Effect of three treatment protocols on acute ocular hypertension after phacoemulsification and aspiration of cataracts in dogs

Objective  To compare the effect of topical latanoprost, intracameral carbachol, or no adjunctive medical therapy on the development of acute postoperative hypertension (POH) and inflammation after routine phacoemulsification and aspiration (PA) of cataracts in dogs.
Design  Retrospective study.
Procedures  Dogs received either one drop of topical 0.005% latanoprost (21 dogs, 39 eyes), an intracameral injection of 0.3 mL of 0.01% carbachol (15 dogs, 30 eyes), or no adjunctive therapy (46 dogs, 90 eyes) immediately following PA of cataract(s). Intraocular pressure (IOP) was measured in all dogs 2 and 4 h after surgery. IOP was measured and aqueous flare assessed at 8 am the day after surgery.
Results  Carbachol-treated dogs had significantly higher mean IOP (33.2 ± SD 20.8 mmHg) 2 h after surgery than dogs receiving no adjunctive therapy (22.0 ± SD 14.1 mmHg) ( P  =  0 .049). There were no significant differences in IOP among groups at any other time point. There were no significant differences in number of POH episodes between dogs treated with carbachol (47%), latanoprost (29%), or dogs that received no adjunctive therapy (33%). There were no significant differences in mean aqueous flare grade between eyes treated with latanoprost (1.7 ± SD 0.4) or carbachol (1.4 ± SD 0.6), and eyes that received no adjunctive therapy (1.7 ± SD 0.4).
Conclusions  Topical 0.005% latanoprost or intracameral injection of 0.3 mL of 0.01% carbachol after PA in dogs did not reduce POH or increase intraocular inflammation compared to dogs not receiving adjunctive therapy after PA of cataracts.     

The relationship of cataract maturity to intraocular pressure in dogs

Objective To determine the distribution of intraocular pressure, as measured by applanation tonometry, in dogs with cataracts, and compare these tonometric results to the different stages of cataract formation (incipient, immature, mature, and hypermature). Animals studied Retrospection study of canine clinical patients (86 dogs). Procedures All records of dogs presented from 1991 to 1996 to the university veterinary medical teaching hospital for diagnosis of cataracts and evaluation for cataract surgery were reviewed. The tonometric measurements from the initial ophthalmic examination were selected in cataractous and nonglaucomatous eyes either receiving no topical or no systemic medications. The stage of cataracts was based on the degree of opacification, tapetal reflection, clinical vision, and visibility of the ocular fundus by indirect ophthalmoscopy. The distribution of tonometric results were grouped by the cataract maturity, and compared by anova and Tukey’s general linear tests. Results Intraocular pressure with incipient cataracts ranged from 9 to 17 mmHg (mean 12.7 ± 1.2 mmHg). Intraocular pressure with immature cataracts ranged from 3 to 27 mmHg (mean 13.6 ± 0.6 mmHg). For the mature cataracts, IOP ranged from 5 to 22 mmHg (mean 11.9 ± 0.7 mmHg). For the hypermature cataract group, IOP ranged from 4 to 23 mmHg (mean 10.8 ± 0.6 mmHg). Comparison of the tonometric results among the different stages of cataract formation indicated a significant difference (P = 0.0086) between only the immature and hypermature groups. Conclusions Intraocular pressure in lens‐induced uveitis (LIU) is lowered but the relationship to the stage of cataract maturity is less clear. Significant tonometric differences were present between the immature and hypermature cataract groups, but these differences are too small to be clinically useful. Decreased intraocular pressure of dogs with all stages of cataract formation suggests concurrent LIU during all stages of cataract formation, especially with the mature and hypermature stages. The average tonometric measurements in dogs with these cataracts were about two standard deviations below the mean IOP reported in normal dogs.     

