Argon Laser

The Argon laser is used to carry out a type of outpatient treatment called photocoagulation. This is a therapeutic technique used in various situations, but especially in retinalvascular diseases.

The Argon Laser is an intense beam of light with two different wavelengths, blue-green (488-514nm) and monochrome green (514nm). This is absorbed by the cells of the retinal pigment epithelium (dark layer that serves as a screen, turning the eye into a dark chamber), and is converted into thermal energy, increasing the temperature of the area where it is applied. When the temperature of the tissue to be treated exceeds 65ºC, its proteins are denatured, with consequent coagulation and formation of scar tissue.

The effectiveness of photocoagulation depends on how the light beam penetrates the ocular media and how it is absorbed by the target tissue. The light beam is absorbed mainly by ocular tissues such as the pigment epithelium, xantholic pigment (which coexists with that in the macula, the central part of the retina where the image is formed) and haemoglobin.

The Argon Laser is indicated for the treatment of several retinal vascular diseases:

• on glaucoma (trabeculoplasty), peripheral iridoplasty (peripheral iridectomy for closed angle glaucoma prophylaxis), lid diseases (trichiasis).
• at diabetic retinopathywhere photocoagulation is important to prevent disease progression.
• in venous thrombosis, aneurysms and retinal vasculitis.
• in all clinical situations that may be complicated by the formation of neovessels.
• when there are holes or tears in the retina, preventing subsequent retinal detachment.
• in diseases of the choroid (the vascular layer of the eye which supplies nutrients and oxygen) such as tumours, haemangiomas and vascular membranes which form in diseases such as age-related macular degeneration.

Once the doctor has identified the disease to be treated, he/she can use OCT and/or angiography (fluorescein or vede indocyanine), examinations that allow locating and characterizing the lesions to be treated. The pupil is then dilated and topical anaesthesia is applied (using anaesthetic eye drops).

The patient is seated under a biomicroscope (commonly known as a slit lamp), a contact lens specific for the treatment is applied, through which the doctor observes the lesions and shines the argon laser beam.

The Argon Laser treatment is practically painless and after a couple of hours, the patient will be able to go back to their daily tasks, once the chafing caused by the intense light and the dilation of the pupil has passed.

It is sometimes necessary to repeat the treatment if it is considered by the doctor to be insufficient, or as a precaution, in situations where the total energy to be used exceeds the tolerance capacity of the tissues, so that the treatment can be carried out in one session.

Laser photocoagulation is an extremely safe procedure, and complications are rare. The effectiveness depends on the way the light beam penetrates the ocular media, the area to be photocoagulated (diameter and depth), the intensity and duration at which the light is applied, and the way it is absorbed by the target tissue.

Possible complications include transient blurred vision, macula oedema, changes in colour vision, difficulties with night vision and visual field defects.