KEEP THESE CLASSIC TECHNIQUES IN MIND FOR DIAGNOSIS
AN 88-YEAR-OLD Caucasian female presented for a glaucoma evaluation. Due to her physical limitations, obtaining an accurate VF and OCT was not possible. How can one ensure an accurate diagnosis when the go-to tools can’t be used or are unobtainable?
Here, I discuss how to accomplish this.
1 PERFORM GONIOSCOPY
Gonioscopy can aid in the diagnosis of glaucoma on patients unable to position themselves for advanced technologies.
When performing a gonioscopy, note the presence of pigment in the trabecular meshwork and extra lines of pigment, indicating pigment dispersion and pseudoexfoliative syndromes or glaucoma. The presence of blood or membranes is typical of pathologies, such as neovascular glaucoma or iridocorneal endothelial syndrome.
In addition to aiding in diagnosis, gonioscopy allows you to determine the best treatment. For example, a patient with an open angle is a candidate for selective laser trabeculoplasty. With the movement toward minimally invasive glaucoma surgery (MIGS), accurate gonioscopy is critical. After all, the angle is where the majority of MIGS procedures are performed, and an open angle with no pathologies is needed for success. (See gonioscopy.org .)
2 USE THE MARCUS GUNN TEST
Although not specific for glaucoma, the Marcus Gunn test does indicate a compromise to the optic nerve head.
3 DO A STEREOSCOPIC EVAL.
Evaluate the optic disc and nerve fiber layer (NFL) for defects. A normal NFL has a striate appearance with underlying vessels obscured, as if a transparent tape is placed over the vessels. NFL defects extend to the disc and can be in a slit, wedge or diffuse pattern. Also, be aware of optic nerve head notching, which appears as focal loss of tissue and vertical elongation and narrowing of the neuroretinal rim, commonly superiorly and inferiorly. In addition, disc hemorrhages should be a red flag for glaucoma. Major studies, including the Early Manifest Glaucoma Trial, indicate that disc hemorrhages are strongly associated with glaucoma progression. Finally, keep an eye out for vascular changes, such as a bayonet sign and vessel baring. The former shows retinal vessels deviating from their normal course. A “z” appearance is common, as vessels emerge at a sharp angle over the edge of the cup. The latter shows that vessels are no longer supported by rim tissue and have an appearance of being suspended over free space.
RETURNING TO OUR ROOTS
Let’s not forget about the classic tools available to aid in diagnosis. The 88-year-old patient mentioned above was ultimately diagnosed with primary open-angle glaucoma based on a stereoscopic evaluation of the optic nerve heads and gonioscopy, showing open normal angles. OM