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

Evaluation of ciliary cleft changes after phacoemulsification using ultrasound biomicroscopy in dogs with cataracts

Introduction

Glaucoma is one of the most serious complications that causes irreversible blindness after phacoemulsification in dogs; however, a clear mechanism has not been elucidated. This study aimed to analyse the possible anatomical factors associated with glaucoma after phacoemulsification using parameters that reflect the anatomical characteristics of dogs.

Materials and methods

A total of 69 eyes of 48 dogs were included in this study. The patients were divided into three groups: normal eye (n = 18), cataract (n = 39), and post-phacoemulsification for at least 2 months after surgery (post-phaco, n = 12). For further analysis, the dogs were subdivided into two groups according to cataract stage: phacoemulsification non-candidate and candidate groups. Non-cataracts and incipient cataracts were categorized into the non-candidate group, whereas immature and mature cataracts were categorized into the candidate group. Measurements of the ciliary cleft parameters, including the area of the ciliary cleft (CCA), length of the ciliary cleft (CCL), width of the ciliary cleft (CCW), iridocorneal angle, and angle opening distance, were obtained using ultrasound biomicroscopy.

Results

CCA, CCL, and CCW were significantly higher in the candidate group than in the non-candidate group. CCA, CCL, and CCW were significantly reduced in the post-phaco group compared to those in the cataract group. Based on these results, we found that the ciliary cleft expanded in cataract-affected eyes and narrowed after phacoemulsification. This may indicate that the space between the trabecular meshworks became narrower, potentially leading to an increase in the resistance of the aqueous humor.

Conclusion

A narrowed ciliary cleft after phacoemulsification may be an anatomical factor associated with glaucoma.

Efficacy of perioperative 2% dorzolamide ophthalmic solution for reduction of postoperative ocular hypertension in dogs following routine phacoemulsification surgery: A prospective clinical trial

OBJECTIVE

To evaluate the efficacy of 2% dorzolamide ophthalmic solution for reduction of postoperative ocular hypertension (POH) following routine phacoemulsification surgery in dogs.

ANIMALS STUDIED

Thirty one dogs (53 eyes) with naturally occurring cataracts undergoing routine phacoemulsification surgery.

PROCEDURE(S)

A prospective, double-masked, randomized, placebo-controlled study design was utilized. Dogs received 2% dorzolamide ophthalmic solution or saline 1 h prior to surgery then three times daily for 21 days postoperatively in the operated eye(s). Intraocular pressure (IOP) was recorded 1 h prior to surgery and 3 h, 7 h, 22 h, 1 week and 3 weeks postoperatively. Statistical analyses were performed using chi-squared and Mann-Whitney U test with a significance level of p < .05.

RESULTS

Postoperative ocular hypertension (IOP ≥25 mmHg, <24 h after surgery) occurred in 28/53 (52.8%) eyes. There was significant reduction in the incidence of POH for eyes receiving dorzolamide (10/26 (38.4%) eyes) versus eyes receiving placebo (18/27 (66.7%) eyes) (p = .0384). Animals were followed for a median of 163 days after surgery. Thirty-seven (37/53 (69.8%)) eyes were visual at final examination and 3/53 (5.7%) globes were enucleated postoperatively. At last follow-up, there was no difference in visual status (p = .9280), need for topical IOP lowering medication (p = .8319) or incidence of glaucoma (p = .5880) based on treatment group.

CONCLUSIONS

Perioperative administration of topical 2% dorzolamide reduced the incidence of POH after phacoemulsification in the dogs studied. However, this was not associated with differences in visual outcome, incidence of glaucoma or need for IOP-lowering medications.

Prevalence and outcome of lens capsule disruption IN routine canine cataract surgery: A retrospective study of 520 eyes (2012-2019)

OBJECTIVE

To investigate the prevalence and surgical outcome of lens capsule disruption (LCD) in dogs undergoing cataract removal.

ANIMALS STUDIED

Medical records of 924 eyes undergoing phacoemulsification were analyzed retrospectively.

PROCEDURES

Routine cataract surgeries with or without LCD were included. Any LCD other than routine anterior capsulorhexis was defined as LCD and classified according to location and etiology. Odds ratios (OR) were calculated for maintaining vision, implantation of an artificial intraocular lens (IOL), and enucleation.

RESULTS

In total, 520 eyes were included. A LCD occurred in 145 eyes (27.8%; 145/520) and affected the posterior (85.5%; 124/145), anterior (6.2%; 9/145), and equatorial lens capsule (4.8%; 7/145) and at multiple locations (3.4%; 5/145). The etiology of the LCD was spontaneous preoperative in 41 eyes (28.3%; 41/145), accidental intraoperative in 57 eyes (39.3%; 57/145), and planned in 47 eyes (32.4%; 47/145). Disruption did not increase the odds of enucleation (OR = 1.48, 95% confidence interval [CI] 0.56-3.67; p = .36). The presence of LCD significantly increased the risk of losing vision 1 year post-operatively (OR = 8.17, 95% CI 1.41-84.93; p = .007) associated with retinal detachment. However, this was not present at 2 years follow-up or in PCCC cases at any time point. An IOL was implanted in 108 eyes (108/145; 75.2%) with LCD and in 45/47 (95.7%) eyes with a PCCC.

CONCLUSION

Increased surgeon awareness of possible intraoperative, accidental LCDs is important, as LCDs were relatively common and associated with increased odds for vision loss after 1 year in the present study. A prospective study investigating the causes of intraoperative, accidental LCD is warranted.

Retrospective study of postoperative intraocular pressure and complications in phacoemulsification combined with endoscopic cyclophotocoagulation and phacoemulsification alone in dogs

BACKGROUND

Long-term comparative data of phacoemulsification combined with endoscopic cyclophotocoagulation (phaco-ECP) versus phacoemulsification (phaco) alone in dogs are rare.

