Refractive outcomes after cataract-trabeculectomy accurate despite biometry changes

The refractive outcome after combined cataract surgery and trabeculectomy was close to the predicted refraction in a recent study, even though axial length and corneal curvature changed from preop to postop.

Simon K. Law, MD, and colleagues at the Jules Stein Eye Institute studied the refractive results and biometric changes in 24 eyes that underwent combined cataract surgery and trabeculectomy. These results were compared with 15 eyes that underwent cataract surgery alone. The main outcome measures were IOP, axial length, corneal curvature and expected and observed refractive errors before and after surgery. Axial length was measured using optical coherence biometry.

The mean IOP in the combined surgical group was 16.6 mm Hg preoperatively, dropping to 10.9 mm Hg (P < .00001) after surgery. The mean axial length was significantly shortened, from 24.1 mm to 23.98 mm (P < .00001). The reduction in mean axial length after the combined operation was significantly greater than the reduction after cataract surgery alone, and it correlated significantly with postoperative IOP.

There was a mean with-the-rule induction of corneal astigmatism and a significant increase of mean keratometry reading after the combined procedure. No significant difference between the expected and observed refractive errors was seen.

“The current study demonstrates that with the use of a noncontact, precise biometric method, the axial length is reduced significantly after a combined operation,” the researchers said in the August issue of the British Journal of Ophthalmology.