Precision of flap measurements for laser in situ keratomileusis in 4428 eyes

Gerald Flanagan, Perry S. Binder

Research output: Contribution to journalArticle

112 Citations (Scopus)

Abstract

PURPOSE: To determine the factor(s) that influence the dimensions and predictability of the LASIK corneal flap with the Automated Corneal Shaper (ACS) or the Summit Krumeich Barraquer microkeratome (SKBM). METHODS: We performed a retrospective, comparative interventional case study of 4,428 eyes. Flap dimensions were measured using subtraction ultrasonic pachymetry during LASIK with one of two microkeratomes. RESULTS: Mean preoperative corneal thickness for all eyes was 555 ± 35 μm. Corneal curvature and refractive astigmatism were inversely related to preoperative corneal thickness (P<.001). With an attempted flap thickness of 160 μm, the ACS flap thickness averaged 119.8 ± 22.9 μm; SKBM flaps averaged 160.9 ± 24.1 μm (P<.001). The coefficient of variation for central pachymetry compared to flap thickness was 6.4% vs. 22.1%. Flap thickness at enhancement was 10 to 17 μm thicker than at primary surgery. An increase in flap thickness was associated with thicker preoperative pachymetry (P<.001) and younger age for both instruments (P<.001) whereas increasing flap thickness was related to flatter preoperative mean keratometry for the ACS (P<.001) and steeper mean keratometry for the SKBM (P=.005). Less preoperative hyperopia or more myopia was related to an increase in flap thickness only for the SKBM (P<.001). CONCLUSIONS: Flap thickness varies significantly depending on the microkeratome used. Factors that influence flap thickness are primarily corneal thickness, patient age, preoperative keratometry, preoperative refraction including astigmatism, and corneal diameter. By understanding the factors that affect flap thickness, one can select a microkeratome system to allow maximum refractive correction while minimizing the risk of ectasia.

Original languageEnglish (US)
Pages (from-to)113-123
Number of pages11
JournalJournal of Refractive Surgery
Volume19
Issue number2
StatePublished - Mar 1 2003

Fingerprint

Laser In Situ Keratomileusis
Astigmatism
Hyperopia
Pathologic Dilatations
Myopia
Ultrasonics

ASJC Scopus subject areas

  • Surgery
  • Ophthalmology

Cite this

Precision of flap measurements for laser in situ keratomileusis in 4428 eyes. / Flanagan, Gerald; Binder, Perry S.

In: Journal of Refractive Surgery, Vol. 19, No. 2, 01.03.2003, p. 113-123.

Research output: Contribution to journalArticle

@article{c606da5fa9884523b9aea40e3ae97e59,
title = "Precision of flap measurements for laser in situ keratomileusis in 4428 eyes",
abstract = "PURPOSE: To determine the factor(s) that influence the dimensions and predictability of the LASIK corneal flap with the Automated Corneal Shaper (ACS) or the Summit Krumeich Barraquer microkeratome (SKBM). METHODS: We performed a retrospective, comparative interventional case study of 4,428 eyes. Flap dimensions were measured using subtraction ultrasonic pachymetry during LASIK with one of two microkeratomes. RESULTS: Mean preoperative corneal thickness for all eyes was 555 ± 35 μm. Corneal curvature and refractive astigmatism were inversely related to preoperative corneal thickness (P<.001). With an attempted flap thickness of 160 μm, the ACS flap thickness averaged 119.8 ± 22.9 μm; SKBM flaps averaged 160.9 ± 24.1 μm (P<.001). The coefficient of variation for central pachymetry compared to flap thickness was 6.4{\%} vs. 22.1{\%}. Flap thickness at enhancement was 10 to 17 μm thicker than at primary surgery. An increase in flap thickness was associated with thicker preoperative pachymetry (P<.001) and younger age for both instruments (P<.001) whereas increasing flap thickness was related to flatter preoperative mean keratometry for the ACS (P<.001) and steeper mean keratometry for the SKBM (P=.005). Less preoperative hyperopia or more myopia was related to an increase in flap thickness only for the SKBM (P<.001). CONCLUSIONS: Flap thickness varies significantly depending on the microkeratome used. Factors that influence flap thickness are primarily corneal thickness, patient age, preoperative keratometry, preoperative refraction including astigmatism, and corneal diameter. By understanding the factors that affect flap thickness, one can select a microkeratome system to allow maximum refractive correction while minimizing the risk of ectasia.",
author = "Gerald Flanagan and Binder, {Perry S.}",
year = "2003",
month = "3",
day = "1",
language = "English (US)",
volume = "19",
pages = "113--123",
journal = "Journal of Refractive Surgery",
issn = "0883-0444",
publisher = "Slack Incorporated",
number = "2",

}

TY - JOUR

T1 - Precision of flap measurements for laser in situ keratomileusis in 4428 eyes

AU - Flanagan, Gerald

AU - Binder, Perry S.

