Repeatability, reproducibility, and agreement of three tonometers for measuring intraocular pressure in rabbits (original) (raw)
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Validation of the Icare® TONOVET plus rebound tonometer in normal rabbit eyes
Experimental Eye Research, 2019
To determine the accuracy and precision of the Icare® TONOVET Plus rebound tonometer for measuring intraocular pressure (IOP) in normal rabbit eyes, as well as compare it to three other commercially available tonometers: the Icare® TONOVET (TV01), Tono-Pen Vet™, and Tono-Pen AVIA Vet™. The anterior chambers of both eyes of three New Zealand White rabbits were cannulated, post-mortem. IOP was measured using each of the above four tonometers at manometric pressures ranging between 5 mmHg and 70 mmHg. Data were analyzed by linear regression, ANOVA, and Bland-Altman plots. A p-value of ≤ 0.05 was considered significant for all statistical tests. IOP values obtained with the TONOVET Plus (in 'lapine' mode) were significantly closer to manometric IOP than those obtained with the other tonometers tested. The TV01 (in 'd' dog setting) and Tono-Pen AVIA Vet™ were significantly more accurate compared to the Tono-Pen Vet™. All tonometers had high levels of precision, though the TONOVET Plus and TV01 were significantly more precise compared to the Tono-Pen AVIA Vet™. All tonometers tended to underestimate IOP, particularly at high pressures, however the TONOVET Plus was highly correlated with manometric IOP in the clinically relevant range of 5-50 mmHg. The TONOVET Plus is an appropriate choice of instrument for measuring IOP in rabbit eyes in both research and clinical settings.
Veterinary World, 2024
Background and Aim: Reference ranges for intraocular pressure (IOP) in healthy animals are device-specific; therefore, it is strongly recommended to use appropriate reference values according to the device. Therefore, our aim was to compare IOP readings made by TonoVet® and TonoVet Plus® in healthy dogs, cats, sheep, cattle, and horses. We compared IOP values measured by TonoVet® and TonoVet Plus® tonometers in clinically normal eyes of dogs, cats, horses, cattle, and sheep. Materials and Methods: Five groups comprising 20 animals each of dogs (various breeds, 9 months–10 years old, 14 females, 6 males), cats (various breeds, 6 months–12 years old, 8 females, 12 males), horses (various breeds, 5–12 years old, 12 females, 8 males), cattle (Holstein, 1–7 lactation, female), and sheep (Latvian Darkhead ewes, 1–8 years old) were included in the study. Both eyes of all animals were subjected to ophthalmic examination, including evaluation of IOP by rebound tonometry using TonoVet® and TonoVet Plus® devices. Normality was determined using the Shapiro–Wilk test. The independent t-test was used to determine differences between IOP values in the right and left eyes and between both tonometers. This study was approved by the Ethical Commission of the Latvia University of Life Sciences and Technologies (Nr. LLU_Dzaep_2022-2-4). Results: No differences in IOP between the right and left eyes were found in all cases (p > 0.05). The mean IOP ± standard deviation values in both eyes for TonoVet® and TonoVet Plus® tonometers were as follows: for dogs, 15.25 ± 2.73 mmHg and 19.65 ± 3.46 mmHg; and in cats, 18.88 ± 3.98 mmHg and 18.78 ± 4.26 mmHg, respectively. In horses, mean IOP was 22.15 ± 3.74 mmHg and 24.28 ± 3.00 mmHg; in cattle, 24.73 ± 2.89 mmHg and 23.28 ± 2.97 mmHg; and in sheep, 18.05 ± 3.54 mmHg and 22.49 ± 4.66 mmHg, respectively. Significant differences in IOP values were observed between the tonometers in sheep, dog, and horse groups (mean difference –4.40, –4.48, and 2.13, respectively). Conclusion: This study showed significantly higher IOP values measured by the TonoVet Plus® tonometer in dogs and sheep. Keywords: cats, cattle, dogs, horses, sheep, TonoVet plus, TonoVet.
