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  • Topography-guided LASEK can treat irregular residual astigmatism

    Refractive Mgmt/Intervention

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    This small case series shows that advanced topography-guided LASEK can significantly reduce irregular astigmatism and improve visual acuity in symptomatic patients after epikeratophakia for keratoconus.

    Subjects included 10 patients (10 eyes) with a mean age of 24 who underwent LASEK with the Allegretto Wave excimer laser (WaveLight Laser Technologie AG, Erlangen, Germany) and Topolyzer software. Average time between procedures was 2.6 years.

    In all patients the difference in curvature in the same meridian was more than 3 D. All were intolerant of contact lenses and had subjective complaints of ghosting, starbursts, halos, or monocular double vision. Exclusion criteria were central corneal scars or central haze interfering with visual acuity, ectasia at corneal graft margins, irregular astigmatism caused by corneal ectasia, and ablations leaving a residual corneal thickness more than 400 µm after treatment.

    At each follow-up, mean UCVA and BSCVA kept improving, whereas corneal asphericity and the index of surface variance kept decreasing. By six months, UCVA improved from 0.61 ± 0.27 logMAR to 0.27 ± 0.07 logMAR, and BSCVA improved from 0.25 ± 0.14 to 0.15 ± 0.09 logMAR. Only one patient lost one line of vision, uncorrected. Refractive cylinder improved from −3.82 ± 2.43 D to −1.43 ± 0.95 D, and the index of surface variance (an indicator of corneal surface irregularity) decreased from 115.1 ± 21.1 to 68.4 ± 18.2. Haze was mild or transient and mostly occurred after three months.

    The authors said they chose LASEK over LASIK because all treated eyes were keratoconus cases that had already undergone epikeratophakia, and greater residual corneal thickness may reduce the risk factor of postoperative ectasia. The main problem of LASIK after epikeratophakia is the risk of a change in the refraction after the microkeratome passes through the graft–host junction. Another possible complication of LASIK is the corneal dehiscence from the high IOP (60–90 mm Hg) induced by the suction ring of the microkeratome. Therefore, LASEK seemed a more suitable treatment.