Use of ketamine, xylazine, and diazepam anesthesia with retrobulbar block for phacoemulsification in dogs

Objective  The study was undertaken to evaluate the use of ketamine, xylazine, and diazepam along with a local retrobulbar nerve block for routine phacoemulsification in the dog.
Animals  Ten clinically healthy mixed-breed dogs of either sex, weighing between 10 and 15 kg.
Procedures  Ten mixed-breed dogs were selected for unilateral cataract removal by phacoemulsification. Standard preoperative preparations for cataract surgery were followed. Pre-anesthetic medication consisted of atropine sulfate (0.02 mg/kg, SC). Anesthesia was induced by xylazine HCl (1.0 mg/kg, IM) followed by ketamine (5.0 mg/kg, IM). Anesthesia was maintained subsequently with IV ketamine and diazepam to effect and depth of anesthesia was assessed clinically by pedal reflex and jaw reflex. After induction of anesthesia, a retrobulbar nerve block was performed using 2 mL of 2% lignocaine. Eye position was graded after retrobulbar block and IOP was examined preoperative, post-anesthetic, 6 h postoperative and 24 h after surgery. Phacoemulsification was performed using the phaco-chop technique and an intraocular lens was placed. Anesthetic recovery and postoperative recovery following surgery was recorded.
Result  The exposure of the globe in all the dogs was adequate; the desired central fixation of the eye was obtained and surgery could be performed uneventfully. The mean IOP recorded after induction of anesthesia was 15.75 ± 0.82, which was not significantly ( P  > 0.01) different from pre-anesthetic values (14.85 ± 0.85).
Conclusion  Phacoemulsification was successfully performed with this anesthetic regimen without encountering major intraoperative or anesthetic complications.     

Change in intraocular pressure during maturation in Labrador Retriever dogs

Objective To measure intraocular pressure (IOP) in a group of dogs as puppies and young adults to determine if there is any change during maturation. Animals studied Thirty‐two healthy Labrador Retriever dogs. Procedures Intraocular pressure was measured using a Tonopen XL initially at approximately 6 weeks of age (T1), then again approximately 1 year later (T2). Exact ages were known based on whelp date. Results The dogs had marginally higher IOP OU at T2 (mean = 14.9 mmHg) compared to T1 (mean = 13.4 mmHg). However, the difference was not statistically significant. No differences were seen based on sex and litter. Intraocular pressure OD was statistically greater than OS at T1 but not at T2. Conclusions Normal values for intraocular pressure are the same in puppies and adults. The results of this study do not support the previously suggested theory that younger dogs have sustained increased IOP as a requirement to drive growth of the globe. However, it does not rule out the possibility that a dynamic relationship between intraocular pressure and expansion of the globe may exist.     

Development of glaucoma after cataract surgery in dogs: 220 cases (1987-1998)

OBJECTIVE: To examine postoperative ocular hypertension (POH) and other variables as predictors of the risk of developing glaucoma after cataract surgery in dogs. DESIGN: Retrospective study. ANIMALS: 220 dogs that had cataract surgery. PROCEDURE: Medical records of 220 dogs (346 eyes) that had extracapsular cataract removal or phacoemulsification of cataracts were reviewed. With respect to glaucoma development, 8 variables were analyzed, which included development of POH, breed, sex, age at time of surgery, eye (right vs left), phacoemulsification time, intraocular lens (IOL) placement (yes or no), and stage of cataract development. Eyes developed glaucoma within 6 or 12 months of surgery or did not have signs of glaucoma at least 6 or 12 months after cataract surgery. RESULTS: Of 346 eyes, 58 (16.8%) developed glaucoma after surgery. At 6 months, 32 of 206 (15.5%) eyes examined had glaucoma; at 12 months, 44 of 153 (28.8%) eyes examined had glaucoma. Median follow-up time was 5.8 months (range, 0.1 to 48 months). Mixed-breed dogs were at a significantly lower risk for glaucoma, compared with other breeds. Eyes with IOL placement were at a significantly lower risk for glaucoma, compared with eyes without IOL placement. Eyes with hypermature cataracts were at a significantly higher risk for glaucoma, compared with eyes with mature or immature cataracts. CONCLUSIONS AND CLINICAL RELEVANCE: Multiple factors appear to contribute to the onset of glaucoma in dogs after cataract surgery. Complications prohibiting IOL placement during cataract surgery may lead to a high risk of glaucoma development.     

