PASCAL Laser Treatment for Retinal Conditions
Understanding PASCAL Laser Technology
PASCAL stands for Pattern Scan Laser. It is a semi-automated laser photocoagulation system originally developed at Stanford University. The system received FDA clearance in 2005. It uses a microprocessor-driven scanner to produce scalable laser patterns that a retina specialist selects on a computer screen.
Rather than firing one laser spot at a time, PASCAL delivers multiple spots in a rapid, predetermined sequence with a single press of a foot pedal. The laser uses a frequency-doubled Nd:YAG laser at a wavelength of 532 nm. This green light wavelength is well-suited for treating retinal tissue.
Conventional single-spot laser therapy uses pulse durations of 100 to 200 milliseconds per spot. PASCAL reduces that pulse duration to about 10 to 20 milliseconds, which is roughly ten times shorter. This shorter burst of energy means less total heat is delivered to surrounding tissue.
Because less energy spreads into the choroid (the blood vessel layer beneath the retina), PASCAL produces more uniform, predictable burns. There is less collateral damage to healthy tissue. The result is a treatment that is faster, more precise, and generally more comfortable for the patient.
One of the key features of PASCAL is its ability to deliver laser energy in different geometric patterns. These patterns are tailored to specific conditions. Common patterns include:
- Square arrays, often used for panretinal photocoagulation in diabetic retinopathy
- Arc patterns, used to treat retinal tears, retinal detachments, and lattice degeneration
- Macular grid and partial modified grid patterns, used for retinal vein occlusion and diabetic macular edema
Conditions Treated with PASCAL Laser
PASCAL is commonly used to perform panretinal photocoagulation (PRP). This procedure treats widespread abnormal blood vessel growth in proliferative diabetic retinopathy. PRP involves placing hundreds or thousands of laser spots across the peripheral retina. These spots reduce the oxygen demand that drives new, fragile blood vessel formation. PASCAL can also deliver focal laser treatment for nonproliferative diabetic retinopathy when specific areas of leakage need attention.
In diabetic macular edema (DME), fluid accumulates in the macula, the central part of the retina responsible for sharp vision. PASCAL can deliver macular grid photocoagulation to reduce this swelling. A newer approach called Endpoint Management, or EpM, uses a subthreshold laser setting. This setting treats the tissue without creating a visible burn. In clinical trials, both standard PASCAL laser and the EpM algorithm have improved visual acuity and reduced central retinal thickness in eyes with DME (Retina Today, 2023).
Retinal vein occlusions occur when a vein carrying blood away from the retina becomes blocked. This leads to swelling, bleeding, and abnormal blood vessel growth. PASCAL can deliver macular grid patterns and panretinal photocoagulation to manage complications. It is used for both branch retinal vein occlusion and central retinal vein occlusion.
When a retinal tear is detected, laser photocoagulation can seal the edges of the tear. This prevents fluid from seeping beneath the retina and causing a detachment. PASCAL uses arc patterns to place laser spots around the tear quickly and precisely. This approach is also used to treat lattice degeneration, a condition where the retina thins and becomes more vulnerable to tearing.
PASCAL can be used for focal treatment of juxtafoveal choroidal neovascularization. This refers to abnormal blood vessels growing near the center of the macula. While anti-VEGF injections are the primary treatment for most cases of wet age-related macular degeneration, laser photocoagulation may still play a role in certain situations. A retina specialist will determine when this approach is appropriate.
What Happens During PASCAL Treatment
Your retina specialist will dilate your pupils using eye drops so the retina can be clearly viewed. You will be seated at the laser delivery system. It looks similar to the slit lamp microscope used during routine eye exams. A special contact lens will be placed on the surface of your eye to help focus the laser beam. Numbing drops are used so this lens is comfortable.
The procedure itself is relatively brief. In a randomized clinical trial comparing PASCAL to conventional laser for panretinal photocoagulation, the average PASCAL treatment time was 3.76 minutes. Conventional laser took 6.65 minutes on average (PMC, 2019). You may see flashes of light as the laser fires. Some patients feel mild discomfort or a brief stinging sensation. Many report that PASCAL is more comfortable than conventional single-spot laser because of the shorter pulse durations.
Your retina specialist will select the appropriate pattern and settings for your specific condition. The laser spots are then delivered in rapid sequences. The entire session is typically completed in under 10 minutes.
Your vision may be blurry for several hours after treatment. This is partly from the dilating drops and partly from the laser itself. Most patients are able to go home shortly after the procedure. Sunglasses can help with light sensitivity. Your retina specialist will provide specific instructions about follow-up visits and any activity restrictions.
Benefits and Potential Risks
PASCAL offers several practical advantages over conventional single-spot laser treatment. The most noticeable benefits for patients include:
- Shorter treatment sessions due to the ability to place multiple spots per foot pedal press
- Less discomfort during the procedure because of shorter pulse durations
- More uniform and predictable laser burns with less collateral tissue damage
- Stable scar size over time, with one study of 20 patients showing no tendency for scars to enlarge at follow-up (Muqit et al., 2012)
The EpM algorithm is a notable advancement within the PASCAL platform. It delivers subthreshold laser energy that treats the retina without creating visible burns. Patients treated with EpM have shown no changes on autofluorescein imaging and no symptoms of scotoma (blind spots) after treatment. Research suggests that EpM is associated with a statistically significant reduction in the number of intravitreal injections needed in the six months following treatment (Retina Today, 2023). For patients receiving ongoing anti-VEGF injections such as Avastin (bevacizumab), which is used off-label for eye conditions, or Eylea (aflibercept), reducing injection frequency can ease the treatment burden.
