photocoagulation

Photocoagulation is a medical procedure that uses focused laser energy to coagulate tissue. The light is absorbed by tissue chromophores such as hemoglobin, melanin, or water, converting photons to heat. This thermal effect denatures proteins, coagulates blood vessels, and can destroy or seal targeted tissue. The approach relies on selective photothermolysis, with wavelength, pulse duration, and energy chosen to affect the intended site while minimizing collateral damage.

Devices and wavelengths vary by application. Common lasers include argon, krypton, Nd:YAG, diode, and pulsed-dye systems. Shorter wavelengths target superficial structures, while longer wavelengths reach deeper layers. In ophthalmology, lasers are used with careful focusing to treat retinal tissue, sometimes with continuous-wave or short-pulse energy.

Applications in ophthalmology are the most prominent. Photocoagulation treats retinal vascular diseases such as diabetic retinopathy and macular edema. Focal or grid photocoagulation reduces leakage from microaneurysms or edema, while panretinal photocoagulation ablates peripheral retina to reduce ischemia-driven neovascularization. Laser retinopexy may seal retinal tears. In dermatology and other fields, photocoagulation coagulates superficial or vascular lesions, such as port-wine stains or telangiectasias, using vascular-targeted lasers like pulsed-dye systems or Nd:YAG-based devices.

Safety and outcomes depend on disease, laser type, and operator skill. Potential risks include inadvertent damage to adjacent tissue, scotomas or blind spots, scarring, pigmentary changes, and transient visual disturbances. Advances in imaging, targeting, and dosing have improved precision and reduced adverse effects.