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Primary Retinal Detachment

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62<br />

4 Pneumatic Retinopexy for <strong>Primary</strong> <strong>Retinal</strong> <strong>Detachment</strong><br />

Paracentesis of the anterior chamber is a controversial step in<br />

the procedure. Some surgeons routinely soften all eyes prior to injection,<br />

while some perform the step only rarely. Others perform<br />

paracentesis after the gas injection as required by the IOP. Paracentesis<br />

is less important with one-step procedures where the<br />

scleral depression associated with cryopexy softens the globe and<br />

in cases where smaller volumes of expansile gas are utilized. Paracentesis<br />

is most often required in two-step (laser) cases and when<br />

injecting large gas volumes. The step is performed by entering<br />

the anterior chamber with a 30-gauge needle affixed to a 1-ml<br />

syringe without the plunger.Aqueous humor is allowed to passively<br />

egress until the anterior chamber shallows. A sterile cotton tip<br />

applicator is rolled onto the needle track as the needle is withdrawn<br />

to avoid additional fluid egress. Care is given to avoid needle<br />

tip-lens touch. Paracentesis is contraindicated in aphakic and<br />

pseudophakic patients with vitreous prolapse into the anterior<br />

chamber.<br />

Gas injection is the most important component step of PR, and<br />

many postoperative complications can be avoided with proper<br />

technique. The surgeon utilizes the indirect ophthalmoscope for<br />

lighting, visualization of needle tip, and later to assess gas location<br />

and patency of the central retinal artery. The patient is placed in a<br />

recumbent position with the head tilted 45° away from the operative<br />

eye. This places the temporal pars plana as the highest point<br />

on the globe. The injection is given 4 mm posterior to the limbus,<br />

usually in the temporal quadrant, unless the retina is bullously detached<br />

in the area. The needle tip is advanced into the mid-vitreous<br />

cavity, under direct visualization with the indirect ophthalmoscope<br />

to penetrate the anterior hyaloid face. Then the needle is<br />

withdrawn until just the tip is visible, 2–3 mm through the pars<br />

plana epithelium. Gas is injected in a brisk but controlled manner.<br />

Following gas injection, the head is carefully rotated to a neutral<br />

position in order to move gas away from the injection site and<br />

avoid egress of gas out the needle track. A sterile cotton tip applicator<br />

is rolled over the track as the needle is removed to minimize

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