Monte Carlo simulation of laser beams interaction with the human eye using Geant4

Area of Science:

• Ophthalmology
• Biomedical Optics
• Computational Physics

Background:

• Ophthalmologic diagnostic techniques utilize photon interactions with the retina to image internal structures.
• Interpretation of images from techniques like scanning laser ophthalmoscopy dark field imaging is not fully understood.
• This limits diagnostic potential for deep retinal abnormalities, such as drusen.

Purpose of the Study:

• To better understand retinal diagnostic images by simulating laser beam interactions with the eye.
• To investigate the impact of drusen on photon behavior and reflected beam characteristics.

Main Methods:

• Computer simulations using the Geant4 toolkit and its optical package.
• Simulated reflection, refraction, absorption, and scattering of 2 eV photons in ocular tissues.
• Analyzed reflected beam characteristics using virtual detectors after simulating a Gaussian orange light beam through eye optics.

Main Results:

• The presence of drusen was found to influence the reflected beam profile.
• Drusen alter the mean free path of photons, modifying reflection patterns.
• Changes in the reflected beam's Gaussian distribution were observed when analyzed outside the eye.

Conclusions:

• Shape analysis of reflected beams in laser scanning techniques can enhance diagnostic capabilities.
• This approach holds potential for improved detection of deeper retinal structures and abnormalities like drusen.