Quantification of hydroxyl radical during phacoemulsification.

Department of Ophthalmology, Dokkyo Medical University (JAPAN)Norihito Gotoh MD PhD, Hiroyuki Matsushima MD PhD, Koichiro Mukai PhD,

Makoto Takayama MD, and Tadashi Senoo MD PhD

The authors have no financial interest in the subject matter of this poster.

QuestionPostoperative inflammation and loss of corneal endothelial cells are still one of important complications after cataract surgery.The mechanisms are still unclear.

phacoemulsification Loss of corneal endothelial cells

Theories about loss of corneal cells after cataract surgery

Oxidation, thermal reaction, water flow, etc…

In this study, we detect the hydroxyl radical during PEA.

Purpose (1)

We drew attention to oxidation by phacoemulsification and aspiration (PEA) may be one of causes for the complication.

Method to detect hydroxyl radical

INFINITITM system (Alcon), a PEA unit was prepared.

To trap the hydroxyl radical, 1.5ml of distilled water with 1% trapping agent (5,5-dimethyl-1-pyrroline N-oxide, LABOTEC) was added in test chamber.

After the oscillation the trapping solution was obtained immediately and electron spin resonance (ESR) trapping methods (JES-RE1X, JEOL) were used to detect the hydroxyl radical production.

Fe2+ + H2O2 → Fe3+ + HO- + HO

Typical hydroxyl radical by ESR(positive control: Fenton reaction)

Hydroxyl radical is a strongest oxidation in some free radicals. Hydroxyl radical bound trapping agent is detected 4 peaks by electron spin resonance (ESR). Fenton reaction is a typical reaction of hydroxyl radical production (positive control).

Control: manganese

Control: manganese

.

Result to detect hydroxyl radical by ESR

Mn MnCondition: 100% traditional-PEA for 30 seconds.

Hydroxyl radical was produced during PEA.

Answer (1)

Comparison of a torsional handpiece through microincision versus standard clear corneal cataract wounds.Berdahl JP, Jun B, DeStafeno JJ, Kim T. J Cataract Refract Surg. 2008;34(12):2091-5.

Comparison of endothelial changes and power settings between torsional and longitudinal phacoemulsification.Reuschel A, Bogatsch H, Barth T, Wiedemann R. J Cataract Refract Surg. 2010;36(11):1855-61

The relationship between different systems of PEA (traditional & torsional) and loss of corneal endothelial cells have been reported in the following.

Next, we quantitate the hydroxyl radical during oscillations using traditional- and torsional-PEAs.

Purpose (2)

<Different settings of PEA>100% traditional-PEA

50% traditional-PEA

100% torsional-PEA

50% torsional-PEA

Traditional- and torsional-PEA was oscillated for 30 seconds with fixing test chamber and cumulative dissipated energy (CDE) was measured.ESR was also used to detect the radical production.

Method to quantitate hydroxyl radical

A B

Method to calculate hydroxyl radical level

AB

The level of hydroxyl radical production were calculated by percentage of manganese peak.

Level of hydroxyl radical (%) = x 100Control: manganese

Results: quantity of hydroxyl radical100% traditional-PEA

50% traditional-PEA

100% torsional-PEA

50% torsional-PEA

Level of hydroxyl radical = 18.9±8.9%CDE = 30.4±0.2

Level of hydroxyl radical = 11.1±2.3%CDE = 14.8±0.2

Level of hydroxyl radical = 6.0±3.1%CDE = 12.1±0.2

Level of hydroxyl radical = 2.5±0.3%CDE = 5.9±0.1

Mn Mn

Mn Mn

Mn Mn

Mn Mn

The quantity of hydroxyl radical was smaller using torsional-PEA than traditional-PEA, and was increased by an increase in US power..

• torsional-PEA <<traditional PEA• low US power << high US power

Results: relationship between level of hydroxyl radical and CDE

The hydroxyl radical production was linear with respect to CDE.The radical production was be positively correlated with CDE (R2 = 0.9578).

0 2 4 6 8 10 12 14 16 18 2005

101520253035

f(x) = 1.42990883993316 x + 2.04462741564329R² = 0.957817810170595

Cumulative dissipated energy (CDE)

Leve

l of h

ydro

xyl r

adic

al(%)

100% traditional

50% traditional100% torsional

50% torsional

•The quantity of hydroxyl radical was affected by PEA system (traditional or torsional) and US power.

torsional-PEA << traditional-PEAlow US power << high US power

•The radical production was be positively correlated with CDE (R2 = 0.9578).

Answer (2)

Conclusions•Hydroxyl radical was produced during PEA and its quantity of production was dependent on CDE during PEA.

•The quantity of hydroxyl radical was smaller using torsional-PEA than traditional-PEA.

•Oxidative stress in the eye may be minimized by using torsional-PEA.