Focal irradiation of perforating eye injuries

Plaques constructed with 125I were used to irradiate the sites of perforating ocular injuries in rabbits. An approximate dose of 16Gy given over a period of 6 days was shown to significantly reduce intraocular cellular proliferation when irradiation was commenced within 24 hours after injury. If irradiation was delayed until day 5, this reduction in cellular proliferation and intraocular membrane formation did not occur. Smaller radiation doses of approximately 6Gy given within 24 hours post-injury and administered over 6 days also reduced the extent of cellular proliferation but was not as effective as the 16Gy dose.

A light microscopic and autoradiographic study of non-irradiated and irradiated ocular wounds

Focal gamma irradiation was used to limit the intraocular extension of scar tissue which typically occurs after posterior perforating injury to the eye. Standard posterior perforating injuries were created in the right eye of forty-eight rabbits, half of which had the site of perforation focally irradiated using a Cobalt 60 ophthalmic plaque. Non-irradiated wounds healed with profuse formation of highly cellular and vascularised granulation tissue which invaded the vitreous to form contractile vitreo-retinal membranes. In irradiated eyes vitreo-retinal membrane formation was infrequent; the wounds showing only sparse granulation tissue with little or no extension into the vitreous cavity. Autoradiographic studies carried out in a second group of 40 animals showed that the episclera was the main source of the proliferating fibroblasts, and cell counts confirmed that the inflammatory and repair responses in irradiated wounds were both delayed and attenuated.

Localised gamma irradiation and experimental intraocular proliferation

A controlled study was undertaken to assess the effect of gamma irradiation on post-traumatic intraocular cellular proliferation. A standard perforating injury in the posterior segment of the rabbit eye was used to induce intraocular cellular proliferation and vitreo-retinal membrane formation. The site of injury was irradiated with an ophthalmic Cobalt60 applicator which provided a continuous source of gamma rays. Non-irradiated eyes developed traction retinal detachments associated with post-traumatic vitreo-retinal membranes. Irradiated eyes developed attenuated membranes or atrophic retinal scars, with the retina remaining attached. The membranes in non-irradiated eyes were highly cellular with abundant collagen, while irradiated membranes had fewer cells within a sparse collagen matrix. The episcleral fibroblasts, on autoradiographic studies appeared to be the main source of the cells that formed the proliferating tissue in both non-irradiated and irradiated eyes. In irradiated eyes both the inflammatory response and division of fibroblasts were delayed and reduced.

Exploring eye movement analysis as a measure of selective visual attention in brain injured individuals

Primary Objective: To investigate the utility of using a new method of assessment for deficits in selective visual attention (SVA). Methods and Procedures: An independent groups design compared six participants with brain injuries with six participants from a non-brain injured control group. The Sensomotoric Instruments Eye Movement system with remote eye-tracking device (eye camera), and 2 sets of eight stimuli were employed to determine if the camera would be a sensitive discriminator of SVA in these groups. Main Outcomes and Results: The attention profile displayed by the brain injured group showed that they were slower, made more errors, were less accurate, and more indecisive than the control group. Conclusions: The utility of eye movement analysis as an assessment method was established, with implications for rehabilitation requiring further development. Key words: selective visual attention, eye movement analysis, brain injury

Surveillance of severe chemical corneal injuries in the UK

AIM: To estimate the incidence of severe chemical corneal injuries in the UK and describe presenting clinical features and initial management.

METHODS: All patients with severe chemical corneal injury in the UK from December 2005 to November 2006 inclusive were prospectively identified using the British Ophthalmological Surveillance Unit. Reporting ophthalmologists provided information regarding presentation and follow-up.

RESULTS: Twelve cases were identified, giving a minimum estimated incidence in the UK of severe chemical corneal injury of 0.02 per 100,000. 66.7% of injuries were in males of working age, 50% occurred at work, and alkali was causative in 66.7%. Only one patient was wearing eye protection at the time of injury, 75% received immediate irrigation. Six patients required one or more surgical procedures, most commonly amniotic membrane graft. At 6 months' follow-up, the best-corrected visual acuity was 6/12 or better in five patients, and worse than 6/60 in two.

