The TGM2 inhibitor cysteamine hydrochloride does not impact corneal epithelial and stromal wound healing in vitro and in vivo.

Corneal wound healing is integral for resolution of corneal disease or for post-operative healing. However, corneal scarring that may occur secondary to this process can significantly impair vision. Tissue transglutaminase 2 (TGM2) inhibition has shown promising antifibrotic effects and thus holds promise to prevent or treat corneal scarring. The commercially available ocular solution for treatment of ocular manifestations of Cystinosis, Cystaran®, contains the TGM2 inhibitor cysteamine hydrochloride (CH). The purpose of this study is to assess the safety of CH on corneal epithelial and stromal wounds, its effects on corneal wound healing, and its efficacy against corneal scarring following wounding. Quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC) were first used to quantify and localize TGM2 expression in the cornea. Subsequently, (i) the in vitro effects of CH at 0.163, 1.63, and 16.3 mM on corneal epithelial cell migration was assessed with an epithelial cell migration assay, and (ii) the in vivo effects of application of 1.63 mM CH on epithelial and stromal wounds was assessed in a rabbit model with ophthalmic examinations, inflammation scoring, color and fluorescein imaging, optical coherence tomography (OCT), and confocal biomicroscopy. Post-mortem assessment of corneal tissue post-stromal wounding included biomechanical characterization (atomic force microscopy (AFM)), histology (H&E staining), and determining incidence of myofibroblasts (immunostaining against α-SMA) in wounded corneal tissue. TGM2 expression was highest in corneal epithelial cells. Application of the TGM2 inhibitor CH did not affect in vitro epithelial cell migration at the two lower concentrations tested. At 16.3 mM, decreased cell migration was observed. In vivo application of CH at 57 mM was well tolerated and did not adversely affect wound healing. No difference in corneal scarring was found between CH treated and vehicle control eyes. This study shows that the TGM2 inhibitor CH, at the FDA-approved dose, is well tolerated in a rabbit model of corneal wound healing and does not adversely affect epithelial or stromal wound healing. This supports the safe use of this medication in Cystinosis patients with open corneal wounds. CH did not have an effect on corneal scarring in this study, suggesting that Cystaran® administration to patients with corneal wounds is unlikely to decrease corneal fibrosis.

Visceral smooth muscle α-actin deficiency associated with chronic intestinal pseudo-obstruction in a Bengal cat (Felis catus x Prionailurus bengalensis).

An adult Bengal cat (Felis catus × Prionailurus bengalensis) with a prolonged history of partial anorexia, regurgitation, and weight loss and a clinical, radiographic, and ultrasonographic diagnosis of persistent megaesophagus and gastrointestinal ileus was submitted for necropsy. The intestinal tract was diffusely distended by gas and fluid with appreciable loss of muscle tone and an absence of luminal obstruction, consistent with the clinical history of chronic intestinal pseudo-obstruction. Histologically, the autonomic nervous system was intact, but the smooth muscle within the gastrointestinal wall exhibited a marked basophilia that was most pronounced in the jejunum. Immunohistochemistry for neurofilament, synaptophysin, CD117, and desmin demonstrated that the number of myenteric ganglia, number of interstitial cells, and leiomyocyte desmin content were similar when compared with the unaffected age- and species-matched control. Immunohistochemistry for smooth muscle α-actin demonstrated a striking loss of immunoreactivity, predominantly in the circular layer of the jejunum, that corresponded with the tinctorial change in leiomyocytes. Transmission electron microscopy revealed loss of myofibrils, loss of organelle polarity, and significantly larger central mitochondria (megamitochondria) in affected leiomyocytes, as well as nonspecific degenerative changes. Although the presence of a primary leiomyopathy and a causal relationship could not be confirmed in this case, leiomyopathies are considered a cause of chronic intestinal pseudo-obstruction in human medicine, and loss of smooth muscle α-actin immunoreactivity is one recognized marker for intestinal dysmotility.

XIAP-mediated neuroprotection in retinal ischemia.

Retinal ischemia results in the loss of vision in a number of ocular diseases including acute glaucoma, diabetic retinopathy, hypertensive retinopathy and retinal vascular occlusion. Recent studies have shown that most of the neuronal death that leads to loss of vision results from apoptosis. XIAP-mediated gene therapy has been shown to protect a number of neuronal types from apoptosis but has never been assessed in retinal neurons following ischemic-induced cell death. We injected an adeno-associated viral vector expressing XIAP or GFP into rat eyes and 6 weeks later, rendered them ischemic by raising intraocular pressure. Functional analysis revealed that XIAP-treated eyes retained larger b-wave amplitudes than GFP-treated eyes up to 4 weeks post-ischemia. The number of cells in the inner nuclear layer (INL) and the thickness of the inner retina were significantly preserved in XIAP-treated eyes compared to GFP-treated eyes. Similarly, there was no significant reduction in optic nerve axon numbers in XIAP-treated eyes. There were also significantly fewer TUNEL (TdT-dUTP terminal nick end labeling) positive cells in the INL of XIAP-treated retinas at 24 h post-ischemia. Thus, XIAP-mediated gene therapy imparts both functional and structural protection to the retina after a transient ischemic episode.

