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Surgical control of late postkeratoplasty astigmatism with or without the use of computerized video keratography: a
C H Karabatsas1, S D Cook, F C Figueiredo
1Department of Ophthalmology, Bristol Eye Hospital, England.
Objective:
To assess the effectiveness of computerized videokeratography (CVK) in refining the surgical design and in improving predictability of surgical correction of postkeratoplasty astigmatism.
Design:
A prospective, controlled, randomized, clinical trial.
Participants:
A total of 31 postkeratoplasty eyes, divided into 2 groups (group A, 16 eyes; group B, 15 eyes), with more than 4 diopters (D) of disabling astigmatism were studied.
Intervention:
All eyes were treated with a combination of arcuate relaxing incisions and compression sutures. The surgical plan in group A was based on topographic information, whereas in the control group B, the surgical plan was based on information obtained by refraction and keratometry alone.
Main Outcome Measures:
Change in the surgical plan induced by the CVK information, astigmatism, topographic patterns, and factors associated with outcome were measured.
Results:
In all 16 cases of group A, the use of CVK changed some aspect of the surgical plan. At 12 months after surgery, both groups showed a significant net reduction (P = 0.001) of baseline astigmatism. However, the reduction (47% and 41 % for groups A and B, respectively) did not differ significantly between the two groups. The topographic astigmatism at 12 months measured 4.24 +/- 0.71 D in group A and 5.60 +/- 0.51 D in group B (P = 0.139). Significant differences between the two groups at 12 months were seen only for keratometric astigmatism (3.60 +/- 0.81 D in group A vs. 5.77 +/- 0.52 D in group B, P = 0.035) and refractive astigmatism (2.34 +/- 0.37 D in group A vs. 4.88 +/- 0.52 D in group B, P = 0.000). The mean vector surgical effect was 91 % for group A and 70% for group B. Regular astigmatism patterns had a greater benefit from surgery than irregular patterns (P = 0.008). Previous refractive surgery was associated with less-favorable outcome (P = 0.045).
Conclusions:
The current study indicates that the use of CVK provides a benefit compared to keratometry and refraction alone in the planning and outcome of surgical treatment for high postgraft astigmatism.
