Quantification of stromal thinning, epithelial thickness, and corneal haze after photorefractive keratectomy using in vivo confocal microscopy

T. Moller-Pedersen, M. Vogel, Fang Li Hong Fang Li, Walter M Petroll, Harrison D Cavanagh, J. V. Jester

Research output: Contribution to journalArticle

182 Citations (Scopus)

Abstract

Purpose: The authors establish, for the first time, observer-independent quantification of stromal thinning, epithelial thickness, and corneal haze after excimer laser photorefractive keratectomy (PRK) using a unique, new form of in vive confocal microscopy. Methods: Rapid, continuous z-scans of high-resolution confocal images, termed confocal microscopy through focusing (CMTF), were performed in the central corneal area of 17 patients before and 1 month after PRK for low- to moderate-grade myopia (-2.88--9.13 diopters [D]). Corneal, epithelial, and stromal thickness measurements and an objective haze estimate were obtained from each CMTF scan by digital image analysis. Results: Epithelial thickness averaged 51 ± 4 μm before and 45 ± 10 μm 1 month post-PRK (P < 0.005), whereas stromal thinning ranged from 20 to 154 pm, representing a direct estimate of the actual photoablation depth. Corneal thickness averaged 560 ± 36 μm before PRK and 462 ± 52 μm at 1 month. The change in corneal thickness correlated closely with the change in spherical equivalent refraction (r = 0.94, P < 0.0001); linear regression analysis revealed a value of 14.3 μm corneal thinning per diopter of correction. A significant correlation was found between the objective CMTF haze estimate and a clinical haze grading obtained by slit-lamp examination (r = 0.73, P < 0.001). Conclusions: Confocal microscopy through focusing is a new, powerful in vivo tool that enables quantitative, unbiased evaluation of PRK procedures over time by providing epithelial and stromal thickness analysis, photoablation depth assessment, and unbiased haze measurement. The method is uniquely valuable in the pre- and postoperative assessment of PRK patients and for determining the optimal treatment strategy, especially in assessing refractive and visual outcomes in individual cases.

Original languageEnglish (US)
Pages (from-to)360-368
Number of pages9
JournalOphthalmology
Volume104
Issue number3
StatePublished - 1997

Fingerprint

Photorefractive Keratectomy
Confocal Microscopy
Laser Corneal Surgery
Excimer Lasers
Myopia
Intravital Microscopy
Linear Models
Regression Analysis

ASJC Scopus subject areas

  • Ophthalmology

Cite this

Quantification of stromal thinning, epithelial thickness, and corneal haze after photorefractive keratectomy using in vivo confocal microscopy. / Moller-Pedersen, T.; Vogel, M.; Hong Fang Li, Fang Li; Petroll, Walter M; Cavanagh, Harrison D; Jester, J. V.

In: Ophthalmology, Vol. 104, No. 3, 1997, p. 360-368.

Research output: Contribution to journalArticle

@article{13b5e25da8a142d7b76569e24c95450f,
title = "Quantification of stromal thinning, epithelial thickness, and corneal haze after photorefractive keratectomy using in vivo confocal microscopy",
abstract = "Purpose: The authors establish, for the first time, observer-independent quantification of stromal thinning, epithelial thickness, and corneal haze after excimer laser photorefractive keratectomy (PRK) using a unique, new form of in vive confocal microscopy. Methods: Rapid, continuous z-scans of high-resolution confocal images, termed confocal microscopy through focusing (CMTF), were performed in the central corneal area of 17 patients before and 1 month after PRK for low- to moderate-grade myopia (-2.88--9.13 diopters [D]). Corneal, epithelial, and stromal thickness measurements and an objective haze estimate were obtained from each CMTF scan by digital image analysis. Results: Epithelial thickness averaged 51 ± 4 μm before and 45 ± 10 μm 1 month post-PRK (P < 0.005), whereas stromal thinning ranged from 20 to 154 pm, representing a direct estimate of the actual photoablation depth. Corneal thickness averaged 560 ± 36 μm before PRK and 462 ± 52 μm at 1 month. The change in corneal thickness correlated closely with the change in spherical equivalent refraction (r = 0.94, P < 0.0001); linear regression analysis revealed a value of 14.3 μm corneal thinning per diopter of correction. A significant correlation was found between the objective CMTF haze estimate and a clinical haze grading obtained by slit-lamp examination (r = 0.73, P < 0.001). Conclusions: Confocal microscopy through focusing is a new, powerful in vivo tool that enables quantitative, unbiased evaluation of PRK procedures over time by providing epithelial and stromal thickness analysis, photoablation depth assessment, and unbiased haze measurement. The method is uniquely valuable in the pre- and postoperative assessment of PRK patients and for determining the optimal treatment strategy, especially in assessing refractive and visual outcomes in individual cases.",
author = "T. Moller-Pedersen and M. Vogel and {Hong Fang Li}, {Fang Li} and Petroll, {Walter M} and Cavanagh, {Harrison D} and Jester, {J. V.}",
year = "1997",
language = "English (US)",
volume = "104",
pages = "360--368",
journal = "Ophthalmology",
issn = "0161-6420",
publisher = "Elsevier Inc.",
number = "3",

