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terminology and guidelines for glaucoma ii - Kwaliteitskoepel

terminology and guidelines for glaucoma ii - Kwaliteitskoepel

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Argon Laser Iridotomy<br />

When no Nd:YAG laser is available, the Argon laser may be used.<br />

There is no single group of laser parameters <strong>for</strong> all types of iris <strong>and</strong> <strong>for</strong> all surgeons<br />

The laser parameters need to be adjusted intraoperatively<br />

Preparatory stretch burns:<br />

Penetration burns:<br />

Spot size: 200-500 µm Spot Size: 50 µm<br />

Exposure time: 0.2-0.6 seconds<br />

Exposure time: 0.2 seconds<br />

Power: 200-600 mW Power: 800-1000 mW<br />

For pale blue or hazel irides, the following parameters are suggested:<br />

First step: to obtain a gas bubble Spot Size 50µm<br />

Exposure time 0.5 seconds<br />

Power:<br />

1500 mW<br />

Second step: penetration through the gas bubble Spot Size 50µm<br />

Exposure time 0.05 seconds<br />

Power<br />

1000 mW<br />

For thick, dark brown irides:<br />

Chipping technique Spot Size 50 µm<br />

Exposure time 0.02 seconds<br />

Power<br />

1500-2500 mW<br />

The purpose of the procedure is to obtain a full thickness hole of sufficient diameter to resolve the pupillary block.<br />

Per<strong>for</strong>ation is assumed when pigment, mixed with aqueous, flows into the anterior chamber. The iris usually falls<br />

back <strong>and</strong> the peripheral anterior chamber deepens. Patency must be confirmed by direct visualization of the lens<br />

through the iridotomy. Transillumination through the pupil or the iridotomy is not a reliable indicator of success.<br />

The optimal size of the iridotomy is 100 to 500 µm.<br />

Complications:<br />

Temporary blurring of vision<br />

Corneal epithelial <strong>and</strong>/or endothelial burns with Argon<br />

Intraoperative bleeding, usually controlled by a gentle pressure applied to the eye with the contact lens<br />

Transient elevation of the IOP<br />

Postoperative inflammation<br />

Posterior synechiae<br />

Late closure of the iridotomy<br />

Localized lens opacities<br />

Endothelial damage<br />

Rare complications include retinal damage, cystoid macular edema, sterile hypopion, malignant <strong>glaucoma</strong>.<br />

Post-operative management:<br />

Check the IOP after 1-3 hours, <strong>and</strong> again after 24-48 hours. When this is not possible, give prophylactic treatment<br />

to avoid IOP spikes<br />

Topical corticosteroids <strong>for</strong> 4-7 days<br />

Repeat gonioscopy<br />

Pupillary dilatation to break posterior synechiae<br />

Verify the patency of the peripheral iridotomy<br />

Ch. 3 - 29 EGS

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