J Korean Ophthalmol Soc.  2017 Sep;58(9):1092-1098. 10.3341/jkos.2017.58.9.1092.

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

• Kim JH
• Ahn YJ
• Whang WJ
• Park SH

• KMID: 2390074
• DOI: http://doi.org/10.3341/jkos.2017.58.9.1092

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.

Keyword

Amblyopia; Astigmatism; Limbal dermoid

MeSH Terms

Amblyopia
Astigmatism
Child
Cornea
Dermoid Cyst*
Humans
Retrospective Studies
Visual Acuity

Figure

• 

  Figure 1 The parameter of limbal dermoid size by graphic program. (a) is limbal dermoid horizontal length to corneal center. (b) is distance between 2 limbal points where the limbal dermoid intersected with the limbus. (c) is area of limbal dermoid on cornea. (d) is total corneal diameter. (e) is total corneal area. Relative length is (a)/(d), relative width is (b)/(d), and relative area is (c)/(e).

• 

  Figure 2 The preoperative astigmatism and the change of astigmatism according to the length of the central invasion of the limbal dermoid. The corneal diameter is assumed to be 11.5 mm. (A) Scatterplot graph showing a positive linear correlation between limbal dermoid length invading cornea (in millimeters) and preoperative astigmatism (in diopters). (B) Scatterplot graph showing a positive linear correlation between limbal dermoid length invading cornea (in millimeters) and variation between preoperative and postoperative astigmatism. Pre op. = preoperative; D = diopter.

• 

  Figure 3 Double-angle scatterplots of astigmatism using AstigPLOT. Only 17 eyes with the center of the limbal dermoid located on the inferotemporal side were included. (A) Scatter plot of polar astigmatic vectors for preoperative astigmatism (n = 17). (B) Scatter plot of polar astigmatic vectors for postoperative astigmatism (n = 17). (C) Scatter plot of calculated surgically induced astigmatism (n = 17). Astigmatism was expressed on a negative scale. Blue one point represents one eye and red point represents centroid. The distance from the origin to a point represents the size of the induced corneal astigmatism, and each graph has a single size displayed. D = diopter.

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