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Comparison of intra-ocular pressure changes with liquid or flat applanation interfaces in a femtosecond laser platform.

Williams GP, Ang HP, George BL, Liu YC, Peh G, Izquierdo L, Tan DT, Mehta JS - Sci Rep (2015)

Bottom Line: We demonstrated through a porcine model that IOP was significantly higher with a flat interface but could be abrogated by reducing surgical compression and vacuum.Pressure was lower with a liquid interface, and further altering angulation of the laser arm could reduce the IOP to 36 mmHg.These strategies may improve the safety profile in patients vulnerable to high pressure when employing FLACS with the Ziemer LDV Z8.

View Article: PubMed Central - PubMed

Affiliation: Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore.

ABSTRACT
Cataract surgery is the most common surgical procedure and femtosecond laser assisted cataract surgery (FLACS) has gained increased popularity. FLACS requires the application of a suction device to stabilize the laser head and focus the laser beam accurately. This may cause a significant escalation in intra-ocular pressure (IOP), which poses potential risks for patients undergoing cataract surgery. In this study we aimed to assess the effect of the Ziemer LDV Z8 femtosecond cataract machine on IOP. We demonstrated through a porcine model that IOP was significantly higher with a flat interface but could be abrogated by reducing surgical compression and vacuum. Pressure was lower with a liquid interface, and further altering angulation of the laser arm could reduce the IOP to 36 mmHg. A pilot series in patients showed comparable pressure rises with the porcine model (30 mmHg). These strategies may improve the safety profile in patients vulnerable to high pressure when employing FLACS with the Ziemer LDV Z8.

No MeSH data available.


Related in: MedlinePlus

The effects of suction (vacuum) and surgeon compression on Intra-Ocular Pressure (IOP) during the Ziemer Z6 LASIK application.In order to determine the effect that vacuum and surgical compression contributed to IOP we attempted to reduce surgeon compression by avoiding post vacuum compression and by reducing mechanical suction. The effect of reduced compression on IOP is demonstrated for the Z6 laser (closed circles) at different stages of the procedure and comparisons with the Z8 (open triangles) are shown in Panel (A) and as an average (B). The sequence of the procedure is: Time ‘0’; a Applanation* (a, Liquid patient interface or a1, Flat applanation attachment to the globe); b Vacuum followed by liquid filling and attachment of laser hand piece, corresponding to the peak IOP (Z8) or b1 Vacuum alone for the flat interface (Z6); c Lens Fragmentation (c1 Lamella cut); d Pause (d1 Pause); e Lens Capsulotomy (e1 Side cut); f /f1 Cessation of suction and normalization of IOP. No significant suction losses (a potential concern with inadequate vacuum) occurred. Representative plots showing the differences in IOP during Z6 LASIK are shown in 4C by conventional compression (black), reduced compression (as outlined above, blue) alone and combined with reduced vacuum from 700 to 500 mbar (green). c = compression, s = suction and w = weight. The hand piece IOP (affect of weight alone) is shown for comparison (red). Comparison is by the unpaired t test (p < 0.05 significant). *NB - the globe was compressed with the applanation device prior to the generation of adequate suction NS = Not Significant.
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f4: The effects of suction (vacuum) and surgeon compression on Intra-Ocular Pressure (IOP) during the Ziemer Z6 LASIK application.In order to determine the effect that vacuum and surgical compression contributed to IOP we attempted to reduce surgeon compression by avoiding post vacuum compression and by reducing mechanical suction. The effect of reduced compression on IOP is demonstrated for the Z6 laser (closed circles) at different stages of the procedure and comparisons with the Z8 (open triangles) are shown in Panel (A) and as an average (B). The sequence of the procedure is: Time ‘0’; a Applanation* (a, Liquid patient interface or a1, Flat applanation attachment to the globe); b Vacuum followed by liquid filling and attachment of laser hand piece, corresponding to the peak IOP (Z8) or b1 Vacuum alone for the flat interface (Z6); c Lens Fragmentation (c1 Lamella cut); d Pause (d1 Pause); e Lens Capsulotomy (e1 Side cut); f /f1 Cessation of suction and normalization of IOP. No significant suction losses (a potential concern with inadequate vacuum) occurred. Representative plots showing the differences in IOP during Z6 LASIK are shown in 4C by conventional compression (black), reduced compression (as outlined above, blue) alone and combined with reduced vacuum from 700 to 500 mbar (green). c = compression, s = suction and w = weight. The hand piece IOP (affect of weight alone) is shown for comparison (red). Comparison is by the unpaired t test (p < 0.05 significant). *NB - the globe was compressed with the applanation device prior to the generation of adequate suction NS = Not Significant.

Mentions: First, the influence of this compression post suction was addressed by neutralizing surgeon compression. This approach resulted in an overall reduction in the IOP with the Z6 from 201.9 to 89.7 (±7.1), p < 0.0001. The average IOP from stages c1 to e1 averaged 108 mmHg by this method suggesting that the effect of compression was approximately 159 mmHg (267–108 mmHg) and suction generated through the Z6 flat interface equated to 64 mmHg (108–43.9 mmHg). No significant suction losses occurred and comparisons between reductions in compression alone with Z8 interface are shown in Fig. 4A,B.


