A masking device and method to create custom laser exposure patterns for verteporfin photodynamic therapy

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Medical Physics

Background:

• Verteporfin photodynamic therapy (PDT) is used for various eye conditions.
• Treating irregularly shaped lesions with standard PDT can be challenging.
• Precise laser targeting is crucial to minimize damage to healthy ocular tissues.

Purpose of the Study:

• To develop and evaluate a method for creating individualized laser exposure patterns for verteporfin PDT.
• To adapt commercially available PDT lasers for precise treatment of peripapillary, juxtafoveal, and irregular lesions.

Main Methods:

• Commercially available PDT lasers (Lumenis Opal, Zeiss Visulas 690s) were utilized.
• Various masking materials, including electrical tape, black card stock, and yellow paper, were tested.
• Masking effectiveness was assessed by measuring light transmission, fluence rate, and edge intensity drop-off.

Main Results:

• Electrical tape proved completely opaque, while black card stock transmitted 0.6% and yellow paper 18% of laser light.
• Mask size to image size ratios were determined for different lasers and spot settings.
• Masked areas showed no effect on fluence rate, and intensity drop-off at the mask edge matched the unmasked beam.

Conclusions:

• Customized laser masks can effectively individualize laser exposure patterns in PDT.
• This technique allows for the safe treatment of irregular lesions.
• It minimizes the risk of exposing healthy tissue to unnecessary laser treatment.