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The Impact of Flap Creation Methods for Sub-Bowman's Keratomileusis (SBK) on the Central Thickness of Bowman's Layer.

Xu Z, Shen M, Hu L, Zhuang X, Peng M, Hu D, Liu J, Wang J, Qu J, Lu F - PLoS ONE (2015)

Bottom Line: For both groups, microdistortions were present in the epithelium and Bowman's layer after SKB.Corneal and sublayer thickness were similar between the two groups.Central Bowman's layer thickness increased 1 day post-SBK.

View Article: PubMed Central - PubMed

Affiliation: School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.

ABSTRACT

Purpose: To determine the impact of flap creation methods for sub-Bowman's keratomileusis (SBK) on central Bowman's layer thickness.

Methods: SBK flaps were made by Moria microkeratome for 20 subjects and by femtosecond (FEMTO) laser for 21 subjects. Corneal sublayer thicknesses were measured by ultra-high resolution optical coherence tomography before SBK and at 1 day, 1 week, 2 weeks, and 1 month afterwards. Each subject was imaged twice on each visit. Thicknesses of central epithelium, Bowman's layer, flap, and total cornea were calculated using a custom-made automated image processing algorithm. The repeatability of sublayer thickness measurements was tested by the intraclass correlation coefficient (ICC) and by the coefficient of repeatability (CoR) at 1 week post-SBK.

Results: ICCs of the Moria and FEMTO groups were ≥ 0.959 and ≥ 0.961 respectively for all sublayer measurements. The segmentation CoRs were less than 6.78% and 5.63% respectively. For both groups, microdistortions were present in the epithelium and Bowman's layer after SKB. The flap thickness of the Moria group was 9.8 μm (95% confidence interval: 4.8 - 14.8 μm) thinner than the FEMTO group one day after SBK (independent samples t-test, P < 0.05). Bowman's layer became thicker by 1.6 ± 1.1 μm and 1.7 ± 1.6 μm one day post-SBK for the Moria and FEMTO groups (repeated ANOVA, P < 0.05) and then remained stable. Corneal and sublayer thickness were similar between the two groups.

Conclusions: Central Bowman's layer thickness increased 1 day post-SBK. Flap creation by Moria microkeratome and femtosecond laser did not have significantly different impacts on Bowman's layer thickness following SBK.

Trial registration: Chinese Clinical Trial Registry (ChiCTR) NO: ChiCTR-OCH-14004525.

No MeSH data available.


Related in: MedlinePlus

Thickness changes in the corneal sublayers of the Moria and FEMTO groups.(A) Epithelial thicknesses measured by UHR-OCT in both groups were increased sharply at 1 day after SBK, and then continued to increase to the end of the follow-up period at 1 month. (B) Bowman′s layer thicknesses also increased by 1 day after SBK, but then remained steady afterwards. (C). Changes in flap thicknesses for both groups were not significantly until the second week post-SBK. Between two weeks and one month, the increase in flap thickness was small but significant for both groups. (D) Total corneal thickness for both groups decreased sharply by 1 day after SBK. Though the decreases were small between 1 day and 1 week after SBK, they were significant. Small but significant decreases continued from 2 weeks through the end of the follow-up period. PRE, pre-SBK; D, day post-SBK; W, week post-SBK; M, month post-SBK.
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pone.0124996.g004: Thickness changes in the corneal sublayers of the Moria and FEMTO groups.(A) Epithelial thicknesses measured by UHR-OCT in both groups were increased sharply at 1 day after SBK, and then continued to increase to the end of the follow-up period at 1 month. (B) Bowman′s layer thicknesses also increased by 1 day after SBK, but then remained steady afterwards. (C). Changes in flap thicknesses for both groups were not significantly until the second week post-SBK. Between two weeks and one month, the increase in flap thickness was small but significant for both groups. (D) Total corneal thickness for both groups decreased sharply by 1 day after SBK. Though the decreases were small between 1 day and 1 week after SBK, they were significant. Small but significant decreases continued from 2 weeks through the end of the follow-up period. PRE, pre-SBK; D, day post-SBK; W, week post-SBK; M, month post-SBK.

Mentions: Compared to the pre-SBK epithelium thickness, one day after SBK the thickness increased significantly by 2.8 ± 3.2 μm and 2.6 ± 1.7 μm for the Moria and FEMTO groups respectively (repeated ANOVA, P < 0.05, Tables 2 and 3, Fig 4). The epithelial thickness continued to increase by 1.2 ± 1.6 μm and 2.0 ± 3.3 μm between 2 weeks and 1 month after Moria and FEMTO surgery respectively (repeated ANOVA, P < 0.05).


