RED-FREE (GREEN) FILTER-ENHANCED GONIOSCOPY

 

A study has shown that gonioscopy using a red-free (green) filter can enhance visibility of the iridocorneal angle.

The angles were imaged with an indirect 4-mirror goniolens with standard halogen light, red-free green filter and also warm light filter of the slit lamp. The images and videos were recorded using a smartphone adaptor to the slitlamp. The illumination was set at 1/4^th with 20x magnification.

The study found that the contrast of the gonioscopy images was enhanced objectively with a red-free filter compared to standard light photos. The built-in warm filter of the slit lamp also provided better visualization of the iridocorneal angle structures.

The evaluation of the images and videos by two glaucoma specialists revealed that the red-free (green) filter provided enhanced tissue visualization for the pigmentation of the trabecular meshwork in 90% (n = 9) of the cases, and the quality of visualization did not worsen during regular gonioscopy.

Also, the warm color provided good contrast between the angle structures, as well as being less irritating to the photosensitive patients. This filter was also found to be superior in identifying the Schlemm’s canal, as it appeared orange or red, unlike the usual halogen light appearance, where it appears white and is often difficult to identify.

This enhancement can facilitate the accurate identification of the angle structures, particularly in instances where gonioscopic interpretation is challenging and when the patient is sensitive to light.

VIEW VIDEO HERE: https://www.youtube.com/watch?v=bgRP3EmCC3Q

REFERENCE: Iqbal MI. Red-Free (Green) Filter-Enhanced Gonioscopy with Smartphone: A Pilot Study. Cureus. 2024 Jan 3;16(1):e51559. doi: 10.7759/cureus.51559. PMID: 38313936; PMCID: PMC10835508.