Irregular Astigmatism in Keratoconus and Corneal Ectasias When Rigid Contact Lenses Have Not Achieved Adequate Vision
Clinical Scenario
Irregular astigmatism occurs when the magnitude and axis of astigmatism vary across different points of the cornea. This is clinically significant in conditions such as keratoconus and other corneal ectasias, corneal dystrophies, corneal scarring, and postsurgical corneas. In these patients, higher-order aberrations cannot be fully corrected by standard spherocylindrical lenses.
Previous Treatment — Insufficient Response
Rigid gas-permeable contact lenses — and large-diameter scleral lenses, which do not contact the cornea — are a first-line approach for irregular corneal surfaces, particularly for high or combined irregular astigmatism. When this strategy does not achieve a corrected visual acuity of 20/25 or better, a further step in management is indicated.
Next Treatment Approach
For patients who have not reached adequate corrected acuity with contact lens correction, a surgical approach directed at the corneal surface is among the structured options. The complete protocol specifies which form of corneal surgery applies, along with the full decision pathway and indications.
References
- In irregular corneal astigmatism, the magnitude and the axis of astigmatism vary in different points of the cornea, which can be clinically significant in conditions such as keratoconus and other corneal ectasias, corneal epithelial basement membrane and stromal dystrophies, corneal scarring, and postsurgical corneas.
- Higher order aberrations cannot be fully corrected by spherocylindrical corrective lenses.
- Correction options include eyeglasses, contact lenses, and surgery.
- These include refractive surgery to the cornea, such as LASIK and photorefractive keratectomy, and lens surgery, such as clear lens extraction, phakic intraocular lenses, and cataract surgery.
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