OBJECTIVES

To investigate the effects of ECP on postoperative intraocular pressure (IOP) and complications after phaco in dogs with normal IOP.

METHODS

Medical records of IOP, conjunctival hyperemia, corneal edema, aqueous flare, posterior synechia, intraocular fibrin, and posterior capsule opacification (PCO) formation in 15 canine eyes that underwent phaco-ECP and 36 eyes that underwent phaco alone were evaluated retrospectively. ECP was applied when either the iridocorneal angle or the ciliary cleft was narrow or closed.

RESULTS

The IOP of the phaco-ECP group persisted within the normal range postoperatively. The phaco-ECP group had a shorter period of dorzolamide use than did the phaco group. PCO was formed earlier in the phaco-ECP group than in the phaco group. The phaco-ECP group showed more severe corneal edema than the phaco group at every follow-up visit. Posterior synechia was more severe in the phaco-ECP group than in the phaco group from two weeks until the last follow-up.

CONCLUSIONS

Although ECP might cause more postoperative complications such as corneal edema and posterior synechia, it could effectively reduce the incidence of IOP increase after phaco in dogs with a high risk of postoperative glaucoma.

Prophylactic efficacy of intravenous paracetamol administration to reduce the incidence of post-operative ocular hypertension in dogs undergoing phacoemulsification: A pilot study

PURPOSE

To determine whether intravenous administration of paracetamol can prevent postoperative ocular hypertension (POH) in dogs following routine phacoemulsification.

METHODS

Diabetic and non-diabetic patients (total 54 dogs) undergoing unilateral or bilateral phacoemulsification were recruited to this placebo-controlled, prospective study. The control group received 1 ml/kg saline via intravenous infusion while the treatment group received 10 mg/kg paracetamol via intravenous infusion. Infusions were administered 30 min prior to surgery and repeated 12 h following initial administration. All patients received topical latanoprost at the conclusion of surgery. Intraocular pressure (IOP) was measured before premedication (baseline), and at 1 h, 3 h, 5 h and 18 h following extubation. POH was defined as an IOP above 25 mmHg (POH25). In addition, the number of patients with an IOP exceeding 20 mmHg was analyzed (POH20).

RESULTS

POH20 occurred in 33 of 54 animals (61.1%), including 19 of 25 animals (76.0%) in the control group and 14 of 29 animals (55.2%) in the treatment group. POH25 occurred in 23 of 44 animals (52.3%), including 13 of 25 animals (52.0%) in the control group and 10 of 29 animals (34.5%) in the treatment group. Paracetamol administration showed a significant positive effect on reducing the incidence of POH20 (p = .048), but not POH25 (p = .221).

CONCLUSIONS

When comparing groups, treatment with paracetamol showed a statistically significant reduction in the incidence of POH20, although no differences were observed in the incidence of POH25 between groups. Further studies are warranted to explore whether alternative drug regimes or routes of administration can provide enhanced efficacy in the prevention of POH25.

Retrospective Study of Long-Term Outcome of Phacoemulsification in 22 Feline Eyes with Presumed Congenital/Juvenile Cataracts (2007-2020)

The objective of this study was to determine the complication risk and prevalence after phacoemulsification in cats with presumed congenital/inherited cataracts. Twelve client-owned cats were included in the study. This retrospective study spanned 13 yr and involved 22 eyes. The median age at the time of surgery was 15 mo (range: 4.5-168 mo of age). Recorded complications were 3 eyes developed postoperative ocular hypertension, 1 eye developed glaucoma, 7 eyes developed feline herpes virus-1 signs, and 7 eyes developed postoperative uveitis >2 wk after surgery. No eyes had developed intraocular sarcomas at the time of their last exam. All eyes remained visual at last follow-up (range: 0.5-121 mo). Success was defined as a comfortable and visual eye without intraocular neoplasia, glaucoma, a partial or complete retinal detachment, or uveitis that occurred >2 wk after surgery or persisted longer than 2 wk. Twenty-one out of 22 eyes had a successful outcome. In this study, cats with presumed congenital/juvenile cataracts who underwent phacoemulsification had an excellent outcome.

Retrospective evaluation of phacoemulsification and aspiration in 182 eyes: Visual outcomes and CDE-predictive value

OBJECTIVE

To determine the effect of cumulative dissipated energy (CDE) on complications and visual outcome following cataract surgery in dogs.

ANIMALS STUDIED

Records of 182 canine eyes that had undergone cataract surgery.

PROCEDURES

Retrospective medical record review was conducted on dogs that underwent unilateral or bilateral elective cataract surgery by a single surgeon. Preoperative variables such as age, cataract duration, and pre-existing conditions were recorded. Intraoperative variables such as intraocular lens (IOL) status, phacoemulsification time, average power, irrigation fluid volume, and CDE were recorded. Postoperative complications and visual status at last follow-up were compared to these variables.

RESULTS

Eighty-six percent of dogs were visual in one or both eyes at last follow-up (LFU) examination. Median follow-up time was 186 days postoperatively. Eyes that developed glaucoma had a significantly greater mean CDE (77.73 ± 80.11) than eyes that did not develop glaucoma (49.21 ± 38.93). Eyes that remained visual at the LFU examination had a significantly lower mean CDE (48.31 ± 37.14) than eyes that were blind at LFU (82.05 ± 82.73). Significantly lower mean CDEs were found in diabetic eyes, younger eyes, early-operated eyes (<1 month duration), and eyes with preoperative lens-induced uveitis.

