| Abstract [eng] |
Background: The cornea is an important part of the optical system of the eye; therefore, changes in its structure and shape can significantly affect visual function. Corneal topography is a non-invasive method that enables the assessment of these changes and helps diagnose corneal diseases, particularly ectatic conditions. With advances in imaging technologies, corneal topography and tomography are becoming increasingly important for early diagnosis, monitoring disease progression, and planning refractive surgery. Aim: Based on literature sources and a clinical case, to review and evaluate the significance of corneal topography in the diagnosis of corneal astigmatism and the main corneal ectasias - keratoconus, pellucid marginal degeneration, and iatrogenic ectasia. Methods: A narrative literature review was conducted using the PubMed, Google Scholar, ScienceDirect, and Vilnius University Library databases. The search was performed using the following keywords in various combinations: cornea, corneal, topography, tomography, imaging, disease, keratoconus, ectasia, astigmatism, pellucid marginal corneal degeneration, refractive surgery. Full-text publications written in Lithuanian and English were included in the analysis. A clinical case of a female patient with keratoconus from the Centre of Ophthalmology at Vilnius University Hospital Santaros Klinikos was also analysed. Results: Corneal topography is significant in the assessment of corneal astigmatism, including the differentiation between regular and irregular astigmatism, and in the diagnosis of ectatic corneal conditions such as keratoconus, pellucid marginal degeneration, and iatrogenic corneal ectasia. Placido-disc-based topography allows assessment of the anterior corneal surface, while tomography based on slit-scanning and Scheimpflug technology additionally provides data on the posterior corneal surface and corneal thickness. It was found that posterior corneal elevation and pachymetric parameters are particularly important for the diagnosis of early and subclinical ectatic changes; therefore, comprehensive evaluation of topographic, tomographic, and pachymetric data has the greatest diagnostic value. Tangential maps are more sensitive than axial maps in detecting localized ectatic corneal changes, while topographic parameters and indices help quantify structural changes more accurately; however, they must be interpreted together with other clinical data. Accurate diagnosis of early or subclinical keratoconus is also important before refractive surgery in order to identify patients who may have an increased risk of ectasia. The clinical case confirmed the importance of topography in the diagnosis of keratoconus and in monitoring disease progression. Conclusions: Corneal topography and tomography are highly important diagnostic tools for the diagnosis and monitoring of various corneal ectasias, the assessment of corneal astigmatism, and patient selection for refractive surgery. For the detection of early and subclinical ectatic changes, the comprehensive evaluation of topographic and tomographic data is the most important. |
