Panretinal Photocoagulation (PRP) is a laser procedure designed to treat serious conditions affecting the back of the eye. It involves applying numerous tiny, scattered laser burns to the peripheral retina, the light-sensitive tissue lining the inside of the eye. This sight-preserving treatment controls the growth of abnormal blood vessels by coagulating small areas of retinal tissue. By treating these outer regions, PRP aims to stabilize the eye and prevent catastrophic vision loss.
Medical Conditions Requiring PRP
Panretinal Photocoagulation is primarily performed to manage severe eye diseases characterized by ischemia, a lack of oxygen reaching the retina. Oxygen-starved retinal tissue releases chemical signals that trigger neovascularization, the growth of new, fragile blood vessels. These vessels are structurally weak and can easily bleed into the vitreous gel, causing severe vision obstruction, or pull on the retina, leading to retinal detachment.
The most frequent reason for performing PRP is Proliferative Diabetic Retinopathy (PDR), the advanced stage of diabetic eye disease. In PDR, widespread retinal ischemia drives the formation of abnormal vessels, posing a high risk for hemorrhage and traction. Severe Retinal Vein Occlusion, where a major vein is blocked, can also lead to extensive ischemia and subsequent neovascularization, making it another common indication for PRP. The laser treatment reduces the overall metabolic demand for oxygen by intentionally destroying the peripheral, oxygen-starved tissue, eliminating the stimulus for abnormal vessel growth.
The Steps of the Photocoagulation Procedure
The Panretinal Photocoagulation procedure is typically performed in an outpatient setting, often over multiple sessions to ensure patient comfort and optimal treatment delivery. Preparation begins with specialized eye drops to achieve maximum pupil dilation, allowing the doctor a clear view of the peripheral retina. Numbing drops are also applied to the eye’s surface to minimize sensation during the treatment.
The patient is seated at a piece of equipment similar to an examination microscope, called a slit lamp, with their chin resting in a cup and their forehead against a band. The ophthalmologist then carefully places a specialized contact lens, sometimes referred to as a gonio lens, directly onto the anesthetized eye. This lens serves the dual purpose of stabilizing the eye and helping to focus the laser light with extreme precision onto the peripheral retinal tissue.
During the procedure, the patient perceives bright flashes of light as the laser energy is delivered to the retina. While the surface of the eye is numb, patients often report mild to moderate discomfort, described as pinching, pressure, or a dull ache as the laser spots are applied. The treatment involves creating a large number of discrete laser burns across the entire periphery of the retina, often totaling between 1,500 and 2,000 spots per eye, usually divided across two or more sessions. This scatter-pattern application systematically covers the ischemic areas while sparing the central macula region responsible for sharp, detailed vision.
Immediate Recovery and Temporary Visual Changes
Following PRP, patients should expect immediate, temporary visual changes resulting from the treatment and preparation. Pupil-dilating drops cause significant blurring and photophobia (heightened sensitivity to light), which typically lasts four to six hours until the medication wears off. The eye may also feel slightly irritated or sore from the contact lens used during the laser session.
A dull ache or headache is common and usually manageable with over-the-counter pain relief medications. Vision may also be “dazzled” or temporarily darker for the first 24 to 48 hours as the eye adjusts to the numerous fresh laser spots on the retina. Due to temporary visual impairment from dilation and initial laser effects, arranging transportation home is necessary, and driving must be avoided for the rest of the day.
Activity restrictions are typically advised for the first day or two to minimize strain on the eye while the initial effects subside. Patients are often instructed to avoid strenuous activity, heavy lifting, or any action that involves bending over, which can increase pressure within the eye. While initial blurring resolves quickly, a slight graininess or increased awareness of “floaters” may persist for a few days as the eye begins the healing process. Any severe pain, sudden worsening of vision, or the appearance of a curtain-like shadow across the visual field should prompt immediate contact with the eye doctor.
Long-Term Visual Adaptation and Follow-Up
The goal of Panretinal Photocoagulation is to prevent severe, irreversible vision loss by stabilizing the underlying disease process. The procedure is not intended to restore vision already lost due to the condition. This sight-preserving trade-off involves a permanent alteration to the visual field resulting from treating the peripheral retina.
Patients must adapt to a reduction in their peripheral, or side, vision, a necessary consequence of the laser burns covering the outer edges. This permanent visual field constriction is accepted because it prevents complete loss of central vision from a vitreous hemorrhage or retinal detachment. Another long-term consequence is often a noticeable decrease in night vision, linked to the intentional destruction of peripheral light-sensitive cells.
Ongoing, regular follow-up examinations are required after the initial treatment sessions to monitor the eye’s response. The ophthalmologist checks that abnormal blood vessels have successfully regressed and that no new areas of neovascularization have formed. Depending on the severity of the original condition and the eye’s response, additional “touch-up” laser treatments may be necessary over time to maintain stability.