Name: a reversible silicon oil-induced ocular hypertension model in mice
Uploaded: 2019-11-15T10:00:00
Description: Watch this Scientific Journal Video about A Reversible Silicon Oil-Induced Ocular Hypertension Model in Mice at JoVE.com

This work is supported by NIH grants EY024932, EY023295, and EY028106 to YH.

All procedures have been approved by the Institutional Animal Care and Use Committee (IACUC) of Stanford University.
1. Ocular hypertension induction by intracameral injection of SO
<ol>
	<li>Prepare a glass micropipette for intracameral SO injection by pulling a glass capillary with a pipette puller to generate a micropipette. Cut an opening at the tip of the micropipette and further sharpen the tip with a microgrinder-beveling machine to make a 35&#176;&#8722;40&#176; bevel.</li>
	<li>Poli...

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Here we demonstrate a simple but effective procedure for inducing sustained IOP elevation in the mouse eye by intracameral injection of SO. This procedure can be learned quickly by anyone with experience in microdissection under a microscope. The primary potential risk of failure is the leakage of SO from the corneal incision. However, one of the advantages of using SO is that because the oil droplet is visible and measurable, we can easily identify mice that received droplets too small to induce stable ocular hypertensi...

The progressive loss of retinal ganglion cells (RGCs) and their axons is the hallmark of glaucoma, a common neurodegenerative disease in the retina1. It will affect more than 100 million individuals 40&#8722;80 years old by 20402. IOP remains the only modifiable risk factor in the development and progression of glaucoma. In order to explore the pathogenesis, progression, and potential treatments of glaucoma, a reliable, reproducible, and inducible experimental ocular hypertension/glaucoma model that replicates key features of human patients is imperative.
IOP depends on aqueous humor inflow to the anterior chamber from the ciliary body in the posterior chamber and outflow through the trabecular meshwork (TM) at the angle of the anterior chamber. Upon reaching a steady state, IOP is maintained. When the inflow exceeds or is less than the outflow, IOP rises or falls respectively. By decreasing the aqueous outflow either by occluding the angle of the anterior chamber or by damaging the TM, several glaucoma models have been established3,4,5,6,7,8,9,10. These models are normally associated with irreversible ocular tissue damage, and the high IOP in the anterior chamber also causes unwanted complications such as corneal edema and intraocular inflammation, which make retinal imaging and visual function assays difficult to perform and interpret.
To develop a model that overcomes these shortcomings, we focused on the well-sudocumented secondary glaucoma caused by silicone oil (SO) that occurs as a postoperative complication of human vitreoretinal surgery11,12. SO is used as a tamponade in retinal surgeries because of its high surface tension. However, SO can physically occlude the pupil because it is lighter than the aqueous and vitreous fluids, which prevents aqueous flow into the anterior chamber. The obstruction causes IOP elevation in the posterior chamber due to the aqueous humor accumulation. This motivated us to develop and characterize a novel ocular hypertension mouse model based on intracameral SO injection and pupillary block13, with key features of the secondary glaucoma: effective pupillary block, significant IOP elevation that can return to normal after SO removal, and glaucomatous neurodegeneration.
Here we present a detailed protocol for SO-induced ocular hypertension in the mouse eye, including SO injection and removal and IOP measurement.

