Clinical relevance: Expanding practitioner knowledge regarding potential changes in ocular structure of keratoconic eyes will improve the eye care practice and patient management.
Background: This study aimed to compare the difference in choroidal thickness between keratoconus patients and two control groups of myopic-astigmatism and emmetropic subjects.
Methods: A case-control study was undertaken which included 50 patients with keratoconus, 50 with myopic-astigmatism, 30 with emmetropia aged between 18 and 39 years. Choroidal thickness was measured at three different locations, including the subfoveal, nasal, and temporal (750 micrometres) to the fovea, using a spectral-domain optical coherence tomography with an enhanced depth imaging technique.
Results: The mean spherical equivalents were 0.03 ± 0.05, -3.00 ± 0.2, and -3.00 ± 0.3 dioptre in emmetropic, myopic-astigmatism and keratoconus subjects, respectively. The choroid was significantly thicker in keratoconus patients than in myopic-astigmatism and emmetropic subjects in the subfoveal (396 ± 14, 314 ± 12, and 320 ± 18 μm, respectively, p < 0.001), temporal (405 ± 14, 317 ± 12, and 328 ± 19 μm, respectively, p < 0.001) and nasal (376 ± 14, 285 ± 12, and 311 ± 18 μm, respectively; p < 0.001).
Conclusion: Choroidal thickness is increased in keratoconus. The exact mechanism for choroidal thickening in individuals with keratoconus is unknown, but inflammatory responses could be the reason.
Keywords: Choroidal thickness; emmetropia; keratoconus; myopia; optical coherence tomography.