Laser treatment of retinal diseases
HOW DOES IT WORK?
The retinal laser (argon laser) is generally used to “burn” areas of the diseased retina. However, in some cases, it is used to fix the healthy retina around pathological areas (holes or lesions). The aim is to obtain scars that reinforce the retina at its more delicate points.
WHAT IS THE ARGON LASER?
It is a kind of laser whose light beam – generated thanks to the argon, a noble gas – has a thermal action: by heating the area on which the instrument is pointed, a series of diseases of the retina can be treated (by virtue of a phenomenon called photocoagulation).
WHEN IS IT USED?
The argon laser is used to treat:
- Diabetic retinopathy (ischemic forms). In the case of a reduced supply of blood and, as a consequence, of oxygen to certain retinal areas, new blood vessels develop to compensate for the reduced supply, causing severe damage (proliferative diabetic retinopathy). In this case, an argon laser is used to “kill” the areas of diseased tissue.
- Macular edemas (collection of fluid under the central area of the retina): these are the result of an inflammatory process and/or blood vessel alterations. Also in this case, the laser works by destroying the zones that “issue the command” to create new blood vessels (secreting a growth factor called VEGF).
- Peripheral retinal degenerations and breaks. In these cases, there is a high risk of retinal detachment. Through the action of the laser, the retina is burned in proximity to any tear or potentially dangerous degeneration. The scar that is created after the laser treatment acts as a welding, reinforcing the retina.
- Retinal Vein Occlusion. In this case, new vessels can develop, which tend to invade other areas (iridocorneal angle), causing a severe kind of glaucoma (called “neovascular”).
- Retinopathy of Prematurity (ROP). Laser surgery is used to prevent the growth of new retinal blood vessels, which are harmful for eyesight, through the “destruction” of the damaged areas of the retina, due to a reduced supply of blood and oxygen (ischemic areas). An Australian study published in 2013 reported a 93% success rate in laser treatments on very young infants (10 months old). [References: Gunn, D. J., Cartwright, D. W., Yuen, S. A. and Gole, G. A. (2013), “Treatment of retinopathy of prematurity in extremely premature infants over an 18-year period“, [Clinical & Experimental Ophthalmology, 41: 159–166. doi: 10.1111/j.1442-9071.2012.02839]]
HOW IS THE TREATMENT PERFORMED?
The eye of the patient, who must have first signed the informed consent to the treatment, is temporarily anesthetized with drops of local anesthetic. Then a contact lens is applied with suitable treatment filters. The doctor will then target the areas of the retina to be treated. During the procedure, the patient may feel a slight pain comparable to small bites or punctures, depending on the energy used with the laser. At the end of the treatment, the lens is removed, lubricating eye drops and an antibiotic are instilled and then the patient can go home.
WHICH PRECAUTIONS SHOULD BE TAKEN BEFORE AND AFTER THE TREATMENT?
In the days prior to surgery, there are no particular indications to follow but the ones linked to the disease for which the laser treatment is performed. On the day of the surgery and in the following days (the number varies depending on the disease) it is important not to exert oneself: for this reason the doctor may request absolute rest. It is important to properly hydrate oneself and, if requested, take mineral salt supplements to better hydrate the vitreous body.
WHAT SIDE EFFECTS COULD BE EXPERIENCED?
When the periphery of the retina is treated, no vision problems related to the surgery are experienced by the patient. However, in the treatment of the macula (the central area of the retina which is responsible for distinct vision), a damage that may be perceived by the patient can occur: since a small part of the retina is burned, the tissue is no longer able to transmit light; in this case the advantages outweigh the disadvantages, even if a minor damage is created to treat a more serious one. The most frequent, but less severe side effect, may be a reddening of the eye due to the use of a contact lens during the surgery; this problem can spontaneously resolve itself within a few days or be calmed down with the use of lubricating eye drops and/or antibiotics, in the case of a mild corneal abrasion.
WHAT IS RECOMMENDED AFTER THE TREATMENT?
Apart from rest, proper hydration is important during the first 15-20 days after argon laser treatment. It is recommended to drink about 1.5 litres of water every day: as the laser acts by heating the retina and piercing through the eyeball, the liquid that is found here is inevitably heated. As a consequence, the quantity of the vitreous body, being composed for the major part by water, is reduced. Dehydration causes a contraction of the vitreous body, leading to an increased risk of vitreous-retinal tractions and peripheral retinal tears.