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			<td height="21" style="height:21px;width:257px;">0.5% proparacaine hydrochloride</td>
			<td style="width:232px;">Akorn, Somerset</td>
			<td style="width:147px;"></td>
			<td style="width:279px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">10mL syinge</td>
			<td style="width:232px;">BD</td>
			<td style="width:147px;"></td>
			<td>Luer-Lok Tip</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:26px;">18G needle</td>
			<td style="width:232px;">BD</td>
			<td style="width:147px;"></td>
			<td>with Regular Bevel, Needle Length:25.4 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">2,2,2-Tribromoethanol (Avertin)</td>
			<td style="width:232px;">Fisher Scientific</td>
			<td style="width:147px;">CAS# 75-80-9</td>
			<td>50g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">32G nano</td>
			<td style="width:232px;">BD</td>
			<td style="width:147px;">320122</td>
			<td>BD Nano Ultra Fine Pen Needle-32G 4mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">33G ophalmology needle</td>
			<td style="width:232px;">TSK/ VWR</td>
			<td style="width:147px;">TSK3313/ 10147-200</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">5mL syinge</td>
			<td style="width:232px;">BD</td>
			<td style="width:147px;"></td>
			<td>Luer-Lok Tip</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">AnaSed Injection (xylazine)</td>
			<td style="width:232px;">Butler Schein</td>
			<td style="width:147px;"></td>
			<td>100 mg/ml, 50 ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">artificial tears</td>
			<td style="width:232px;">Alcon Laboratories</td>
			<td style="width:147px;">300651431414</td>
			<td>Systane Ultra Lubricant Eye Drops</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">BSS PLUS Irrigating solution</td>
			<td style="width:232px;">Alcon Laboratories</td>
			<td style="width:147px;">65080050</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dual-Stage Glass Micropipette Puller</td>
			<td style="width:232px;">NARISHIGE</td>
			<td style="width:147px;">PC-10</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:257px;">EZ-7000 Classic System</td>
			<td style="width:232px;">EZ system</td>
			<td style="width:147px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">Isoflurane</td>
			<td style="width:232px;">VetOne</td>
			<td style="width:147px;">502017</td>
			<td>isoflurane, USP, 250ml/bottle</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">IV Administration sets</td>
			<td style="width:232px;">EXELint/ Fisher</td>
			<td style="width:147px;">29081</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">KETAMINE HYDROCHLORIDE INJECTION</td>
			<td style="width:232px;">VEDCO</td>
			<td style="width:147px;">50989-996-06</td>
			<td>KETAVED 100mg/ml * 10ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">microgrind bevelling machine</td>
			<td style="width:232px;">NARISHIGE</td>
			<td style="width:147px;">EG-401</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">Miniature EVA Tubing</td>
			<td style="width:232px;">McMaster-Carr</td>
			<td style="width:147px;">1883T4</td>
			<td>0.05&#34; ID, 0.09&#34; OD, 10 ft. Length</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">silicon oil (SILIKON)</td>
			<td style="width:232px;">Alcon Laboratories</td>
			<td style="width:147px;">8065601185</td>
			<td>1,000 mPa.s</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">Standard Glass Capillaries</td>
			<td style="width:232px;">WPI/ Fisher</td>
			<td style="width:147px;">1B150-4</td>
			<td>4 in. (100mm) OD 1.5mm ID 0.84mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TonoLab tonometer</td>
			<td style="width:232px;">Colonial Medical Supply, Finland</td>
			<td style="width:147px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:257px;">veterinary antibiotic ointment</td>
			<td style="width:232px;">Dechra Veterinary</td>
			<td style="width:147px;">1223RX</td>
			<td>BNP ophthalmic ointment, Vetropolycin</td>
		</tr>
	</tbody>
</table>

a reversible silicon oil-induced ocular hypertension model in mice

Elevated intraocular pressure (IOP) is a well-documented risk factor for glaucoma. Here we describe a novel, effective method for consistently inducing stable IOP elevation in mice that mimics the post-operative complication of using silicone oil (SO) as a tamponade agent in human vitreoretinal surgery. In this protocol, SO is injected into the anterior chamber of the mouse eye to block the pupil and prevent inflow of aqueous humor. The posterior chamber accumulates aqueous humor and this in turn increases the IOP of the posterior segment. A single SO injection produces reliable, sufficient, and stable IOP elevation, which induces significant glaucomatous neurodegeneration. This model is a true replicate of secondary glaucoma in the eye clinic. To further mimic the clinical setting, SO can be removed from the anterior chamber to reopen the drainage pathway and allow inflow of aqueous humor, which is drained through the trabecular meshwork (TM) at the angle of the anterior chamber. Because IOP quickly returns to normal, the model can be used to test the effect of lowering IOP on glaucomatous retinal ganglion cells. This method is straightforward, does not require special equipment or repeat procedures, closely simulates clinical situations, and may be applicable to diverse animal species. However, minor modifications may be required.

Soon after the injection we can easily identify mice that do not produce stable ocular hypertension because of the SO droplets being too small (&#8804;1.5 mm)13. These animals are excluded from subsequent experiments. Following the injection procedures, more than 80% of SO injected mice end up with droplets larger than 1.6 mm. We measured the IOP of these mouse eyes once a week for 8 weeks after a single SO injection. The IOP of the eye receiving SO remained high, generally double the IOP of the c...

Watch this Scientific Journal Video about A Reversible Silicon Oil-Induced Ocular Hypertension Model in Mice at JoVE.com

A Reversible Silicon Oil-Induced Ocular Hypertension Model in Mice

Here, we present a protocol to induce ocular hypertension and glaucomatous neurodegeneration in mouse eyes by intracameral injection of silicone oil and the procedure for silicone oil removal from the anterior chamber to return elevated intraocular pressure to normal.

Elevated intraocular pressure (IOP) is a well-documented risk factor for glaucoma. Here we describe a novel, effective method for consistently inducing ...

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