Like any medical procedure, PASCAL laser treatment carries some risks. In a study of 1,301 consecutive PASCAL cases, reported complications included 17 cases of retinal bleeding at 1.3 percent and two cases of choroidal detachment at 0.15 percent. One case of exudative retinal detachment occurred at 0.07 percent (Muqit et al., 2010). These complication rates are comparable to those seen with conventional laser treatment.
A 2017 review of pattern scanning lasers noted that some studies suggested a potentially higher rate of persistent retinal neovascularization compared to the conventional approach. In some comparative studies, complications such as vitreous hemorrhage, neovascular glaucoma, retinal hemorrhage, and choroidal detachment were reported in a small number of PASCAL patients. Your retina specialist will weigh these considerations when planning your treatment.
PASCAL and Anti-VEGF Combination Therapy
Many patients with diabetic retinopathy, diabetic macular edema, or retinal vein occlusion receive intravitreal injections of anti-VEGF medications. Anti-VEGF agents block abnormal blood vessel growth and reduce fluid leakage in the retina. Common anti-VEGF medications for these conditions include Eylea (aflibercept), Lucentis (ranibizumab), and Vabysmo (faricimab). Avastin (bevacizumab), which is FDA-approved for cancer but used off-label for eye conditions, is also widely used.
PASCAL laser treatment can complement anti-VEGF therapy. By treating the underlying retinal disease with laser, the need for frequent injections may be reduced over time. This combined approach is determined on a case-by-case basis by your retina specialist.
In one reported case, a 61-year-old patient with proliferative diabetic retinopathy and diabetic macular edema was receiving monthly Avastin (bevacizumab) injections. Avastin is used off-label for eye conditions. Her vision in the affected eye was 20/70 despite the injections. After receiving PASCAL laser treatment with the EpM algorithm, her injection requirement dropped from six in the six months before treatment to two in the six months after (Retina Today, 2023). While individual results vary, this example illustrates how PASCAL may help reduce treatment burden.
Living with Your Condition After PASCAL Treatment
Regular follow-up visits are essential after PASCAL laser treatment. Your retina specialist will monitor your retina to evaluate the treatment response and check for complications. Additional laser sessions or other treatments may be needed. The number and frequency of follow-up appointments depend on your specific condition and how your eye responds.
Laser photocoagulation, including PASCAL, aims to stabilize retinal conditions and prevent further vision loss. It does not restore vision that has been lost. In many cases, additional treatments such as anti-VEGF injections may still be necessary. Patients with diabetes should continue to manage their blood sugar, blood pressure, and cholesterol levels. These factors directly affect retinal health.
Keeping scheduled appointments with your retina specialist is one of the most important things you can do after treatment. Many retinal conditions are chronic, meaning they require ongoing monitoring and management. If you notice any sudden changes in your vision between appointments, take action right away. A sudden increase in floaters, flashes of light, a shadow or curtain across your vision, or sudden vision loss in one eye are warning signs. See a retina specialist or go to the emergency room immediately.
When to See a Retina Specialist
If you have been diagnosed with diabetic retinopathy, diabetic macular edema, a retinal vein occlusion, or a retinal tear, ask your eye care provider about PASCAL laser treatment. A retina specialist can evaluate your condition and recommend the best treatment approach.
Patients who are receiving frequent anti-VEGF injections may benefit from discussing PASCAL with their retina specialist. Adding laser treatment could help reduce the number of injections needed. This decision depends on the specific diagnosis, severity of the condition, and how the eye has responded to previous treatment.
Certain symptoms require urgent evaluation regardless of your treatment history. If you experience a sudden increase in floaters, flashes of light, a curtain or shadow over part of your vision, or sudden vision loss, seek care immediately. See a retina specialist or go to the emergency room. These symptoms can indicate a retinal tear, retinal detachment, or other serious condition requiring prompt treatment.
Questions and Answers
Most patients report that PASCAL is more comfortable than conventional single-spot laser treatment. The shorter pulse durations of 10 to 20 milliseconds mean less heat is delivered with each spot. This results in less discomfort. Some patients may feel mild stinging during the procedure, particularly during panretinal photocoagulation where many spots are placed. Numbing eye drops are applied before treatment, and the procedure is typically completed in under 10 minutes.
The number of sessions depends on your specific condition and its severity. Some patients need only a single session, such as when treating a retinal tear. Panretinal photocoagulation for diabetic retinopathy may require one or more sessions. Your retina specialist will determine the treatment plan based on your individual needs. Response is monitored at follow-up visits.
For most patients, PASCAL does not completely eliminate the need for anti-VEGF injections. However, research suggests that PASCAL treatment, particularly with the Endpoint Management algorithm, may reduce the number of injections needed over time (Retina Today, 2023). Your retina specialist will determine the best combination of treatments for your situation. The goal is to manage your condition effectively while minimizing the overall treatment burden.
The main differences are speed, comfort, and precision. PASCAL delivers multiple laser spots in a predetermined pattern with a single activation. Conventional laser delivers one spot at a time. PASCAL pulse durations are about 10 to 20 milliseconds compared to 100 to 200 milliseconds for conventional laser. Clinical studies have shown that treatment time with PASCAL is roughly 40 percent shorter for panretinal photocoagulation (PMC, 2019). The clinical outcomes of both approaches are similar, but patients generally experience less discomfort with PASCAL.
Your retina specialist will determine whether PASCAL is appropriate for your specific condition. Some situations may require conventional laser treatment instead. This is particularly true if the clinical circumstances call for longer pulse durations or different energy settings. A 2017 review of pattern scanning lasers noted that some studies observed a higher rate of persistent retinal neovascularization with pattern scanning. This finding may influence treatment decisions in certain cases. Your retina specialist will discuss the best option based on your diagnosis and treatment history.