CONCLUSIONS

Higher CDE may be associated with an increased risk of postoperative glaucoma and loss of vision in dogs. Cumulative dissipated energy may be a useful prognostic indicator for success of canine cataract surgery.

Post-operative outcomes in canine eyes receiving a rhexis-fixated prosthetic intra-ocular lens: 30 cases (2014-2020)

OBJECTIVES

To report the outcomes following the insertion of a rhexis-fixated prosthetic intraocular lens (IOL) in dogs undergoing lens removal.

MATERIALS AND METHODS

The results are from 30 eyes of 28 dogs, undergoing lendectomy, in which the lens capsule could not accommodate a conventional prosthetic endo-capsular IOL. The reported cases had sustained either spontaneous or traumatic lens capsule rupture, or accidental intra-operative iatrogenic lens capsule disruption, or had required a planned, large, anterior or posterior continuous curvilinear capsulorhexis, all of which precluded insertion of a prosthetic IOL within the lens capsule. An acrylic IOL (XVET; Medicontur) was modified and positioned across the anterior and/or posterior capsulorhexes.

RESULTS

Other than haptic luxation in three cases, no complications were seen that were directly attributable to the rhexis-fixated lens. Over a follow-up period from three to 76 months (mean 20.7 months) 26/30 eyes remained visual. Blindness developed in three eyes due to retinal detachment and one eye was enucleated due to regrowth of a ciliary body adenoma.

CLINICAL SIGNIFICANCE

Rhexis fixation provided an alternative method to implant a prosthetic IOL when the lens capsule was unable to accommodate a conventional endo-capsular IOL.

Cataracts and phacoemulsification in the Siberian Husky: A retrospective and multicentric study (2008-2018)

PURPOSE

To compare cataract characteristics and complications related to cataracts and phacoemulsification in the Siberian Husky (Huskies) versus other canine breeds (non-Huskies).

ANIMALS

A total of 50 Huskies (92 eyes) and 96 non-Huskies (182 eyes) were evaluated.

METHODS

Medical records of Huskies (at four university veterinary hospitals, 2008-2018) and non-Huskies (Colorado State University, 2017-2018) diagnosed with cataracts were reviewed. Age of dog, cataract stage at presentation, and pre- and post-operative complications were recorded and analyzed.

RESULTS

Mean (±standard deviation) age at presentation was significantly lower in Huskies (3.5 ± 3.3 years) compared to non-Huskies (9.5 ± 2.9 years) (p < .0001). Huskies more commonly presented with hereditary cataracts than non-Huskies (84% versus 52%) and a significantly higher percentage of non-Huskies presented with diabetic cataracts than Huskies (48% versus 16%; p = .0001). Cataract stage at presentation did not differ between Huskies and non-Huskies. Phacoemulsification was performed in 40% (20 out of 50 dogs, 39 out of 92 eyes) of Huskies and 42% (40 out of 96 dogs, 74 out of 182 eyes) of non-Huskies. Pre-operative and post-operative retinal detachment were more common in Huskies than non-Huskies (13% versus 2% and 10% versus 1%, respectively) but the difference was not significant. Other post-operative complications occurred with similar frequency in both groups (p ≥ .17).

CONCLUSIONS

Huskies evaluated for cataracts were younger and less likely to present with diabetic cataracts than other canine breeds and, although not statistically significant, had a clinically important increased risk of retinal detachment pre- and post-phacoemulsification.

Looking into the future: Gene and cell therapies for glaucoma

Glaucoma is a complex group of optic neuropathies that affects both humans and animals. Intraocular pressure (IOP) elevation is a major risk factor that results in the loss of retinal ganglion cells (RGCs) and their axons. Currently, lowering IOP by medical and surgical methods is the only approved treatment for primary glaucoma, but there is no cure, and vision loss often progresses despite therapy. Recent technologic advances provide us with a better understanding of disease mechanisms and risk factors; this will permit earlier diagnosis of glaucoma and initiation of therapy sooner and more effectively. Gene and cell therapies are well suited to target these mechanisms specifically with the potential to achieve a lasting therapeutic effect. Much progress has been made in laboratory settings to develop these novel therapies for the eye. Gene and cell therapies have already been translated into clinical application for some inherited retinal dystrophies and age-related macular degeneration (AMD). Except for the intravitreal application of ciliary neurotrophic factor (CNTF) by encapsulated cell technology for RGC neuroprotection, there has been no other clinical translation of gene and cell therapies for glaucoma so far. Possible application of gene and cell therapies consists of long-term IOP control via increased aqueous humor drainage, including inhibition of fibrosis following filtration surgery, RGC neuroprotection and neuroregeneration, modification of ocular biomechanics for improved IOP tolerance, and inhibition of inflammation and neovascularization to prevent the development of some forms of secondary glaucoma.

Association between preoperative gonioscopic status and postoperative glaucoma after phacoemulsification in dogs: A retrospective cohort study of 505 eyes

OBJECTIVE

To assess whether preoperative gonioscopy status is associated with the development of postoperative glaucoma after phacoemulsification.

PROCEDURE

Eligible dogs and eyes were selected from medical records (2007-2017), and each eye was classified as having normal or abnormal gonioscopy status. Records were examined for postoperative glaucoma, and data were collected for baseline variables including patient signalment, surgical factors, and pre, intra, and postoperative medications.

RESULTS

Of 305 dogs (505 eyes) selected for review in this study, 111 dogs (163 eyes) had abnormal gonioscopy findings, and 194 dogs (342 eyes) had normal gonioscopy findings. Postoperative glaucoma occurred in 24% (39/163) of eyes with abnormal gonioscopy and in 14% (49/342) eyes with normal gonioscopy. Eyes with abnormal gonioscopy status were at higher risk of postoperative glaucoma compared to normal eyes (P = .025). There was no important confounding due to the numerous baseline variables summarised above. Regardless of gonioscopy status, the risk of glaucoma was highest during the first 2 months after surgery.

