If you’ve been in clinic for more than a few weeks, chances are you’ve noticed that diagnosing glaucomatous optic neuropathy is rarely black and white. Rather, the disease occurs on a continuum that can make the “suspect vs. diagnosis” call come down to some pretty subtle observations! One of my attending doctors shared with me some tips to help make sure that I am looking for all of those sneaky changes that may occur in a glaucoma patient.
The original authors of the excellent review article called these the “5 R’s,” though I find it is enough to jog my memory if I just remember that there are 5 main things on my checklist:
1) Examine the scleral ring to identify the disc margins and the disc size
|Tip: Optic nerve size is an easily overlooked part of an ocular health evaluation! Even a quick estimation of size is helpful; go here for more details!|
2) Quantify the size of the neuroretinal rim. This is basically a way of reminding yourself to check C/D ratios, while taking special care to look for the ISNT rule. Really looking at the rim will help you catch subtle localized rim thinning or loss in a glaucomatous nerve.
3) Examine the retinal nerve fiber layer (RNFL). Under red-free light, the RNFL should appear bright and striated. The loss of RNFL fibers can be localized into wedge-shaped defects, but can also be more diffuse (and easier to miss) – so look closely!
4) Observe any region of peripapillary atrophy (PPA). There are two types of peripapillary atrophy: zone alpha and zone beta.
- Zone alpha occurs as a result of areas of hypo- and hyperpigmentation in the RPE.
- Zone beta occurs as a result of atrophy of the RPE and choriocapillaris. Based on the anatomy of the retina, it makes sense why the underlying choroidal vessels and sclera would become visible!
If zone alpha and beta occur together, alpha is always more peripheral than beta. Zone alpha is common to see in normal eyes as well as in glaucomatous eyes, whereas beta is much more suggestive of possible glaucoma.
5) Look for retinal and optic disc hemorrhages. These are usually transient but can also recur, and (most importantly!) are an indication that the patient’s condition is not stable. The classic optic disc hemorrhage is seen in the normotensive type of glaucoma, but it can also been seen in other etiologies.
With the five steps above, you can feel confident that you performed a methodical and comprehensive exam of your patient’s optic nerve and nerve fiber layer. Do you have any rules or mnemonics to help you remember sections of your ocular health check? Please share in the comments below!