Which change is associated with patient comfort via cooling?

• A. Increasing spot size
• B. Increasing wavelength
• C. Increasing energy
• D. Increasing repetition rate

Answer: (A)

When aiming for patient comfort through cooling, how energy is delivered to the skin matters. A larger spot size spreads the laser energy over a wider area, which lowers the peak surface fluence. This makes it easier for the epidermal cooling system (whether contact cooling or cryogen spray) to protect the skin and remove heat between pulses, reducing the sensation of heat and overall discomfort. Additionally, treating with a bigger spot size covers more area per shot, shortening the session and further limiting cumulative heat exposure.

In contrast, increasing wavelength affects how deeply and selectively the light is absorbed but doesn’t directly enhance cooling; increasing energy raises heat in the skin and can increase discomfort; increasing repetition rate can increase heat buildup unless cooling keeps up, so it’s not inherently linked to improved comfort via cooling.