Study on blood-ocular barrier between the anterior and posterior chamber after peripheral iridectomy by contrast-enhanced magnetic resonance in rabbit / 中华实验眼科杂志

Background Whether ocular anterior and posterior chamber exist a blood-aqueous barrier is in controversy.Conventional method can not offer a good evidence because it is unable to detect the aqueous component in the posterior chamber.Objective This study was to investigate the distribution of Gadolinium-diethylene triamine pentaacetic acids(Gd-DTPA)after peripheral iridectomy with magnetic resonance imaging(MRI)in rabbit.Methods Monocular peripheral iridectomy was performed on the right eyes in 8 clean New Zealand white rabbits and the fellow eyes were as controls.0.2 ml/kg(0.5 mol/L)Gd-DTPA,a tracer of MRI,was injected into ear vein in vivo to scan the eyes with MRI for the observation of the permeability and distribution.The signal enhanced ratio of interest region associated with time were analyzed.Results The signal in ciliary body of both eyes showed an immediately sharp enhancement within 10 minutes following the injection of Gd-DTPA with a peak intensity at 30-40 minutes,and then the intensity was gradually weaken over time.The signal was stronger in the operative eyes than that in the fellow eyes.The signal in the posterior chamber was gradually increased after operation,however,that in posterior chamber of the control eyes was lower.The interest regions of Gd-DTPA were ciliary,anterior chamber and posterior chamber,and the enhanced signal intensities were consisted in the posterior chamber after operation.However,the increase of the signal was not seen in the posterior chamber in the control eyes.Conclusions The pathway of plasma protein entering into the anterior chamber is very different from that of aqueous secretion.There exists a barrier between the anterior and posterior chamber which might be an integral part of the blood-ocular barrier.

The Steroid Effect on the Blood-Ocular Barrier Change Induced by Triolein Emulsion as seen on Contrast-Enhanced MR Images

OBJECTIVE: The purpose of this study is to evaluate the effect of dexamethasone on the damaged blood-ocular barrier caused by triolein emulsion, using contrast-enhanced MR imaging. MATERIALS AND METHODS: An emulsion of 0.1-mL triolein in 20 mL of saline was infused into the carotid arteries of 32 cats, 12 cats were placed in the treatment group and 18 cats were placed in the Control group. Thirty minutes after the infusion of triolein emulsion, a set of orbital pre- and post-contrast T1-weighted MR images (T1WIs) were obtained. Infusion of 10 mg/kg dexamethasone into the ipsilateral carotid artery of each of the cats in the treatment group cats and 20 mL saline in each of the cats in the control group was given. A second set of pre- and post-contrast orbital T1WIs were obtained three hours following triolein emulsion infusion. Qualitative analysis was performed for the the anterior chamber (AC), the posterior chamber (PC), and in the vitreous humor of the ipsilateral and contralateral eyes. The signal intensity ratios of the ipsilateral eye over the contralateral eye were quantitatively evaluated in the three ocular chambers on the first and second set of T1WIs, and were then statistically compared. RESULTS: Qualitatively, the AC, the PC or the vitreous did not show immediate contrast enhancement on the first and the second set of post-contrast T1WIs. However, the AC and the PC showed delayed contrast enhancement for both groups of cats on the second pre-contrast T1WIs. No enhancement or minimally delayed enhancement was seen for the vitreous humor. Quantitatively, the signal intensity ratios in the PC of the treatment group of cats were statistically lower than the ratios of the control group of cats for the second set of T1WIs (p = 0.037). The AC and vitreous showed no statistically significant difference between the feline treatment group and control group (p > 0.05). CONCLUSION: Contrast-enhanced MR images revealed increased vascular permeability in the PC of the eye after infusion of triolein emulsion. Dexamethasone seems to decrease the breakdown of the blood-aqueous barrier in the PC.

Protecting effects of topical hypothermia to blood-ocular barriers in intraocular operation / 医学研究生学报

Objective:To investigate whether topical hypothermia circumstance has the protective effects to the blood-ocular barriers during intraocular operations.Methods:Twenty New Zealand albino rabbits accepted vitrectomy in both eyes,useing hypothermal(4-10℃) intraocular irrigating solution in left eye(hypothermal intraocular irrigating solution group),and useing room temperature(25℃) intraocular irrigating solution in right eye(room temperature intraocular irrigating solution group)during the vitrectomy.Twenty-four hours after the operation,the retina of both eyes were checked;each eye accepted cavum vitreum perforation,and 0.5 ml of intraocular fluid were aspirsted for biochemical detection as well;as well as the retinas cut off for transmission electron microscopical(TEM) observations. Results:Inflammatory reaction of anterior ocular and the uvea in left eyes were generally slighter than the right eyes;dioptric media clarity of left eyes were also better than that in left eyes;average total protein concentration of the intraocular fluid was obviously lower than that in left eye(P