Veterinary World, 2021
Background and Aim: Tonometers are an important instrument for measuring intraocular pressure (IOP) in the diagnosis of glaucoma or uveitis. This study aimed to compare the accuracy of the main types of tonometers with different IOP measurement methodologies in dogs: TonoVet and TonoVet Plus (rebound), Tono-Pen Avia Vet (applanation), and Kowa HA-2 (Goldmann applanation). Materials and Methods: IOP was measured in 152 eyes of 76 dogs. A postmortem study was performed by comparing manometry and tonometry values and calculating the correlation coefficient (r2), in vivo real IOP (manometry) among the tonometers was compared, and an outpatient study was conducted with healthy eyes and eyes with signs of glaucoma and uveitis. Results: In the postmortem study, the values of r2 in descending order were Kowa (0.989), TonoVet Plus (0.984), TonoVet (0.981), and Tono-Pen Avia Vet (0.847). The IOP values in mmHg in the in vivo study were as follows: Aneroid manometer (16.8±2.5.7), TonoVet (18.1±2.9), TonoVet Plus (20.6±2.3), Tono-Pen Avia Vet (17.1±2.5), and Kowa (16.1±1.7); in outpatient clinics: TonoVet (16.8±3.8), TonoVet Plus (19.2±2.9), Tono-Pen Avia Vet (16.2±2.4), and Kowa (15.0±1.3); glaucoma: TonoVet (30.2±3.5), TonoVet Plus (35.0±6.1), Tono-Pen Avia Vet (29.5±4.2), and Kowa (23.9±5.0); and uveitis: TonoVet (14.2±1.4), TonoVet Plus (17.6±1.9), Tono-Pen Avia Vet (13.7±2.1), and Kowa (12.6±1.7). Conclusion: There was a strong correlation between IOP values and manometry in all the tonometers. The highest values were obtained with TonoVet Plus and the lowest with Kowa HA-2. All tonometers accurately measured IOP in dogs, including the latest TonoVet Plus, which showed an excellent correlation coefficient.
Journal of Exotic Pet Medicine, 2018
Fifty-two guinea pigs (Cavia porcellus) with normal ophthalmic examination were included in this study to determine whether there are differences in the intraocular pressure (IOP) according to age, while assessing the clinical usefulness of two different tonometry methods for this species. The animals were divided into 2 groups according to age: young (4 weeks-old, 29 animals) and adult (3-36 months, 23 animals). Tonometry was performed oculus utro (OU) in the central cornea according to the manufacturer's recommendations. Only measurements with low standard deviation (SD<5%) were included. Rebound tonometry was performed first OU; following topical anesthesia, applanation tonometry was then performed OU. The time required to obtain an IOP value was recorded for each eye. Descriptive statistics were calculated and Lin Concordance Coefficient (LCC) was performed to describe concordance between methods. Mean TonoVet ® IOP readings were 8.53±1.28 mmHg and 13.20±1.28 mmHg for young and adults, respectively (p<0.05). Tono-Pen VET ® readings could not be obtained in young animals, but yielded a mean of 10.93±3.61 mmHg in adults. No differences were found between left and right eyes (p>0.05) nor between genders (p>0.05). TonoVet ® readings were obtained faster than Tono-Pen VET ® readings (less than 1 min vs 3.38±1.27 min, respectively (p<0.05)). Lin Concordance Coefficient between methods was 0.37 (95% CI 0.19; 0.53), documenting a poor concordance between the two methods. The study states that normal IOP values are lower in young than in adult guinea pigs. Moreover, the results obtained from this investigation demonstrated that TonoVet ® tonometry is a rapid and well-tolerated procedure when performed on guinea pigs of any age, whereas Tono-Pen VET ® tonometry is a more timeconsuming technique that can only be used on guinea pigs older than 3 months.