The Impact of Flap Creation Methods for Sub-Bowman's Keratomileusis (SBK) on the Central Thickness of Bowman's Layer.

Xu Z, Shen M, Hu L, Zhuang X, Peng M, Hu D, Liu J, Wang J, Qu J, Lu F - PLoS ONE (2015)

Thickness changes in the corneal sublayers of the Moria and FEMTO groups.(A) Epithelial thicknesses measured by UHR-OCT in both groups were increased sharply at 1 day after SBK, and then continued to increase to the end of the follow-up period at 1 month. (B) Bowman′s layer thicknesses also increased by 1 day after SBK, but then remained steady afterwards. (C). Changes in flap thicknesses for both groups were not significantly until the second week post-SBK. Between two weeks and one month, the increase in flap thickness was small but significant for both groups. (D) Total corneal thickness for both groups decreased sharply by 1 day after SBK. Though the decreases were small between 1 day and 1 week after SBK, they were significant. Small but significant decreases continued from 2 weeks through the end of the follow-up period. PRE, pre-SBK; D, day post-SBK; W, week post-SBK; M, month post-SBK.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4418749&req=5

pone.0124996.g004: Thickness changes in the corneal sublayers of the Moria and FEMTO groups.(A) Epithelial thicknesses measured by UHR-OCT in both groups were increased sharply at 1 day after SBK, and then continued to increase to the end of the follow-up period at 1 month. (B) Bowman′s layer thicknesses also increased by 1 day after SBK, but then remained steady afterwards. (C). Changes in flap thicknesses for both groups were not significantly until the second week post-SBK. Between two weeks and one month, the increase in flap thickness was small but significant for both groups. (D) Total corneal thickness for both groups decreased sharply by 1 day after SBK. Though the decreases were small between 1 day and 1 week after SBK, they were significant. Small but significant decreases continued from 2 weeks through the end of the follow-up period. PRE, pre-SBK; D, day post-SBK; W, week post-SBK; M, month post-SBK.
Mentions: Compared to the pre-SBK epithelium thickness, one day after SBK the thickness increased significantly by 2.8 ± 3.2 μm and 2.6 ± 1.7 μm for the Moria and FEMTO groups respectively (repeated ANOVA, P < 0.05, Tables 2 and 3, Fig 4). The epithelial thickness continued to increase by 1.2 ± 1.6 μm and 2.0 ± 3.3 μm between 2 weeks and 1 month after Moria and FEMTO surgery respectively (repeated ANOVA, P < 0.05).

Bottom Line: For both groups, microdistortions were present in the epithelium and Bowman's layer after SKB.Corneal and sublayer thickness were similar between the two groups.Central Bowman's layer thickness increased 1 day post-SBK.

View Article: PubMed Central - PubMed

Affiliation: School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.

ABSTRACT

Purpose: To determine the impact of flap creation methods for sub-Bowman's keratomileusis (SBK) on central Bowman's layer thickness.

Methods: SBK flaps were made by Moria microkeratome for 20 subjects and by femtosecond (FEMTO) laser for 21 subjects. Corneal sublayer thicknesses were measured by ultra-high resolution optical coherence tomography before SBK and at 1 day, 1 week, 2 weeks, and 1 month afterwards. Each subject was imaged twice on each visit. Thicknesses of central epithelium, Bowman's layer, flap, and total cornea were calculated using a custom-made automated image processing algorithm. The repeatability of sublayer thickness measurements was tested by the intraclass correlation coefficient (ICC) and by the coefficient of repeatability (CoR) at 1 week post-SBK.

Results: ICCs of the Moria and FEMTO groups were ≥ 0.959 and ≥ 0.961 respectively for all sublayer measurements. The segmentation CoRs were less than 6.78% and 5.63% respectively. For both groups, microdistortions were present in the epithelium and Bowman's layer after SKB. The flap thickness of the Moria group was 9.8 μm (95% confidence interval: 4.8 - 14.8 μm) thinner than the FEMTO group one day after SBK (independent samples t-test, P < 0.05). Bowman's layer became thicker by 1.6 ± 1.1 μm and 1.7 ± 1.6 μm one day post-SBK for the Moria and FEMTO groups (repeated ANOVA, P < 0.05) and then remained stable. Corneal and sublayer thickness were similar between the two groups.

Conclusions: Central Bowman's layer thickness increased 1 day post-SBK. Flap creation by Moria microkeratome and femtosecond laser did not have significantly different impacts on Bowman's layer thickness following SBK.

Trial registration: Chinese Clinical Trial Registry (ChiCTR) NO: ChiCTR-OCH-14004525.

No MeSH data available.


Related in: MedlinePlus