White lesion in the corneal pigmented ring associated with orthokeratology

The development of the pigmented corneal arc and a white lesion near the inner margin of the arc in a girl wearing overnight orthokeratology (ortho-k) lenses for myopic control is reported. The girl was examined before and followed up every 6 months after the treatment over a 3-year period. The initial spherical equivalent refractive error and keratometric readings (flattest/steepest meridians) were -2.37 D and 45.00 D/46.75 D respectively in the right eye and -3.12 D and 45.25 D/46.00 D respectively in the left eye. She was wearing ortho-k lenses of a four-zone design made of Boston XO material on a nightly basis. The same lens design was used throughout the monitoring period. Corneal topography showed a rather well-centred treatment zone but vision varied between visits because of fluctuations in residual refractive error. The corneal condition of each eye was unremarkable except for the presence of the pigmented corneal arc first observed 6 months after the commencement of the treatment. The intensity of the arc did not change over the years in the right eye but increased in the left eye. A faint white lesion within the inner border of the left pigmented arc was first observed at the end of the second year and it became more obvious at the end of the third year. This lesion appears to be similar to those reported in intense Fleischer's rings associated with keratoconus. Although the presence of the arc may have no clinical ramification, the change in the intensity and the development of the white lesion may reflect an increased stress exerted on the cornea with continued ortho-k lens wear.