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Published on: October 21, 2022
[Analysis of flap thickness created with mechanical microkeratome in LASIK by using anterior segment optical
Qing-wei Zhang1, Yue-hua Zhou, Lei Tian
1Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing 100730, China.
Objective:
To evaluate the accuracy, uniformity and relevant factors of LASIK flaps created with a mechanical microkeratome Moria II (90, 110 and 130 heads).
Methods:
It was a case-control study. Eighty-seven patients underwent LASIK in both eyes using Moria II 90 head (52 eyes, 26 cases), 110 head (58 eyes, 29 cases), or 130 head (64 eyes, 32 cases). One week after surgery, anterior segment optical coherence tomography was performed four times on each eye to measure flap thickness at 20 points in four meridians. The results were assessed for accuracy, uniformity and relevant factors.
Results:
The central thickness of corneal flaps was (119.23±15.65), (140.42±12.26), and (165.92±17.00) µm by Moria II 90, 110 and 130 heads, respectively. The shape of the corneal flaps in the three groups resembled a concave lens, the central zone was significantly thinner than the paracentral and peripheral zones. The central flap thicknesses were statistically significantly more accurate and regular than the flap in the peripheral zone (F=212.419, P<0.05). The mean difference of right eye (19.58±0.44) µm was higher than that of the left eye (16.55±0.44) µm. The mean difference of knife in-side (21.30±0.55) µm was higher than the knife out-side (14.36±0.64) µm (F=25.341, 44.461; P<0.05).
Conclusions:
The central flap thicknesses were more accurate as compared with the expected value. The mean flap thickness in the three groups was not uniform. Variation of the thickness in corneal flaps was greater in thicker flaps. The flap thickness in right eye was greater than that in left eye, according to the surgical sequence between two eyes. The flap thickness of blade in-side was thicker than that of out-side.
Insights
LASIK flap thickness using the Moria II microkeratome varied by head size, with thicker flaps showing greater variation. Central flap thickness was more accurate than peripheral thickness.
Area of Science:
- Ophthalmology
- Refractive Surgery
- Ophthalmic Devices
Background:
- Laser-assisted in situ keratomileusis (LASIK) is a common refractive surgery.
- The accuracy and uniformity of LASIK flaps are critical for surgical outcomes.
- Mechanical microkeratomes are widely used for flap creation.
Purpose of the Study:
- To evaluate the accuracy and uniformity of LASIK flaps created with the Moria II mechanical microkeratome.
- To identify factors influencing LASIK flap thickness and regularity.
Main Methods:
- A case-control study involving 87 patients (174 eyes) undergoing LASIK.
- Moria II microkeratome with 90, 110, or 130 heads was used.
- Anterior segment optical coherence tomography (AS-OCT) measured flap thickness at 20 points in four meridians one week post-surgery.
Main Results:
- Central flap thicknesses were 119.23±15.65 µm (90 head), 140.42±12.26 µm (110 head), and 165.92±17.00 µm (130 head).
- Flaps were thinner centrally than paracentrally/peripherally, with central thickness being more accurate and regular.
- Thicker flaps exhibited greater variation in thickness; right eye flaps and in-side blade passes were thicker.
Conclusions:
- The Moria II microkeratome produced flaps with varying uniformity across different head sizes.
- Central flap thickness accuracy was good, but overall uniformity was limited.
- Flap thickness variation increased with flap thickness and was influenced by surgical factors like eye laterality and blade pass direction.