}

TY - JOUR

T1 - Quantification of stromal thinning, epithelial thickness, and corneal haze after photorefractive keratectomy using in vivo confocal microscopy

AU - Moller-Pedersen, T.

AU - Vogel, M.

AU - Hong Fang Li, Fang Li

AU - Petroll, Walter M

AU - Cavanagh, Harrison D

AU - Jester, J. V.

PY - 1997

Y1 - 1997

N2 - Purpose: The authors establish, for the first time, observer-independent quantification of stromal thinning, epithelial thickness, and corneal haze after excimer laser photorefractive keratectomy (PRK) using a unique, new form of in vive confocal microscopy. Methods: Rapid, continuous z-scans of high-resolution confocal images, termed confocal microscopy through focusing (CMTF), were performed in the central corneal area of 17 patients before and 1 month after PRK for low- to moderate-grade myopia (-2.88--9.13 diopters [D]). Corneal, epithelial, and stromal thickness measurements and an objective haze estimate were obtained from each CMTF scan by digital image analysis. Results: Epithelial thickness averaged 51 ± 4 μm before and 45 ± 10 μm 1 month post-PRK (P < 0.005), whereas stromal thinning ranged from 20 to 154 pm, representing a direct estimate of the actual photoablation depth. Corneal thickness averaged 560 ± 36 μm before PRK and 462 ± 52 μm at 1 month. The change in corneal thickness correlated closely with the change in spherical equivalent refraction (r = 0.94, P < 0.0001); linear regression analysis revealed a value of 14.3 μm corneal thinning per diopter of correction. A significant correlation was found between the objective CMTF haze estimate and a clinical haze grading obtained by slit-lamp examination (r = 0.73, P < 0.001). Conclusions: Confocal microscopy through focusing is a new, powerful in vivo tool that enables quantitative, unbiased evaluation of PRK procedures over time by providing epithelial and stromal thickness analysis, photoablation depth assessment, and unbiased haze measurement. The method is uniquely valuable in the pre- and postoperative assessment of PRK patients and for determining the optimal treatment strategy, especially in assessing refractive and visual outcomes in individual cases.

AB - Purpose: The authors establish, for the first time, observer-independent quantification of stromal thinning, epithelial thickness, and corneal haze after excimer laser photorefractive keratectomy (PRK) using a unique, new form of in vive confocal microscopy. Methods: Rapid, continuous z-scans of high-resolution confocal images, termed confocal microscopy through focusing (CMTF), were performed in the central corneal area of 17 patients before and 1 month after PRK for low- to moderate-grade myopia (-2.88--9.13 diopters [D]). Corneal, epithelial, and stromal thickness measurements and an objective haze estimate were obtained from each CMTF scan by digital image analysis. Results: Epithelial thickness averaged 51 ± 4 μm before and 45 ± 10 μm 1 month post-PRK (P < 0.005), whereas stromal thinning ranged from 20 to 154 pm, representing a direct estimate of the actual photoablation depth. Corneal thickness averaged 560 ± 36 μm before PRK and 462 ± 52 μm at 1 month. The change in corneal thickness correlated closely with the change in spherical equivalent refraction (r = 0.94, P < 0.0001); linear regression analysis revealed a value of 14.3 μm corneal thinning per diopter of correction. A significant correlation was found between the objective CMTF haze estimate and a clinical haze grading obtained by slit-lamp examination (r = 0.73, P < 0.001). Conclusions: Confocal microscopy through focusing is a new, powerful in vivo tool that enables quantitative, unbiased evaluation of PRK procedures over time by providing epithelial and stromal thickness analysis, photoablation depth assessment, and unbiased haze measurement. The method is uniquely valuable in the pre- and postoperative assessment of PRK patients and for determining the optimal treatment strategy, especially in assessing refractive and visual outcomes in individual cases.

UR - http://www.scopus.com/inward/record.url?scp=0030985492&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030985492&partnerID=8YFLogxK

M3 - Article

C2 - 9082257

AN - SCOPUS:0030985492

VL - 104

SP - 360

EP - 368

JO - Ophthalmology

JF - Ophthalmology

SN - 0161-6420

IS - 3

ER -