Novel grid and sectoral analyses in monitoring corneal scars

Ka Wai Kam, Anita Li, Rachel Pui Wai Kwok, Michael W Belin, Alvin L. Young

Research output: Contribution to journalArticle

Abstract

Purpose: We aim to design two sampling methods, the grid and sectoral methods, to provide more precise detection of focal corneal scar changes with time following pterygium excision with the Pentacam imaging system. Methods: This is a retrospective study of our previous prospective observational case series. Thirty patients underwent primary pterygium excision with adjuvant topical mitomycin-C application were followed up and imaged with Pentacam system at postoperative weeks 1, 4, 12 and month 18. Grid and sectoral methods were used to sample density changes (in grayscale units, GSU) over the scarred areas as well as the clear pole of the same cornea. Results: Using the grid method, the average corneal densities were 39.4, 37.1, 36.7 and 34.7 GSU at postoperative 1, 4, 12 weeks and 18 months, respectively. On the other hand, using the sectoral method, the average corneal densities were 35.3, 33.3, 32.5 and 31.9 GSU at postoperative 1, 4, 12 weeks and 18 months, respectively. Paired t tests achieved statistical significance when comparing all follow-up time points to first postoperative visit. A statistically significant effect of time on the average density was shown on ANOVA (p < 0.001) using both analyses over the scarred areas, but not over the clear pole of the same cornea (p > 0.05). Conclusion: Our novel approach to monitor corneal density changes using the grid or sectoral sampling methods seemingly enhances the power in monitoring density changes in corneal scars when compared to conventional total-diameter average densitometry.

Original languageEnglish (US)
Pages (from-to)1-6
Number of pages6
JournalInternational Ophthalmology
DOIs
StateAccepted/In press - Jun 19 2018

Fingerprint

Pterygium
Densitometry
Mitomycin
Corneal Injuries
Cornea
Analysis of Variance
Retrospective Studies

Keywords

  • Cornea
  • Densitometry
  • Pterygium
  • Scar
  • Scheimpflug image

ASJC Scopus subject areas

  • Ophthalmology

Cite this

Novel grid and sectoral analyses in monitoring corneal scars. / Kam, Ka Wai; Li, Anita; Kwok, Rachel Pui Wai; Belin, Michael W; Young, Alvin L.

In: International Ophthalmology, 19.06.2018, p. 1-6.

Research output: Contribution to journalArticle

Kam, Ka Wai ; Li, Anita ; Kwok, Rachel Pui Wai ; Belin, Michael W ; Young, Alvin L. / Novel grid and sectoral analyses in monitoring corneal scars. In: International Ophthalmology. 2018 ; pp. 1-6.
@article{899a4a8a416d4580b90f4d829663894a,
title = "Novel grid and sectoral analyses in monitoring corneal scars",
abstract = "Purpose: We aim to design two sampling methods, the grid and sectoral methods, to provide more precise detection of focal corneal scar changes with time following pterygium excision with the Pentacam imaging system. Methods: This is a retrospective study of our previous prospective observational case series. Thirty patients underwent primary pterygium excision with adjuvant topical mitomycin-C application were followed up and imaged with Pentacam system at postoperative weeks 1, 4, 12 and month 18. Grid and sectoral methods were used to sample density changes (in grayscale units, GSU) over the scarred areas as well as the clear pole of the same cornea. Results: Using the grid method, the average corneal densities were 39.4, 37.1, 36.7 and 34.7 GSU at postoperative 1, 4, 12 weeks and 18 months, respectively. On the other hand, using the sectoral method, the average corneal densities were 35.3, 33.3, 32.5 and 31.9 GSU at postoperative 1, 4, 12 weeks and 18 months, respectively. Paired t tests achieved statistical significance when comparing all follow-up time points to first postoperative visit. A statistically significant effect of time on the average density was shown on ANOVA (p < 0.001) using both analyses over the scarred areas, but not over the clear pole of the same cornea (p > 0.05). Conclusion: Our novel approach to monitor corneal density changes using the grid or sectoral sampling methods seemingly enhances the power in monitoring density changes in corneal scars when compared to conventional total-diameter average densitometry.",
keywords = "Cornea, Densitometry, Pterygium, Scar, Scheimpflug image",
author = "Kam, {Ka Wai} and Anita Li and Kwok, {Rachel Pui Wai} and Belin, {Michael W} and Young, {Alvin L.}",
year = "2018",
month = "6",
day = "19",
doi = "10.1007/s10792-018-0897-z",
language = "English (US)",
pages = "1--6",
journal = "International Ophthalmology",
issn = "0165-5701",
publisher = "Springer Netherlands",