CONCLUSIONS

Eyes with abnormal gonioscopy findings are at increased risk of postoperative glaucoma compared with eyes with normal gonioscopy findings. Gonioscopy is recommended as a part of presurgical assessment in all dogs prior to phacoemulsification. Further study is needed to assess whether the incidence of postoperative glaucoma can be reduced by increased monitoring or altered treatment protocols in cases that are known to have abnormal gonioscopy findings prior to cataract surgery.

Gonioscopic iridocorneal angle morphology and incidence of postoperative ocular hypertension and glaucoma in dogs following cataract surgery

PURPOSE

To investigate the relationship between gonioscopic iridocorneal angle (ICA) morphology and the incidence of postoperative ocular hypertension (POH) and postoperative glaucoma in dogs undergoing cataract surgery.

ANIMALS STUDIED

Retrospective analysis of 138 eyes of 78 canine patients who underwent phacoemulsification at North Carolina State University from December 1, 2015 through April 30, 2017.

METHODS

Medical records of all phacoemulsification patients with preoperative RetCam gonioscopic images were reviewed for preoperative, intraoperative, and postoperative variables. Gonioscopic angle indices were calculated using a novel (ZibWest) angle grading system, and these indices were analyzed for outcome-related significance.

RESULTS

Increased surgeon experience was associated with increased probability of POH and vision loss. Higher average ZibWest Angle indices (ie, more open angles with less pectinate ligament dysplasia/ abnormality) were associated with a significantly decreased probability of medically unresponsive glaucoma. Increased patient age was significantly associated with an increased probability of both postoperative glaucoma and vision loss. Female dogs were significantly more likely to experience postoperative glaucoma compared to male dogs. Increased surgery time was significantly associated with increased probability of vision loss.

CONCLUSIONS

The ZibWest angle index may predict increased risk for developing medically unresponsive glaucoma with cataract surgery. Female sex, and increased patient age, surgical time, and surgeon experience were associated with increased postoperative morbidity.

Preliminary report of postoperative complications of phacoemulsification in Pugs: A multicenter retrospective study of 32 cases

OBJECTIVE

To compare complication rates and visual outcomes following phacoemulsification in Pugs versus dogs of other breeds.

ANIMALS STUDIED

Thirty-two pure-bred Pugs (55 eyes) and 32 dogs of other breeds (56 eyes) undergoing phacoemulsification.

PROCEDURES

Multi-institutional retrospective medical record review of perioperative factors, postoperative complications, and visual outcomes. The reference population of dogs of varying breeds included surgical cases following each Pug case at the same institutions. Perioperative risk factors and postoperative complication rates were compared between the two populations.

RESULTS

Pigmentary keratitis and diabetes mellitus were the most common preoperative comorbidities, found in 75% (P < .001) and 72% (P = .12) of Pugs, respectively. No perioperative factors were significantly associated with postoperative complications in Pugs. Postoperative complication rates were similar between groups; however, the most common complication in Pugs was corneal ulceration (15% of operated eyes), whereas glaucoma was most common in the reference population (13% of operated eyes). Three months postoperatively, vision was preserved in 91% of eyes of Pugs (50/55) and 95% of the reference population (53/56). One year postoperatively, 80% (32/40) of Pug eyes and 82% (28/34) of eyes in the reference population remained sighted.

CONCLUSIONS

Comorbidities and complications of cataract surgery in Pugs of this study demonstrate a predisposition for corneal disease. This highlights the importance of preoperative evaluation of factors associated with PK and corneal clarity, and postoperative monitoring for corneal ulceration in this breed.

Comparison of outcomes in cataractous eyes of dogs undergoing phacoemulsification versus eyes not undergoing surgery

OBJECTIVE

To compare outcomes of surgical intervention and nonsurgical management of canine cataracts.

METHODS

Records of patients examined for cataracts from January 2007 to February 2018 were divided into two groups: nonsurgical and surgical. The nonsurgical group was further subdivided based on whether the decision not to pursue surgery was elected by owners, or based on ophthalmologist's advice. Inclusion criteria included 6 months of follow-up. Success in the nonsurgical group was defined as a comfortable eye with no potentially painful complications, and success in the surgical group additionally required vision. Time-to-failure (complications) was assessed with Cox proportional hazards models.

RESULTS

A total of 72 eyes (41 dogs) were included in the nonsurgical group, and 126 eyes (67 dogs) were surgically treated. There was no difference in gender or age; however, the surgical group had significantly more diabetic eyes (56.3% vs 15.3%; P < .001) and patient eyes with longer follow-up times (median 37.6 months vs 22.1 months; P < .001) than the nonsurgical group. There was no statistically significant difference in complication rates between the nonsurgical group (15/72 [20.8%]) and the surgical group (23/126 [18.3%]; HR: 2.22 [0.97, 5.0]; P = .060). However, the complication rate in the ophthalmologist-led nonsurgical group was significantly greater than in the owner-led nonsurgical group (P = .019) and the surgical group (P = .002).

CONCLUSIONS

When using relevant outcomes, whether or not a cataractous eye has surgery does not affect long-term complications; additionally, nonsurgical eyes that are poor surgical candidates have a higher complication rate than eyes deemed suitable for phacoemulsification for which owners elected not to pursue cataract surgery.

