Cataract surgery. Current approaches

Avaliação ultrassonográfica do bulbo ocular em cães submetidos à facoemulsificação com ou sem implante de lente intraocular

Este trabalho objetivou descrever e comparar as alterações ultrassonográficas encontradas em bulbos oculares de cães submetidos à facoemulsificação, com ou sem implante de lente intraocular (LIO), no intuito de auxiliar no diagnóstico de alterações decorrentes da cirurgia e do implante da LIO, bem como sua correspondência com alterações clínicas. Dezenove cães portadores de catarata (21 olhos) foram submetidos ao procedimento de facoemulsificação e avaliados no pós-operatório tardio, aos cinco anos de evolução. Constituíram-se três grupos experimentais: afácicos (CA), formados por 11 cães; pseudofácicos (PP), com implante de duas LIOs em piggyback (n=5); e pseudofácicos (PL), com implante de uma LIO veterinária (n=5). Após exame oftálmico, todos foram submetidos ao exame ultrassonográfico, sob anestesia tópica, com transdutor linear multifrequencial de 10MHz; adicionalmente foram avaliadas medidas biométricas dos bulbos do olho. As principais alterações observadas foram: luxação da LIO, descolamento de retina, hialose asteroide e degeneração vítrea. O exame ultrassonográfico mostrou-se como excelente ferramenta diagnóstica e possibilitou a confirmação e a classificação dessas alterações. Na biometria ocular, pelas medidas entre o corpo ciliar e a câmara vítrea, o implante em piggyback resultou em redução destas em relação aos demais procedimentos instituídos, não havendo diferença ente o comprimento axial e a câmara anterior.

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.

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.

Uso de viscoelásticos na facoemulsificação em cães portadores de catarata: efeitos sobre a pressão intraocular, a morfologia das células endoteliais e a espessura corneana

Avaliaram-se as células endoteliais, a espessura corneana e a pressão intraocular (PIO) de cães portadores de catarata madura, empregando-se viscoelástico à base de hialuronato de sódio 3% e sulfato de condroitina 4% e hidroxipropilmetilcelulose 2%, utilizando-se 20 cães, distribuídos entre os dois grupos dos viscoelásticos. A técnica cirúrgica adotada foi a da facoemulsificação bimanual. As avaliações tonométricas foram efetuadas antes e após o ato cirúrgico, aos 1, 7, 14, 21, 28 e 60 dias de pós-operatório, e a microscopia especular, antes e após 7, 28 e 60 dias. Não houve diferença estatística entre os grupos quanto à PIO, com exceção aos 14 dias, em que se observou maior PIO com o uso de hialuronato de sódio 3% e sulfato de condroitina 4%. Não houve diferença entre os grupos quanto aos parâmetros relacionados ao endotélio, com diminuição discreta da densidade celular endotelial e aumento da área celular com a utilização de hidroxipropilmetilcelulose 2%. A utilização de ambos os dispositivos viscoelásticos analisados é recomendada para o procedimento de facoemulsificação em cães.

Modified extracapsular extraction versus endocapsular phacoemulsification: intraoperative and immediate postoperative events

The clinical events and variations in intraocular pressure (IOP) that occur in endocapsular phacoemulsification technique were compared to the modified extracapsular extraction technique during the intraoperative and immediate postoperative periods. Phacoemulsification technique caused less corneal edema, less ocular discomfort and fewer postoperative complications than the modified extracapsular extraction technique. The observed increase in postoperative IOP, especially in the case of phacoemulsification, makes pressure monitoring mandatory, as well as the use of ocular hypotensive agents when the IOP exceeds acceptable limits.

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.

Combined transscleral diode laser cyclophotocoagulation and Ahmed gonioimplantation in dogs with primary glaucoma: 51 cases (1996-2004)

OBJECTIVE

To evaluate the combined diode laser cycloablation procedure and adjunctive Ahmed gonioimplant use in dogs with primary glaucoma.

DESIGN

Retrospective study.

