In children, how does the magnitude of myopia (≥ ‑3.00 D) or hyperopia (≥ +2.00 D) affect peripapillary retinal nerve‑fiber‑layer thickness on optical‑coherence tomography, and what monitoring is recommended?

RNFL Thickness in Pediatric Myopia and Hyperopia

In children, myopia ≥ -3.00 D is associated with significantly thinner peripapillary RNFL thickness compared to emmetropic and hyperopic children, while hyperopia ≥ +2.00 D shows thicker RNFL measurements that normalize when age-adjusted; however, no specific monitoring protocols are established for these refractive variations alone in the absence of other pathology.

Key Findings on RNFL Thickness by Refractive Status

Myopic Children

• Myopic children consistently demonstrate thinner RNFL measurements across multiple studies, with the effect becoming more pronounced with increasing myopia severity 1, 2, 3, 4.
• The mean RNFL thickness in myopic children ranges from 95.7 μm to 99.17 μm, compared to emmetropic children at 100-102 μm 1, 3.
• For every diopter shift toward myopia, RNFL thickness decreases by approximately 1.7 μm 5.
• The thinning correlates strongly with longer axial length (r = -0.4, P < 0.0001), suggesting that scleral and retinal stretching mechanically reduces RNFL thickness 1, 2.

Hyperopic Children

• Hyperopic children initially appear to have thicker RNFL (107.2 μm), but this difference disappears after age adjustment 1.
• When controlled for age, hyperopic and emmetropic children show equivalent RNFL thickness, indicating the apparent thickness difference is confounded by younger age in hyperopic cohorts 1.
• Hyperopic children (≥+0.50 D) maintain slightly thicker measurements than emmetropes (102.45 μm vs 100.81 μm), though the clinical significance is minimal 3.

Mechanism and Clinical Implications

Pathophysiologic Basis

• The RNFL thinning in myopia results from mechanical stretching of the posterior globe as axial length increases, causing physical elongation and thinning of retinal structures 2, 4.
• This represents an anatomical variation rather than pathologic nerve fiber loss in most cases 1, 3.
• The negative correlation between RNFL thickness and axial length is consistent across studies (β = -1.53, P < 0.0001) 4.

Age Considerations

• Advancing age independently correlates with thinner RNFL (r = -0.4, P < 0.0001), making age adjustment critical when interpreting pediatric measurements 1.
• Myopic children tend to be older in study cohorts (mean 9.6 years) compared to hyperopic children (mean 6.5 years), which can confound direct comparisons 1.

Monitoring Recommendations

Clinical Approach

• Baseline OCT documentation is reasonable for high myopes (≥ -3.00 D) to establish individual normative values, particularly if there are additional risk factors for glaucoma or optic neuropathy 1, 3.
• No routine serial monitoring is indicated based solely on refractive error magnitude in otherwise healthy children without optic nerve abnormalities or family history of glaucoma 1, 4.
• For hyperopic children (≥ +2.00 D), RNFL measurements should be interpreted with age-matched normative data, as apparent thickness increases are age-related rather than pathologic 1.

Important Caveats

• The coefficient of determination for RNFL-refractive error associations is small (R² = 0.01-0.03), meaning refractive error explains only 1-3% of RNFL thickness variation 3.
• Clinicians must distinguish physiologic RNFL thinning from pathologic processes; any asymmetry, progressive thinning, or visual field defects warrant further investigation regardless of refractive status 1, 4.
• Signal strength index should exceed 45 on SD-OCT for reliable measurements 4.
• Spherical equivalent is the only significant predictor of RNFL thickness after controlling for age, gender, and technical factors 5.

Practical Algorithm

• For myopia ≥ -3.00 D: Consider baseline OCT if family history of glaucoma, optic nerve abnormalities on examination, or progressive myopia; otherwise, standard ophthalmologic surveillance suffices 1, 3.
• For hyperopia ≥ +2.00 D: No specific RNFL monitoring indicated; interpret any OCT measurements with age-matched controls 1.
• Serial monitoring: Reserve for children with documented optic nerve pathology, glaucoma risk factors, or unexplained visual symptoms—not for refractive error alone 4.