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Table 2 Features of fiberoptic and gradient index lens ophthalmic microendoscopes

From: Endoscopic vitreoretinal surgery: principles, applications and new directions

Fiberoptic microendoscopes Gradient index (GRIN) lens microendoscopes
A fiberoptic image guide bundle extends from the distal tip of the rigid intraocular probe through the probe and its attached handpiece to the central console A video camera or viewing eyepiece attaches directly to the comparatively fragile GRIN lens handpiece-intraocular probe
Readily maneuverable in surgery Less maneuverable in surgery because of the direct attachment of the video camera and/or viewing eyepiece to the handpiece-probe unit
The entire fiberoptic microendoscope can be autoclaved The handpiece-GRIN lens assembly can be autoclaved but not its video camera which must be draped separately for operating room use
Image resolution is limited by the number of optical fibers in the image guide: smaller caliber microendoscopes have fewer fibers, lower resolution and smaller imaging fields GRIN lenses in the probe-handpiece relay the intraocular ophthalmoscopic image directly to the video camera, retaining much of its high spatial frequency, fine detail information
Coaxial illumination may be supplemented with additional chandelier or endoilluminator lighting Coaxial illumination may be supplemented with additional chandelier or endoilluminator lighting