Effects of topical administration of timolol maleate on intraocular pressure and pupil size in cats

Effects of topical administration of a single dose of timolol maleate, a nonselective beta-adrenergic blocking agent, on intraocular pressure (IOP) and pupil diameter were evaluated in the normotensive eyes of 10 clinically normal cats over 12 hours. Mean (+/- SEM) normal IOP was 17.1 (+/- 1.1) mm of Hg and diurnal fluctuation was observed, with the highest IOP seen in the evening. Mean (+/- SEM) normal pupil diameter was 10.1 (+/- 0.5) mm. Topical treatment with 0.5% timolol resulted in reduction of IOP in treated and nontreated eyes. This effect was time-dependent and was first observed at 6 hours after treatment. Mean reduction of IOP was 22.3% in the treated eye and 16.3% in the nontreated eye. The treated eye had reduced pupil diameter at 30 minutes after treatment, and miosis persisted throughout the 12 hours of the study. Mean reduction of pupil diameter was 38.7%. A contralateral effect on pupil diameter was not seen in the nontreated eye. Topical administration of timolol maleate results in a reduction of IOP in treated and contralateral eyes, which supports the use of timolol for treatment of glaucoma in cats. In addition, the treated eye becomes miotic. This effect may indicate beta-adrenergic inhibition or alpha-adrenergic activation of the iris sphincter muscle. beta-Adrenergic blockade would then result in miosis.     

Effects of topical administration of 2.0% pilocarpine on intraocular pressure and pupil size in cats

Effects of topical administration of a single dose of 2% pilocarpine on intraocular pressure (IOP) and pupil diameter were evaluated in normotensive eyes of 10 clinically normal cats over 12 hours. Mean (+/- SEM) normal IOP was 17.1 (+/- 1.1) mm of Hg and, diurnal fluctuation was observed, with the highest IOP seen in the evening. Mean (+/- SEM) normal pupil diameter was found to be 10.1 (+/- 0.5) mm. Topical treatment with pilocarpine resulted in reduction of IOP in treated and nontreated eyes. This effect was time-dependent and was first observed at 4 hours after treatment. Mean reduction of IOP was 15.2% in the treated eye and 9.3% in the nontreated eye. The treated eye had reduced pupil diameter at 30 minutes after treatment, and miosis persisted throughout the 12 hours of the study. Mean reduction in pupil diameter was 28.5% in the treated eye and 14.2% in the nontreated eye. Topically administered pilocarpine results in reduction of IOP and pupil diameter in treated and contralateral eyes, which supports the use of pilocarpine for treatment of glaucoma in cats.     

Effect of single- and multiple-dose 0.5% timolol maleate on intraocular pressure and pupil size in female horses

OBJECTIVE: To determine the effect of single and multiple-dose 0.5% timolol maleate on intraocular pressure (IOP) and pupil size between 8 AM and 8 PM. Animals Nine female horses with normotensive eyes. Procedure IOP, horizontal and vertical pupil size were measured on a single day, between 8 AM and 8 PM at hours 0, 0.5, 1, 2, 4, 6, 8, 10, and 12. A single dose of 0.5% timolol maleate was applied to both eyes immediately after the first measurement at 8 AM. IOP and pupil size were measured at 8 AM and 4 PM in a 5-day experiment of twice-daily application of 0.5% timolol maleate. RESULTS: A significant decrease in IOP from 24.9 +/- 4.2 mmHg prior to application of timolol maleate to 20.7 +/- 3.1 mmHg (4.2 mmHg = 17%) was observed 8 h after single-dose application. A significant decrease in horizontal pupil size (2.0 mm = 11%) was present 6 h after single-dose application. In the multiple-dose experiment, a significant decrease in IOP was present on days 4 and 5 as compared to IOP measured prior to application of timolol maleate. A significant decrease in horizontal and vertical pupil size was present throughout the 5-day study as compared to the values obtained prior to treatment. CONCLUSIONS: 0.5% timolol maleate significantly decreased IOP and pupil size in normo-tensive eyes of this group of female horses in both single and multiple twice daily applications.     

