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Novel grid and sectoral analyses in monitoring corneal scars

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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.

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Authors and Affiliations

  1. Department of Ophthalmology and Visual Sciences, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong

    Ka Wai Kam, Rachel Pui Wai Kwok & Alvin L. Young

  2. Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong

    Anita Li & Alvin L. Young

  3. Department of Ophthalmology and Visual Science, University of Arizona, Tucson, USA

    Michael W. Belin

Authors
  1. Ka Wai Kam
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  2. Anita Li
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  3. Rachel Pui Wai Kwok
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  4. Michael W. Belin
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  5. Alvin L. Young
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Corresponding author

Correspondence to Alvin L. Young.

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Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

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Kam, K.W., Li, A., Kwok, R.P.W. et al. Novel grid and sectoral analyses in monitoring corneal scars. Int Ophthalmol 39, 911–916 (2019). https://doi.org/10.1007/s10792-018-0897-z

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  • DOI: https://doi.org/10.1007/s10792-018-0897-z

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