Ahmed valve implantation to control intractable glaucoma after phacoemulsification and intraocular lens implantation in a dog

An 11-year-old spayed female Miniature Poodle presented with bilateral senile cataracts. Treatment was cataract removal by phacoemulsification and intraocular lens implantation. Five hours after surgery the operated right eye was partially closed and painful. The right pupil was fully dilated, there was generalized corneal edema, and intraocular pressure (IOP) was increased. After 12 h of medication IOP was controlled. Ten weeks after surgery the owners reported cloudiness of right eye, and the dog was again evaluated. The IOP was again increased and an Ahmed valve was implanted. This case describes describe the progression of this case and benefits of controlling postcataract surgery glaucoma by the implantation of an Ahmed valve.     

Effects of diazepam, ketamine, and their combination on intraocular pressure in normal dogs

Ketamine has been implicated as causing increases in intraocular pressure. The purpose of this study is to document the effects of ketamine, diazepam, and their combination on intraocular pressure (IOP) in normal, unpremedicated dogs. Random-source dogs were assigned to one of five groups of 10 dogs each: ketamine 5 mg kg^–1 (KET5), ketamine 10 mg kg^–1 (KET10), diazepam 0.5 mg kg^–1 (VAL), ketamine 10 mg kg^–1 with diazepam 0.5 mg kg^–1 (KETVAL), saline 0.1 mL kg^–1 (SAL), all given intravenously. A baseline IOP was measured before injection, immediately after injection, and at 5, 10, 15, and 20 minutes following injection. IOP was increased over baseline immediately after injection in the KET5, KET10, and KETVAL groups; at 5, 10, and 15 minutes in the KET5 group; and at 20 minutes in the KETVAL group. The mean IOP change compared to SAL increased immediately after injection and at 5 minutes in the KET5, KET10, and KETVAL groups; at 10 and 15 minutes in the KET5 group, and at 20 minutes in the KETVAL group. The mean IOP increased up to 5.7, 3.2, and 3.1 mm Hg over mean baseline in the KET5, KET10, and KETVAL groups, respectively. All dogs in the KET5 group and the majority in the KETVAL and KET10 groups had an increase in their IOP over baseline. Ketamine caused a clinically and statistically significant elevation in IOP over baseline and compared to SAL. The concurrent addition of diazepam did not blunt this increase. Ketamine should be avoided in dogs with corneal trauma, glaucoma, or in those undergoing intraocular surgery.     

Distribution of intraocular pressure in dogs

Intraocular pressure (IOP) was measured by four different applanation tonometers in normal dogs. By MacKay-Marg tonometry in 391 dogs (772 eyes) the mean ± SD IOP was 18.8 ± 5.5 mmHg (range 8–52 mmHg). Using Tono-Pen XL tonometry in 421 dogs (823 eyes) the mean IOP was 19.2 ± 5.9 mmHg, and the range was 4.42 mmHg. With MMAC-II tonometry in 80 dogs (158 eyes), the mean IOP was 15.7 ± 2.8 mmHg with a range of 10–30 mmHg. By pneumatonograph tonometry in 135 dogs (255 eyes), the mean IOP was 22.9 ± 6.1 mmHg and the range was 10–47 mmHg. In this study 53 breeds were represented. Of those breeds with six animals or more, no significant differences were detected in IOP between breeds ( P > 0.353) or sex ( P > 0.270). There was a significant decline of 2–4 mmHg ( P > 0.0001) in IOP as age increased from less than 2 years to greater than 6 years of age. This trend was present with all of the four tonometers. There were no significant differences between the MacKay-Marg and TonoPen-XL tonometers ( P > 0.198), but significant differences with the MMAC-II ( P > 0.001) and pneumatonograph ( P > 0.001) tonometers existed compared to the first two instruments. Based on this study and the literature, the mean IOP for the normal dog is 19.0 mmHg with a range of 11 (5%) and 29 (95%) mmHg.     

