J Korean Ophthalmol Soc.  2018 May;59(5):484-490. 10.3341/jkos.2018.59.5.484.

Repositioning of a Free Cap after Laser-assisted in situ Keratomileusis

• Na M
• Chung SK
• Pak KH
• Choi JS

• KMID: 2411459
• DOI: http://doi.org/10.3341/jkos.2018.59.5.484

Abstract

PURPOSE
To report a case of irregular astigmatism caused by a free flap during laser-assisted in situ keratomileusis (LASIK) surgery that was treated with a flap rotation based on postoperative topography.
CASE SUMMARY
A 21-year-old female underwent LASIK, which was complicated by a free cap on her right eye. Because the gentian violet markings were no longer present, the exact orientation of the cap was unknown. At 3 months after surgery, the astigmatism of the right eye was −3.00 diopters (D) with an uncorrected visual acuity (UCVA) of 0.4, and the astigmatism of the left eye was −0.75 D with an UCVA of 1.0. The corneal topography was analyzed in order to return to the existing position. Free cap repositioning was performed and irregular astigmatism was corrected to improve the UCVA to 1.0.
CONCLUSIONS
If the preoperative markings cannot be identified on a free flap during LASIK, secondary postoperative corneal topographic analysis can be performed to restore the corneal free flap to its original position to minimize astigmatism with good visual outcomes.

Keyword

Flap rotation; Free cap; Laser-assisted in situ keratomileusis (LASIK)

MeSH Terms

Astigmatism
Corneal Topography
Female
Free Tissue Flaps
Gentian Violet
Humans
Keratomileusis, Laser In Situ
Visual Acuity
Young Adult
Gentian Violet

Figure

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  Figure 1. Topography measured before laser-assisted in situ keratomileusis (LASIK). (A) Preoperative Pentacam®, front sagittal curvature maps of both eyes show with the rule astigmatism. (B) Preoperative Orbscan. Anterior elevation maps of both eyes show with the rule astigmatism. OD = oculus dexter; OS = oculus sinister; Sim K = simulated keratometry; Astig = astigmatism; T = temporal; N = nasal.

• 

  Figure 2. Topography measured after laser-assisted in situ keratomileusis (LASIK). (A) Pentacam® measured 3 months after LASIK of both eyes and before flap reposition of right eye, frontal corneal astigmatism is −3.2 D on right eye. (B) Orbscan measured 3 months after LASIK of both eyes and before flap reposition of right eye, front sagittal curvature maps of both eyes show with the rule astigmatism. OD = oculus dexter; OS = oculus sinister; Sim K = simulated keratometry; Astig = astigmatism; T = temporal; N = nasal.

• 

  Figure 3. The schematic figure of reposition procedures. (A) Detachment of prepositioned free cap and dialing 100 degrees clockwise. (B) Reposition of free cap. In both figures, ‘T’ represents the temporal side of eye and ‘N’ represents the nasal side of eye. The red star on (A) and (B) represents marking for same location of flap. The red arrow on (A) represents degrees of flap rotation.

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  Figure 4. Topography measured before and after flap reposition. (A) Pentacam® measured after laser-assisted in situ keratomileusis (LASIK) (before flap reposition) of right eye, frontal corneal astigmatism is −3.2 D on right eye. (B) Pentacam® measured 1 month after flap reposition of right eye, frontal corneal astigmatism is −1.3 D on right eye. OD = oculus dexter; Astig = astigmatism; T = temporal.

Reference

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