Retinal photocoagulation lasers are sold mainly in two wavelengths: green at 532 nm and yellow at 577 nm. Practices replacing or adding a laser often ask which one to buy. The answer depends less on the wavelength alone than on the delivery systems, treatment modes and support that come with the platform. This guide sets out what to compare.
What the wavelength changes
Both wavelengths are absorbed by melanin in the retinal pigment epithelium, which is what makes photocoagulation possible. They differ in how other tissues absorb and scatter them.
Green 532 nm light, usually from a frequency-doubled solid-state laser, has been the standard for decades. Most retina specialists trained on it, and a large installed base means parts, service and pre-owned units are easy to find.
Yellow 577 nm light sits close to an absorption peak of oxygenated haemoglobin and is absorbed less by the yellow macular pigment. It also scatters somewhat less through media that are not perfectly clear. Those physical differences are the reasons commonly given for choosing yellow, particularly by practices that do a lot of work close to the macula.
Which conditions a particular laser is cleared to treat is set by its manufacturer's labeling. Check the labeling of the exact model, not the wavelength in general.
Delivery systems matter as much as wavelength
A photocoagulator is only as useful as the ways it can deliver light. Compare the delivery options each unit includes, because they are often priced separately:
- Slit-lamp adapter, the everyday office delivery, and whether it fits a slit lamp you already own.
- Laser indirect ophthalmoscope (LIO) for peripheral retina and patients who cannot sit at a slit lamp.
- Endoprobes for use in the operating room during vitrectomy, and which vitrectomy systems they connect to.
- Pattern scanning, if the platform offers it, which places multiple spots per activation.
Treatment modes
Beyond conventional continuous-wave treatment, some platforms offer a micropulse or subthreshold mode, such as Iridex's MicroPulse. Whether that mode is included, licensed or available at all differs by model and generation, so confirm it for the specific unit rather than the product line.
What to check on a pre-owned unit
Photocoagulators are robust and well suited to the refurbished market. Before buying, confirm the following:
- Measured output power at the treatment plane against the manufacturer's specification, with the report.
- The condition of the fibre and delivery devices, which wear before the laser console does.
- Aiming beam brightness and alignment.
- Which delivery devices, filters, footswitch and interlocks are included.
- Laser safety requirements for the room, including eyewear rated for the wavelength you buy.
How MP MedPharma can help
We stock green and yellow photocoagulators from Iridex and Ellex when available. Tell us how and where you treat — office, operating room or both — and we will match a unit and its delivery devices to that. Every laser ships with its service documentation and warranty coverage, and pricing is quoted per unit.
More guides
- Refurbished vs New Ophthalmic Equipment: What Actually Differs
- What to Check Before Buying a Used Excimer Laser
- Alcon Centurion vs Infiniti: What Changed and Which to Buy
- How to Sell Used Ophthalmic Equipment: Valuation, Paperwork and Logistics
- How to Choose a Dental Chair Unit: A Practice Owner's Guide
- SLT vs YAG Laser: Which Should Your Practice Buy First?
- Buying a Used OCT: Zeiss Cirrus 4000 vs 5000 vs AngioPlex
- Buying a Used Ophthalmic Surgical Microscope: What to Check
- What a Phaco Service Contract Should Include
- Buying a Used Femtosecond Laser for LASIK: What to Check
- How to Prepare a Room for an Excimer Laser
- Slit Lamp Buying Guide: What to Compare
- Corneal Topographer Buying Guide: What to Compare
- Microkeratome vs Femtosecond Laser for LASIK Flaps
- How to Choose a Fundus Camera: What to Compare