Time-specific intraocular pressure curves in Rhesus macaques (Macaca mulatta) with laser-induced ocular hypertension

Objective To detect and categorize time‐specific variations in daytime intraocular pressure (IOP) found in Rhesus monkeys with laser‐induced ocular hypertension. Procedures Ten male monkeys with argon laser‐induced ocular hypertension in one eye were anesthetized with ketamine hydrochloride, and the IOP measured in both eyes at 7 a.m., 7.30 a.m., and then hourly until 1 p.m. with a Tonopen? XL applanation tonometer. Intraocular pressure time profiles for both eyes in each animal were developed. The means ± SD of the IOPs for both eyes were calculated for the whole 6‐h study period, and the values compared statistically. The difference between the lasered eye mean IOP standard deviation and the normal eye mean IOP standard deviation for each animal during the 6‐h follow‐up was also calculated and compared. Results Mean IOP (± SD) in the glaucoma and normal eyes for the 10 animals during the 6‐h study was 32.6 ± 2.5 and 14.9 ± 2.5 mmHg, respectively. The IOP was significantly higher in the experimental eye than in the normal eye (P = 0.0008). The mean IOP in the lasered eye did not significantly change during the study period, whereas a slight but significant increase in IOP of the normal eye over the study period was recorded (P = 0.003). The variance in IOP in the hypertensive eyes was considerably greater than that in the untreated control eyes. From 7 a.m. to 1 p.m. the IOP declined in five eyes and increased in the other five eyes with laser‐induced ocular hypertension. Conclusions The time‐specific IOP variation pattern in the daytime in the laser treated eyes is significantly greater than the variation in the normotensive eyes. This shows that in order to detect statistical differences between IOP variations induced by an IOP‐reducing drug, and the exaggerated spontaneous IOP variations present in the laser‐induced hypertensive eye, sufficient animals should be included in any study. Understanding the time‐specific IOP variation present in a group of monkeys with laser‐induced ocular hypertension is essential prior to using the model for the evaluation of IOP‐reducing drugs.     

Intracapsular lensectomy and sulcus intraocular lens fixation in dogs with primary lens luxation or subluxation

Objective  To evaluate the postoperative results of lensectomy and sulcus intraocular lens fixation (SIOLF) via an ab interno approach in dogs with progressive lens subluxation or early luxation.
Study design  Retrospective study.
Animals studied  Twenty eyes from 19 dogs presented to the Animal Eye Clinic for lens luxation or subluxation between 1999 and 2006.
Methods  Medical records were reviewed to evaluate preoperative lens position, vision status, intraocular pressure (IOP), and whether surgery was performed on an emergent or elective nature. Lensectomy and SIOLF were performed and postoperative status including vision, glaucoma, and retinal detachment was assessed.
Results  Average age was 8.6 years (range 4–14 years) and 55% (11/20) were terriers. Patients were followed a mean of 29.2 months (range 1–92 months) after surgery. Retinal detachment or secondary glaucoma was observed in 1 of 20 (5%) and 5 of 20 (20%) eyes, respectively, with 1 of 20 (5%) exhibiting both. Mean preoperative IOP was 16 mmHg and preoperative lens position was equally divided between luxated and subluxated lenses. Surgery was performed more frequently as an elective procedure (18/20; 90%) due to normalized IOP vs. an emergency procedure (2/20; 10%). Vision was retained in 70% (14/20) of eyes with a mean time to vision loss of 41 months in the remaining eyes due to glaucoma, retinal detachment, or retinal degeneration.
Conclusions  Complications of glaucoma and retinal detachment after SIOLF in this study were less when compared with previously reported incidence rates in the literature for lensectomy alone which may reflect improved patient selection.     

