Proper case selection is critical to success with PR. The "ideal" scenario involves an acute, phakic retinal detachment due to a single break or small cluster of breaks located in the superior 8 clock hours of the fundus. Careful preoperative examination is exceedingly important when considering PR. Clear ocular media are essential to allow visualization of all breaks. Sector cataract, vitreous hemorrhage, and pseudophakic lens capsular opacification are relative contraindications. In general, pseudophakic and aphakic detachments are more prone to multiple small breaks than phakic cases. However, if the view to peripheral retina affords a view sufficient to disclose all the breaks, these detachments can be managed with PR. A single break is most easily covered with bubble tamponade. If multiple, the breaks must be close enough together to be covered by a single bubble. Breaks greater than 90-120° apart require large volume injections and, as a result, are relative contraindications. Retinal tears located in the superior 8 clock hours are easier to treat because gas bubbles float in the fluid vitreous. Although retinal tears in attached retina located inferiorly are easily managed with barricade laser, breaks in detached retina in the inferior 4 clock hours present a relative contraindication for PR (see below - New possibilities).
There are several other contraindications to PR. Required patient air travel while the bubble is in place is an absolute contraindication. There is no relief of vitreoretinal traction with PR; the adhesion formed must be stronger than the tractional forces generated to achieve long-term success. As a result, patients with severe traction due to proliferative vitreoretinopathy (PVR) are not good candidates. Subretinal fluid is removed by the pigment epithelial pump. This process is much more efficient with the liquid SRF of acute detachments than with the viscid proteinaceous fluid encountered with chronic detachments. Pneumatic retinopexy can be successfully utilized with the latter, but there may be loculated pockets of chronic SRF that persist for months due to delayed resorption. The combination of glaucoma with retinal detachment leads to several considerations with respect to PR. Patients with a functioning bleb or tube shunt device in place may be better managed by PR than scleral buckle (SB). Although an expanding gas bubble has the potential to dramatically raise the intraocular pressure (IOP), bubble expansion typically occurs simultaneously with resorption of SRF. The resolution of SRF provides potential space for bubble expansion without perturbations in the IOP. Only detachments with scant SRF or chronic, thick SRF are more prone to IOP problems and, as a result, are relative contraindications to PR in patients with coexisting glaucoma.
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