Patient Comfort Using Green vs. Yellow Pan Retinal Photocoagulation

Wills Eye

Status: Completed

Conditions: Proliferative Diabetic Retinopathy - High Risk

Treatments: Procedure: laser indirect ophthalmoscopy pan retinal photocoagulation

Study type: Interventional

Funder types: Other

Identifiers

NCT02995629

16-560

Details and patient eligibility

About

Our aim is to compare patient comfort when using the 532 nanometer (green) wavelength laser to the 577 nanometer (yellow) wavelength laser during pan retinal photocoagulation to treat patients with diabetic retinopathy. Secondary outcome measures will be power (mW) required to achieve gray-white retinal burns and duration of treatment.

Full description

As demonstrated in the Diabetic Retinopathy Study (DRS), panretinal photocoagulation (PRP) reduces the risk of severe vision loss in patients with proliferative diabetic retinopathy. The DRS recommended that PRP treatment consist of 1,200 - 1,600 laser burns 500 µm in size, one half to one burn width apart, applied to the peripheral retina in a scatter fashion. Most patients who undergo PRP experience discomfort/pain during the procedure. Once present, pain can affect the number and quality of burns delivered and can indirectly increase the number of sessions required to complete the therapy.This may in turn adversely affect patient compliance. Although retrobulbar and peribulbar blocks can provide adequate anesthesia for PRP, these anesthetic methods carry rare but serious risks such as retrobulbar hemorrhage. Previous studies have explored other ways to reduce discomfort related to PRP, including optimization of laser settings, oral and topical analgesics, subconjunctival anesthesia, and even acupuncture.

Currently, green lasers (521 - 532 nm wavelength) are most commonly utilized for performing PRP in clinical practice. Yellow lasers (577 nm wavelength) have been of recent interest in treating diabetic macular edema with micropulse subthreshold grid photocoagulation, but have not been extensively studied in PRP for diabetic retinopathy. Compared to shorter wavelength laser, yellow laser comports high transmission through dense ocular media and less light scattering than shorter wavelengths which minimizes spot size and reduces thermal spread. The limited literature comparing green and yellow laser for PRP in diabetic retinopathy has shown that yellow laser requires less power to achieve a retinal burn. In theory this should translate into a reduction in perceived pain experienced during PRP, however a comparison of green and yellow lasers in this regard has not yet been directly examined and quantified.

Enrollment: 40 patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• patient of Wills Eye Hospital Retina Service and/or Mid Atlantic Retina
• volunteer patients age 18 years and older.
• healthy enough to participate in the study.
• willing and able to consent to participation in the study.
• diagnosis of PDR with HRC based on clinical criteria outlined by the DRS.

Exclusion criteria

• patient less than 18 years of age
• institutionalized patient
• prisoner
• significant media opacity obscuring a view of the superior retina
• history of intra-ocular surgery except cataract surgery
• history of PRP laser within the last 30 days

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Single Blind

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40 participants in 2 patient groups

green (532 nm) laser

Experimental group

Description:

scatter laser indirect ophthalmoscopy pan retinal photocoagulation

Treatment:

Procedure: laser indirect ophthalmoscopy pan retinal photocoagulation

yellow (577 nm) laser

Experimental group

Description:

scatter laser indirect ophthalmoscopy pan retinal photocoagulation

Treatment:

Procedure: laser indirect ophthalmoscopy pan retinal photocoagulation