Effect of topical 0.5% tetracaine hydrochloride on intraocular pressure in ophthalmologically normal cats.

OBJECTIVES: The aim of this study was to assess the effect of topical tetracaine hydrochloride 0.5% on intraocular pressure (IOP) in ophthalmologically normal cats. METHODS: Twenty domestic shorthair cats (40 eyes) were used in this study. Each cat was randomly allocated to one of two groups (treatment or control). Baseline IOP (T0) was measured in each cat, and then one drop of tetracaine hydrochloride 0.5% or artificial tears was administered into a randomly chosen eye of each cat in the treatment and control groups, respectively. Repeat IOP measurements were performed at 2 mins (T2), 5 mins (T5), 15 mins (T15) and 30 mins (T30) with a rebound tonometer. RESULTS: Mean baseline IOP in all eyes was 20.6 ± 2.5 mmHg. After the unilateral administration of tetracaine, mean IOP decreased significantly in the treated eye at T2 (P = 0.01). Mean IOP returned to baseline values at T15. The mean IOPs in the treated eyes at T0, T2, T5, T15 and T30 were 20.6 ± 3.3 mmHg, 18.2 ± 2.5 mmHg, 18.2 ± 3.4 mmHg, 20.2 ± 3.2 mmHg and 19.8 ± 2.7 mmHg, respectively. A significant difference in IOP was found at all time points between the tetracaine and control groups (P <0.03). CONCLUSIONS AND RELEVANCE: The results of the present study showed a statistically significant reduction in mean IOP 2 mins after the administration of tetracaine hydrochloride 0.5% in the treated eyes of the cats.

Effects of 0.0015% preservative-free tafluprost on the equine eye.

OBJECTIVE: The purpose of this study was to determine the effects and potential side effects of topical preservative-free (PF) tafluprost 0.0015% in ophthalmologically normal horses. ANIMALS: Five adult grade horses. PROCEDURES: One of the eyes of each horse was randomly chosen as the "treatment" eye, and consequently, the contralateral eye served as the "control." A single dose of PF tafluprost 0.0015% (0.2 mL) was instilled in the treated eye of each horse. Intraocular pressure (IOP), Schirmer's tear test (STT) levels of each eye, and an ophthalmic examination were performed at T0 (baseline), T30, T120, T24 h, and T48 h. RESULTS: The mean IOP values of the treated eyes at baseline (T0), T30, T120, T24 h, and T48 h were 25.4 ± 4.8 mmHg, 21.2 ± 1.92 mmHg, 15.20 ± 2.48 mmHg, 18.40 ± 1.51 mmHg, and 24.60 ± 1.94 mmHg, respectively. Significant differences were observed between the mean baseline IOP level and the T120 and T24 h time points (p = .001 and p = .009). The mean STT levels at each time point showed insignificant fluctuations during the study (p = .140). Adverse effects such as chemosis and episcleral injection were observed 30 min after the instillation of tafluprost 0.0015% (T30). Blepharospasm and conjunctival hyperemia were observed 120 min (T120) after the administration of the medication. CONCLUSION AND CLINICAL RELEVANCE: Tafluprost 0.0015% showed potential in reducing IOP, but due to its local side effects, it is not a good candidate for management of glaucoma in horses. Tafluprost did not notably affect STT.

Intraocular Pressure Measurements Using Rebound Tonometry in Eight Different Species of Companion Birds.

The purpose of this study was to determine reference interval intraocular pressure (IOP) values in 8 different species of companion birds. One hundred and nineteen companion birds (238 eyes) from a captive colony were examined: 21 pigeons (Columba livia; 18%), 17 African grey parrots (Psittacus erithacus; 14%), 22 common mynahs (Acridotheres tristis; 18%), 24 cockatiels (Nymphicus hollandicus; 20%), 12 zebra finches (Taeniopygia guttata; 10%), 9 budgerigars (Melopsittacus undulatus; 8%), 6 domestic canaries (Serinus canaria domestica; 5%), and 8 ring-necked parakeets (Psittacula krameri; 7%). Intraocular pressure was measured by rebound tonometry (TonoVet) avoiding induced, undesired pressure on the head, neck, or eyes. Mean IOP values varied by species. Mean (± SD) IOP values determined for each species were pigeon (5.42 ± 2.06 mm Hg), African grey parrot (4.93 ± 1.91 mm Hg), common mynah (6.22 ± 2.04 mm Hg), cockatiel (5.08 ± 1.76 mm Hg), zebra finch (5.90 ± 2.11 mm Hg), budgerigar (5.88 ± 2.31mm Hg), canary (5.83 ± 1.60 mm Hg), and ring-necked parakeet (6.25 ± 1.75 mm Hg). No statistically significant differences were found in IOP values between right and left eyes for the species studied (P > .22), with the exception of the ring-necked parakeet (P = .001). The results of this study provide representative IOP values measured using rebound tonometry in 8 different species of companion birds.

Comparison of the Schirmer tear test I values after placement in ventral and dorsal conjunctival fornices in healthy cats.