The effect of 0.12% unoprostone isopropyl (rescula) on intraocular pressure in normotensive dogs

Rescula (0.12% unoprostone isopropyl) is the first docosanoid compound approved for treatment of glaucoma in humans. It is commercially available in Japan, and is undergoing clinical testing elsewhere. The aim of this study was to evaluate the effect of Rescula on intraocular pressure (IOP) in normotensive dogs. After establishing a baseline diurnal IOP curve, six dogs were unilaterally treated with Rescula while the contralateral eye was treated with a placebo. Applanation tonometry was performed in both eyes, and pupil size was evaluated, 30 min after treatment, and at 1-hr intervals for the next 9 hr. Rescula caused a significant (p=0.014) and long-lasting decrease in IOP, from 20.49+/-2.02 mm Hg in control eyes to 15.49+/-0.69 mm Hg in treated eyes. These results suggest that Rescula is potentially efficacious in treatment of canine glaucoma.     

The effects of a timolol maleate gel-forming solution on normotensive beagle dogs

The effects of a timolol maleate gel-forming solution (TMGS) on intraocular pressure (IOP), blood pressure (BP), and pupil size (PS) were evaluated in normotensive dogs. TMGS was administered once daily to six normotensive beagle dogs. TMGS administration reduced IOP and PS. The hypotensive effect persisted for 24 hr after the administration. The mean reduction in IOP was 5.3 mm Hg (P<0.01). The changes in BP and PS were not significant. These results suggest that TMGS can potentially be used in the treatments of glaucoma and ocular hypertension in dogs.     

Effect of topical administration of 2% dorzlamide hydrochloride or 2% dorzlamide hydrochloride-0.5% timolol maleate on intraocular pressure in clinically normal horses

OBJECTIVE: To evaluate the effect of topical administration of 2% dorzolamide hydrochloride or 2% dorzolamide hydrochloride-0.5% timolol maleate on intraocular pressure (IOP) in clinically normal horses. ANIMALS: 18 healthy adult horses without ocular abnormalities. PROCEDURE: The IOP was measured at 5 time points (7 AM, 9 AM, 11 AM, 3 PM, 7 PM) over 11 days. On days 1 and 2, baseline values were established. On days 3 through 5, horses received 2% dorzolamide HCI (group D, n = 9) or 2% dorzolamide HCl-0.5% timolol maleate (group DT, 9) in 1 randomly assigned eye every 24 hours immediately following each daily 7 AM IOP measurement. On days 6 through 9, each drug was given every 12 hours (7 AM and 7 PM) in the treated eye. Measurements on days 10 and 11 assessed return to baseline. Mixed linear regression models compared mean IOP difference for each drug at each time period. RESULTS: Mean IOP decreased significantly in all eyes during the 2 dose/d period, compared with the baseline, 1 dose/d, and follow-up periods. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of either drug every 24 hours for short-term treatment does not reduce IOP significantly. Administering either drug every 12 hours induced a significant reduction of IOP; however, controlling for all variables, the reduction was less than 2 mm Hg.     

Effects of topical application of a 2% solution of dorzolamide on intraocular pressure and aqueous humor flow rate in clinically normal dogs

OBJECTIVE: To evaluate effects of topical application of a 2% solution of dorzolamide on intraocular pressure (IOP) and aqueous humor flow rate in clinically normal dogs. ANIMALS: 15 Beagles. PROCEDURE: The IOP was measured in both eyes of all dogs for 3 days to determine baseline values. In a single-dose study, 50 microl of dorzolamide or control solution was applied in both eyes at 7:00 AM, and IOP was measured 7 times/d. In a multiple-dose study, dorzolamide or control solution was applied to both eyes 3 times/d for 6 days, and IOP was measured 4 times/d during treatment and for 5 days after cessation of treatment. Aqueous humor flow rate was measured for all dogs fluorophotometrically prior to treatment and during the multiple-dose study. RESULTS: In the single-dose study, dorzolamide significantly decreased IOP from 30 minutes to 6 hours after treatment. Mean decrease in IOP during this time span was 3.1 mm Hg (18.2%). Maximal decrease was detected 6 hours after treatment (3.8 mm Hg, 22.5%). In the multiple-dose study, dorzolamide decreased IOP at all time points, and maximal decrease was detected 3 hours after treatment (4.1 mm Hg, 24.3%). Mean aqueous humor flow rate decreased from 5.9 to 3.4 microl/min (43%) after treatment in the dorzolamide group. CONCLUSIONS AND CLINICAL RELEVANCE: Topical application of a 2% solution of dorzolamide significantly decreases IOP and aqueous humor flow rate in clinically normal dogs. Therefore, topical administration of dorzolamide should be considered for the medical management of dogs with glaucoma.     

