A Comparative Study of Rebound Tonometry With Tonopen and Goldmann Applanation Tonometry Following Vitreoretinal Surgery

Comparison of intraocular pressure measured by iCare tonometers and Goldmann applanation tonometer

OBJECTIVE

To evaluate the relationship between the Goldmann applanation tonometer (GAT) and the iCare PRO and iCare IC200 tonometers in measuring intraocular pressure (IOP) in adult eyes with a diagnosis of glaucoma or glaucoma suspect.

PARTICIPANTS AND METHODS

One hundred and one eyes from 101 participants diagnosed with glaucoma or glaucoma suspect were evaluated in this study. IOP was measured by iCare PRO and iCare IC200 tonometers in a randomized sequence followed by IOP measurements by the GAT tonometer and then central corneal thickness measurements. After the IOP measurements, participants scored their comfort level using a visual analog scale with each tonometer. Intraclass correlation coefficient (ICC) and Bland-Altman analysis were used to investigate the agreement among tonometers. SPSS and Microsoft Excel programs were used for statistical analysis.

RESULTS

Overall, there was good agreement among the 3 tonometers used in this study. The ICC for the iCare PRO and the iCare IC200 was 0.95 (p < 0.001), and the ICC for the iCare PRO and the GAT and the iCare IC200 and the GAT was >0.80 (p < 0.001). However, both iCare tonometers underestimated IOP by approximately 2 mm Hg compared with the GAT. Furthermore, 84% of iCare readings fall within ±5 mm Hg of GAT measurements. Neither body mass index nor central corneal thickness affected the IOP agreement among the tonometers. Participant response on visual analog scale rated IOP measurements by iCare tonometers to be more comfortable than the GAT.

CONCLUSION

Our results demonstrated a good agreement between iCare tonometers and GAT; but iCare tonometers underestimated IOP compared to the GAT.

Comparison among TonoVet, TonoVet Plus, Tono-Pen Avia Vet, and Kowa HA-2 portable tonometers for measuring intraocular pressure in dogs

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.

Effect of four local anesthetics (tetracaine, proparacaine, lidocaine, and bupivacaine) on intraocular pressure in dogs

PURPOSE

To measure IOP in animals, it is often necessary to use topical anesthetics. The use of these drugs may cause changes in IOP and interfere with the final results. To address this issue, the effects of four local anesthetics (tetracaine, proparacaine, lidocaine, and bupivacaine) on IOP were investigated in ten adult dogs.

METHODS

One drop of tetracaine was instilled in the right eye of half of the dogs and in the left eye of the other dogs; normal saline was instilled in the fellow eyes. The IOP in each dog was measured before and at 0, 5, 10, 15, 20, 25, 30, and 35 min after drug instillation using an electronic rebound tonometer. The effects of the other anesthetics were studied in the same way at intervals of at least 1 week.

RESULTS

After instillation of tetracaine, the IOP decreased gradually, such that after 15 min, the IOP was significantly lower than the baseline (p = 0.022) and control values (p = 0.048). Proparacaine also reduced IOP after 10 min compared to baseline values (p = 0.046), but the two other drugs, bupivacaine and lidocaine, had no significant effect on IOP. The duration of eye anesthesia was 16, 20, 22, and 34 min for tetracaine, lidocaine, bupivacaine, and proparacaine, respectively.

CONCLUSION

We recommend using drugs that combine inducing longer anesthesia with producing the smallest change in IOP, such as bupivacaine and, subsequently, lidocaine. Tetracaine and proparacaine have a significant effect on IOP, and if these drugs are used, this effect should be considered.