Cataract surgeon viewpoints on the need for novel preventative anti-inflammatory and anti-posterior capsular opacification therapies

Purpose: To determine cataract surgeon viewpoints on the efficacy of available therapies/preventatives for two common sequelae of cataract surgery: inflammation and posterior capsular opacification (PCO). Methods: Cataract surgeons practicing worldwide specializing in adult, pediatric and veterinary patients were interviewed between March and August 2018. Results: Ocular inflammation following cataract surgery is treated by either corticosteroids and/or nonsteroidal anti-inflammatories (NSAIDs). Adult and pediatric cataract surgeons are satisfied with current treatments whereas this inflammation is still considered a problem by some in veterinary practice due to its slow resolution. Yttrium-aluminum-garnet (YAG) laser therapy is the PCO treatment of choice for adult cataract surgeons and they are generally pleased with its outcome. However, pediatric cataract surgeons find YAG problematic, especially in patients under 6 years of age, and invasive surgery is often needed to correct PCO/visual axis opacification (VAO). Veterinary ophthalmologists report that YAG is not effective for PCO in animals, especially dogs, due to the density of the fibrotic plaques; 86% of adult and 100% of veterinary and pediatric cataract surgeons surveyed agree that effective anti-PCO therapeutics would improve clinical care. Conclusions: Surgeons treating human patients are pleased with the available treatments for ocular inflammation following cataract surgery, although some veterinary ophthalmologists disagree. The surgeons surveyed agree that PCO/VAO remains an unsolved problem in pediatric and veterinary cataract surgery while the long-term outcome of adult cataract surgery could be improved by additional attention to this issue.

Outcome of phacoemulsification in 71 cats: A multicenter retrospective study (2006-2017)

PURPOSE

To assess outcome of phacoemulsification in cats.

METHODS

Records of 71 cats (82 eyes) from five referral centers were reviewed. Groups were divided by cause of cataract (congenital/juvenile [n = 32], traumatic [n = 33], and secondary to uveitis [n = 6]), and group comparisons were performed for the most common complications: postoperative ocular hypertension (POH), uveitis, corneal ulceration, synechia/dyscoria, and posterior capsular opacity (PCO) in three different time periods: immediately postoperatively, at 1-90 days, and at >90 days.

RESULTS

Median follow-up was 198 days (interquartile range 64-518 days). The overall visual success rate of the cats with a 12-month follow-up was 92.6% (25/27 eyes). POH occurred in 35/82 (42.6%) eyes. Immediately postoperatively, uveitis was the most common complication in 28/82 eyes (34.1%) followed by corneal ulceration in 22/82 eyes (26.8%). At 1-90 days, uveitis in 41/81 eyes (50.6%) remained the most common complication, followed by synechia/dyscoria in 21/81 eyes (25.9%), corneal ulceration in 16/81 eyes (19.7%), and PCO in 15/81 eyes (18.5%). At >90 days, PCO in 17/47 eyes (36.1%), followed by synechia/dyscoria in 16/47 eyes (34%), was the most common complications. The number of eyes with synechia/dyscoria in the trauma group was higher (13/33 [39.3%]) than in the congenital/juvenile group (5/31 [16.1%]) at 1-90 days (P = .039). No statistical difference was found for the other group comparisons. Three eyes in total were enucleated owing to endophthalmitis, post-traumatic ocular sarcoma, and secondary glaucoma.

CONCLUSION

Uveitis in the short-term and PCO and synechia/dyscoria in the long-term were the most common complications following phacoemulsification in cats.

The future of canine glaucoma therapy

Canine glaucoma is a group of disorders that are generally associated with increased intraocular pressure (IOP) resulting in a characteristic optic neuropathy. Glaucoma is a leading cause of irreversible vision loss in dogs and may be either primary or secondary. Despite the growing spectrum of medical and surgical therapies, there is no cure, and many affected dogs go blind. Often eyes are enucleated because of painfully high, uncontrollable IOP. While progressive vision loss due to primary glaucoma is considered preventable in some humans, this is mostly not true for dogs. There is an urgent need for more effective, affordable treatment options. Because newly developed glaucoma medications are emerging at a very slow rate and may not be effective in dogs, work toward improving surgical options may be the most rewarding approach in the near term. This Viewpoint Article summarizes the discussions and recommended research strategies of both a Think Tank and a Consortium focused on the development of more effective therapies for canine glaucoma; both were organized and funded by the American College of Veterinary Ophthalmologists Vision for Animals Foundation (ACVO-VAF). The recommendations consist of (a) better understanding of disease mechanisms, (b) early glaucoma diagnosis and disease staging, (c) optimization of IOP-lowering medical treatment, (d) new surgical therapies to control IOP, and (e) novel treatment strategies, such as gene and stem cell therapies, neuroprotection, and neuroregeneration. In order to address these needs, increases in research funding specifically focused on canine glaucoma are necessary.

Cataracts in Labrador Retriever and Jack Russell Terrier From the United Kingdom: A Two-Year Retrospective Study

