Proliferative Diabetic Retinopathy - High Risk
Conditions
Brief summary
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.
Detailed 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.
Interventions
PROCEDURElaser indirect ophthalmoscopy pan retinal photocoagulation
* Prior to procedure, eligible patient is dilated and a topical anesthesia is administered 3 to 5 minutes prior to treatment initiation * Treatment duration is fixed at 50 minutes and power is titrated until moderate gray-white burns are achieved, avoiding long ciliary nerves * Target treatment of 250 spots * Only one eye per eligible patient randomized with regard to whether green or yellow laser utilized first * After treatment,pain assessment conducted:spot count, laser parameters and treatment duration recorded for each respective laser wavelength
Sponsors
Mid Atlantic Retina
Wills Eye
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
SINGLE (Subject)
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Perceived patient pain assessment | a single time point within 2 minutes of completing laser treatment | Assessed using a standardized Wong-Baker faces pain scale |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Minimum power requirement to achieve moderate gray-white retinal burns | During treatment | — |
| Time of treatment | During treatment | Time required to treat with each laser |
Countries
United States
Outcome results
None listed