press Inc., Boca Raton, FL; Pp. 920-921.

3.  Knollinger A., C. Noelle, P. Barrett, and P. Miller. 2005. Evaluation of a rebound tonometer for measuring intraocular pressure in dogs and horses. J Am Vet Assoc 227: 244-47.

 

Speaker Information
(click the speaker's name to view other papers and abstracts submitted by this speaker)

Johanna C. Mejia
Miami Seaquarium
Miami, FL, USA


MAIN : Ophthalmology : Rebound Tonometry
Powered By VIN

Friendly Reminder to Our Colleagues: Use of VIN content is limited to personal reference by VIN members. No portion of any VIN content may be copied or distributed without the expressed written permission of VIN.

Clinicians are reminded that you are ultimately responsible for the care of your patients. Any content that concerns treatment of your cases should be deemed recommendations by colleagues for you to consider in your case management decisions. Dosages should be confirmed prior to dispensing medications unfamiliar to you. To better understand the origins and logic behind these policies, and to discuss them with your colleagues, click here.

Images posted by VIN community members and displayed via VIN should not be considered of diagnostic quality and the ultimate interpretation of the images lies with the attending clinician. Suggestions, discussions and interpretation related to posted images are only that -- suggestions and recommendations which may be based upon less than diagnostic quality information.

CONTACT US

777 W. Covell Blvd., Davis, CA 95616

vingram@vin.com

PHONE

  • Toll Free: 800-700-4636
  • From UK: 01-45-222-6154
  • From anywhere: (1)-530-756-4881
  • From Australia: 02-6145-2357
SAID=27