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Evaluation of intraocular pressure in conscious Hermann's tortoises (Testudo hermanni) by means of rebound tonometry

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  • 1 Clinica per Animali Esotici, Centro Veterinario Specialistico, Via Sandro Giovannini 53,00137 Rome, Italy.
  • | 2 Clinica per Animali Esotici, Centro Veterinario Specialistico, Via Sandro Giovannini 53,00137 Rome, Italy.
  • | 3 Department of Ophthalmology, Centro Veterinario Specialistico, Via Sandro Giovannini 53,00137 Rome, Italy.
  • | 4 Department of Ophthalmology, Centro Veterinario Specialistico, Via Sandro Giovannini 53,00137 Rome, Italy.
  • | 5 Department of Ophthalmology, Centro Veterinario Specialistico, Via Sandro Giovannini 53,00137 Rome, Italy.

Abstract

Objective—To determine intraocular pressure (IOP) in healthy Hermann's tortoises (Testudo hermanni).

Animals—26 outdoor-housed Hermann's tortoises (13 males and 13 females); body weight ranged from 255 to 2,310 g, and age ranged from 4 to > 50 years.

Procedures—After a preliminary ophthalmic evaluation was performed, IOP was measured by means of a rebound tonometer in both eyes of each tortoise. Three measurements were obtained for each eye; successive measurements were obtained from alternate eyes. Each measurement was based on the mean of 6 values automatically provided by the rebound tonometer. Statistical analysis was used to evaluate correlations between variables and to identify sex- or size-related IOP variations, and changes in IOP over multiple measurements.

Results—Mean ± SEM IOP of the 52 eyes was 15.74 ± 0.20 mm Hg (range, 9 to 22 mm Hg). Results for t tests did not reveal significant differences in IOP between the right and left eyes or between males and females. A significant moderate negative correlation (r = −0.41; r2 = 0.169) between IOP and body weight was detected. Results of repeated-measures ANOVA revealed a significant increase in IOP over multiple measurements.

Conclusions and Clinical Relevance—Rebound tonometry was a practical and rapid means of determining IOP in small- to medium-sized tortoises that required minimal manual restraint of the animals. Establishing IOP values in healthy Hermann's tortoises will provide a reference frame for use during complete ophthalmic examinations, thus allowing clinicians to diagnose a broader spectrum of ocular pathological conditions in tortoises.

Abstract

Objective—To determine intraocular pressure (IOP) in healthy Hermann's tortoises (Testudo hermanni).

Animals—26 outdoor-housed Hermann's tortoises (13 males and 13 females); body weight ranged from 255 to 2,310 g, and age ranged from 4 to > 50 years.

Procedures—After a preliminary ophthalmic evaluation was performed, IOP was measured by means of a rebound tonometer in both eyes of each tortoise. Three measurements were obtained for each eye; successive measurements were obtained from alternate eyes. Each measurement was based on the mean of 6 values automatically provided by the rebound tonometer. Statistical analysis was used to evaluate correlations between variables and to identify sex- or size-related IOP variations, and changes in IOP over multiple measurements.

Results—Mean ± SEM IOP of the 52 eyes was 15.74 ± 0.20 mm Hg (range, 9 to 22 mm Hg). Results for t tests did not reveal significant differences in IOP between the right and left eyes or between males and females. A significant moderate negative correlation (r = −0.41; r2 = 0.169) between IOP and body weight was detected. Results of repeated-measures ANOVA revealed a significant increase in IOP over multiple measurements.

Conclusions and Clinical Relevance—Rebound tonometry was a practical and rapid means of determining IOP in small- to medium-sized tortoises that required minimal manual restraint of the animals. Establishing IOP values in healthy Hermann's tortoises will provide a reference frame for use during complete ophthalmic examinations, thus allowing clinicians to diagnose a broader spectrum of ocular pathological conditions in tortoises.

Contributor Notes

Presented in abstract form at the International Conference on Reptilian and Amphibian Medicine, Cremona, Italy, May 2012.

The authors thank Dr. Danilo De Pasquale for assistance with the video recordings.

Address correspondence to Dr. Di Girolamo (nicoladiggi@gmail.com).