PY - 2003/3/1

Y1 - 2003/3/1

N2 - PURPOSE: To determine the factor(s) that influence the dimensions and predictability of the LASIK corneal flap with the Automated Corneal Shaper (ACS) or the Summit Krumeich Barraquer microkeratome (SKBM). METHODS: We performed a retrospective, comparative interventional case study of 4,428 eyes. Flap dimensions were measured using subtraction ultrasonic pachymetry during LASIK with one of two microkeratomes. RESULTS: Mean preoperative corneal thickness for all eyes was 555 ± 35 μm. Corneal curvature and refractive astigmatism were inversely related to preoperative corneal thickness (P<.001). With an attempted flap thickness of 160 μm, the ACS flap thickness averaged 119.8 ± 22.9 μm; SKBM flaps averaged 160.9 ± 24.1 μm (P<.001). The coefficient of variation for central pachymetry compared to flap thickness was 6.4% vs. 22.1%. Flap thickness at enhancement was 10 to 17 μm thicker than at primary surgery. An increase in flap thickness was associated with thicker preoperative pachymetry (P<.001) and younger age for both instruments (P<.001) whereas increasing flap thickness was related to flatter preoperative mean keratometry for the ACS (P<.001) and steeper mean keratometry for the SKBM (P=.005). Less preoperative hyperopia or more myopia was related to an increase in flap thickness only for the SKBM (P<.001). CONCLUSIONS: Flap thickness varies significantly depending on the microkeratome used. Factors that influence flap thickness are primarily corneal thickness, patient age, preoperative keratometry, preoperative refraction including astigmatism, and corneal diameter. By understanding the factors that affect flap thickness, one can select a microkeratome system to allow maximum refractive correction while minimizing the risk of ectasia.

AB - PURPOSE: To determine the factor(s) that influence the dimensions and predictability of the LASIK corneal flap with the Automated Corneal Shaper (ACS) or the Summit Krumeich Barraquer microkeratome (SKBM). METHODS: We performed a retrospective, comparative interventional case study of 4,428 eyes. Flap dimensions were measured using subtraction ultrasonic pachymetry during LASIK with one of two microkeratomes. RESULTS: Mean preoperative corneal thickness for all eyes was 555 ± 35 μm. Corneal curvature and refractive astigmatism were inversely related to preoperative corneal thickness (P<.001). With an attempted flap thickness of 160 μm, the ACS flap thickness averaged 119.8 ± 22.9 μm; SKBM flaps averaged 160.9 ± 24.1 μm (P<.001). The coefficient of variation for central pachymetry compared to flap thickness was 6.4% vs. 22.1%. Flap thickness at enhancement was 10 to 17 μm thicker than at primary surgery. An increase in flap thickness was associated with thicker preoperative pachymetry (P<.001) and younger age for both instruments (P<.001) whereas increasing flap thickness was related to flatter preoperative mean keratometry for the ACS (P<.001) and steeper mean keratometry for the SKBM (P=.005). Less preoperative hyperopia or more myopia was related to an increase in flap thickness only for the SKBM (P<.001). CONCLUSIONS: Flap thickness varies significantly depending on the microkeratome used. Factors that influence flap thickness are primarily corneal thickness, patient age, preoperative keratometry, preoperative refraction including astigmatism, and corneal diameter. By understanding the factors that affect flap thickness, one can select a microkeratome system to allow maximum refractive correction while minimizing the risk of ectasia.

UR - http://www.scopus.com/inward/record.url?scp=0037344313&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0037344313&partnerID=8YFLogxK

M3 - Article

VL - 19

SP - 113

EP - 123

JO - Journal of Refractive Surgery

JF - Journal of Refractive Surgery

SN - 0883-0444

IS - 2

ER -