The Induction/Impact Tonometer: a New Instrument to Measure Intraocular Pressure in the Rat
Experimental Eye Research, 2001
Non-invasive intraocular pressure (IOP) measurement in rats can be performed with a variety of methods, none of which seems appropriate for scaling down for the mouse eye. In an attempt to develop such a method for non-invasive IOP measurement in mice, an alternative concept, that of rebound tonometry, was explored using an induction/impact (I/I) tonometer probe. IOP measurement using the rebound concept is based on bouncing a probe onto the eye and detecting its motion. Motion parameters of the probe, which vary according to eye pressure, are used to calculate the IOP. As a first step towards this goal a prototype I/I tonometer was evaluated for IOP measurement of the rat eye. Two similar instruments were constructed and tested for their ability to measure accurately and reliably rat IOP by comparing the measurements against the manometric (true) IOP as determined by cannulation ex vivo. Good correlation between the true IOP and the I/I measurements (R(2) = 0.95) was detected for IOP between 7.4 and 56 mmHg. Although individual eyes tested showed some variability in the relationship of the measured IOP with the true IOP, this variability was minimal. Starting probe-cornea distance between 3 and 5 mm, and angle of impact up to 25 degrees relative to the visual axis at the corneal apex, did not affect the reproducibility of the I/I tonometer. Comparison of I/I tonometer measurements to direct manometric determination of IOP by in vivo cannulation of eyes in anesthetized normal female Wistar rats correlated reasonably well (R(2) = 0.67) with manometrically determined IOP within the narrow range of normal rat IOPs (10-16.5 mmHg), underestimating the true (manometric) IOP by an average of 11.6%. The I/I tonometer is a reliable and accurate instrument for non-invasive IOP measurement in rat eyes that can potentially be adapted for IOP measurement in mice.
Ciência Rural, 2013
The objective of this study was to compare the accuracy between two applanation tonometers, Tono-Pen XL® and Perkins®, in horses and cattle. The eyes of 20 horses and 20 cattle conscious and healthy were evaluated for the in vivo study and both eyes of 5 horses and 5 cattle were used as controls for the postmortem study. In conscious animals, the tonometry was performed with auriculopalpebral nerve block and then topical anesthesia for both tonometers and 1% fluorescein eye drops only for the Perkins tonometer. Readings of intraocular pressure (IOP) in the postmortem study were taken using manometry and tonometry by Tono-Pen XL® and Perkins®. The correlation coefficient (r²) between manometry and applanation tonometers Tono-Pen XL® and Perkins®, in horses, were 0.845 and 0.989, respectively, and in cattle, were 0.772 and 0.988, respectively. The mean IOP values in conscious horses with Tono-Pen XL® and Perkins® were 20.1±3.9mmHg and 20.9±3.2mmHg, respectively, and in conscious cattl...
Semina-ciencias Agrarias, 2017
The objective of this study was to evaluate the use of the Kowa HA-2 applanation tonometer in measuring intraocular pressure (IOP) in cats. Ten healthy eyes were used in an ex vivo study in which the calibration curve for manometry vs. tonometry was determined by artificially raising the IOP in 5 mmHg increments up to 60 mmHg (10-60 mmHg). Both eyes of 10 anesthetized cats were studiedin vivo to compare manometry vs. tonometry. In the ambulatory study, 78 healthy eyes, 7 eyes with glaucoma and 20 eyes with uveitis were evaluated by tonometry, which was performed with topical anesthesia and 1% fluorescein eye drops for the formation of fluorescein semicircles. The correlation coefficient (r²) between the manometer and the Kowa HA-2 tonometer was 0.993 and the linear regression equation was y = 0.0915x + 0.0878 in the ex-vivo study. In the in vivo study, the IOP values (mean±SD, in mmHg) in manometry were 15.6 ± 1.1(14.0-17.5) and in tonometry were 15.5 ± 1.2(13.5-17.2), with no significant difference (P > 0.05) between manometry and tonometry. In ambulatory study, using the Kowa HA-2 tonometer, the IOP values (mean±SD, in mmHg) were 15.0 ± 1.5 (11.8-18.3) for the healthy eyes, 38.4 ± 8.1(29.6-53.7) for glaucomatous eyes and 10.4 ± 2.0(5.3-12.2) for eyes with uveitis. There was a strong correlation and accuracy between the IOP values with the manometry and the Kowa HA-2 tonometer. In the ambulatorystudy the IOP values obtained with the tonometer were compatible for animals with healthy eyes and with clinical signs of glaucoma and uveitis. We conclude that the Kowa HA-2 tonometer can be used in the measurement of IOP in cats, since it is a practical and accurate method in this species.
