Small gauge vitrectomy: Recent update

Abstract

Small gauge vitrectomy, also known as minimally invasive vitreous surgery (MIVS), is a classic example of progress in biomedical engineering. Disparity in conjunctival and scleral wound location and reduction in wound diameter are its core principles. Fluidic changes include increased pressure head loss with consequent reduction in infusional flow rate and use of higher aspiration vacuum at the cutter port. Increase An increase in port open/port closed time maintains an adequate rate of vitreous removal. High Intensity Discharge (HID) lamps maintain adequate illumination in spite of a decrease in the number of fiberoptic fibers. The advantages of MIVS are, a shorter surgical time, minimal conjunctival damage, and early postoperative recovery. Most complications are centered on wound stability and risk of postoperative hypotony, endophthalmitis, and port site retinal break formation. MIVS is suited in most cases, however, it can cause dehiscence of recent cataract wounds. Retraction of the infusion cannula in the suprachoroidal space may occur in eyes with scleral thinning. As a lot has been published and discussed about sutureless vitrectomy a review of this subject is necessary. A PubMed search was performed in December 2011 with terms small gauge vitrectomy, 23-gauge vitrectomy, 25-gauge vitrectomy, and 27 gauge vitrectomy, which were revised in August 2012. There were no restrictions on the date of publication but it was restricted to articles in English or other languages, if there abstracts were available in English.

Keywords: Pars plana vitrectomy; sutureless vitrectomy; vitreoretinal surgery.

Figure 1

Two-step entry system, as described by Eckardt, using an angled microvitreoretinal blade (MVR) followed by placement of cannula (a,b) placement of fixation plate at appropriate distance from limbus and initiation of creation of sclerotomy using angled MVR. (c) Insertion of trocar mounted cannula. (d) Complete insertion of trocar mounted cannula. (e) Removal of trocar, to leave the cannula in place. (f) Attachment of infusion line on the cannula (g) Insertion of second trocar cannula assembly (h) Removal of trocar leaving the cannula in place

Figure 2

Components of the entry alignment system (ESA): Cannule mounted trocars

Figure 3

23-G cannulae and trocars separately

Figure 4

23-G self-retaining infusion cannula

Figure 5

Single-step entry technique using the entry site alignment system (ESA), using angled incision. (a) Measurement of distance from pars plana. (b) Scleral entry at 45°. (c) Change in the direction, from oblique to vertical. (d) Entry into the vitreous cavity perpendicularly. Note the buckling of the sclera due to preoperative hypotony

Figure 6

Graphic representation of various single-step entry techniques. (a) Perpendicular entry, (b) Angled entry, (c) Zorro’s incision, 6d: Pollack’s incision

Figure 7

Comparison of the port diameter of 20-G and 23-G vitrectomy cutter