Effects of the topically applied calcium-channel blocker flunarizine on intraocular pressure in clinically normal dogs

OBJECTIVE: To determine effects of the topically applied calcium-channel blocker flunarizine on intraocular pressure (IOP) in clinically normal dogs. ANIMALS: 20 dogs. PROCEDURES: Baseline diurnal IOPs were determined by use of a rebound tonometer on 2 consecutive days. Subsequently, 1 randomly chosen eye of each dog was treated topically twice daily for 5 days with 0.5% flunarizine. During this treatment period, diurnal IOPs were measured. In addition, pupillary diameter and mean arterial blood pressure (MAP) were evaluated. Serum flunarizine concentrations were measured on treatment day 5. Intraday fluctuation of IOP was analyzed by use of an ANOVA for repeated measures and a trend test. Changes in IOP from baseline values were assessed and compared with IOPs for the days of treatment. Values were also compared between treated and untreated eyes. RESULTS: A significant intraday fluctuation in baseline IOP was detected, which was highest in the morning (mean +/- SE, 15.8 +/- 0.63 mm Hg) and lowest at night (12.9 +/- 0.61 mm Hg). After 2 days of treatment, there was a significant decrease in IOP from baseline values in treated (0.93 +/- 0.35 mm Hg) and untreated (0.95 +/- 0.34 mm Hg) eyes. There was no significant treatment effect on pupillary diameter or MAP. Flunarizine was detected in serum samples of all dogs (mean +/- SD, 3.89 +/- 6.36 microg/L). CONCLUSIONS AND CLINICAL RELEVANCE: Topically applied flunarizine decreased IOP in dogs after 2 days of twice-daily application. This calcium-channel blocker could be effective in the treatment of dogs with glaucoma.     

Effects of topical nipradilol and timolol maleate on intraocular pressure, facility of outflow, arterial blood pressure and pulse rate in dogs

Nipradilol is an alpha(1), beta-blocker with milder side effects than other beta-blockers used in humans. In this study the effects of nipradilol were compared with those of timolol maleate in dogs. Twelve clinically normal dogs (nine mongrels, two beagles, and one Akita) were used. We applied 0.25% nipradilol or 0.5% timolol maleate drops for a period of 28 days. Intraocular pressure (IOP) was measured before and after administration on the 2nd, 4th, 7th, 14th, 21st and 28th day. Blood pressure, pulse rate and coefficient of aqueous outflow (C-value) were also measured before and after administration on the 7th, 14th, 21st and 28th day. Both nipradilol and timolol maleate significantly lowered IOP from the 2nd day to the end of the study period. Nipradilol lowered IOP to an equivalent degree to timolol maleate. There was no significant change in blood pressure and pulse rate throughout the study period with administration of nipradilol. C-value showed a significant rise from the 14th day with administration of nipradilol, while it did not show any significant change during the study period with administration of timolol maleate. The reduction of IOP by nipradilol was similar to that by an existing beta-adrenergic antagonist, timolol maleate, but nipradilol was associated with fewer systemic side effects in dogs. Nipradilol appears to be a useful drug for treatment of glaucoma in dogs.     

Evaluation of a rebound tonometer for measuring intraocular pressure in dogs and horses

OBJECTIVE: To compare intraocular pressure (IOP) measurements obtained with a rebound tonometer in dogs and horses with values obtained by means of applanation tonometry and direct manometry. DESIGN: Prospective study. ANIMALS: 100 dogs and 35 horses with clinically normal eyes, 10 enucleated eyes from 5 dogs, and 6 enucleated eyes from 3 horses. PROCEDURES: In the enucleated eyes, IOP measured by means of direct manometry was sequentially increased from 5 to 80 mm Hg, and IOP was measured with the rebound tonometer. In the dogs and horses, results of rebound tonometry were compared with results of applanation tonometry. RESULTS: For the enucleated dog and horse eyes, there was a strong (r2 = 0.99) linear relationship between pressures obtained by means of direct manometry and those obtained by means of rebound tonometry. Mean +/- SD IOPs obtained with the rebound tonometer were 10.8 +/- 3.1 mm Hg (range, 5 to 17 mm Hg) and 22.1 +/- 5.9 mm Hg (range, 10 to 34 mm Hg) for the dogs and horses, respectively. Mean IOPs obtained with the applanation tonometer were 12.9 +/- 2.7 mm Hg (range, 8 to 18 mm Hg) and 21.0 +/- 5.9 mm Hg (range, 9 to 33 mm Hg), respectively. Values obtained with the rebound tonometer were, on average, 2 mm Hg lower in the dogs and 1 mm Hg higher in the horses, compared with values obtained with the applanation tonometer. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the rebound tonometer provides accurate estimates of IOP in clinically normal eyes in dogs and horses.     

