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Pig Eyes (pig + eye)

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Medical Sciences	100%

Selected Abstracts

Wireless contact lens sensor for intraocular pressure monitoring: assessment on enucleated pig eyes

ACTA OPHTHALMOLOGICA, Issue 4 2009
Matteo Leonardi
Abstract. Purpose:, Assessment on enucleated pig eyes of a novel and minimally invasive method for the continuous monitoring of intraocular pressure (IOP), based on a novel wireless contact lens sensor (CLS). Methods:, The wireless CLS is a disposable silicone soft contact lens with a sensor embedded in it, allowing the wireless measurement of changes in corneal curvature induced by IOP variations. A CLS was adapted and tested on enucleated pig eyes. To demonstrate the measurement principle of the device, the enucleated pig eye was cannulated, allowing precise control of IOP. The CLS signal was then compared to the imposed IOP. Results:, First, the IOP of enucleated pig eyes was changed between 11 and 14 mmHg, simulating ocular pulsation. Then, IOP was changed with static steps of 1 mmHg between 20 and 30 mmHg to assess the reproducibility and linearity of the CLS. In both cases, measurements from the CLS and IOP showed very good correlation. A calibration graph shows that the CLS is capable of monitoring the IOP of each individual eye with a reproducibility of ± 0.2 mmHg (95% confidence interval). Conclusion:, The wireless CLS shows a good functionality to monitor the IOP on enucleated pig eyes. The device is placed in the same way as a soft disposable contact lens. This device would allow a minimally invasive and continuous monitoring of IOP over prolonged periods of up to 24 hr, regardless of patient activity, thus opening up new diagnostic and therapeutic methods to manage glaucoma. [source]

Effects of intraperitoneal vitamin E, melatonin and aprotinin on leptin expression in the guinea pig eye during experimental uveitis

ACTA OPHTHALMOLOGICA, Issue 1 2006
Aysel Kükner
Abstract. Purpose:,To observe ultrastructural changes and leptin expression in the guinea pig eye during experimental uveitis (EU) and the effects of vitamin E, melatonin and aprotinin on leptin expression. Methods:,Thirty male guinea pigs were randomly classified into five groups. Group 1 was the control group. Groups 2, 3, 4 and 5 received intravitreal injections of bovine serum albumin (BSA) to induce EU. At the same time on the third day, groups 3 (EU + vitamin E), 4 (EU + melatonin) and 5 (EU + aprotinin) received intraperitoneal vitamin E (150 mg/kg), melatonin (10 mg/kg) and aprotinin (20 000 IU/kg), respectively. On the sixth day, histopathological and clinical scoring of inflammation were performed, and leptin expression was investigated in the retina, choroid, sclera, episclera and cornea, and compared. Results:,There was a remarkable increase in leptin expression in the retina, choroid, sclera and episclera in the EU group. Leptin expression in the treatment groups was similar to that in the control group. At light and electron microscopic levels, ganglion cells were oedematous and inner plexiform layer thickness had increased in the EU group retinas. Oedema was decreased in the treatment groups. Comparison of the EU and treatment groups revealed significant differences histopathologically and clinically. Conclusion:,Experimental uveitis causes an increase in leptin expression in the retina, choroid, sclera and episclera of guinea pigs. Vitamin E, melatonin and aprotinin inhibit this increase. Leptin seems to be closely related to ocular inflammation. [source]

Wireless contact lens sensor for intraocular pressure monitoring: assessment on enucleated pig eyes

Computer-assisted training system for pars plana vitrectomy

ACTA OPHTHALMOLOGICA, Issue 6 2003
Jost B. Jonas
Abstract. Purpose:,To evaluate whether microsurgical steps in vitreoretinal surgery can be taught by a computer-assisted training system. Methods:,This prospective, randomized experimental study included 14 ophthalmic residents and medical students who were completely inexperienced in microsurgery. They were randomized into two groups. The study group underwent training programmes in a computer-assisted training system for simulation of pars plana vitrectomy. The control group did not participate in any in vitro training. In the second phase of the study, participants of both groups performed a pars plana vitrectomy in three pig eyes, which included picking a metallic foreign body from the retinal surface. Results:,The amount of retinal detachment and the number of retinal defects at the end of the vitrectomies were smaller, the time needed to remove the foreign body was shorter, the number of retinal lesions associated with the foreign body removal was lower, and the mark given was better in the trained study group than in the untrained group. The relatively small number of study participants did not allow the differences between the study and control groups to reach the 5% level of error probability. Conclusions:,In an animal model, training by a computer-based medical work station for simulation of pars plana vitrectomy showed better outcome measures for trained study participants compared with untrained study participants. Future studies may show whether further refinements of such training programmes will result in statistically significantly better results in surgical outcome parameters. [source]

Mapping the surface astrocytes of the optic disc: a fluid-conducting role of the astrocytic covering of the central vessels

CLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 3 2010
Francisco J Carreras MD PhD
Abstract Background:, The vitreous interface of the optic nerve has been studied to delimit the covering of Elschnig's astrocytes and interstitial pathways of flow through the prelaminar region. Methods:, Perfusion of the prelaminar tissue under controlled pressure with a fluorescent marker injected into the vitreous cavity in pig eyes. The prelaminar region of the optic nerve and adjacent retina was fixed and flatmounted or frozen and cryosectioned and examined with the confocal laser microscope. Samples were also prepared for conventional transmission electron microscopy. Results:, The surface of the vitreous surface of the optic nerve is covered by a cobblestone-like pavement made of astrocytic projections. Intensely stained passages of different thickness indicate the presence of wide interconnected intercellular spaces in the covering of Elschnig's astrocytes. Those passages are absent in the intervascular areas occupied by axons and axon-linked astrocytes. Conclusions:, Delineation of the astrocytic pavement and the preferred flow routes formed by wide extracellular spaces are conspicuous features of the prelaminar region when examined with the confocal laser microscope and the help of sticky fluorescent tracer. This suggests that excess extracellular fluid can be interchanged with the vitreous by a network of interconnected extracellular spaces or preferred flow routes. Some pathogenic mechanisms can be related to fluid interchange in the optic nerve head. [source]