CONCLUSION: The incidence of severe chemical corneal injury in the UK is low. The cases that occur can require extended hospital treatment, with substantial ocular morbidity and visual sequelae. Current enforcement of eye protection in the workplace in the UK has probably contributed to a reduced incidence of severe ocular burns.

Eye Spy Private High: Re-conceptualizing High Policing Theory

This paper contests traditional analyses of high policing, suggesting that it needs to be decoupled (in theoretical terms) from its umbilical linkage to public actors and the preservation and augmentation of state authority. Arguing that conventional conceptualizations of high policing fail to acknowledge the role of private actors, we adopt the term `private high policing' to more accurately reflect the complexity of this paradigm. In particular, we note a long legacy of protecting dominant interests within corporate power structures, as well as increased involvement in outsourced security services for Western states. This has reached its zenith in the recent conflict/reconstruction efforts in Iraq. Eschewing conventional notions of the `proxy' debate, we propose a more complex relationship of obfuscation whereby both public and private high policing actors cross-permeate and coalesce in the pursuit of symbiotic state and corporate objectives.

Effects of amisulpride, risperidone and chlorpromazine on auditory and visual latent inhibition, prepulse inhibition, executive function and eye movements in healthy volunteers.

In view of the evidence that cognitive deficits in schizophrenia are critically important for long-term outcome, it is essential to establish the effects that the various antipsychotic compounds have on cognition, particularly second-generation drugs. This parallel group, placebo-controlled study aimed to compare the effects in healthy volunteers (n = 128) of acute doses of the atypical antipsychotics amisulpride (300 mg) and risperidone (3 mg) to those of chlorpromazine (100 mg) on tests thought relevant to the schizophrenic process: auditory and visual latent inhibition, prepulse inhibition of the acoustic startle response, executive function and eye movements. The drugs tested were not found to affect auditory latent inhibition, prepulse inhibition or executive functioning as measured by the Cambridge Neuropsychological Test Battery and the FAS test of verbal fluency. However, risperidone disrupted and amisulpride showed a trend to disrupt visual latent inhibition. Although amisulpride did not affect eye movements, both risperidone and chlorpromazine decreased peak saccadic velocity and increased antisaccade error rates, which, in the risperidone group, correlated with drug-induced akathisia. It was concluded that single doses of these drugs appear to have little effect on cognition, but may affect eye movement parameters in accordance with the amount of sedation and akathisia they produce. The effect risperidone had on latent inhibition is likely to relate to its serotonergic properties. Furthermore, as the trend for disrupted visual latent inhibition following amisulpride was similar in nature to that which would be expected with amphetamine, it was concluded that its behaviour in this model is consistent with its preferential presynaptic dopamine antagonistic activity in low dose and its efficacy in the negative symptoms of schizophrenia.

Eye movements and neurocognitive function in treatment resistant schizophrenia: a pilot study.

Objectives: It is increasingly important to develop predictors of treatment response and outcome in schizophrenia. Neuropsychological impairments, particularly those reflecting frontal lobe function, appear to predict poor outcome. Eye movement abnormalities probably also reflect frontal lobe deficits. We wished to see if these two aspects of schizophrenia were correlated and whether they could distinguish a treatment resistant from a treatment responsive group. Methods: Ten treatment resistant schizophrenic patients were compared with ten treatment responsive patients on three eye movement paradigms (reflexive saccades, antisaccades and smooth pursuit), clinical psychopathology (BPRS, SANS and CGI) and a neuropsychological test battery designed to detect frontal lobe dysfunction. Ten aged-matched controls also carried out the eye movement tasks. Results: Both treatment responsive (p = 0.038) and treatment resistant (p = 0.007) patients differed significantly from controls on the antisaccade task. The treatment resistant group had a higher error rate than the treatment responsive group, but the difference was not statistically significant. Similar poor neuropsychological test performance was found in both groups. Conclusions: To demonstrate the biological differences characteristic of treatment resistance, larger sample sizes and wider differences in outcome between the two groups are necessary.