OBJECTIVES: The objective of this study was to compare the Schirmer tear test I values obtained from placement of Schirmer tear test (STT) strips in ventral and dorsal conjunctival fornices and to investigate any correlation between age, body weight and STT values in clinically normal cats. METHODS: Twenty-eight intact adult domestic shorthair and Persian cats were used in this study. The cats were gently physically restrained in a sternal position, and a Schirmer tear strip was placed on each eye in the ventral conjunctival fornix at one-third of the distance from the temporal to nasal canthus for 60 s. Then, the wetted portion of the strips was measured as mm/min (L-STT I). After 48 h, the same procedure was performed on each eye in the dorsal conjunctival fornix (U-STT I). RESULTS: Mean ± SD STT values of the ventral and dorsal conjunctival fornices were 20.80 ± 2.25 mm/min (range 14-25 mm/min; 95% confidence interval [CI] 19.92-21.67) and 18.28 ± 2.27 mm/min (range 15-22 mm/min; 95% CI 17.39-19.16) in all of the study population, respectively. A significant difference was found between STT values obtained from the ventral and dorsal conjunctival fornices ( P <0.001). There was no correlation between the age and body weight of the animals and STT I values. CONCLUSIONS AND RELEVANCE: This study compared the STT I values of the dorsal and ventral conjunctival fornices in cats. The difference was significant between the L-STT I and U-STT I values; however, the L-STT I and U-STT I values were within normal reference intervals. The U-STT I data have diagnostic value that might be of benefit in cases where there is a problem in the ventral conjunctival fornix.

Effects of two concentrations of topical tropicamide on the Schirmer tear test in clinically normal cats.

OBJECTIVES: The aim of this study was to evaluate the effect of topical tropicamide at two concentrations (0.5% and 1.0%) on the Schirmer tear test (STT) results in clinically normal cats. METHODS: Twenty-four adult domestic shorthair cats were randomly assigned to three groups. In all three groups, ophthalmic solutions were instilled in a randomly selected eye and the opposite eye served as the control. In groups 1, 2 and 3 one drop of 0.5% tropicamide, 1.0% tropicamide and distilled water was used, respectively. Tear production in both eyes was tested 30 and 60 mins after instillation in all three groups. RESULTS: Baseline mean ± SEM STT values for the treated eyes in groups 1, 2 and 3 were 13.37 ± 2.91 mm/min, 10.87 ± 1.39 mm/min and 11.37 ± 1.65 mm/min, respectively. Thirty minutes after the drug instillation in the treated eye, mean ± SEM STT values in groups 1, 2 and 3 were 4.87 ± 3.05 mm/min, 2.00 ± 0.84 mm/min and 11.25 ± 1.81 mm/min, respectively. The mean ± SEM STT levels of the treated eye after 60 mins were 3.75 ± 1.87 mm/min, 0.5 ± 0.37 mm/min and 11.42 ± 1.78 mm/min in groups 1, 2 and 3, respectively. CONCLUSIONS AND RELEVANCE: Use of 0.5% topical tropicamide, instead of 1.0% tropicamide, as a mydriatic agent, can be recommended in cats. Tear production measurement should be performed prior to the administration of tropicamide, regardless of the concentration of this drug.

Measurement of Tear Production and Intraocular Pressure in Healthy Captive Helmeted Guinea Fowl ( Numida meleagris ).

We establish reference values of tear production by the phenol red thread test (PRTT) and intraocular pressure (IOP) by rebound tonometry in helmeted guinea fowl ( Numida meleagris ). Aqueous tear production and IOP were measured in 44 (22 males, 22 females) clinically normal captive helmeted guinea fowl. Birds were gently physically restrained in the sitting position without any pressure to the head or neck. In each bird, aqueous tear production was measured by placing phenol red threads in the superior conjunctival fornix, and IOP was measured by using a Tonovet rebound tonometer. Overall mean ± standard deviation (SD) values of PRTT and IOP of all eyes were 16.5 ± 1.3 mm/15 s (ranging from 14-18 mm/15 s) and 9.1 ± 0.9 mm Hg (ranging from 7-10 mm Hg), respectively. No significant differences were found in IOP or PRTT between males and females (P = .76; P = .83, respectively) or between the left and right eyes (P = .34 and .66, respectively) in the guinea fowl. Results of this study may be beneficial for the diagnosis and therapy of keratoconjunctivitis sicca, glaucoma, and uveitis in helmeted guinea fowl.

Measurement of Tear Production Using the Phenol Red Thread Test in the Common Mynah ( Acridotheres tristis ).

To evaluate tear production in the common mynah ( Acridotheres tristis ) using the phenol red thread test (PRTT) and to make a comparison of measurements with the PRTT placed in the fornices of lower and upper eyelids, tear production of both eyes in 22 healthy adult captive mynah birds was evaluated. After positioning of threads in the fornices of upper and lower eyelids, the PRTT values of the birds were 17.5 ± 3.1 mm/15 s and 19.2 ± 2.5 mm/15 s, respectively. A significant difference was found between PRTT values for upper eyelids and lower eyelids (P = 0.01). This study provides novel data for normal reference ranges of PRTT values in healthy common mynah birds and shows that a difference is found depending on where the PRTT thread is placed.