Vigabatrin effect on inner retinal function.

OBJECTIVE: To determine the degree of electroretinal dysfunction in a group of patients taking Vigabatrin (VGB). Additionally, to investigate the role of cumulative dosage, the role of VGB alone or in combination with other anticonvulsants, and whether recent discontinuance of VGB affects electroretinal function as measured by the electroretinogram (ERG). DESIGN: Retrospective, comparative case series. PARTICIPANTS: Forty patients (18 male, 22 female) with a mean age of 35 years were studied as three groups: the VGB multitherapy group (n = 24) included those taking VGB with other anticonvulsants, the VGB monotherapy group (n = 9) included those taking VGB alone, and the off-VGB group (n = 7) included those who had discontinued VGB in the last 6 months. METHODS: Scotopic flash, photopic flash, and 30-Hz flicker ERG results were recorded according to the International Society for Clinical Electrophysiology of Vision (ISCEV) standard. The clinical electro-oculogram (EOG) results were recorded according to the ISCEV standard. MAIN OUTCOME MEASURES: Implicit time and amplitudes of the A- and B-waves of the flash and 30-Hz flicker ERGs were recorded. Summed amplitude of the first three oscillatory potential wavelets were recorded. The light-peak to-dark-trough Arden ratio of the EOG was evaluated. RESULTS: Although photopic ERG B-wave reduction was most frequent in patients in the VGB multitherapy group (48% of eyes), a significant number of eyes in all three groups had scotopic ERG B-wave reduction. The 30-Hz flicker ERG result was abnormally reduced in all three groups. There was no significant difference in the frequency of occurrence in ERG result abnormalities between the VGB monotherapy and VGB multitherapy groups. The EOG results revealed reduced Arden ratios in all three groups; however, there was a significantly lower frequency of EOG abnormalities noted in the off-VGB group (P = 0. 0373). There was no statistically significant relationship between the frequency of electrodiagnostic abnormalities and the duration of use or the total cumulative dosage of Vigabatrin in any of the three groups. CONCLUSIONS: These findings of scotopic ERG result abnormalities suggest that VGB alone has an effect on inner electroretinal function at the level of the Müller cell. Concomitant EOG abnormalities suggest a substantial effect of VGB on outer retinal function that may be reversible after cessation of VGB treatment.

Prevalence of factor V Leiden and activated protein C resistance in central retinal vein occlusion.

PURPOSE: Factor V Leiden is a common inherited mutation that is a significant risk factor for deep vein thrombosis. It results in resistance to activated protein C (APC). The association between factor V Leiden and central retinal vein occlusion (CRVO) remains controversial. This study was designed to determine the prevalence of APC resistance and the factor V Leiden mutation in patients with CRVO in a controlled study. METHODS: The study was designed as a case control study conducted in a tertiary care retina practice. The prevalence of APC resistance and factor V Leiden was determined by genetic testing of blood samples obtained from patients with CRVO and clinic control patients. RESULTS: Factor V Leiden was identified in 2.3% of patients with CRVO and 3.5% of clinic control patients. There was no significant association between the presence of factor V Leiden and CRVO (odds ratio, 1.13; 95% confidence interval, 0.65-1.98; P = 0.66). CONCLUSION: Factor V Leiden does not appear to be associated with CRVO. Routine screening of patients with CRVO does not appear to be warranted.

Management of submacular hemorrhage with intravitreal sulfur hexafluoride: a pilot study.

BACKGROUND: Some success has been reported with the intravitreal use of tissue plasminogen activator (tPA) and perfluoropropane gas in the management of large submacular hemorrhages. However, the dosage of tPA that has been used (100 micrograms) has a narrow margin of safety, and it remains to be shown that intravitreal tPA can cross the retina and effect subretinal clot lysis. We carried out a pilot study to evaluate the efficacy of intravitreally administered sulfur hexafluoride (SF6) gas alone in the management of large submacular hemorrhages secondary to age-related macular degeneration (AMD). METHODS: Three patients with large submacular hemorrhages secondary to AMD seen at a university-affiliated teaching hospital in Ottawa were treated with an intravitreal injection of 0.6 mL of SF6 gas. They were instructed to assume a prone position for 7 to 10 days. The patients were followed 3, 7, 14 and 28 days after the procedure and monthly thereafter for at least 6 months. Colour photography and fluorescein and indocyanine green angiography were performed immediately before and 2 weeks after the procedure and, thereafter, at the discretion of the treating ophthalmologist. RESULTS: In all three cases significant inferior displacement of the submacular blood was observed. Two patients showed an improvement of vision from counting fingers to 20/70 and to 20/200. In one case the submacular blood was displaced such that laser photocoagulation of a juxtafoveal choroidal neovascular membrane became possible. INTERPRETATION: The results suggest that intravitreally administered SF6 alone may have a role in the management of selected cases of neovascular AMD complicated by significant submacular hemorrhage. These results call into question the utility of adjunctive intravitreal tPA in such cases.

