Munson's Sign in Keratoconus

Clinical Significance

• Munson's sign is a nonspecific finding seen only in severe, advanced ectasia, indicating significant corneal protrusion and structural compromise, according to the American Academy of Ophthalmology 1, 2, 3, 4
• The sign represents a late-stage clinical manifestation of keratoconus and is not present in early or moderate disease, as stated by the American Academy of Ophthalmology 5, 6

Associated Clinical Context

• Severe corneal thinning and protrusion in the area of maximal ectasia are expected to be found when Munson's sign is present, as reported by the American Academy of Ophthalmology 1, 4
• Corneal scarring at Bowman's layer or deeper stroma are also expected to be found when Munson's sign is present, according to the American Academy of Ophthalmology 1, 4
• Vogt striae (vertical fine folds in mid and deep stroma) are associated with Munson's sign, as stated by the American Academy of Ophthalmology 1, 4
• Marked visual impairment that cannot be corrected to 20/20 with spectacles is common in patients with Munson's sign, as reported by the American Academy of Ophthalmology 2, 7
• Scissors reflex on retinoscopy indicating severe irregular astigmatism is also associated with Munson's sign, according to the American Academy of Ophthalmology 2, 7

Clinical Implications

• Munson's sign is not sensitive for keratoconus detection—its absence does not rule out keratoconus, as most patients with mild to moderate disease will not demonstrate this finding, as stated by the American Academy of Ophthalmology 1, 5
• Early keratoconus detection requires corneal topography and tomography, not clinical signs alone, according to the American Academy of Ophthalmology 1
• The sign is nonspecific and can theoretically occur with any severe corneal ectasia, not just keratoconus, as reported by the American Academy of Ophthalmology 1, 2