ACD measurements should be standardized

Anterior chamber depth measurements using an optical pachymeter should be standardized, according to two surgeons.

Rupert R. Bourne, FRCOphth, MD, in London and P.H. Alsbirk in Denmark independently conducted two studies evaluating patients for possible angle closure. Dr. Bourne measured 109 people consecutively from a population-based study. Dr. Alsbirk measured 127 consecutive patients in a clinical setting. The mean age of Dr. Bourke’s subjects was 61.3 years old; the mean age of the Dr. Alsbirk’s patients was 66.9 years old.

According to the study, Haag-Streit recommends that accurate anterior chamber depth results can be achieved by determining corneal thickness with attachment 1, and deducting that figure from the measurement of the corneal epithelium to the anterior lens surface made with attachment 2 (for this study, Method A). Ophthalmologists may use only the corneal endothelium to anterior lens surface measurement (for this study, Method B), as it is quicker and easier, the study said.

Using Method A, the mean anterior chamber depth was 1.97 mm in Dr. Alsbirk’s study and 2.59 mm in Dr. Bourne’s study. When anterior chamber depth was measured with Method B, it was “significantly deeper than Method A in both studies,” researchers said.

“This is the first study to quantify the difference in anterior chamber depth using these two methods in two samples,” the authors wrote. They call for standardizing anterior chamber depth measurements.

The study is published in the April issue of British Journal of Ophthalmology.