Primary Retinal Detachment
Primary Retinal Detachment
Primary Retinal Detachment
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58<br />
resorption. The combination of glaucoma with retinal detachment<br />
leads to several considerations with respect to PR. Patients with<br />
a functioning bleb or tube shunt device in place may be better<br />
managed by PR than scleral buckle (SB). Although an expanding<br />
gas bubble has the potential to dramatically raise the intraocular<br />
pressure (IOP), bubble expansion typically occurs simultaneously<br />
with resorption of SRF. The resolution of SRF provides potential<br />
space for bubble expansion without perturbations in the IOP. Only<br />
detachments with scant SRF or chronic, thick SRF are more prone<br />
to IOP problems and, as a result, are relative contraindications to<br />
PR in patients with coexisting glaucoma.<br />
Gas Selection<br />
4 Pneumatic Retinopexy for <strong>Primary</strong> <strong>Retinal</strong> <strong>Detachment</strong><br />
Intraocular gas works by temporarily closing retinal breaks via the<br />
surface tension properties of the bubble meniscus. Blocking the<br />
movement of liquid vitreous into the subretinal space allows the<br />
retinal pigment epithelium to actively pump fluid from the subretinal<br />
space and flatten the detachment. Once the neurosensory<br />
retina is in apposition to the pigment epithelial layer, the adhesive<br />
properties of cryopexy or laser retinopexy permanently close the<br />
break(s). The most commonly utilized gases are air, sulfur hexafluoride<br />
(SF 6), and perfluoropropane (C 3F 8). Choice of gas is based<br />
upon volume issues, arc length of contact/bubble size requirements,<br />
and bubble duration (Table 4.1) [7]. The tamponade must<br />
last until the laser or cryopexy adhesion is strong enough to resist<br />
reopening – generally 3–5 days for laser and 5–7 days for cryopexy.<br />
Air is non-expansile and quickly disappears from the eye. Sulfur<br />
hexafluoride and C 3F 8 are expansile and have longer half-lives. In<br />
general, a 1-ml final bubble size tamponades a 120° arc length,<br />
which is sufficient for most cases of PR (Table 4.2) [8]. There is,<br />
however, considerable variation based on the axial length/ size of<br />
the globe, so that larger bubbles are required in myopic individuals<br />
to achieve the desired arc length of contact.