Treatment of equine glaucoma by transscleral neodymium:yttrium aluminum garnet laser cyclophotocoagulation: a retrospective study of 23 eyes of 16 horses

Contact neodymium:yttrium aluminum garnet (Nd:YAG) laser transscleral cyclophotocoagulation (TSCP) was performed on 23 eyes of 16 horses for treatment of glaucoma. The mean highest preoperative IOP was 51 ± 17 mmHg. Follow-up evaluation was available for 19 eyes 1 day after surgery, 14 eyes from 1 to 2 weeks, 16 eyes from 4 to 6 weeks, 9 eyes from 12 to 16 weeks, and 10 eyes greater than 20 weeks after laser treatment. The mean intraocular pressure (IOP) the day following surgery was 34 ± 13 mmHg. The mean IOP for each follow-up period was: one to two weeks postoperative, 23 ± 9 mmHg; four to six weeks, 24 ± 7 mmHg; 12–16 weeks, 28 ± 10 mmHg; and  20 weeks, 22 ± 9 mmHg. IOP measurements were significantly different from pretreatment values for all follow-up intervals except for weeks 12–16 ( P < 0.05). Treatment success was defined as maintenance of IOP < 30 mmHg. Treatment success was achieved in 93%, 88%, 78%, and 70% of the treated eyes at the 1–2 weeks, 4–6 weeks, 12–16 weeks, and the  20 weeks re-evaluation, respectively. No significant difference was found between the number of eyes visual at presentation (52.2%) and visual at 20 weeks (60%). The most common laser complications were conjunctival hyperemia (21.7%) and corneal ulcers (13.0%). Results of this study indicate that Nd:YAG TSCP is an effective method of controlling IOP and preserving vision in horses with glaucoma. An effective Nd:YAG laser protocol for TSCP in the equine glaucomatous eye is a power setting of 11 W, duration of 0.4 s, applied 5 mm posterior to the limbus at 60 sites, resulting in a total energy dose of 264 J.     

Diurnal variations of central corneal thickness and intraocular pressure in dogs from 8:00 am to 8:00 pm

Diurnal variations in central corneal thickness (CCT) and intraocular pressure (IOP) and their relationships were studied in healthy dogs. Central corneal thickness was measured by ultrasonic pachymetry and IOP by applanation tonometry in 16 beagle dogs. Measurements were taken every 90 min over 12 h (08:00 am to 08:00 pm). The mean CCT and IOP values obtained during the sampling period were 545.6 ± 21.7 μm (range: 471 to 595 μm) and 15 ± 2.2 mmHg (range: 10 to 19 mmHg), respectively. The CCT and IOP showed statistically significant decreases at 6:30 pm and 5:00 pm, respectively (P < 0.001). Central corneal thickness and IOP values were lower in the afternoon/evening than in the morning and were positively correlated. Both findings are important for the diagnostic interpretation of IOP values in dogs.     

The use of transscleral cyclophotocoagulation with a diode laser for the treatment of glaucoma occurring post intracapsular extraction of displaced lenses: a retrospective study of 15 dogs (1995-2000)

The objective of this retrospective study was to evaluate transscleral cyclophotocoagulation (TSCP) using a diode laser for treating aphakic glaucoma that developed after intracapsular lens extraction (ICLE) had been performed for displaced lenses. Records of 15 dogs (21 eyes) were reviewed. The intraocular pressure (IOP) and the presence of vision were recorded at the time of ICLE and TSCP and at 1, 3, 6-9, 12 and 24 months post TSCP. The glaucoma was considered controlled if the IOP was less than 25 mmHg. The results indicated that the effectiveness of TSCP using a diode laser for treating aphakic glaucoma was of a short-term duration (1-3 months), with three patients needing repeat TSPC. In addition, adjunctive antiglaucoma medications were often required to maintain an adequately controlled IOP. Over the 24-month period the number of dogs requiring intrascleral prosthesis, intraocular gentamicin or enucleation, or that were lost to follow-up, increased.     