Effects of intracameral injection of tissue plasminogen activator on corneal endothelium and intraocular pressure in dogs.

Contact wide-field specular microscopy was performed on eyes of 16 healthy dogs after tissue plasminogen activator at a concentration of 25 micrograms/100 microliters (group 1, n = 8) or 50 micrograms/100 microliters (group 2, n = 8) was injected into 1 anterior chamber of each dog. The contralateral eye served as a nontreated control. Applanation tonometry was used to measure intraocular pressure in both eyes for up to 168 hours. By use of computerized morphometric analysis and pachymetry, changes from baseline values in endothelial cell density, cell morphologic features, and corneal thickness were evaluated at postinjection hours 24, 48, and 168. Significant mean differences in intraocular pressure were not detected between treated eyes of group-1 dogs and those in group 2 at designated times, or between treated and nontreated eyes of dogs in either group. Mean corneal thickness of treated and nontreated eyes was similar in both groups through postinjection hour 168. Changes in mean percentage of endothelial cell sides were observed only in treated eyes of group-2 dogs, with the mean percentage of hexagons at postinjection hour 168 decreasing by 18%, a decrease that was significantly (P less than 0.05) greater than the decrease in nontreated eyes. The mean percentage of 6-sided cells in treated eyes of group-2 dogs was significantly (P less than 0.05) less than that in treated eyes of group-1 dogs at postinjection hour 168.     

Evaluation of intraocular pressure in eyes of clinically normal llamas and alpacas

OBJECTIVE: To estimate intraocular pressure (IOP) in eyes of healthy camelids, using applanation tonometry. ANIMALS: The eyes of 34 camelids (16 llamas [Lama glamal and 18 alpacas [L. pacos]) that did not have major abnormalities of the ocular surface or intraocular abnormalities. PROCEDURE: Tonometry measurements were obtained from each eye 3 times during a 24-hour period. Each measurement was the mean of several corneal applanations obtained by use of an applanation tonometer. Data were analyzed, using an ANOVA for a repeated-measures design. RESULTS: Mean (+/- SEM) IOP of llamas and alpacas was 13.10+/-0.35 and 14.85+/-0.45 mm Hg, respectively. Range of IOP was 7 to 18 mm Hg for llamas and 11 to 21 mm Hg for alpacas. Mean IOP of llamas was significantly less than the mean IOP of alpacas. Significant differences in IOP were not detected between the right and left eye of animals. Significant differences in IOP were not attributed to sex, age, or time of measurement within llamas or alpacas. CONCLUSIONS AND CLINICAL RELEVANCE: Establishing the mean and range of IOP of clinically normal llamas and alpacas provides a frame of reference that is important for use in a complete ophthalmic examination of camelids, which can assist clinicians in the diagnosis of glaucoma and uveitis. Reasons for the difference in mean IOP between llamas and alpacas are unknown. Although the difference may be unimportant clinically, this finding reiterates the fact that caution must be used when extrapolating IOP among species.     

Effect of topical 1% atropine sulfate on intraocular pressure in normal horses

OBJECTIVE: To determine the effect of topical 1% ophthalmic atropine sulfate on intraocular pressure (IOP) in ocular normotensive horses. Animals Studied Eleven clinically healthy horses. Procedures IOP was measured bilaterally twice daily, at 8 AM and 4 PM, for 5 days. No medication was applied for the first 2 days of the study. Thereafter, one eye of each horse was treated with 0.1 mL of topical 1% atropine sulfate ointment twice daily (7 AM and 7 PM) for 3 days. The contralateral eye served as a control. In eight of the horses, an additional IOP reading was taken 3 days following cessation of the atropine treatment. RESULTS: There was no significant difference in the IOP of control vs. treatment eyes in the pretreatment period, days 1 and 2 (P = 0.97 and 0.55, respectively). During the treatment period, treated eyes of 10 of the horses had significantly lower IOP than control eyes (P = 0.03). The mean IOP reduction in treated eyes, relative to untreated eyes, was 11.2%. One horse had a significant rise in IOP in the treated eye compared to the remaining study animals. The IOP of control eyes did not vary significantly over the observation period (P = 0.27). There was no significant variation in IOP between the 8 AM and 4 PM measurement (P = 0.9). CONCLUSIONS: Topical 1% atropine sulfate causes a small, but significant decline in IOP in most ocular normotensive horses. Because topical atropine may elevate IOP in some horses, it should be used with caution in the treatment of glaucoma in this species.     