Comparison of intra-ocular pressure changes with liquid or flat applanation interfaces in a femtosecond laser platform.

Williams GP, Ang HP, George BL, Liu YC, Peh G, Izquierdo L, Tan DT, Mehta JS - Sci Rep (2015)

The effects of suction (vacuum) and surgeon compression on Intra-Ocular Pressure (IOP) during the Ziemer Z6 LASIK application.In order to determine the effect that vacuum and surgical compression contributed to IOP we attempted to reduce surgeon compression by avoiding post vacuum compression and by reducing mechanical suction. The effect of reduced compression on IOP is demonstrated for the Z6 laser (closed circles) at different stages of the procedure and comparisons with the Z8 (open triangles) are shown in Panel (A) and as an average (B). The sequence of the procedure is: Time ‘0’; a Applanation* (a, Liquid patient interface or a1, Flat applanation attachment to the globe); b Vacuum followed by liquid filling and attachment of laser hand piece, corresponding to the peak IOP (Z8) or b1 Vacuum alone for the flat interface (Z6); c Lens Fragmentation (c1 Lamella cut); d Pause (d1 Pause); e Lens Capsulotomy (e1 Side cut); f /f1 Cessation of suction and normalization of IOP. No significant suction losses (a potential concern with inadequate vacuum) occurred. Representative plots showing the differences in IOP during Z6 LASIK are shown in 4C by conventional compression (black), reduced compression (as outlined above, blue) alone and combined with reduced vacuum from 700 to 500 mbar (green). c = compression, s = suction and w = weight. The hand piece IOP (affect of weight alone) is shown for comparison (red). Comparison is by the unpaired t test (p < 0.05 significant). *NB - the globe was compressed with the applanation device prior to the generation of adequate suction NS = Not Significant.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4593965&req=5

f4: The effects of suction (vacuum) and surgeon compression on Intra-Ocular Pressure (IOP) during the Ziemer Z6 LASIK application.In order to determine the effect that vacuum and surgical compression contributed to IOP we attempted to reduce surgeon compression by avoiding post vacuum compression and by reducing mechanical suction. The effect of reduced compression on IOP is demonstrated for the Z6 laser (closed circles) at different stages of the procedure and comparisons with the Z8 (open triangles) are shown in Panel (A) and as an average (B). The sequence of the procedure is: Time ‘0’; a Applanation* (a, Liquid patient interface or a1, Flat applanation attachment to the globe); b Vacuum followed by liquid filling and attachment of laser hand piece, corresponding to the peak IOP (Z8) or b1 Vacuum alone for the flat interface (Z6); c Lens Fragmentation (c1 Lamella cut); d Pause (d1 Pause); e Lens Capsulotomy (e1 Side cut); f /f1 Cessation of suction and normalization of IOP. No significant suction losses (a potential concern with inadequate vacuum) occurred. Representative plots showing the differences in IOP during Z6 LASIK are shown in 4C by conventional compression (black), reduced compression (as outlined above, blue) alone and combined with reduced vacuum from 700 to 500 mbar (green). c = compression, s = suction and w = weight. The hand piece IOP (affect of weight alone) is shown for comparison (red). Comparison is by the unpaired t test (p < 0.05 significant). *NB - the globe was compressed with the applanation device prior to the generation of adequate suction NS = Not Significant.
Mentions: First, the influence of this compression post suction was addressed by neutralizing surgeon compression. This approach resulted in an overall reduction in the IOP with the Z6 from 201.9 to 89.7 (±7.1), p < 0.0001. The average IOP from stages c1 to e1 averaged 108 mmHg by this method suggesting that the effect of compression was approximately 159 mmHg (267–108 mmHg) and suction generated through the Z6 flat interface equated to 64 mmHg (108–43.9 mmHg). No significant suction losses occurred and comparisons between reductions in compression alone with Z8 interface are shown in Fig. 4A,B.

Bottom Line: We demonstrated through a porcine model that IOP was significantly higher with a flat interface but could be abrogated by reducing surgical compression and vacuum.Pressure was lower with a liquid interface, and further altering angulation of the laser arm could reduce the IOP to 36 mmHg.These strategies may improve the safety profile in patients vulnerable to high pressure when employing FLACS with the Ziemer LDV Z8.

View Article: PubMed Central - PubMed

Affiliation: Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore.

ABSTRACT
Cataract surgery is the most common surgical procedure and femtosecond laser assisted cataract surgery (FLACS) has gained increased popularity. FLACS requires the application of a suction device to stabilize the laser head and focus the laser beam accurately. This may cause a significant escalation in intra-ocular pressure (IOP), which poses potential risks for patients undergoing cataract surgery. In this study we aimed to assess the effect of the Ziemer LDV Z8 femtosecond cataract machine on IOP. We demonstrated through a porcine model that IOP was significantly higher with a flat interface but could be abrogated by reducing surgical compression and vacuum. Pressure was lower with a liquid interface, and further altering angulation of the laser arm could reduce the IOP to 36 mmHg. A pilot series in patients showed comparable pressure rises with the porcine model (30 mmHg). These strategies may improve the safety profile in patients vulnerable to high pressure when employing FLACS with the Ziemer LDV Z8.

No MeSH data available.


Related in: MedlinePlus