Astigmatic Analysis before and after Surgical Excision of Limbal Dermoid: Functional Outcome

ABSTRACT

PURPOSE: To analyze the length and area of limbal dermoid invading the cornea and to evaluate the effects on visual acuity and astigmatism before and after surgery. METHODS: This retrospective study included 20 eyes of 20 patients who underwent surgical removal of limbal dermoid. The preoperative and postoperative visual acuity and astigmatism level were measured. In addition, we evaluated the correlations of astigmatism with the length ratio (length of limbal dermoid invading the cornea/total corneal diameter), width ratio (width of limbal dermoid invading the cornea/total corneal diameter), and area ratio (area of limbal dermoid invading the cornea/total corneal area) using preoperative anterior segment photographs. RESULTS: The mean preoperative astigmatism was 0.85 ± 0.71 D in the sound eye and 3.00 ± 3.14 D in the affected eye (p = 0.004). Length, width, and area ratio of limbal dermoid have positive correlation with astigmatism (p < 0.010 for all variables), with a larger length ratio of limbal dermoid invading the cornea producing greater reduction in postoperative astigmatism (p = 0.010, r = 0.816). The amount of astigmatism was significantly higher in patients with amblyopia in the affected eye (p = 0.030). Visual acuity gain more than 2 lines was achieved in 8 among 10 patients with amblyopia under the age of 7 years through the appropriate refractive correction and occlusion 1 year after surgery. CONCLUSIONS: Astigmatism is a major cause of amblyopia in pediatric patients with limbal dermoid. The degree of astigmatism can be predicted by the size factors of the limbal dermoid. In particular, the relative length of limbal dermoid invading the cornea has a stronger correlation with preoperative astigmatism than other factors and has correlation with postoperative reduction of astigmatism. It should be emphasized that children with limbal dermoid need appropriate refractive correction and occlusion in addition to surgical excision.