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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 reducing the counterweight (cantilever) and surgical compression on intra-ocular pressure during Ziemer Z8 fragmentation and capsulotomy.The weight of the laser handpiece is reduced by a supporting weight acting as a cantilever, with a manufacturers angulation recommended at 0°. Decreasing the angulation has the effect of increasing the effective lift on the handpiece. Colour photograph showing the angulation of the Ziemer LDV Z8 arm with hand piece positioned on weighing scale to determine the contribution of angulation on the effective weight on the globe. The effective weight at ≈0° and −10° were 310 and 110 g respectively (panel (A)). Comparison for individual stage and overall IOP between the conventional 700 mbar Z8 settings at both 0° (open triangles) and −10° angulation (closed circles) (panel (B)) and as an average (panel (C)) are shown. The sequence of the procedure is: Time ‘0’; a Applanation*; b Vacuum followed by liquid filling and attachment of laser hand piece, corresponding to the peak IOP (Z8); c Lens Fragmentation; d Pause; e Lens Capsulotomy; f Cessation of suction and normalization of IOP. Analysis was by the unpaired t test (p < 0.05 significant). (Representative plots showing the differences in IOP during Z8 Fragmentation/Capsulotomy in D by conventional angulation (black), reduced angulation (blue) and the hand piece alone (no suction) for comparison (red). s = suction and w = weight.*NB - the globe was compressed with the applanation device prior to the generation of adequate suction. Comparison is by the unpaired t test (p < 0.05 significant). p < 0.01**, p < 0.05*.
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f5: The effects of reducing the counterweight (cantilever) and surgical compression on intra-ocular pressure during Ziemer Z8 fragmentation and capsulotomy.The weight of the laser handpiece is reduced by a supporting weight acting as a cantilever, with a manufacturers angulation recommended at 0°. Decreasing the angulation has the effect of increasing the effective lift on the handpiece. Colour photograph showing the angulation of the Ziemer LDV Z8 arm with hand piece positioned on weighing scale to determine the contribution of angulation on the effective weight on the globe. The effective weight at ≈0° and −10° were 310 and 110 g respectively (panel (A)). Comparison for individual stage and overall IOP between the conventional 700 mbar Z8 settings at both 0° (open triangles) and −10° angulation (closed circles) (panel (B)) and as an average (panel (C)) are shown. The sequence of the procedure is: Time ‘0’; a Applanation*; b Vacuum followed by liquid filling and attachment of laser hand piece, corresponding to the peak IOP (Z8); c Lens Fragmentation; d Pause; e Lens Capsulotomy; f Cessation of suction and normalization of IOP. Analysis was by the unpaired t test (p < 0.05 significant). (Representative plots showing the differences in IOP during Z8 Fragmentation/Capsulotomy in D by conventional angulation (black), reduced angulation (blue) and the hand piece alone (no suction) for comparison (red). s = suction and w = weight.*NB - the globe was compressed with the applanation device prior to the generation of adequate suction. Comparison is by the unpaired t test (p < 0.05 significant). p < 0.01**, p < 0.05*.

Mentions: At a recommended angulation close to zero degrees, the hand piece was measured at 310 g (Fig. 5A, upper panel). By reducing the angulation to −10°, the weight was reduced to 110 g due to the cantilever effect of the counterweight on the laser arm (Fig. 5B, lower panel). In turn this resulted in a measurable overall reduction in the IOP exerted on the porcine globe from 72.5 mmHg (±24.2) to 36.4 mmHg (±7.7), (Fig. 5B,C), p = 0.006. A representative example is seen in Fig. 5D and compared to the IOP without the use of suction.


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 reducing the counterweight (cantilever) and surgical compression on intra-ocular pressure during Ziemer Z8 fragmentation and capsulotomy.The weight of the laser handpiece is reduced by a supporting weight acting as a cantilever, with a manufacturers angulation recommended at 0°. Decreasing the angulation has the effect of increasing the effective lift on the handpiece. Colour photograph showing the angulation of the Ziemer LDV Z8 arm with hand piece positioned on weighing scale to determine the contribution of angulation on the effective weight on the globe. The effective weight at ≈0° and −10° were 310 and 110 g respectively (panel (A)). Comparison for individual stage and overall IOP between the conventional 700 mbar Z8 settings at both 0° (open triangles) and −10° angulation (closed circles) (panel (B)) and as an average (panel (C)) are shown. The sequence of the procedure is: Time ‘0’; a Applanation*; b Vacuum followed by liquid filling and attachment of laser hand piece, corresponding to the peak IOP (Z8); c Lens Fragmentation; d Pause; e Lens Capsulotomy; f Cessation of suction and normalization of IOP. Analysis was by the unpaired t test (p < 0.05 significant). (Representative plots showing the differences in IOP during Z8 Fragmentation/Capsulotomy in D by conventional angulation (black), reduced angulation (blue) and the hand piece alone (no suction) for comparison (red). s = suction and w = weight.*NB - the globe was compressed with the applanation device prior to the generation of adequate suction. Comparison is by the unpaired t test (p < 0.05 significant). p < 0.01**, p < 0.05*.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f5: The effects of reducing the counterweight (cantilever) and surgical compression on intra-ocular pressure during Ziemer Z8 fragmentation and capsulotomy.The weight of the laser handpiece is reduced by a supporting weight acting as a cantilever, with a manufacturers angulation recommended at 0°. Decreasing the angulation has the effect of increasing the effective lift on the handpiece. Colour photograph showing the angulation of the Ziemer LDV Z8 arm with hand piece positioned on weighing scale to determine the contribution of angulation on the effective weight on the globe. The effective weight at ≈0° and −10° were 310 and 110 g respectively (panel (A)). Comparison for individual stage and overall IOP between the conventional 700 mbar Z8 settings at both 0° (open triangles) and −10° angulation (closed circles) (panel (B)) and as an average (panel (C)) are shown. The sequence of the procedure is: Time ‘0’; a Applanation*; b Vacuum followed by liquid filling and attachment of laser hand piece, corresponding to the peak IOP (Z8); c Lens Fragmentation; d Pause; e Lens Capsulotomy; f Cessation of suction and normalization of IOP. Analysis was by the unpaired t test (p < 0.05 significant). (Representative plots showing the differences in IOP during Z8 Fragmentation/Capsulotomy in D by conventional angulation (black), reduced angulation (blue) and the hand piece alone (no suction) for comparison (red). s = suction and w = weight.*NB - the globe was compressed with the applanation device prior to the generation of adequate suction. Comparison is by the unpaired t test (p < 0.05 significant). p < 0.01**, p < 0.05*.
Mentions: At a recommended angulation close to zero degrees, the hand piece was measured at 310 g (Fig. 5A, upper panel). By reducing the angulation to −10°, the weight was reduced to 110 g due to the cantilever effect of the counterweight on the laser arm (Fig. 5B, lower panel). In turn this resulted in a measurable overall reduction in the IOP exerted on the porcine globe from 72.5 mmHg (±24.2) to 36.4 mmHg (±7.7), (Fig. 5B,C), p = 0.006. A representative example is seen in Fig. 5D and compared to the IOP without the use of suction.

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