Toxicity of intravitreal interferon alpha-2b in the rabbit.

OBJECTIVE: To investigate the toxicity of single doses of intravitreally administered interferon alpha-2b in the New Zealand white albino rabbit. INTERVENTIONS: One eye each of six rabbits received an intravitreal injection of 1000, 10,000, 100,000, 500,000, 1 million or 2 million units of interferon alpha-2b reconstituted in 0.1 mL of balanced salt solution. The fellow eye of the first three rabbits received an intravitreal injection of the same volume of balanced salt solution. OUTCOME MEASURES: Media opacities, toxic effects to the retina, optic nerve or other ocular structures. RESULTS: The injection of 2 million units of interferon alpha-2b elicited an immediate dense vitreous haze that largely cleared within 24 hours as well as numerous intraretinal hemorrhages that were no longer visible 7 days after injection. Histopathological study of this eye 14 days after injection showed a diffuse mixed inflammatory cell infiltrate with retinal vacuolation and ganglion cell dropout. In the remaining eyes, to dosages of 1 million units, the agent produced no clinically or pathologically evident toxic ocular effects. CONCLUSIONS: Interferon alpha-2b appears to be safe and well tolerated up to dosages of 1 million units.

Fifteen year review of treated cases of retinal angiomatosis.

This study describes the experience of the Wills Eye Hospital Retina Service in the treatment of 125 eyes with retinal angiomatosis, with follow-up ranging from 1 to 15 years. The results of several treatment modalities are compared. In lesions smaller than 2.5 DD, xenon arc photocoagulation, argon laser photocoagulation, and cryotherapy all appear to be effective in eradicating the tumor and salvaging useful visual acuity. For lesions larger than 2.5 DD, cryotherapy appeared to offer the best results. The advantages and disadvantages of the various treatment modalities are discussed.

The diagnosis of uveal malignant melanomas in eyes with opaque media.

Of 358 eyes enucleated between 1962 and 1975, and found to contain posterior uveal melanomas, 31 had opaque media (8.6%). Eighteen of these patients with opaque media were seen between 1962 and 1971, before the use of combined ultrasonography and the radioactive phosphorus uptake (32P) test. Melanoma was unsuspected at enucleation in one third of these patients and there was often a long delay in diagnosis. Of the 13 patients seen between 1971 and 1975, after the initiation of combined ultrasonography and 32P) test, there was no delay in diagnosis becuase a melanoma pattern was recognized immediately with ultrasonography and confirmed with a positive 32P test. During the latter part of this study, 19 patients with opaque media had a "melanoma pattern" with ultrasonography. The 32P test was positive in 12 cases and a melanoma was confirmed histologically in every instance. The 32P test was negative in seven cases and all were documented on follow-up to have benign lesions, such as subretinal hemorrhages.

Multilobed uveal melanoma masquerading as postoperative choroidal detachment.

A case of multilobed malignant melanoma with a haemorrhagic retinal detachment which mimicked a postoperative choroidal detachment is described. Because the lesion showed no resolution six weeks after cataract surgery a tumour evaluation was undertaken. The diagnosis was established with a positive radioactive phosphorus uptake (32P) test and biopsy of the intraocular mass. A suggested approach to the diagnosis in such difficult cases is proposed.

B-scan ultrasonography in the diagnosis of atypical retinoblastomas.

Contact B- scan ultrasonography (Bronson-Turner unit) was performed on fourteen patients with retinoblastoma. In ten cases, the patient presented with leukocoria, and ultrasonography was helpful in confirming the clinical diagnosis. In four atypical cases contact B-scan ultrasonography was instrumental in making the diagnosis. The ultrasonographic pattern for retinoblastoma is characteristic but not pathognomic. There is a solid intraocular echo corresponding to the tumor and within it are numerous dense focal echoes which persist at lower sensitivities, suggesting calcification. Calcification was demonstrated ultrasonographically and confirmed histologically in all four of these atypical cases, but routine skull x-rays failed to demonstrate calcium in three of the four children. Contact B- scan ultrasonography is a safe and simple procedure which may provide valuable diagnostic information in children with suspected retinoblastoma.

Malignant melanomas of the uveal tract in children and young adults.

The Wills Eye Hospital experience with 17 cases of malignant melanoma of the uvea affecting children and young adults was reviewed. They did not appear to differ clinically or histologically from uveal melanomas in older patients, except that in most cases there was a considerable delay in diagnosis, perhaps reflecting a lack of clinical suspicion. Ancillary diagnostic techniques, such as fluorescein angiography, ultrasonography, and 32P studies were often helpful in arriving at the correct diagnosis once the lesion was suspected and referred for evaluation. Malignant melanoma of the uveal tract is not exclusively a disease of old age, and this diagnosis should not be excluded on the basis of the patient's age alone.