What does it mean for a patient with high myopia and existing retinal nerve fiber layer (RNFL) thinning if their values remain the same after 6 months?

Stable RNFL Values at 6 Months in High Myopia with Existing Thinning

If RNFL values remain unchanged after 6 months in a patient with high myopia and existing RNFL thinning, this stability is reassuring and suggests the thinning may be physiologic rather than progressive glaucomatous damage, though continued monitoring remains essential. 1, 2

What Stability Means Clinically

Stable RNFL measurements over 6 months indicate no detectable progression, which is the critical distinction between physiologic myopic changes and active glaucomatous damage. 3

• In glaucoma suspects, distinguishing between glaucomatous and nonglaucomatous RNFL thinning is often based on the presence or absence of progression, respectively 3
• Structural alterations in the optic nerve head and RNFL may occur before functional visual field changes, but stability over time argues against active disease 3
• High myopia inherently causes RNFL thinning independent of glaucoma, with mean RNFL thickness of 80.0 μm in highly myopic eyes versus 108.8 μm in controls 4

Required Next Steps After Demonstrating Stability

Continue monitoring every 6 months with repeat OCT, visual field testing, and IOP measurements to confirm sustained stability over a longer observation period. 1, 2

• Baseline comprehensive evaluation must include multiple IOP measurements at different time points, gonioscopy to confirm open angles, central corneal thickness measurement, and standard automated perimetry 1, 2
• Repeat testing is essential when new changes are detected to confirm findings before concluding progression has occurred 3
• Both structural (OCT) and functional (visual field) assessments remain integral because some patients show visual field loss without corresponding optic nerve progression 3

Risk Stratification Based on Stability

Stable measurements reduce immediate concern but do not eliminate glaucoma risk, as you remain a glaucoma suspect requiring ongoing surveillance. 1, 2

• First-degree relatives of those with glaucoma have 9.2-fold higher odds of developing POAG, making family history a critical risk factor 3
• Myopia itself is an established independent risk factor for developing POAG 1, 2
• The focal nature of inferior RNFL thinning remains concerning because inferior and superior thinning are the most common early manifestations of glaucomatous damage 1

Treatment Decision Framework

Treatment is NOT indicated if RNFL remains stable, IOP is normal, and visual fields show no glaucomatous defects. 1, 2

Treatment becomes necessary only if:

• Serial OCT demonstrates progression of RNFL thinning 1, 2
• Visual field testing reveals defects consistent with glaucomatous damage 1, 2
• IOP elevation develops 1, 2

If treatment becomes indicated in the future, target 20-30% IOP reduction from baseline, as clinical trials demonstrate this reduces risk of developing POAG and slows progression. 1, 2

Critical Pitfalls to Avoid

Do not dismiss ongoing monitoring needs simply because values are stable at 6 months—glaucoma can develop slowly over years. 1, 2

• High myopia complicates interpretation because highly myopic individuals without glaucoma may have diffusely thin RNFL, but focal thinning patterns suggest glaucomatous rather than purely myopic changes 1
• OCT results outside normative ranges do not always represent disease, but the specific pattern of focal inferior thinning with asymmetric cupping requires continued vigilance 1
• Avoid relying solely on summary statistics; the patterns of cup-to-disc ratio asymmetry and focal RNFL loss are more diagnostically significant than absolute numbers 1
• In highly myopic eyes, RNFL measurements can show supranormal values due to peripapillary chorioretinal atrophy and scleral birefringence, potentially masking true thinning 5

Long-Term Monitoring Strategy

Extend monitoring intervals to every 6-12 months if stability persists beyond the first year, but never discontinue surveillance entirely. 3

• Progression analysis programs for computer-based imaging devices continue to evolve for better detection of optic nerve and RNFL changes 3
• Some patients demonstrate structural alterations before functional changes occur, making serial OCT imaging essential even with normal visual fields 3
• In normal-tension glaucoma patients with myopia, inferotemporal RNFL thinning specifically has been identified as a risk factor for progression 6