Tonometry in three herbivorous wildlife species

Tonometry was performed to estimate intraocular pressure (IOP) in 12 Nubian ibexes ( Capra ibex nubiana ), 10 Grant zebras ( Equus burchelli  ) and five Arabian oryxes ( Oryx leucoryx ), using both applanation (Tono-Pen) and/or indentation (Schiotz) tonometers. Animals were anesthetized with a mixture of etorphine hydrochloride and acepromazine maleate. Mean (± SD) IOP in the ibex was 17.95 ± 4.78 mmHg (24 eyes, indentation tonometry). In the zebra, indentation tonometry (20 eyes) yielded a mean IOP of 25.30 ± 3.06 mmHg, and applanation tonometry (six eyes) yielded a mean IOP of 29.47 ± 3.43 mmHg. In the oryx, indentation tonometry (five eyes) yielded a mean IOP of 22.68 ± 8.15 mmHg, and applanation tonometry (10 eyes) yielded a mean IOP of 11.76 ± 3.43 mmHg. There were no significant effects of gender, age, weight, side or reading number on the IOP measured in any of the three species. No significant differences were found between the IOP of the three species, nor between the readings of the two instruments, although some of the P -values were close to the significance level.     

Changes in intraocular pressure and pupil size following intramuscular administration of hydromorphone hydrochloride and acepromazine in clinically normal dogs

Objective To investigate the effects of intramuscularly administered hydromorphone hydrochloride and acepromazine on intraocular pressure (IOP) and pupil size (PS). Animals studied Seventeen dogs free of clinically relevant ocular abnormalities. Procedure Measurements of IOP and PS were obtained and the dogs were injected intramuscularly with hydromorphone (0.04–0.08 mg/kg) and acepromazine (0.04 mg/kg). Measurements of IOP and PS were repeated 10 min and 25 min later. Results Though a decreasing trend in IOP values was demonstrated, no significant difference was noted in IOP from the initial examination to examination following intramuscular administration of hydromorphone and acepromazine. Significant miosis was present in 16 of 17 dogs at 10 min and 25 min following administration of hydromorphone and acepromazine. Conclusion Hydromorphone (0.04–0.08 mg/kg) and acepromazine (0.04 mg/kg) cause significant miosis in dogs at 10 and 25 min following intramuscular administration.     

Effect of different dose schedules of travoprost on intraocular pressure and pupil size in the glaucomatous Beagle

Objective To evaluate changes in intraocular pressure and pupil size in glaucomatous dogs after instillation of 0.004% travoprost once in the morning, or once in the evening, or twice daily in 5‐day multiple dose studies. Materials and methods Applanation tonometry (IOP) and pupil size (PS) measurements were obtained at 8 a.m., 10 a.m., 12 noon, 2 p.m. and 4 p.m. in eight glaucoma dogs. Methylcellulose (0.5% as placebo) was instilled in the control eye, and 0.004% travoprost was instilled in the opposite drug eye. Methylcellulose (0.5%) and 0.004% travoprost were instilled on the 2nd through to the 5th day with instillations in the morning (8.30 a.m.), or evening (8 p.m.), or twice daily (8.30 a.m. and 8 p.m.). Results The mean ± SEM diurnal changes from baseline IOP in the control and placebo eyes in all three studies ranged from 1.2 ± 0.3 mmHg to 3.2 ± 0.9 mmHg. The mean ± SEM diurnal changes from the baseline IOP after 0.004% travoprost at 8 a.m. once daily for the next 4 days were 19.0 ± 2.7 mmHg, 24.7 ± 2.7 mmHg, 24.9 ± 3.1 mmHg, and 24.7 ± 3.1 mmHg, respectively, and were significantly different from the control eye. After travoprost was instilled at 8 p.m., the mean ± SEM baseline changes from the baseline IOP in the drug eyes were 23.5 ± 2.2 mmHg, 24.2 ± 2.2 mmHg, 24.5 ± 2.3 mmHg, and 24.2 ± 2.3 mmHg, respectively. When 0.004% travoprost was instilled twice daily, the mean ± SEM baseline IOP changes were 27.7 ± 2.1 mmHg, 28.1 ± 2.1 mmHg, 28.4 ± 2.2 mmHg, and 28.5 ± 2.2 mmHg, respectively, and were significantly different from the control eyes. Miosis of varying duration was frequent during the three studies. Conclusion Travoprost instilled once daily (a.m. or p.m.) as well as twice daily produces significant decreases in IOP and PS in the glaucomatous Beagle.     

