Abstract
Purpose: :
Wide-angle viewing systems have significantly improved intraoperative visualization of peripheral retina. The static field of view for most systems is in the range 120 to 140 degrees. Intraoperative manipulations such as ocular rotation, lens tilting, and lens decenteration can further enhance peripheral viewing. From a surgical perspective it is more relevant to know the distance of an area of interest from the Ora Serrata, than from the optic disc. The current study evaluated the distance of the retina area that corresponded to A) the internal tip of the sclerotomy cannula and B) edge of the viewing field from the ora serrata.
Methods: :
Interventional, non-comparative, clinical case series.
Results: :
35 eyes of 35 patients were included in the study. Contact lens viewing system (OVI 130) was used in 23 eyes (group1) and a non-contact viewing system (BIOM) was used in 12 eyes (group2). The cannula tip was visualized in 22 (95%) eyes in group1, and in 10 (83%) eyes in group 2. The mean distance from the edge of the viewing field to ora serrata was 1.1 mm (range 0-2.9 mm) for group 1 and 1.2 mm (range 0.4-3.3 mm) for group 2. The mean distance from the cannula tip to ora serrata was 1.4 mm (range 0.3 to 2.9 mm) for the 32 subjects in which the tip of cannula could be visualized. The 3 eyes in which the cannula tip could not be visualized also had a longer field edge-ora distance.
Conclusions: :
Internal tip of a sclerotomy cannula can serve as a useful landmark indicating proximity to the ora serrata. With the current wide-angle systems it is possible to visualize the peripheral retina to the vicinity of the vitreous base without the need for scleral depression in most cases.
Keywords: vitreoretinal surgery • retinal detachment