Ultrasound biomicroscopy and corneal endothelium in Nd:YAG-laser iridotomy

Thirty eyes affected by angle-closure glaucoma that had undergone YAG-laser iridotomy were studied to evaluate variations of central anterior chamber depth, width of the angle, and loss of endothelial cells after laser treatment.

These parameters were determined before and after iridotomy: endothelial cell count using a "non-contact" specular biomicroscope, and anterior chamber depth and angle width using ultrasound biomicroscopy (UBM). The width of the iridotomy and the distance of the iridotomy from the scleral spur and from the corneal endothelium were also measured by UBM, after laser treatment.

Results confirmed that, after iridotomy, there is not a significant variation in the central depth of the anterior chamber: it goes from 2.02 mm pre-laser to 2.07 +/- 0.38 mm post-laser. There is, however, a statistically significant increase in the angle (P < .001), which goes from 10.69 +/- 8.88 degrees (0.109 +/- 0.07 mm) to 21.03 +/- 11.28 degrees (0.183 +/- 0.09 mm). The mean dimension of the iridotomies was 0.46 +/- 0.13 mm. The mean endothelial cell count was 55.8 +/- 4.08 cells per linear millimeter before laser treatment and 47.01 +/- 5.39 cells per linear millimeter afterward (P <.001).

This study confirms that YAG-laser iridotomy leads to a reduction in the average endothelial cell density. The loss of these cells is inversely proportional to the distance of the iridotomy from the endothelium and the scleral spur.