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Jodhbir S. Mehta, Romesh I. Angunawela, Andri Riau, Shyam S. Chaurasia, Donald T. Tan; Manual Suction Trephination Versus Femtosecond Laser Corneal Trephination: Real Time Intraocular Pressure, Endothelial Cell Loss And Wound Healing Responses. Invest. Ophthalmol. Vis. Sci. 2011;52(14):352.
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To measure real time intraocular pressure (IOP) changes during manual suction trephination (MST) and suction trephination using the femtosecond laser (FSL). And to assess the degree of endothelial cell damage and wound healing response to the 2 methods of trephination.
16 New Zealand white rabbits were used. A cannula attached to a pressure monitor (Powerlab) was introduced into the anterior chamber of the operated eye prior to trephination. IOP was also measured with a Tonopen prior to surgery. 8 rabbits underwent manual suction trephination (Hessburg Barron trephine) in one eye to partial depth. The remaining 8 rabbits had FSL trephination (FSL-T) to partial depth in 1 eye only (Visumax, Carl Zeiss Meditec). IOP was monitored throughout. All rabbits had slit lamp photography, confocal microscopy and anterior segment OCT performed prior and post surgery. At 4 hours, 2 rabbits in each group had full thickness MST or FSL-T on the fellow eye. 4 rabbits in each group were sacrificed at this time point (8 total). The process was repeated again at 3 days post op with the remaining 8 rabbits sacrificed. Tissue from the full thickness trephinations were preserved for scanning electron microscopy (SEM) (4MST, 4FSL-T). The remaining tissue was cryo-preserved for immunohistochemistry.
Average IOP during MST and FSL-T were similar (37mmHg), however whilst the IOP remained fairly constant during FSL-T, there was wide fluctuation during the MST cutting phase (60mmHg max). SEM showed endothelial cell loss 1-2 cell rows either side of the trephine incision for FSL-T and 2-5 cells deep for MST. Immunohistochemistry showed comparable immune cell responses at 4 hours (CD11b), greater apoptosis with FSL-T (TUNEL) at 4 hrs and increased keratocyte proliferation at 3 days (Ki67) with FSL-T
There is considerable IOP variation during MST compared to FSL-T, although the average IOP is 37mmHg for both techniques. 3-5 rows of endothelial cells are lost during MST, which is great than during FSL-T. The wound healing response to FSL-T appears greater than that to MST at 3 days.
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