ANIMALS

48 dogs, 51 eyes with primary glaucoma.

PROCEDURE

Medical records from two large private clinical ophthalmology services were reviewed. Signalment, duration of glaucoma, gonioscopic evaluation, laser power and duration settings, immediate postoperative and final intraocular pressure and visual results, short and long-term visual outcome, and surgical complications were recorded.

RESULTS

The age range of affected dogs was 3.0-14.0 years, with a mean age of 7.5 +/- 2.6 years. Eleven pure breeds were represented, with the most common being the American Cocker Spaniel. The sex distribution was 22 neutered males, 1 intact male, 23 spayed females, and 2 intact female dogs. The right eye was affected in 33 cases, and the left eye in 18 cases. The average total joules, which was administered with the diode laser, was 109.6 +/- 23.6 J. Immediate surgical complications included fibrin formation in the anterior chamber (15), corneal ulcers (4), hyphema (7), and focal retinal detachment (1). Long-term complications included cataract formation (8 total, 2 of which were significant, vision-threatening), elevated intraocular pressure (IOP) (6), unstable gonioimplant (1), and glaucoma recurrence (14). Additional surgeries performed on the eyes over the course of study included: intrascleral prosthesis (4), enucleation (1), resection of fibrotic scar tissue (5), and repeat laser cycloablation (8). The dogs were examined for a mean follow-up time of 17.6 months (range: 2-83 months postoperatively). Twenty-nine cases were followed greater than one year. Vision was maintained in 42/51 eyes (82%) in the immediate short-term of this study. In all cases included in the study, good control of IOP was achieved in 39/51 (76%) of eyes, and IOP was poor or uncontrolled in 12/51 (24%) of eyes. Twenty out of 41 eyes (49%) maintained fair to excellent vision six months after surgery. Twelve months postoperative observations demonstrated that 12/29 (41%) of the eyes were still visual.

CONCLUSIONS

In primary glaucoma, the combined procedure of laser diode cyclophotocoagulation and Ahmed valve implant was associated with return or maintenance of vision in 42/51 eyes (82%) in the immediate short-term of this study, and a long-term IOP control in 39/51 (76%) of the cases, with 12/29 eyes (41%) visual after 12 months.

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.

Lasers in ophthalmology

Laser technology continues to progress with the addition of new lasers, new delivery systems, and new applications. The introduction of lasers to veterinary ophthalmology has radically changed the level of care that we can provide to our patients. The development of the diode laser has particularly had an impact on veterinary ophthalmology. The diode's affordability, portability, and broad applications for veterinary patients have allowed laser surgery to become a routine part of veterinary ophthalmology practice. Educating the public and veterinary community in available laser techniques will generate improved ophthalmic care and provide more data on which to build future applications.

Uveitis and pupillary block glaucoma in an aphakic dog

Unilateral uveitis with pupillary occlusion and secondary glaucoma was treated with neodymium:YAG laser iridotomy and iridencleisis in an aphakic 2-year-old male Miniature Schnuauzer. The dog presented 4 months after bilateral phacoemulsification with a complaint of blepharospasm of the left eye. Examination revealed anterior uveitis with pupillary occlusion and iris bombé. A slit-lamp mounted Q-switched Nd:YAG laser was used to create a central iridotomy to deepen the anterior chamber and an iridencleisis was performed to recreate a pupil. The eye remained visual and normotensive over a 6-month follow-up period.

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.

Ocular manifestations of diabetes mellitus: diabetic cataracts in dogs

Cataracts form in diabetic dogs because of the disruption of normal lens metabolism. The pathophysiology seems to be a combination of increased lens cell membrane permeability, reduced cell membrane function, damage from accumulating osmotic products (polyols), glycosylation of lens proteins, and oxidative injury. Lens-induced uveitis must be recognized and managed in presurgical preparation of dogs with diabetes cataracts. Phacoemulsification is the current treatment of choice for diabetic cataracts in dogs and can be performed at an earlier time than traditional extracapsular lens extraction. This may allow for greater success rates after surgery.