1. The Effect of Target Color on Laser Absorption
Ben Azar
Grade 9
Central Catholic High School

2. Rationale
To determine the effects of target color on the absorption of a Nidek GYC nm frequency-doubled green ophthalmic YAG laser.
Laser test fire experience
Could target color possibly enhance the laser’s effectiveness and safety?
Will target color have an effect on laser absorption?

3. Purpose
To test if there could be a way to possibly use target color to enhance the safety of laser procedures and surgeries.
To find a way to make surgeries safer by treating only the target tissue and not the surrounding normal tissue. This is especially important when working with delicate structures such as the eye.

4. Lasers
Acronym for Light Amplification by Stimulated Emission of Radiation
Excitatory material which is stimulated
Displaces electrons
Emission of energy/photons
Laser beam power, duration, and spot size can be modified

5. Ophthalmic 532nm Frequency Doubled YAG
Green variant
Makes delicate small burns
Excitatory material: neodymium-doped, yttrium-aluminum-garnet crystal
1064nm
Frequency doubling/532nm
Visible spectrum

6. Duration and Power Play a big role in absorption
More power=more intense burn
Can be modified to fit the needs of the procedure
Glaucoma treatment with frequency doubled YAG
ms  ns

7. Target Manipulation
The target’s characteristics can also have an effect on laser absorption
PDT
Visudyne is a drug that collects in abnormal blood vessels in the retina
Specific wavelength activates
Destroys abnormal blood vessels
Protects normal blood vessels

8. Changing Eye Color
It is uncommon but some scientists claim to be able to change the colors of eyes
Green lasers are absorbed well by melanin
The settings are adjusted to destroy melanin without destroying surrounding normal tissue
Destroying melanin changes eye color
What if I could stain tissues to increase laser absorption?

9. Experimental Target
Animal tissues were beyond the scope of this experiment
Lasers are usually tested on paper before used on patients in order to ensure that they are working properly
Paper is readily accessible and comes in multiple colors
Tissue paper was too porous
Construction paper worked best
POC

10. Hypotheses
Null=Target color will have no significant effect on laser absorption
Alternative=Target color will have an effect on laser absorption

11. Materials
Nidek GYC nm frequency-doubled ophthalmic YAG laser (green variant)
60 lb. construction paper (Blue, Green, Yellow, Brown, and Red)
Haag Streit 900 slit lamp
20 diopter magnifying lens

12. Procedures The laser was turned on and calibrated.
Paper was centered and taped to the slit lamp in consistent fashion.
The laser settings were adjusted.
The laser was focused on the target.
A spot size of 500 microns and a pulse duration of 0.15 seconds was used in all trials.
The laser was fired three times for each power ( mW in 100 mW increments).
Once all of the bursts had been fired, the paper was taken off of the slit lamp and the results were recorded by looking at the ultra fine holes under a 20 diopter magnifying lens.
Steps two through seven were repeated for all five colors of paper.

13. Pictures of Laser Burns

14. Effect of Blue Paper on Laser Absorption
No Penetration=0
Partial Penetration=1
Full Penetration=2

15. Effect of Red Paper on Laser Absorption
No Penetration=0
Partial Penetration=1
Full Penetration=2

16. Effect of Brown Paper on Laser Absorption
No Penetration=0
Partial Penetration=1
Full Penetration=2

17. Effect of Yellow Paper on Laser Absorption
No Penetration=0
Partial Penetration=1
Full Penetration=2

18. Effect of Green Paper on Laser Absorption
No Penetration=0
Partial Penetration=1
Full Penetration=2

19. Effect of All Colored Paper on Laser Absorption
No Penetration=0
Partial Penetration=1
Full Penetration=2

20. Conclusion Yellow differed significantly from the other colors
Yellow and green were lower than the other colors at 500 and 600 nm
Yellow remained lower than the other colors
Not much variation seen among the following colors: blue, red, and brown
The null was rejected for yellow and green

21. Limitations and Extensions
Data was qualitative. A key had to be made.
Holes were very small so it was hard to measure (especially between partial and full penetration).
Only one type of material used
Only one wavelength used
Unknown relationship to bodily tissues
Extensions
More replicates
Other wavelengths
Natural tissues
Could have used more increments of power.

22. Sources
provides-efficiencies-in-the-clinic eyes-blue Lasers-in-Ophthalmology/