Straight Lines Appearing Distorted: Metamorphopsia and Visual Perceptual Abnormalities
When straight lines appear distorted, wavy, or "dizzy," this is called metamorphopsia and most commonly indicates a retinal problem affecting the macula, though it can also result from neurological conditions affecting visual processing.
Primary Ophthalmologic Causes (Most Common)
The distortion of straight lines is a hallmark symptom of macular pathology and requires urgent ophthalmologic evaluation:
Age-related macular degeneration (AMD) is the most common cause in adults over 50, where fluid or blood accumulates under the macula causing straight lines to appear wavy or bent 1
Macular edema from any cause (diabetic retinopathy, retinal vein occlusion, uveitis) produces similar distortions as fluid disrupts the normal retinal architecture 1
Epiretinal membrane or macular pucker causes mechanical distortion of the retinal surface, making straight lines appear irregular 1
Central serous chorioretinopathy causes fluid accumulation under the retina, leading to metamorphopsia particularly in younger to middle-aged adults 1
Complete ophthalmologic examination including dilated fundoscopy and optical coherence tomography (OCT) is essential to identify these treatable conditions 1.
Neurological Causes of Visual Distortion
When ophthalmologic examination is normal, consider neurological etiologies:
Migraine aura can cause transient visual distortions including metamorphopsia, typically lasting 5-60 minutes and often followed by headache 1
Visual snow syndrome may include distortions of straight lines along with continuous perception of flickering dots throughout the visual field, though visual acuity and standard testing remain normal 2
Occipital lobe lesions (stroke, tumor, epilepsy) can produce persistent visual perceptual abnormalities including dysmetropsia (distorted size/shape perception) 3
Critical Distinction: This is NOT Vertigo
It is crucial to distinguish visual distortion (metamorphopsia) from dizziness/vertigo:
Metamorphopsia describes distorted visual perception where objects appear bent, wavy, or irregular 1, 3
Vertigo is a false sensation of spinning or movement, defined by the Barany Society as "a false sensation of self-motion" 1, 4
Oscillopsia is the illusion of an unstable visual world where objects appear to move or jump, typically caused by abnormal eye movements or vestibulo-ocular reflex dysfunction 5
If the patient describes the visual environment itself as distorted (lines bent, wavy), this suggests retinal pathology 1. If they describe a sensation of movement or spinning, this indicates vestibular dysfunction 1.
Diagnostic Approach
Immediate ophthalmology referral is warranted for:
- New onset metamorphopsia (distorted straight lines)
- Associated vision loss
- Flashes of light or floaters
- Any concern for macular pathology 1
Consider neurology evaluation if:
- Ophthalmologic examination is completely normal including OCT
- Associated with headache patterns suggesting migraine 1
- Other neurological symptoms present (weakness, sensory changes, speech difficulties) 1
- Visual snow or other persistent visual phenomena without structural findings 2
Common Pitfalls
Do not dismiss metamorphopsia as "just dizziness" - this symptom specifically indicates potential macular disease requiring urgent evaluation 1
Do not confuse visual distortion with vestibular symptoms - the mechanisms and treatments are entirely different 1, 4, 5
Do not delay ophthalmologic evaluation - conditions like wet AMD have time-sensitive treatments that can preserve vision 1
Medication side effects should be considered, particularly with topiramate which can cause acute myopia and visual disturbances, though typically with decreased acuity and ocular pain rather than isolated metamorphopsia 6