Primary Retinal Detachment

Technique 59
Table 4.1. Gas characteristics (from [7])
The volume of the initial injection is a key consideration in gas
selection. Intravitreal injections of 0.1–0.2 ml usually result in
modest IOP rises, but increasing the initial volume beyond this
point dramatically increases pressure. Paracentesis provides potential
space within the globe, but is usually limited to 0.1–0.2 ml.
As a result of these considerations, the authors routinely use
0.25 ml of pure (100%) C 3F 8 gas, which provides a small initial injected
volume and a large final volume (~1 ml) sufficient to tamponade
most breaks.
Technique
Expansion Half-life Isoexpansile Standard volume
(days) concentration (pure gas)
Air 0 1 100% 0.5–1.0 ml
SF 6 2.0–2.5¥ 2.5 18% 0.5 ml
C 3F 8 4¥ 4 14% 0.3 ml
Table 4.2. Bubble size/tamponade arc. Arc varies with axial length/size
of globe (from [8])
Final bubble size Arc of contact
0.30 ml 90°
1.0 ml 120°
3.0 ml 180°
Pneumatic retinopexy is either performed in one or two steps,
depending on whether cryopexy or laser is utilized to form the
chorioretinal adhesion (Tables 4.3, 4.4). Anesthesia may be applied