Visual Field Differences: Glaucomatous vs Non-Glaucomatous Optic Atrophy
Glaucomatous optic atrophy produces characteristic visual field defects that respect the horizontal midline and follow retinal nerve fiber layer anatomy, while non-glaucomatous optic atrophy typically causes diffuse visual field loss without respecting anatomical boundaries or the horizontal raphe. 1, 2
Characteristic Glaucomatous Visual Field Patterns
Glaucomatous visual field defects directly reflect the anatomical organization of retinal nerve fiber bundles, with preferential damage to arcuate bundles from the superior and inferior retina at the optic disc poles. 2 The four major patterns include:
Classic Glaucomatous Defects
Arcuate scotomas that respect the horizontal midline, resulting from damage to arcuate nerve fiber bundles as they pass through the superior and inferior poles of the optic disc 3, 2, 4
Nasal step defects occurring when arcuate bundle damage is asymmetric between superior and inferior hemifields 3, 4
Paracentral depressions in clusters of test sites representing focal areas of retinal ganglion cell loss 3, 2
Visual field loss across the horizontal midline in one hemifield that exceeds loss in the opposite hemifield (particularly in early to moderate cases) 3, 1
Anatomical Correlation
The location of visual field defects in glaucoma corresponds with high accuracy to areas of retinal nerve fiber layer atrophy. 5 This structure-function relationship is fundamental: 84% of eyes with glaucomatous field loss demonstrate corresponding NFL atrophy in the same retinal location. 5 Importantly, nerve fiber layer defects often precede detectable visual field loss—60% of eyes showed NFL defects up to 6 years before field loss developed. 6
Non-Glaucomatous Optic Atrophy Patterns
Non-glaucomatous causes of optic atrophy produce distinctly different visual field patterns that do not follow the anatomical constraints of retinal nerve fiber bundles:
Key Distinguishing Features
Absence of horizontal midline respect: Non-glaucomatous field defects typically cross the horizontal raphe without the characteristic asymmetry seen in glaucoma 3
Diffuse or generalized depression: Rather than arcuate patterns, non-glaucomatous atrophy often causes more uniform visual field loss 4
Central scotomas: Optic nerve pathology from other causes (optic neuritis, ischemic optic neuropathy, compressive lesions) frequently produces central or cecocentral scotomas that do not respect nerve fiber layer anatomy 3
Altitudinal defects without arcuate configuration: While both glaucoma and ischemic optic neuropathy can cause altitudinal loss, non-glaucomatous causes lack the characteristic arcuate shape and horizontal midline asymmetry 3
Structural Examination Differences
Glaucomatous Optic Nerve Changes
Absence of pallor in the neuroretinal rim despite cupping—the remaining rim tissue maintains normal color, distinguishing glaucomatous cupping from other causes of optic nerve damage 1
Vertical elongation of the optic cup with preferential loss at inferior and superior poles, following the ISNT rule violation 1
Beta-zone parapapillary atrophy that correlates significantly with visual field defects and their location 1, 7
Optic disc hemorrhages at the disc rim or parapapillary RNFL 3, 1
Non-Glaucomatous Optic Nerve Changes
Pallor of the optic disc is typically present in non-glaucomatous optic atrophy (from optic neuritis, ischemic neuropathy, compressive lesions, hereditary optic neuropathies) 1
Absence of progressive cupping: Non-glaucomatous atrophy may show disc pallor without the characteristic excavation and progressive cup enlargement seen in glaucoma 3
Progression Patterns
Glaucoma Progression
Glaucomatous damage follows a predictable pattern where structural changes often precede functional defects. 2, 6 Nerve fiber layer defects expand over time through development and coalescence of adjacent areas of damage. 6 The progression respects anatomical boundaries:
Early stage: Localized NFL thinning at superior/inferior poles, often before visual field defects appear 2, 5, 6
Moderate stage: Visual field abnormalities in one hemifield, remaining outside 5 degrees of fixation 3, 2
Severe stage: Both hemifields affected and/or loss within 5 degrees of fixation 3, 2
Clinical Pitfalls to Avoid
Do not rely solely on IOP: Nearly 40% of patients with characteristic glaucomatous damage may not have elevated IOP during office hours 3, 2
Highly myopic patients may have diffusely thin RNFL without glaucoma, potentially causing false-positive interpretations 3
Computerized imaging abnormalities do not always represent disease—results must be interpreted in clinical context with all structural and functional information 3
Confirm new visual field defects by repeating the same testing strategy before concluding glaucomatous progression 3