Femtosecond-Assisted Elliptical LASIK Flap for the Correction of Post-Arcuate Keratotomy Residual Astigmatism

case reports in ophthalmology
13 Jan, 2020 ,

An 82-year-old male was referred to our institute for evaluation of his right eye due to residual regular astigmatism 1 year after AK. On examination, uncorrected distance visual acuity (UDVA) was 20/50 and corrected distance visual acuity was 20/25 (+3.25 −5.50 × 125). Slit-lamp examination revealed two 70-arc length peripheral corneal incisions at the 7.50-mm zone. The patient underwent femtosecond-assisted LASIK for the correction of residual astigmatism. An elliptical LASIK flap was adjusted intraoperatively with a 2-dimension diameter of 7.98 × 6.69 mm in order to avoid intersection of the flap with the AK incisions. The short flap diameter was placed along the meridian of the incisions and the long diameter in the perpendicular meridian, corresponding to the excimer laser astigmatic ablation pattern. No intraoperative or postoperative complications were encountered. Six months postoperatively, UDVA improved to 20/25 with a manifest refraction of pl −0.75 × 5. No AK incision flap-related complications were observed.

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The procedure was performed under topical anesthesia. A femtosecond laser Femto LDV Z8 (Ziemer Ophthalmic Systems, Port, Switzerland) was utilized. To avoid intersection of the flap with the AK incisions at 7.50 mm, we decided to use the elliptical flap mode and place the short diameter along the meridian of the incisions and the long diameter in the perpendicular meridian. The ablation pattern was adjusted to remain within the limits of the exposed stromal bed and we took advantage of the elliptical flap shape.

A corneal elliptical LASIK flap with a 2-dimension diameter of 7.98 × 6.69 mm and a planned depth of 110 μm, a nasally based 0.6-mm hinge and a 90° side cut angle was created. The flap was lifted using a flap manipulator leading to exposure of the stromal bed. Excimer laser photoablation (+2.75 −4.00 × 123) was performed using the Alcon WaveLight® EX500 laser (WaveLight GmbH, Erlangen, Germany). The interface was then rinsed with balanced salt solution and the flap repositioned. A standard postoperative regimen was prescribed. No intraoperative or postoperative complications occurred. At 6 months postoperatively, UDVA improved to 20/25 with a manifest refraction of pl −0.75 × 5, and corneal astigmatism was significantly reduced. No AK incision-related flap complications were encountered