Anterior chamber depth, white-to-white corneal diameter may be important to IOL performance in myopes

J Refract Surg. 2010;26(11):891-898.

Issue: January 25, 2011

The average difference in pupil size between mesopic and photopic conditions was consistent among myopic patients between the ages of 18 years and 62 years, a study found.

Anterior chamber depth and white-to-white corneal diameter may prove critical to the performance of multifocal refractive or diffractive IOLs.

"This may predict the optimal dimensions of the implant warranting better stability and preventing postoperative complications related to forward or backward displacement," the study authors said.

The study included 964 eyes with myopia ranging from 3 D to 20 D. Patients were deemed candidates for implantation of the Implantable Collamer Lens (STAAR Surgical).

Infrared pupillometry was used to measure mesopic and photopic pupil size. The Orbscan II (Bausch + Lomb) was used to measure anterior chamber depth and white-to-white corneal diameter.

Study data showed that the range between mesopic and photopic pupil size was about 1.5 mm.

There was a statistically significant correlation between anterior chamber depth and white-to-white corneal diameter (P < .001). White-to-white corneal diameter and anterior chamber depth correlated with neither age alone (P < .001) nor anterior chamber depth as a function of age (P < .001).

Anterior chamber depth decreased with age, the authors said.

This paper is interesting for the reason that it draws our attention, once again, to the significance of actually measuring photopic and mesopic pupillary size in patients who are being considered for multifocal IOL implantation. Pupil size is frequently an influential factor in the selection of which multifocal to implant. Additionally the study helps us to recognize that the relationship of pupil size under different lighting conditions remains constant with age. This is helpful when considering refractive lens exchange.

Also, although there is corroboration of the correlation between white-to-white and anterior chamber depth, the authors recommend anterior chamber imaging to determine depth and size for the STAAR ICL.

Finally, the negative correlation between anterior chamber depth, white-to-white distance and age is counterintuitive. With age, the crystalline lens diameter increases as more lens epithelial cell fibers are produced. One would expect the anterior chamber depth to decrease with age. This is an essential factor for vault selection for patients undergoing ICL implantation.

– William J. Fishkind, MD, FACS
OSN Cataract Surgery Board Member
Disclosure: Dr. Fishkind has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned.