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Proposed classification for topographic patterns seen after penetrating keratoplasty
C H Karabatsas1, S D Cook, J M Sparrow
1Department of Ophthalmology, Bristol Eye Hospital.
The British Journal of Ophthalmology
|August 6, 1999
Summary
Post-keratoplasty (PKP) corneas show a higher prevalence of irregular astigmatism. This classification system aids in understanding corneal topography changes after PKP surgery.
Area of Science:
- Ophthalmology
- Corneal Surgery
- Optometry
Background:
- Corneal topography is crucial for assessing refractive outcomes after penetrating keratoplasty (PKP).
- Existing classification systems may not fully capture the diverse topographic patterns observed post-PKP.
Purpose of the Study:
- To develop a clinically applicable classification system for post-keratoplasty corneas based on corneal topography.
- To categorize and quantify astigmatic patterns following PKP.
Main Methods:
- 360 topographic maps from 95 post-PKP eyes were analyzed using the TMS-1 device.
- Two masked examiners independently categorized the maps according to a proposed classification scheme.
- Interobserver agreement was assessed to ensure reliability.
Main Results:
- High interobserver agreement (88%) was achieved in the classification.
- At 12 months post-PKP, irregular astigmatism (72%) was more prevalent than regular astigmatism (24%).
- Specific subtypes of regular and irregular astigmatism were identified and quantified.
Conclusions:
- Irregular astigmatism is approximately twice as common as regular astigmatism in post-PKP corneas.
- There is a tendency for irregular astigmatic patterns to increase over time after PKP.
- This classification provides a framework for understanding and managing post-keratoplasty corneal irregularities.
