Surgical control of late postkeratoplasty astigmatism with or without the use of computerized video keratography: A prospective, randomized study1☆
Received 16 December 1997; accepted 24 June 1998.
Abstract
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 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.
Manuscript no. 97856.
aDepartment of Ophthalmology, Bristol Eye Hospital, Bristol, England UK
Address correspondence and reprint requests to Constantinos H. Karabatsas, MD, FRCS, P.O. Box 16757, Athens 11502, Greece
☆ Supported in part by a grant (to CHK) from the Greek State Foundation (IKY) (grant no: 721472787).
1 None of the authors have any proprietary interest in any of the instruments used in the study.
ABSTRACT