Understanding Astigmatism
Why astigmatism matters at surgery
Astigmatism is an irregular curve of the cornea that can blur vision at every distance. Some people never notice it in their glasses because their natural lens quietly balances it out — but once that lens is replaced during surgery, the balance is gone, and correction may be needed.
Cataract surgery is a unique, one-time opportunity to correct astigmatism. Treating it during the procedure can greatly reduce your dependence on glasses for distance vision. Astigmatism is measured in diopters (D):
Mild · about 0.5–1.4 D
Very common
May affect up to half of all cataract patients. Often treated during surgery with advanced lens technology and small, precise corneal incisions (limbal relaxing incisions).
Moderate · about 1.5–2.9 D
Toric lens territory
Typically calls for a specially designed toric intraocular lens for more reliable, lasting correction.
High · 3.0 D and above
Stronger correction
Treated with stronger toric lenses, sometimes paired with additional corneal incisions for the clearest possible result.