Effect of topical 0.03% flurbiprofen and 0.005% latanoprost, alone and in combination, on normal canine eyes

Objective Evaluate the influence of topically applied flurbiprofen 0.03% and latanoprost 0.005%, alone or in combination, in normal canines. Animals studied 10 Normal Beagles. Procedures Intraocular pressure (IOP), pupil size, aqueous flare, conjunctival hyperemia, and blepharospasm were evaluated bilaterally five times daily (8 am , 11 am , 2 pm , 5 pm, and 8 pm ). The study consisted of a training and acclimation period, followed by 3, 1‐week experiment periods. A 2‐week washout period occurred between each experiment period. During period 1, all dogs received flurbiprofen (three doses 6‐h apart) in the treated eye, whereas in period 2, all dogs received latanoprost (one dose 24‐h apart). During period 3, both latanoprost (one dose 24‐h apart) and flurbiprofen (three doses 6‐h apart) were administered in the treated eye. Results Flurbiprofen resulted in a mean IOP elevation of 1.1 mmHg (8.65%) in the treated eye, as compared with the control eye. No effect on pupil size, conjunctival hyperemia, or aqueous flare was noted. Latanoprost resulted in a mean IOP reduction of 3.4 mmHg (30.19%). Combined latanoprost and flurbiprofen resulted in a mean IOP reduction of 2.7 mmHg (24.56%). Miosis was noted in the treated eyes during both latanoprost periods, with maximal pupil constriction 3‐h post‐dose. This was followed by relative mydriasis 24‐h post‐dose, persisting 48 h after the last dose. The degree of conjunctival hyperemia varied between individuals. Neither blepharospasm nor aqueous flare was noted at any time point. Conclusion Concurrent administration of latanoprost and flurbiprofen resulted in a 20.41% reduction in the ocular hypotensive effect relative to latanoprost therapy alone.     

Changes in intraocular pressure associated with topical dorzolamide and oral methazolamide in glaucomatous dogs

Objective To compare the reduction in intraocular pressure (IOP) by topical 2% dorzolamide to oral methazolamide (5 mg/kg) in dogs, and determine if the combination of both drugs would reduce IOP more than either drug administered alone. Animals studied Thirteen glaucomatous beagles. Procedures Measurements, including applanation tonometry, pupil size and heart rate, were obtained at 8 am, 12 noon, and 5 pm on days 1, 3 and 5. The 5‐day drug studies included placebo (0.5% methylcellulose); 2% dorzolamide administered in one eye twice daily (8 am and 5 pm), and repeated again in one eye three times (8 am, 12 noon and 5 pm) daily; methazolamide (5 mg/kg per os administered at 8 am and 5 pm); 2% dorzolamide instilled twice daily (5 days) combined with oral methazolamide on the last 3 days, and methazolamide (5 days) combined with 2% dorzolamide on the last 3 days and instilled twice daily. Statistical comparisons between drug groups included control (nondrug) eye and treated (placebo/drug) eyes for days 1, day 3 and 5. Results Topical 2% dorzolamide, administered twice and three times daily, significantly decreased IOP (mean ± SEM) in glaucomatous dogs on the first day (twice daily 7.6 ± 2.4 mmHg, and three times daily 16.4 ± 3.6 mmHg) that was even greater by day 5 (twice daily 10.4 ± 2.0 mmHg, and three times daily 13.9 ± 2.7). Oral methazolamide also significantly lowered IOP in both eyes. Oral methazolamide (administered from day 1 through to day 5) combined with 2% topical dorzolamide (instilled in the drug eye for day 3 through to day 5) also significantly lowered IOP of both eyes for all days, and for day 5 the mean ± SEM IOP was decreased by 7.9 ± 1.7 mmHg (methazolamide plus dorzolamide) and 7.5 ± 2.6 mmHg (methazolamide only). Topical dorzolamide (instilled in the drug eye for day 1 through to day 5) combined with oral methazolamide (administered from day 3 through to day 5) significantly lowered IOP in the drug eye on day 1 (5 pm: 9.6 ± 1.9 mmHg), for day 3 (11 am and 5 pm) and for all of day 5 for both eyes (5 pm: control eye 9.5 ± 1.8 mmHg; drug eye 9.2 ± 1.9 mmHg). Topical dorzolamide (2%) instilled three times daily produces similar IOP declines compared to the combination of oral methazolamide and 2% dorzolamide administered twice daily. Conclusions Dorzolamide (2%) instilled twice or three times daily causes significant decreases in IOP in glaucomatous dogs. Twice daily instillations caused progressive declines in IOP from day 1 to day 5. Dorzolamide (2%) combined with oral methazolamide (5 mg/kg per os twice daily) produces similar but not additional declines in IOP.     

