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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

Fluctuation of IOP and time course of fragmentation/capsulotomy with a liquid interface (Z8) or LASIK flap cutting with a flat interface (Z6) with a Ziemer femtosecond laser.Representative timeline for the liquid (Z8) and flat (non-liquid, Z6) interface systems. Panel (A) shows the time-course from docking (applanation and vacuum) and the different stages of Femto-fragmentation and Capsulotomy for the Z8 liquid interface and panel (B) the Z6 Flat Interface for LASIK flap cutting. The sequence 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. Panel (C) shows the average IOP for the Z8 and Z6 during the whole procedure and (D) shows the schematic average IOP (mmHg) for the Z8 liquid interface (closed triangles) and the Z6 flat interface (closed circles). Comparison was by the unpaired t test (n = 12) (p < 0.05 significant). *NB - the globe was compressed with the applanation device prior to the generation of adequate suction. p < 0.001***.
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f2: Fluctuation of IOP and time course of fragmentation/capsulotomy with a liquid interface (Z8) or LASIK flap cutting with a flat interface (Z6) with a Ziemer femtosecond laser.Representative timeline for the liquid (Z8) and flat (non-liquid, Z6) interface systems. Panel (A) shows the time-course from docking (applanation and vacuum) and the different stages of Femto-fragmentation and Capsulotomy for the Z8 liquid interface and panel (B) the Z6 Flat Interface for LASIK flap cutting. The sequence 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. Panel (C) shows the average IOP for the Z8 and Z6 during the whole procedure and (D) shows the schematic average IOP (mmHg) for the Z8 liquid interface (closed triangles) and the Z6 flat interface (closed circles). Comparison was by the unpaired t test (n = 12) (p < 0.05 significant). *NB - the globe was compressed with the applanation device prior to the generation of adequate suction. p < 0.001***.

Mentions: The set up of the instrumentation is shown in Fig. 1A/B. The average IOP was 74.2 mmHg (±18.31) during the procedure with the Z8. Representative plots of the time course and average IOP during the procedure illustrate the different profiles seen with fragmentation/capsulotomy (Fig. 2A,B). Sub-group comparison also revealed that the average IOP was significantly lower with the Z8 fragmentation/capsulotomy 72.50 mmHg (±24.2) than with Z6 LASIK flap creation, 201.9 mmHg (±18.55) (p < 0.0001). The average IOP rise between platforms is shown in Fig. 2C. This was evident in every step of the procedure with exception of the initial docking stage a/a1 (Fig. 2D, Supplementary Table). A stable profile was observed during the laser cutting stages following a peak IOP at the end of the docking stage b/b1.


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)

Fluctuation of IOP and time course of fragmentation/capsulotomy with a liquid interface (Z8) or LASIK flap cutting with a flat interface (Z6) with a Ziemer femtosecond laser.Representative timeline for the liquid (Z8) and flat (non-liquid, Z6) interface systems. Panel (A) shows the time-course from docking (applanation and vacuum) and the different stages of Femto-fragmentation and Capsulotomy for the Z8 liquid interface and panel (B) the Z6 Flat Interface for LASIK flap cutting. The sequence 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. Panel (C) shows the average IOP for the Z8 and Z6 during the whole procedure and (D) shows the schematic average IOP (mmHg) for the Z8 liquid interface (closed triangles) and the Z6 flat interface (closed circles). Comparison was by the unpaired t test (n = 12) (p < 0.05 significant). *NB - the globe was compressed with the applanation device prior to the generation of adequate suction. p < 0.001***.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: Fluctuation of IOP and time course of fragmentation/capsulotomy with a liquid interface (Z8) or LASIK flap cutting with a flat interface (Z6) with a Ziemer femtosecond laser.Representative timeline for the liquid (Z8) and flat (non-liquid, Z6) interface systems. Panel (A) shows the time-course from docking (applanation and vacuum) and the different stages of Femto-fragmentation and Capsulotomy for the Z8 liquid interface and panel (B) the Z6 Flat Interface for LASIK flap cutting. The sequence 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. Panel (C) shows the average IOP for the Z8 and Z6 during the whole procedure and (D) shows the schematic average IOP (mmHg) for the Z8 liquid interface (closed triangles) and the Z6 flat interface (closed circles). Comparison was by the unpaired t test (n = 12) (p < 0.05 significant). *NB - the globe was compressed with the applanation device prior to the generation of adequate suction. p < 0.001***.
Mentions: The set up of the instrumentation is shown in Fig. 1A/B. The average IOP was 74.2 mmHg (±18.31) during the procedure with the Z8. Representative plots of the time course and average IOP during the procedure illustrate the different profiles seen with fragmentation/capsulotomy (Fig. 2A,B). Sub-group comparison also revealed that the average IOP was significantly lower with the Z8 fragmentation/capsulotomy 72.50 mmHg (±24.2) than with Z6 LASIK flap creation, 201.9 mmHg (±18.55) (p < 0.0001). The average IOP rise between platforms is shown in Fig. 2C. This was evident in every step of the procedure with exception of the initial docking stage a/a1 (Fig. 2D, Supplementary Table). A stable profile was observed during the laser cutting stages following a peak IOP at the end of the docking stage b/b1.

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