Refractive surgery for astigmatism

Refractive surgical techniques employed for myopia
can be adapted to correct astigmatism alone or
simultaneously with myopia as follows:
1. Astigmatic keratotomy (AK) refers to making
transverse cuts in the mid periphery of the steep
corneal meridian (Fig. 1).

Fig. 1. Astigmatic keratotomy. (A) showing flat and deep meridians of cornea; (B) paired transverse incisions to flattern
the steep meridian; (C) showing correction of astigmatism after astigmatic keratotomy.

AK can be performed
alone (for astigmatism only) or along with RK (for
associated myopia).
2. Photo-astigmatic refractive keratotomy (PARK)
is performed using  excimer laser.
3. LASIK procedure can also be adapted to correct
astigmatism upto 5D.
Management of post-keratoplasty astigmatism
1. Selective removal of sutures in steep meridians
may improve a varying degree of astigmatism and
should be tried first of all.
Note: Other procedures mentioned below should be
performed only after all the sutures are out and
refraction is stable.
2. Arcuate relaxing incisions in the donor cornea
along the steep meridian may correct astigmatism
up to 4-6 D.
3. Relaxing incisions combined with compression
sutures may correct astigmatism up to 10 D.
4. Corneal wedge resection with suture closure of
the wound may be performed in the flat meridian
to correct astigmatism greater than 10 D.
5. LASIK procedure can also be adopted to correct
post-keratoplasty astigmatism.