Background: Only a few case reports have described the ultrasound biomicroscopic features of limbal dermoids. It remains unclear whether examination by ultrasound biomicroscopy (UBM) can detect the corneal depth of penetration which would improve planning of surgery.
Methods: Eight consecutive patients [two female, six male, 1-24 years old (median 8.5 years)] examined by UBM (Zeiss-Humphrey, 50 MHz) were retrospectively studied. Five of the dermoids were excised without corneal grafting and histopathological evaluation was obtained.
Results: Seven out of eight dermoids were located in the temporal lower quadrant. A Goldenhar syndrome was known in three cases. In all cases but one, UBM showed a more reflective and predominantly homogeneous lesion compared with the unaffected corneal stroma, so that the lateral margins of the lesion could be clearly identified. Incomplete stromal penetration of the dermoid was noticed in four cases; one eye showed a corneal full thickness dermoid. An intraocular protrusion was seen in one eye. Two more cases remained unclear because of reduced compliance. Descemet's membrane beneath the dermoid could not be visualized in most cases (seven out of eight) because of strong sound attenuation inside the lesion. Histopathological evaluation of five cases revealed the typical signs of a limbal dermoid.
Conclusion: UBM improves the preoperative evaluation of limbal dermoids. Subtle examination technique for the depth of corneal penetration is required because of the strong sound attenuation in this tissue, reducing the visibility of deep corneal structures.