Comparison of three methodologies for measuring intraocular pressure in healthy cats
Veterinary World, 2024
Background and Aim: Measuring intraocular pressure (IOP) is crucial for identifying potentially damaging changes in the eyes, including diseases as glaucoma and uveitis. This study compared intraocular pressure (IOP) measurements in cats using the Tonovet and Tonovet Plus (rebound), Tono-Pen Avia Vet (applanation), and Kowa HA-2 (Goldman’s methodology applanation) tonometers. Materials and Methods: 55 healthy cats (108 eyes) were assessed through three distinct studies: An ex vivo experiment (10 eyes of five cats) to correlate IOP manometry and tonometry values and ascertain the correlation coefficient (r2); an in vivo study (10 eyes of five sedated cats) to contrast manometer and tonometer readings; and an outpatient clinical trial (80 eyes of 45 cats) to analyze only tonometer measurements. Results: The r2 values observed in the ex vivo study were Tonovet (0.923), Tonovet Plus (0.925), Tono-Pen Avia Vet (0.877), and Kowa HA-2 (0.901). The IOP values in mmHg in the in vivo study were as follows: Manometer (16.1 ± 2.7), Tonovet (21.1 ± 3.6), Tonovet Plus (19.7 ± 7.2), Tono-Pen Avia Vet (17.6 ± 7.9), and Kowa HA-2 (16.8 ± 2.0). In the outpatient clinical study, the IOP values in mmHg were as follows: Tonovet (19.7 ± 6.6), Tonovet Plus (17.1 ± 5.4), Tono-Pen Avia Vet (16.3 ± 4.3), and Kowa HA-2 (14.5 ± 2.2). Conclusion: IOP and manometry readings were strongly correlated by all tonometers. In the clinical setting, the most and least IOP measurements were recorded using Tonovet and Kowa HA-2, respectively, stressing the importance of an IOP reference table for each tonometer in feline practice. Keywords: applanation tonometry, goldmann tonometry, intraocular pressure, ocular manometry, rebound tonometry.
Evaluation of Changes in Intraocular Pressure with a Noncontact Tonometer in Healthy Volunteers
Clinical Ophthalmology, 2020
We investigated whether or not intrasession or intersession fluctuations in intraocular pressure occur in healthy people using a noncontact tonometer. Materials and Methods: A noncontact tonometer was used to measure intraocular pressure in the bilateral eyes of healthy subjects for 5 consecutive days. Paired t-tests and one-and two-way repeated-measures analyses of variance were performed for the acquired data. A p-value <0.05 was considered to indicate statistical significance. Results: Eighty eyes of 40 healthy subjects were enrolled in the study. On day 1, intraocular pressure was significantly higher in the right eye than in the left eye (P = 0.014). The oneway repeated-measures analysis of variance revealed that intraocular pressure in the left eye was significantly lower on day 1 than on days 2 to 5 (P = 0.000-0.018); however, there were no significant differences among intraocular pressures measured on days 1 to 5 in the right eye. The two-way repeated-measures analysis of variance revealed no significant difference in intraocular pressure between the right and left eyes (P = 0.913). Conclusion: Although measurements using the noncontact tonometer were relatively stable, intraocular pressure was high on day 1.