Cataracts are among the most common ocular diseases, and are a leading cause of vision loss in humans and dogs. Jack Russell Terriers (JRT) and Labrador Retrievers (LR) are among the most popular canine breeds in the United Kingdom, and also among the most affected by cataracts. This study aimed to analyze the clinical features and the surgical outcome of cataracts in JRT and LR in an ophthalmologic reference Veterinary Hospital in the United Kingdom. For that purpose, medical records from JRT and LR diagnosed with cataracts between January 2015 and December 2016 were retrospectively evaluated. Data related to identification, clinical history, preoperative features, and surgical outcomes were analyzed. Forty-four dogs (81 eyes), including 26 JRT and 18 LR, were enrolled in the study. Mean ages were 10.2 ± 3.2 years in JRT and 8.5 ± 3.7 years in LR. Twenty-eight (63.6%) were females and 16 (36.4%) were males. Most dogs (84.1%) presented with bilateral cataracts. Nuclear and cortical cataracts were the most prevalent type in both breeds (JRT: n = 30, 61.2%; LR: n = 16, 50.0%), although subcapsular cataracts were also frequent in LR (n = 10, 31.3%). Significant differences in cataract location within the lens were detected between the two breeds (P = .002). Senile in JRT (n = 7) and genetic in LR (n = 7) were the most common etiologies. Concomitant ocular lesions were more frequent in dogs presented with cataracts in advanced stages, and included lens (n = 18; JRT: n = 15; LR: n = 3) and retinal alterations (n = 8; JRT: n = 2; LR: n = 6), and glaucoma (n = 6; JRT: n = 5; LR: n = 1). Thirty-three animals (75.0%, 51 eyes) were submitted to phacoemulsification with intraocular lens placement. Of these, 28 eyes (54.9%; JRT: n = 21; LR: n = 7) were visual, 19 eyes (37.3%; JRT: n = 11; LR: n = 8) presented impaired vision and four eyes (7.8%; JRT: n = 0; LR: n = 4) were blind at last clinical record. Postoperative complications were detected in 11 eyes (21.6%), and were more frequent in dogs presented with cataracts in advanced stages. These results and the multifactorial nature of cataracts call for further studies to identify and characterize the variables in a broader assessment, including other breeds and influencing factors.

Surgical outcome of cats treated for aqueous humor misdirection syndrome: a case series

OBJECTIVE

To evaluate the clinical outcome of cats treated surgically for aqueous humor misdirection syndrome.

METHODS

A retrospective analysis of cats treated surgically between January 1, 2006, and January 1, 2013, for aqueous humor misdirection syndrome was performed. Signalment, medical therapy, eyes affected, intraocular pressures prior to and after surgery, surgical procedures performed, postoperative complications, and visual status were evaluated.

RESULTS

Seven cats (nine eyes) fit the inclusion criteria. Six of seven cats were female, and five of seven cats were diagnosed with bilateral aqueous humor misdirection syndrome. Three surgical approaches were evaluated as follows: (i) phacoemulsification and posterior capsulotomy, (ii) phacoemulsification, posterior capsulotomy and anterior vitrectomy, and (iii) phacoemulsification, posterior capsulotomy, anterior vitrectomy, and endocyclophotocoagulation. The mean age at diagnosis was 12.9 years. Seven of nine eyes had controlled intraocular pressure (≤25 mmHg) during the first 6 months postoperatively. All cats were visual with controlled intraocular inflammation at 1 year postoperatively; however, one eye had an elevated intraocular pressure. All cats were continued on topical antiglaucoma and anti-inflammatory medications following surgery with the mean number of drops per day decreasing from 3.9 drops/day prior to surgery to 2.2 drops/day postoperatively.

CONCLUSIONS

Surgical management for feline aqueous humor misdirection syndrome may be a viable option to maintain a visual and normotensive status in cats that no longer have successful control of intraocular pressure with medical therapy.

Lens-Related Emergencies: Not Always So Clear

Emergencies involving the crystalline lens are not common; however, their clinical signs must be recognized quickly to begin treatment or referred immediately to improve the chances of retaining sight. The lens is a unique structure because of its immunologically privileged status and its imperative clarity for vision. Any insult to the lens capsule's integrity, its position within the globe, or to its clarity may result in undesirable sequelae.

Fluid dynamics and intraocular pressure using venturi phacoemulsification machine in dogs ex vivo

OBJECTIVE

To optimize fluid dynamics through measuring intraocular pressure (IOP) in a venturi phacoemulsification machine in dogs.

PROCEDURES

In step I, flow and IOP of the test chamber were measured using a pressure transducer with the bottle height (BH) set at 50, 70, 100, and 120 cm and the vacuum from 30 to 450 mmHg. A 19-gauge phaco and a 0.3-mm irrigation/aspiration (I/A) handpiece were used. In step II, flow and IOP were measured in an enucleated canine eye with a 3.0- and a 3.2-mm clear corneal incision (CCI), respectively. IOP was measured using the pressure transducer at a 30-mmHg vacuum to allow corneal deformation, to define the fluidic parameters for preventing surge.

RESULTS

Flow was directly proportional to the BH and vacuum, whereas IOP was directly proportional to the BH and inversely to the vacuum. Flow with an I/A handpiece was significantly less than with a phaco handpiece, explaining why IOP with an I/A handpiece was significantly higher than with a phaco handpiece. With the I/A handpiece, vacuum parameters less than 450 mmHg did not result in corneal deformation. IOP with a 3.2-mm CCI was significantly lower than with a 3.0-mm CCI, with the 3.2-mm flow being greater than the 3.0-mm flow.

CONCLUSIONS

BH during the I/A stage could be reduced to avoid unnecessary stress on the canine eye when using a venturi system. Although phacoemulsification with a 3.2-mm CCI could induce lower IOP, a 3.0-mm CCI might lessen the irrigation flow stress on the eye.

Effects of peribulbar anesthesia (sub-Tenon injection of a local anesthetic) on akinesia of extraocular muscles, mydriasis, and intraoperative and postoperative analgesia in dogs undergoing phacoemulsification

OBJECTIVE

To evaluate the effects of peribulbar anesthesia (sub-Tenon injection of lidocaine hydrochloride) on akinesia of extraocular muscles, mydriasis, and intraoperative and postoperative analgesia in dogs undergoing phacoemulsification.

