LARGE STUDY MAY PROVIDE NORMATIVE DATA FOR CORNEAL ASTIGMATISM, BIOMETRY

A clinical study in Germany has reported biometry and astigmatism data for a large cohort of cataract patients.¹ The study authors suggest that their findings may serve as a normative reference for surgeons and may help manufacturers tailor toric IOLs to the cataract marketplace.

With data from 23,239 eyes, the retrospective study is the largest of its kind ever published, more than tripling the number of data sets included in Hoffer’s series of 7,500 eyes in 1980.² Additionally, it updates the technology, with measurements taken using the current standard of partial coherence interferometry, rather than immersion ultrasound, the state of the art in1980.

Researchers found that anterior chamber depth and axis of astigmatism correlated with age. Mean axial length was 23.45 ±1.51 mm (standard deviation), mean corneal radius was 7.69 ±0.28 mm, mean white-to-white distance was 11.82 ±0.40 mm, and mean anterior chamber depth was 3.11 ±0.43 mm. The axial length, corneal radius, and white-to-white distance correlated with one another. Eight percent of eyes had corneal astigmatism greater than 2.00 D, and 2.6% had more than 3.00 D. Withthe- rule astigmatism was found in 46.8% of eyes, against-the-rule in 34.4%, and oblique in 18.9%. High astigmatism was predominantly with-the-rule, the study authors said.

1. Hoffmann PC,Hütz WW.Analysis of biometry and prevalence data for corneal astigmatism in 23,239 eyes.J Cataract Refract Surg.2010;36(9):1479-1485.
2. Hoffer KJ.Biometry of 7,500 cataractous eyes.Am J Ophthalmol.1980;90:360-368;correction,890.