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Updated: Aug 21, 2026
Correction of Presbyopia by Monocular Bi-Aspheric Ablation Profile
Published on: September 20, 2024
Laser in situ keratomileusis for high myopia using a small ablation zone and large aspheric transition zone
Anun Vongthongsri1, Nutharin Phusitphoykai, Tulaya Tungsiriput
1Department of Ophthalmology, Ramathibodi Hospital School of Medicine, Mahidol University, Bangkok, Thailand. teawt@mahidol.ac.th
Purpose:
To evaluate the efficacy and predictability of laser in situ keratomileusis (LASIK) using the Nidek NAVEX system with a small ablation (optical, OZ) zone and a large aspheric transition zone (OATz).
Methods:
We report a prospective nonrandomized study of LASIK for high myopia using a small ablation in 23 eyes of 18 patients. The optical zone was between 3 and 3.8 mm and transition zone (TZ) was between 7 and 7.8 mm. Preoperative examination included best-spectacle corrected visual acuity (BSCVA), refraction, and corneal topography. All eyes were measured by the Nidek OPD-Scan and data were imported to FinalFit software. Aspheric profile (OATz) numbers 5 to 7 were used. BSCVA, uncorrected spectacle visual acuity (UCVA), refraction, and subjective evaluation of glare and night vision by questionnaire were recorded after surgery.
Results:
At baseline, mean spherical equivalent refraction was -7.03 +/- 2.39 D (range -5.50 to -15.50 D). Postoperative UCVA was better than 20/25 in 95.65% of eyes 3 months after LASIK. Postoperative refraction was within +/- 0.50 D of emmetropia in 91.3% of eyes and within +/- 1.00 D in all eyes. No eye lost lines of BSCVA; 52.17% of eyes gained 1 line and 13.04% of eyes gained 2 lines. No patient reported significant glare or night vision problems on subjective questionnaire.
Conclusion:
LASIK with a small ablation (optical) zone and high aspheric transition zone using the Nidek NAVEX system was effective, predictable, and relatively safe for correction of high myopia.
