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Primary Retinal Detachment

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Technique 61<br />

solution; however,these need to be started 24–48 h prior to the procedure<br />

with frequent use to substantially affect the ocular flora,<br />

limiting their usefulness as a true prophylactic method in this setting.<br />

A wire-lid speculum is used to open the lids, avert the lashes<br />

from the field, and protect the lid margin from cryopexy damage.<br />

If the patient is to undergo a one-step procedure, then cryopexy is<br />

performed prior to gas injection, as small breaks may be difficult<br />

to visualize following gas injection. Cryopexy is the preferred<br />

method in cases where media opacities limit the view, when the<br />

break(s) are located in the far periphery, or when there is underlying<br />

pigment epithelial atrophy. Laser, via a two-step method, is<br />

preferred with bullous superior detachments with large retinal<br />

breaks, when breaks occur over a previously placed buckle element,<br />

and with posteriorly located tears. Some surgeons feel that there<br />

is a lower incidence of PVR with laser retinopexy compared with<br />

cryopexy. Laser can be difficult to perform through or around the<br />

gas bubble and will not provide adequate adhesion if there is still a<br />

small amount of fluid present near the tear site. Small breaks may<br />

be difficult to find with the laser once the retina is reattached. Laser<br />

might form a chorioretinal adhesion faster than cryopexy, which<br />

decreases the critical duration of required post-operation positioning.<br />

Multiple rows of confluent laser are placed around each<br />

tear with careful attention to carry the treatment anterior to the<br />

ora serrata. It should be noted that the two methods are not<br />

mutually exclusive, and many instances are best managed by a<br />

combination of both modalities.<br />

Preparation of the chosen gas is performed by withdrawing gas<br />

from a cylinder via a valve system through a Millipore filter into a<br />

1-ml or 3-ml syringe. The valve, tubing, filter, and syringe are<br />

flushed with gas once, and the process is repeated to eliminate<br />

room air from the system. High pressures may damage Millipore<br />

filters, so care must be taken to maintain lower pressures during<br />

gas filtration. The filter is replaced with a 30-gauge needle, and<br />

excess gas is pushed out of the syringe until the desired amount for<br />

injection remains behind.

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