Comparison of the effects of topical administration of a fixed combination of dorzolamide-timolol to monotherapy with timolol or dorzolamide on IOP, pupil size, and heart rate in glaucomatous dogs

OBJECTIVE: To determine whether the combination multiple-dose dorzolamide-timolol administered topically has any greater effects on the reduction of intraocular pressure, pupil size, and heart rate in dogs with glaucoma than do either timolol or dorzolamide alone. PROCEDURE: Applanation tonometry, pupil size, and heart rate measurements were made at 7 a.m., 1 p.m., and 7 p.m. daily of 12 laboratory Beagles with inherited primary open-angle glaucoma during each active phase of this study. Timolol 0.5% was administered first twice daily for 4 consecutive days. Dorzolamide 2.0% was administered next three times daily for 4 consecutive days. The fixed combination of the two (timolol 0.5% and dorzolamide 2.0%) was administered twice daily for 4 consecutive days during the final week of the study. Between administration of each drug, a withdrawal period of at least 10 days was instituted. Statistical comparisons between the effects of the three drugs were performed. RESULTS: Intraocular pressure (IOP) was decreased with the administration of all three drugs: timolol alone, dorzolamide alone, and the combination of the two decreased IOP after 1 day of treatment 2.83 +/- 0.70 mmHg, 6.47 +/- 0.32 mmHg, and 6.56 +/- 0.37 mmHg, respectively. After 4 days of treatment, the IOP decreased even further: timolol alone, dorzolamide alone, and the combination of the two decreased IOP 3.75 +/- 0.88 mmHg, 7.50 +/- 0.29 mmHg, and 8.42 +/- 0.58 mmHg, respectively. Heart rate was significantly decreased with timolol (-11.9 +/- 2.0 bpm) and the combination preparation (-8.6 + 2.4 bpm), but not with dorzolamide (-3.7 +/- 1.8 bpm) alone. Pupil size was significantly decreased with timolol (-1.42 + 0.40 mm) and the combination preparation (-1.3 + 0.33 mm), but not with dorzolamide (0.97 +/- 0.36 mm) alone. CONCLUSIONS: The combination dorzolamide-timolol appears to be more effective at reducing intraocular pressure in glaucomatous dogs than is either timolol or dorzolamide alone.     

The ocular effects of intravitreal triamcinolone acetonide in dogs

The aim of the study was to determine the ocular safety of a single intravitreal dose of triamcinolone acetonide (IVTA) in dogs. Eleven healthy dogs received a single IVTA injection (8 mg) through the mid-temporal pars-plana of the left eye (OS) using a 27G needle. The dogs were re-evaluated immediately post-IVTA, every 5 min until pre-IVTA values had returned, then daily for 3 days, weekly for 1 month and monthly for 3 months. Immediately post-IVTA, all the treated eyes showed a rise in intraocular pressure (IOP) with a mean value of 41.8+/-8.9 mm Hg. The IOP values then decreased progressively to 14.5+/-2.1 mm Hg at 12.2+/-3.8 min post-IVTA. From then on, normal IOP values were maintained throughout the 3-month monitoring period. The most frequently observed clinical sign post-IVTA was conjunctival hyperaemia. The presence of triamcinolone acetonide in the vitreous was observed in all subsequent examinations of 10/11 eyes and there were still triamcinolone crystals in 5/11 eyes after 90 days. It was concluded that intravitreal injection of triamcinolone acetonide in dogs is feasible under sedation. The immediate increase in IOP post-IVTA is short-lived and pressure quickly returns to pre-IVTA levels.     

