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Thermal Study of Longitudinal and Torsional Ultrasound Phacoemulsification : Tracking the Temperature of Corneal Surface, Incision and Handpiece Bokkwan Jun MD, John P Berdahl MD, Terry Kim MD* Duke University Eye Center Durham, North Carolina

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bokkwan jun md john p berdahl md terry kim md duke university eye center durham north carolina

Thermal Study of Longitudinal and Torsional Ultrasound Phacoemulsification:

Tracking the Temperature of Corneal Surface, Incision and Handpiece

Bokkwan Jun MD, John P Berdahl MD, Terry Kim MD*

Duke University Eye Center

Durham, North Carolina

Supported by a research grant from Alcon, Inc., Consultant, Alcon, Inc.*

purpose
Purpose
  • To investigate the change and difference in temperature at the corneal surface, incision, and handpiece
    • Two different modalities of ultrasound
      • Longitudinal
      • Torsional
    • Two different sizesof incision
      • Standard (2.75mm)
      • Microincisional (2.2mm)
  • To observe thermal effect on the wounds
    • Operating microscopy
    • Scanning electron microscopy (SEM)
methods
Methods
  • Prospective study
    • Twelve human cadaver eyes
    • Four groups of 3 eyes/group
      • Group 1: 2.75mm, 100% longitudinal
      • Group 2: 2.2mm, 100% longitudinal
      • Group 3: 2.75mm, 100% torsional
      • Group 4: 2.2mm, 100% torsional
  • System settings and accessories
    • Fluidics: Vacuum: 300mmHg, Aspiration: 12cc/min, Bottle height: 100cm and simulated On/Off occlusion approx. every 7 seconds
    • Phacoemulsification time: ~ 40 seconds with full power and instrument manipulation to simulate surgical use
    • Tip: Mini-Flared 30° Kelman tip
    • Sleeve: MicroSleeve for 2.75mm, UltraSleeve for 2.2mm
slide4

Methods

  • Thermocamera

(ThermaCAMTM, FLIR system, Danderyd, Sweden)

    • Thermal images were captured every 5 sec
    • The temperature of three areas was measured
      • Corneal surface
      • Incision
      • Handpiece
  • Operating microscopy
    • To observe wound burn with OR microscope

(whitening and edema of the wound edge)

  • Scanning electron microscopy(SEM)

3

2

1

slide5

Results

  • The average of maximum temperature of incision, handpiece and corneal surface in each group
slide6

Results

  • Comparison of Thermal images at maximum temperature

Group 1 (2.75mm, 100% longitudinal)

Group 2 (2.2mm, 100% longitudinal)

Group 1 (2.75mm, 100% torsional)

Group 1 (2.2mm, 100% torsional)

slide7

Results

  • Temperature changes of corneal surface, incision and hand piece

Group 1 (2.75mm, 100% longitudinal)

Group 2 (2.2mm, 100% longitudinal)

Group 3 (2.75mm, 100% torsional)

Group 4 (2.2mm, 100% torsional)

slide8

Results

  • Comparison of incision temperature

with 2.75mm and 2.2mm incision

Group 1

(2.75mm, 100% longitudinal)

vs

Group 2

(2.2mm, 100% longitudinal)

(p=0.002)

Group 3

(2.75mm, 100% torsional)

vs

Group 4

(2.2mm, 100% torsional)

(p<0.001)

slide9

Results

  • Comparison of incision temperature

between longitudinal and torsional groups

Group 1

(2.75mm, 100% longitudinal)

vs

Group 3

(2.75mm, 100% torsional)

(p<0.001)

Group 2

(2.2mm, 100% longitudinal)

vs

Group 4

(2.2mm, 100% torsional)

(p<0.001)

slide10

Results

  • Operating microscopy
    • Group 1 and 2 (longitudinal US groups)
      • Wound burn (whitening and edema of the wound edge) was observed in 6/6
      • Incision temperature was 43~45℃ when the first sign of wound burn was observed
    • Group 3 and 4 (torsional US groups)
      • No wound burn was evident in 0/6
results sem endothelial view
Results(SEM, endothelial view)
  • SEM images demonstrating wound gap of inner surface and partial loss of Descemet’s membrane

Group 1 (2.75mm, 100% longitudinal)

Group 2 (2.2mm, 100% longitudinal)

Group 4 (2.2mm, 100% torsional)

Group 3 (2.75mm, 100% torsional)

conclusions
Conclusions
  • Incision temperature
    • Can be influenced by ultrasound modality.
    • Was significantly lower in torsional ultrasound as compared to longitudinal ultrasound.
    • To a lesser extent, smaller incisions may also increase incision temperature, but not to a significant degree.
  • The combination of torsional ultrasound and small incisions
    • A safe way to decrease the risk of wound burn in patients with dense cataracts.