}

TY - JOUR

T1 - Novel grid and sectoral analyses in monitoring corneal scars

AU - Kam, Ka Wai

AU - Li, Anita

AU - Kwok, Rachel Pui Wai

AU - Belin, Michael W

AU - Young, Alvin L.

PY - 2018/6/19

Y1 - 2018/6/19

N2 - Purpose: We aim to design two sampling methods, the grid and sectoral methods, to provide more precise detection of focal corneal scar changes with time following pterygium excision with the Pentacam imaging system. Methods: This is a retrospective study of our previous prospective observational case series. Thirty patients underwent primary pterygium excision with adjuvant topical mitomycin-C application were followed up and imaged with Pentacam system at postoperative weeks 1, 4, 12 and month 18. Grid and sectoral methods were used to sample density changes (in grayscale units, GSU) over the scarred areas as well as the clear pole of the same cornea. Results: Using the grid method, the average corneal densities were 39.4, 37.1, 36.7 and 34.7 GSU at postoperative 1, 4, 12 weeks and 18 months, respectively. On the other hand, using the sectoral method, the average corneal densities were 35.3, 33.3, 32.5 and 31.9 GSU at postoperative 1, 4, 12 weeks and 18 months, respectively. Paired t tests achieved statistical significance when comparing all follow-up time points to first postoperative visit. A statistically significant effect of time on the average density was shown on ANOVA (p < 0.001) using both analyses over the scarred areas, but not over the clear pole of the same cornea (p > 0.05). Conclusion: Our novel approach to monitor corneal density changes using the grid or sectoral sampling methods seemingly enhances the power in monitoring density changes in corneal scars when compared to conventional total-diameter average densitometry.

AB - Purpose: We aim to design two sampling methods, the grid and sectoral methods, to provide more precise detection of focal corneal scar changes with time following pterygium excision with the Pentacam imaging system. Methods: This is a retrospective study of our previous prospective observational case series. Thirty patients underwent primary pterygium excision with adjuvant topical mitomycin-C application were followed up and imaged with Pentacam system at postoperative weeks 1, 4, 12 and month 18. Grid and sectoral methods were used to sample density changes (in grayscale units, GSU) over the scarred areas as well as the clear pole of the same cornea. Results: Using the grid method, the average corneal densities were 39.4, 37.1, 36.7 and 34.7 GSU at postoperative 1, 4, 12 weeks and 18 months, respectively. On the other hand, using the sectoral method, the average corneal densities were 35.3, 33.3, 32.5 and 31.9 GSU at postoperative 1, 4, 12 weeks and 18 months, respectively. Paired t tests achieved statistical significance when comparing all follow-up time points to first postoperative visit. A statistically significant effect of time on the average density was shown on ANOVA (p < 0.001) using both analyses over the scarred areas, but not over the clear pole of the same cornea (p > 0.05). Conclusion: Our novel approach to monitor corneal density changes using the grid or sectoral sampling methods seemingly enhances the power in monitoring density changes in corneal scars when compared to conventional total-diameter average densitometry.

KW - Cornea

KW - Densitometry

KW - Pterygium

KW - Scar

KW - Scheimpflug image

UR - http://www.scopus.com/inward/record.url?scp=85048743171&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85048743171&partnerID=8YFLogxK

U2 - 10.1007/s10792-018-0897-z

DO - 10.1007/s10792-018-0897-z

M3 - Article

SP - 1

EP - 6

JO - International Ophthalmology

JF - International Ophthalmology

SN - 0165-5701

ER -