Treatment of glaucoma by use of transscleral neodymium:yttrium aluminum garnet laser cyclocoagulation in dogs

Neodymium:yttrium aluminum garnet (Nd:YAG) laser energy was transsclerally applied to the ciliary body of 56 eyes of 37 dogs for treatment of glaucoma. Forty-four eyes were glucomatous at the time of treatment, and 12 normotensive eyes with ciliary cleft closure were treated prophylactically. Glaucoma was primary in 35 dogs and secondary in 2 dogs (1 eye in each dog). Energy was delivered by a general surgical Nd:YAG laser via a hand-held, 600-muc-diameter flexible quartz fiber. The mean (+/- SD) number of spots treated per eye was 35 (+/- 9.7), with mean energy per burst of 7.1 (+/- 2.6) J; mean total energy delivered to the eyes was 228 (+/- 81) J. Follow-up evaluation was available for 42 eyes from 2 to 4 weeks after treatment, and for 32 eyes from 12 to 24 weeks after treatment. Treatment success, defined as maintenance of intraocular pressure less than 25 mm of Hg, was achieved in 83% (20/24) of glaucomatous eyes evaluated between 12 and 24 weeks of treatment. Of 4 treatment failures, 3 were eyes devoid of uveal pigment. The consistent acute effects of treatment were conjunctival vascular congestion and blood-aqueous barrier disruption, recognized clinically by the presence of aqueous flare. Hyphema developed in 16% (9/56) of eyes; hyphema resolved without complication in all but 2 eyes. A common long-term complication of treatment was cataract formation, recognized in 37% (12/32) of eyes evaluated at 12 to 24 weeks. Cataracts were sufficiently dense to obstruct vision in 4 eyes. Phthisis bulbi was observed in 1 eye.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of travoprost 0.004% compared with latanoprost 0.005% on the intraocular pressure of normal dogs

PURPOSE: To compare the effects of travoprost 0.004% and latanoprost 0.005% on the intraocular pressure (IOP) of normal dogs. METHODS: Twenty mixed breed dogs were randomized to two groups: latanoprost was used in group A and travoprost in group B. The drugs were instilled in the right eye of the dogs, whereas the left eye received placebo. Both drugs were instilled once a day at 8 am during 5 days. IOP measurements were made at 8 am, 10 am, 2 pm and 8 pm during the 5 days of treatment, the 3 days that preceded treatment, and 3 days following treatment. Presence of blepharospasm, miosis, anterior chamber flare, and conjunctival hyperemia were evaluated during the study. RESULTS: Mean IOP was significantly reduced in the eyes treated with both latanoprost and travoprost, when compared with the eyes treated with placebo (P<0.05). There was no statistically significant difference between the mean IOPs of eyes treated with latanoprost and travoprost at all time intervals during baseline, treatment, and recovery (P>0.05). On the fifth day of treatment and on the first day of the recovery period, a severe ocular hypotension was noted with both drugs, resulting in imprecise readings with the tonometer. Miosis and conjunctival hyperemia were observed in the treated eyes of both groups, whereas flare was noticed in one latanoprost-treated eye. CONCLUSION: Travoprost 0.004% significantly reduces the IOP in normal dogs. The hypotensive effect obtained with travoprost 0.004% is comparable to that obtained with latanoprost 0.005%.     

Effects of 4% pilocarpine gel on normotensive and glaucomatous canine eyes

A 4% pilocarpine gel applied topically to eyes was evaluated in glaucomatous Beagles and normotensive Miniature Schnauzers to determine its efficacy in reducing intraocular pressure (IOP) and to assess any side effects. Pilocarpine gel significantly (P less than 0.05) reduced IOP for 24 hours after treatment, compared with baseline (pre-drug) values, untreated fellow eyes, and placebo-treated eyes. The IOP remained significantly lower (P less than 0.05) during 3 treatment days, as well as the first 2 days after treatment. The pupil sizes were significantly smaller (P less than 0.01) in all treated dogs after the first administration of pilocarpine, compared with baseline values, untreated eyes, and placebo-treated eyes. The subsequent pilocarpine gel administrations induced significant miosis (P less than 0.01), compared with baseline values, but the extent of miosis and duration were significantly less (P less than 0.01) as the number of treatments increased. Conjunctival irritation and blepharospasm were observed mainly in the first 2 days of treatment and were minimal after subsequent applications. There was no contralateral effect on IOP or pupil size, compared with baseline values and placebo-treated eyes.