ANIMALS

14 Beagles with ophthalmically normal eyes.

PROCEDURES

A blinded randomized controlled trial was performed. Dogs were anesthetized and assigned to 2 treatments: concurrent sub-Tenon injection of 2% lidocaine hydrochloride solution (2 mL) and IV injection of saline (0.9% NaCl) solution (0.02 mL/kg; lidocaine group [n = 7]) or concurrent sub-Tenon injection of saline solution (2 mL) and IV injection of 0.2 mg of atracurium/kg (0.02 mL/kg; control group [7]). Pupils were dilated by topical application of a combined tropicamide and phenylephrine ophthalmic solution. Ten minutes after the injections, pupil diameter was measured and phacoemulsification was performed. End-tidal isoflurane concentration was used to evaluate intraoperative pain. Subjective pain scores were recorded during the postoperative period.

RESULTS

Akinesia was induced and maintained throughout the surgery in all eyes. Mean ± SD pupil diameter was significantly greater in the lidocaine group (13.7 ± 0.7 mm) than in the control group (12.2 ± 0.8 mm). Isoflurane requirements were significantly lower in the lidocaine group than the control group. However, postoperative pain scores were not significantly different between the groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Sub-Tenon injection of lidocaine was an effective method for inducing akinesia of extraocular muscles, mydriasis, and intraoperative analgesia for phacoemulsification in dogs. Therefore, this could be another option for surgical field exposure and pain management during phacoemulsification in dogs.

Major breed distribution of canine patients enucleated or eviscerated due to glaucoma following routine cataract surgery as well as common histopathologic findings within enucleated globes

PURPOSE

To identify the most significantly represented breeds that were enucleated or eviscerated due to intractable glaucoma following elective cataract surgery and to describe the major histopathologic features of enucleated globes.

METHODS

A retrospective review of the Comparative Ocular Pathology Laboratory of Wisconsin database revealed 153 canine evisceration or enucleation submissions that met inclusion criteria. The most commonly represented breeds were identified, and enucleated globes of these breeds were further evaluated histologically (n = 69). Following standard hematoxylin & eosin staining, globes were evaluated for the presence of; corneal pathology, goniodysgenesis, pigment dispersion, pre-iridal fibrovascular membranes (PIFVMs), peripheral anterior, and/or posterior synechiation, inflammatory infiltrates, lens pathology, retinal pathology, and/or endophthalmitis.

RESULTS

The most significantly represented breeds were the Cocker Spaniel (11.7%), Boston Terrier (10.5%), Labrador Retriever (6.5%), Bichon Frise (6.5%), Shih Tzu (5.8%), and Jack Russell Terrier (5.8%). Common histopathologic findings included inflammatory keratitis, the presence of PIFVMs, and lymphoplasmacytic uveal infiltrates.

CONCLUSIONS

The Cocker Spaniel, Boston Terrier, Labrador Retriever, Bichon Frise, Shih Tzu, and Jack Russell Terrier may be at increased risk of the development of glaucoma following elective cataract surgery. These findings have potential clinical implications.

Update on veterinary cataract surgery

PURPOSE OF REVIEW

The purpose of this review is not to specifically discuss the techniques of veterinary cataract surgery, but rather to emphasize some of the differences between the veterinary and human cataract patients, procedures and outcomes.

RECENT FINDINGS

In general, veterinary cataract surgery has more similarities than differences when compared to its human counterpart. This is especially true when comparing pediatric cataract patients. Veterinary cataract surgery has changed dramatically in recent years with regards to surgical technique, ocular pharmacology, viscoelastic devices, phacoemulsification, and the most recent advancement, intraocular lens implantation for dogs, cats, and horses.

SUMMARY

It is hoped that the exchange of information between the human and veterinary specialties can be of benefit to both groups as we all work to improve outcomes and resolve complications.

Cataracts: when to refer

Unique stages of cataract development have been characterized in both human and animal lenses. These lens opacities impair visual acuity and are associated with inflammation. Total lens removal is typically followed by implantation of an artificial intraocular lens to restore vision. The success of this procedure is mainly dependent on the developmental stage of the cataract to be removed. This article reviews cataract development and provides the clinician with cataract referral criteria.

Clinical features and outcomes of phacoemulsification in 39 horses: a retrospective study (1993–2003)

OBJECTIVE

To identify visual outcome and postoperative complications following phacoemulsification of equine cataracts.

ANIMALS

Records of 39 horses (55 eyes) with cataracts were reviewed.

METHODS

Eyes with cataracts removed by phacoemulsification were included in the study. Data collected included age, breed, sex, stage and etiology of cataract, unilateral vs. bilateral involvement, and ultrasound findings. Horses were grouped by etiology of the cataract. Visual outcome and complications were evaluated for each group and the overall population.

RESULTS

Immediately postoperatively 46 out of 47 eyes (98%) were sighted. Four weeks postoperatively 23 of 29 operated eyes (79%) were sighted [13/18 (72%) eyes with congenital/juvenile onset, 6/6 (100%) eyes with traumatic and 4/5 (90%) eyes with uveitis-induced cataracts], with 18 eyes lost to follow-up. The most common postoperative complications included corneal edema (19 eyes/40%), fibrin in the anterior chamber (11 eyes/23%), postoperative ocular hypertension (9 eyes/19%), synechia/dyscoria (9 eyes/19%), and hyphema (7 eyes/15%).

CONCLUSIONS

Prognosis for vision is favorable for horses following phacoemulsification and planned posterior continuous tear circular capsulorrhexis. Success rates depend on age of patient, cause of cataract and pre-existing intraocular disease. The highest success rate occurred in eyes with traumatic cataracts.

Evaluation of client perceptions concerning outcome of cataract surgery in dogs

OBJECTIVE

To compare client perception of outcome of phacoemulsification in dogs with information obtained from medical records.

DESIGN

Retrospective cohort study.

ANIMALS

108 dogs (203 eyes) undergoing phacoemulsification from May 1999 through April 2004.

