Immunohistochemical analysis of lens epithelial-derived membranes following cataract extraction in the dog

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.

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.

Immunohistochemical Characteristics of Normal Canine Eyes

Immunohistochemistry is widely utilized in diagnostic laboratories to study neoplastic and nonneoplastic diseases. Knowledge of the immunohistochemical characteristics of normal tissue is essential for interpretation of immunoreactivity in pathologic conditions. In this study, immunohistochemistry was performed with a broad panel of diagnostically relevant antibodies on 4 normal canine globes—namely, vimentin, pan-cytokeratin (AE1/AE3), cytokeratin 7, cytokeratin 8/18, cytokeratin 20, α–smooth muscle actin, muscle specific actin, desmin, Melan-A, microphthalmia transcription factor, S-100, glial fibrillary acidic protein, triple neurofilaments, neuron-specific enolase, chromogranin A, synaptophysin, laminin and CD31. Results include cytokeratin immunoreactivity limited to the conjunctival epithelium, corneal epithelium, and retinal pigment epithelium; distinct patterns of immunopositivity of muscle markers; and widespread immunoreactivity for vimentin and most neural/neuroendocrine markers. These findings in normal eyes provide the basis for interpretation of ocular immunohistochemistry in dogs. Published immunophenotypes of primary ocular neoplasms are also reviewed.

Meet the corneal myofibroblast: the role of myofibroblast transformation in corneal wound healing and pathology

In recent years the role of the myofibroblast in corneal wound healing has been extensively studied. The transformation of the corneal keratocyte to the fibroblast and myofibroblast phenotypes is a critical process in normal and pathologic corneal wound healing. This review will introduce this important transformation and its role in corneal wound healing and pathology.

Protein expression profiling of lens epithelial cells from Prdx6-depleted mice and their vulnerability to UV radiation exposure

Oxidative stress is one of the causative factors in progression and etiology of age-related cataract. Peroxiredoxin 6 (Prdx6), a savior for cells from internal or external environmental stresses, plays a role in cellular signaling by detoxifying reactive oxygen species (ROS) and thereby controlling gene regulation. Using targeted inactivation of the Prdx6 gene, we show that Prdx6-deficient lens epithelial cells (LECs) are more vulnerable to UV-triggered cell death, a major cause of skin disorders including cataractogenesis, and these cells display abnormal protein profiles. PRDX6-depleted LECs showed phenotypic changes and formed lentoid body, a characteristic of terminal cell differentiation and epithelial-mesenchymal transition. Prdx6(-/-) LECs exposed to UV-B showed higher ROS expression and were prone to apoptosis compared with wild-type LECs, underscoring a protective role for Prdx6. Comparative proteomic analysis using fluorescence-based difference gel electrophoresis along with mass spectrometry and database searching revealed a total of 13 proteins that were differentially expressed in Prdx6(-/-) cells. Six proteins were upregulated, whereas expression of seven proteins was decreased compared with Prdx6(+/+) LECs. Among the cytoskeleton-associated proteins that were highly expressed in Prdx6-deficient LECs was tropomyosin (Tm)2beta. Protein blot and real-time PCR validated dramatic increase of Tm2beta and Tm1alpha expression in these cells. Importantly, Prdx6(+/+) LECs showed a similar pattern of Tm2beta protein expression after transforming growth factor (TGF)-beta or H(2)O(2) treatment. An extrinsic supply of PRDX6 could restore Tm2beta expression, demonstrating that PRDX6 may attenuate adverse signaling in cells and thereby maintain cellular homeostasis. Exploring redox-proteomics (Prdx6(-/-)) and characterization and identification of abnormally expressed proteins and their attenuation by PRDX6 delivery should provide a basis for development of novel therapeutic interventions to postpone ROS-mediated abnormal signaling deleterious to cells or tissues.

Effect of ophthalmic Nd:YAG laser energy on intraocular lenses after posterior capsulotomy in normal dog eyes

OBJECTIVE

To determine Nd:YAG laser energy requirements for posterior capsulotomy and intraocular lens (IOL) damage threshold for foldable acrylic IOLs as compared to traditional polymethylmethacrylate (PMMA). MATERIALS AND PROCEDURES: Four groups of five-six fresh canine cadaver eyes were used in this study. The groups included (1) unaltered eyes (2) aphakic eyes (3) eyes implanted with PMMA IOLs, and (4) eyes implanted with acrylic IOLs. Laser energy was delivered to the posterior capsule in grid fashion for 10 sites each of five levels of laser energy ranging from 0.5 mJ to 9 mJ. Number of successful capsulotomy sites was recorded based on slit-lamp observation. Sites of IOL damage were evaluated using scanning electron microscopy (SEM). Statistical analysis of number of capsulotomies and IOL defects per laser energy level was conducted among and between groups using anova with Tukey's HSD test.

RESULTS

When comparing groups (a) including all energy levels (n = 25) and (b) by specific energy levels (n = 5), there was no significant difference (P < 0.05) in number of successful capsulotomy sites between IOL types. The 50% incidence threshold for successful capsulotomy was 2.74 mJ for acrylic IOLs and 2.64 mJ for PMMA IOLs. Energy-dependent damage to both types of IOL was detected for medium, high-medium, and high laser energy. Calculated 50% damage threshold was 4.9 mJ for acrylic IOL and 5.7 mJ for PMMA IOL. Damage to the IOL varied subjectively between IOL type, but there was no significant difference in number of defects caused, with the exception of high-medium energy.

CONCLUSIONS

Both posterior lens capsules and IOLs were disrupted in an energy-dependent manner with minimal difference in number of capsulotomy sites or damage to the IOL between acrylic and PMMA IOLs. A therapeutic margin between capsulotomy threshold (2.6-2.7 mJ) and IOL damage threshold (4.9-5.7 mJ) was determined to reliably achieve capsulotomies with minimal IOL damage for both acrylic and PMMA IOLs in normal canine cadaver eyes.

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.

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.

Feline intraocular tumors may arise from transformation of lens epithelium

Feline ocular sarcomas are malignant intraocular neoplasms that are frequently associated with a history of ocular trauma. They usually present as fibrosarcomas, but some have both epithelial and mesenchymal features. The purpose of this study was to determine the cell of origin of a subset of feline intraocular sarcomas that display a mixed epithelial-mesenchymal phenotype, with elaboration of basement membrane-type matrix. We examined the morphology and histochemical and immunohistochemical phenotypes of nine feline intraocular sarcomas. Immunohistochemistry and in situ hybridization were performed to detect expression of crystallin alpha A. In addition, tumors were examined for expression of vimentin, cytokeratin, smooth muscle actin, desmin, melan A, neural cell adhesion molecule, S-100, glial fibrillary acidic protein, nerve growth factor receptor, and collagen type IV. Animals ranged from 7 to 17 years of age--no breed or sex predilection for tumor occurrence was present. Tumors were characterized by mixed epithelial and mesenchymal phenotypes, both of which elaborated basement membrane-type material and expressed vimentin highly. On the basis of collagen type IV and crystallin alpha A immunopositivity, we established that three of nine tumors were of lens epithelial origin. Expression of desmin and smooth muscle actin identified one tumor as a leiomyosarcoma. The remainder were undifferentiated sarcomas of myofibroblastic origin. This is the first report of lens epithelial neoplasia in clinical material from any species. The history and morphologic features of feline ocular sarcomas are reminiscent of feline vaccine-induced sarcomas. These tumors may share pathophysiologic similarities unique to this species.