Intraocular and Cardiopulmonary Effects of Low-dose Mannitol in the Dog

Fatal complications have been reported during anesthesia in dogs that received a standard (1–2 g/kg IV) dose of mannitol during intraocular surgery. A lower dose (0.25 g/kg IV), which had been shown to reduce intracranial pressure in humans, was evaluated during halothane anesthesia in dogs. There were no significant changes in intraocular pressure (IOP) or cardiovascular variables. This lower dose (0.25 g/kg IV) did not reduce IOP and would not be of benefit in dogs undergoing intraocular surgery.     

Secondary glaucomas in the dog in North America

OBJECTIVE: To determine the prevalence of secondary glaucomas in dogs associated with cataract formation, lens luxation or displacement, cataract surgery, uveitis, hyphema and intraocular neoplasia. METHODS: Information was obtained from the Veterinary Medical Data Base (VMDB) from all veterinary medical teaching hospitals in North America from March 1964 to March 2003. Secondary glaucomas were diagnosed at the same examination or after the primary diagnosis was made, and included those associated with cataract formation, lens luxation, cataract surgery, uveitis of unknown cause, hyphema of unknown cause, and intraocular neoplasia. The data were evaluated by decade, breed, gender and age of presentation. RESULTS: A total of 1 592 831 dogs were presented, and 9695 canine secondary glaucomas. Secondary glaucoma associated with cataract formation represented 81% of all the canine secondary glaucomas. Breeds (n = 7890 dogs) predisposed to secondary glaucoma and cataracts had an overall prevalence of 0.5%, but nearly 20% of all the cataractous dogs developed secondary glaucoma in at least one eye. For the years 1994-2003, these breeds included the American Cocker Spaniel; Boston Terrier; Toy, Miniature and Standard Poodle; English Springer Spaniel; Bichon Frise; and Labrador Retriever. The other forms of secondary glaucoma occurred less frequently, and included those glaucomas with lens luxation or displacement (779 dogs; 12.0%), postcataract surgery (528 dogs; 5.1%), with uveitis from unknown cause (399 dogs; 7.1%), with hyphema from unknown cause (117 dogs; 7.3%), and with intraocular neoplasia (19 dogs; 3.5%). The risk of the secondary glaucomas from 1984 to 2002 was highest after the intracapsular lens extraction (ICLE), less in the extracapsular technique (ECLE), and lowest for the phacoemulsification/phacofragmentation method. CONCLUSION: Prevalence of the canine secondary glaucomas ranges from 0.25% (1964-1973), 0.46% (1974-1983), 0.79% (1984-1993), to 0.80% (1994-2003) and are as frequent as the primary or breed-related glaucomas during these same time periods.     

Pathology of canine cataract surgery complications

AIM: To compare pathological complications arising from 2 methods of canine cataract surgery, manual extracapsular cataract extraction (MECCE) and the more automated phacoemulsification and aspiration (PA). METHODS: Case material presented to the Comparative Ophthalmic Pathology Laboratory, University of North Carolina over the previous 20 years (1979-1999) was searched for cases with a history of prior cataract surgery. Data were obtained from the pathology accession forms, and submitting veterinarians were contacted to verify and complete missing data where possible. The slides were re-examined, histological features of surgical complications were noted and secondary changes recorded. RESULTS: Fourteen canine post-cataract-surgery cases were reviewed, the average age of the group being 7.7 years. Of the 14 eyes, 7 had surgery performed using MECCE, and 7 using PA. Of the 7 eyes that underwent MECCE surgery, 5 were enucleated and diagnosed on both clinical and pathological grounds with glaucoma. Of the 7 eyes that underwent PA, 4 were diagnosed with infectious endophthalmitis. CONCLUSIONS: Complications observed were related to the surgical technique performed. Failures of manual extracapsular surgical procedures were more commonly associated with postoperative synechia and glaucoma, compared with failures of phacoemulsification, which were more commonly associated with infection and rhegmatogenous retinal detachments. CLINICAL RELEVANCE: To minimise post surgical complications, MECCE should be accompanied by rigorous efforts to reduce surgically induced inflammation, while PA should be performed using excellent aseptic technique. It is important with both techniques to totally remove cortical material while maintaining the integrity of the posterior capsule.