Temperature-Controlled Retinal Photocoagulation Reliably Generates Uniform Subvisible, Mild, or Moderate Lesions

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Laser Medicine

Background:

• Conventional retinal photocoagulation often results in irregular lesions and lacks precise control, especially for subvisible pathologies.
• Manual titration of laser power is required, introducing variability and dependence on physician skill.

Purpose of the Study:

• To evaluate automatically controlled retinal photocoagulation (TTC) for creating predictable, uniform lesions in rabbit eyes.
• To assess the feasibility of achieving five distinct lesion intensities using this automated method.

Main Methods:

• A 532-nm laser combined with a pulsed probe laser enabled real-time fundus temperature monitoring and automatic exposure control.
• Time/temperature dependent characteristics (TTC) were applied to 794 lesions across five intensities in rabbit eyes.
• Lesion morphology was assessed using funduscopy and optical coherence tomography (OCT) over three months.

Main Results:

• Lesion visibility and intensity increased with TTC groups, with high visibility (>94%) for groups 3-5.
• Increasing TTC intensity correlated with greater morphological lesion severity and larger diameters on funduscopy and OCT.
• Group 5 lesions demonstrated increased intensity compared to Group 4, despite similar sizes.

Conclusions:

• Automatic, temperature-controlled photocoagulation offers predictable lesion creation without manual power titration.
• This technology facilitates standardized, physician-independent photocoagulation at ETDRS-equivalent intensities for various retinal conditions.