Diabetic retinopathy is an eye complication of diabetes that can lead to vision loss if unmanaged. This condition affects the retina, the light-sensitive tissue at the back of the eye, where high blood sugar levels can damage delicate blood vessels. Laser coagulation, also known as laser photocoagulation, is an effective treatment to preserve vision. It aims to halt disease progression by targeting and treating compromised blood vessels in the retina.
Understanding Diabetic Retinopathy
Diabetic retinopathy develops when high blood sugar levels damage the tiny blood vessels in the retina. These vessels can swell, leak fluid, or close off, obstructing blood flow to parts of the retina. Sometimes, abnormal, fragile new blood vessels (neovascularization) grow on the retina. These new vessels are weak and can bleed into the vitreous, the clear gel that fills the eye, or cause scar tissue to form.
The condition progresses through stages: non-proliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR). NPDR, the early stage, involves microaneurysms, tiny bulges in blood vessels that can leak fluid, causing the retina, particularly the macula, to swell. This macular swelling, known as macular edema, is a common cause of vision loss. As NPDR advances, more blood vessels can become blocked, reducing blood flow to the retina.
PDR is the more advanced stage, characterized by the growth of new, abnormal blood vessels on the retina or optic nerve. These fragile vessels can bleed into the vitreous, causing dark floaters or vision blockage. Scar tissue can also form, potentially pulling on the retina and causing a retinal detachment, which can result in severe central and peripheral vision loss.
The Laser Coagulation Procedure
Laser coagulation for diabetic retinopathy involves two types of treatment: panretinal photocoagulation (PRP) and focal/grid laser treatment. PRP, also known as scatter photocoagulation, is used for proliferative diabetic retinopathy. It involves applying numerous laser burns across the peripheral retina. This widespread treatment reduces the retina’s oxygen demand, discouraging the growth of new, abnormal blood vessels and causing existing ones to shrink.
Focal or grid laser treatment is used to address macular edema, where fluid leaks into the macula, the central part of the retina responsible for sharp, detailed vision. This procedure precisely targets individual leaking microaneurysms or applies a grid pattern of gentle, low-power laser burns to areas of diffuse leakage near the macula. The laser creates microscopic scars that seal off problematic blood vessels, reducing fluid accumulation and stabilizing vision.
Before the procedure, the patient’s pupils are dilated with eye drops to allow the ophthalmologist a clear view of the retina. Topical anesthetic drops are also applied to numb the eye, minimizing discomfort. The patient sits at a specialized machine with their chin resting on a support. A special contact lens is then placed on the eye to focus the laser beam and keep the eye still.
During laser application, patients may experience bright flashes of light and a mild pricking or stinging sensation with each laser burn. The procedure is relatively quick, often taking 10 to 60 seconds for focal treatment or 20 to 40 minutes for PRP, depending on the extent needed. PRP may require multiple sessions, with hundreds to thousands of laser spots applied across the retina over several visits.
After the Procedure
After laser coagulation, patients can expect temporary side effects. Blurred vision is common, usually improving within hours to a day, though it can last several days after extensive PRP. Mild discomfort, eye ache, or irritation may occur, manageable with over-the-counter pain relievers. Increased light sensitivity and dilated pupils are also common due to the eye drops used.
Post-procedure care includes avoiding driving for 24 hours due to blurred vision and light sensitivity. Wearing sunglasses outdoors is recommended to protect the eyes from bright light. Most patients can resume normal activities like work or school the day after, but consult your doctor regarding physical activities. Follow-up appointments monitor the eye’s response and determine if additional laser sessions are necessary.
The expected outcome of laser coagulation is to stabilize vision and prevent further loss, not to restore lost vision. For PDR, PRP significantly reduces the risk of severe vision loss. For macular edema, focal/grid laser treatment reduces swelling and can stabilize or improve vision over weeks to months. Potential complications, though rare, include reduced peripheral vision, decreased night vision, or altered color vision, particularly after PRP. In rare cases, a permanent small blind spot or accidental laser damage to the central macula can occur.