PROCEDURE

Data obtained from medical records included signalment, presence of diabetes mellitus, cataract stage, whether surgery was unilateral or bilateral, intraocular lens (IOL) placement, and postoperative complications. Owners completed a survey concerning outcome of phacoemulsification in their dog. Survey responses from owners classified as satisfied or dissatisfied with the outcome of phacoemulsification on the basis of their willingness, in retrospect, to have the surgery performed again were compared.

RESULTS

Data from medical records and survey responses were available for 108 dogs (203 eyes). Median follow-up was 3 months via medical record review and 12 months via owner survey responses. Most (81%) owners were satisfied with outcome. The most common reason for dissatisfaction was loss of vision after surgery; however, most dissatisfied owners did not return their dog for examinations. Owner perception of success was not associated with patient age, sex, presence of diabetes mellitus, cataract stage, or IOL placement in at least 1 eye but was associated with perceived improvement of their pet's vision and activity level. Dissatisfied owners were significantly more likely to report that explanation of risks and complications before surgery was inadequate.

CONCLUSIONS AND CLINICAL RELEVANCE

Owner perception of outcome after phacoemulsification in dogs was highly favorable. However, surgical risks and the importance of postoperative examinations, particularly in dogs undergoing visual deterioration, must be conveyed to clients.

Long-term complications after phacoemulsification for cataract removal in dogs: 172 cases (1995–2002)

OBJECTIVE

To determine common postoperative complications and risk factors for development of postoperative glaucoma or failure to preserve vision after phacoemulsification for cataract removal in dogs. Design-Retrospective case series.

ANIMALS

172 dogs (290 eyes) that underwent phacoemulsification surgery for cataract removal.

PROCEDURE

Medical records were reviewed for postoperative complications; prevalence rates for each complication were calculated for follow-up periods of 3 months, > 3 to 6 months, > 6 months to 1 year, > 1 to 2 years, > 2 to 3 years, > 3 to 4 years, and > 4 years. Odds ratios for breed, age, sex, cataract hypermaturity, lens-induced uveitis, and diabetes mellitus were determined with respect to glaucoma and failure (ie, blindness, enucleation, or evisceration).

RESULTS

The most common complication was mild posterior capsule opacification. Retinal detachment was uncommon (1% to 2%) for all time periods. Prevalence of glaucoma increased with time, although it remained < 10% until after the 1-year follow-up period. Boston Terriers, Cocker Spaniels, Cocker Spaniel-Poodle crosses, and Shih Tzus had increased risk of developing glaucoma. Eyes with hypermature cataracts were more likely to develop glaucoma. Prevalence of failure increased with time, although it remained < 10% until after the 3-year follow-up period. Cocker Spaniel-Poodle cross and Shih Tzus were more likely to have failure.

CONCLUSIONS AND CLINICAL RELEVANCE

Evaluation of breed and cataract hypermaturity may aid in the selection of patients. The increasing prevalence of postoperative complications with time indicated that longterm monitoring is warranted.

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.

Cardiovascular effects of topical ophthalmic 10% phenylephrine in dogs

OBJECTIVE

To evaluate the effect of topical ophthalmic 10% phenylephrine on systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), pulse rate (PR) and electrocardiogram (ECG) in dogs.

ANIMALS STUDIED

Nine clinically normal dogs.

PROCEDURE

Arterial catheters were placed in the dorsal pedal artery of awake dogs and ECG leads were attached. After a 15-min acclimatization period, baseline PR, SAP, DAP and MAP were recorded every 5 min for 20 min. Two treatment groups (eight dogs each) were studied. Group I: one drop of phenylephrine was placed in each eye once. Group II: one drop of phenylephrine was placed in each eye three times at 5-min intervals. Following treatment, PR, SAP, DAP and MAP were recorded every 5 min for 90 min. The mixed procedure of the SAS system was used to perform a repeated measures analysis of variance to test for linear and quadratic trends across time.

RESULTS

Group I: There was a significant quadratic decrease in PR across time (P = 0.0051). Systolic arterial pressure increased linearly with time (P = 0.0002), MAP increased linearly with time (P = 0.0131), and DAP increased linearly with time (P = 0.0001). Group II: There was a significant quadratic decrease in PR across time (P = 0.0023). There was a significant quadratic increase in SAP (P = 0.0324), MAP (P = 0.0103) and DAP (P = 0.0131) across time.

CONCLUSIONS

Topical ophthalmic application of 10% phenylephrine in normal dogs results in elevation of arterial blood pressure and reflex bradycardia.

A study of the morphology of canine eyes enucleated or eviscerated due to complications following phacoemulsification

This study was undertaken to describe the histopathologic abnormalities observed in canine eyes enucleated or eviscerated due to complications following phacoemulsification; to correlate these findings with the clinical abnormalities reported, and to suggest, if apparent, likely causes and effects of these abnormalities. Sixty-six canine globes or evisceration samples received for histopathologic interpretation over a 10-year period (1990-2000) were studied. All globes and evisceration samples were obtained from clinical patients examined by board-certified ophthalmologists. Hematoxylin and eosin (H&E) and alcian blue/periodic acid Schiff (PAS) stained sections were examined by light microscopy in every case. A tissue Gram stain was used when indicated. Clinical information obtained from the pathology submission form was reviewed in all cases, and obtained from questionnaires completed and returned by an ophthalmologist for 51 cases (77%). The most frequent histopathologic diagnoses were glaucoma (76%) and retinal detachment (64%). The most frequently reported clinical abnormalities in this series were glaucoma (86%) and uveitis (82%). Five problem areas were identified that appear to make a significant contribution to the failure of canine cataract surgery and merit further investigation: pre-iridal fibrovascular membranes; lens fiber regrowth; lens epithelial membranes; endophthalmitis, and the health of the corneal surgical incision.