Optimizing the vault of collagen copolymer phakic intraocular lenses in eyes with keratoconus and myopia: Comparison of 2 methods

PURPOSE: To compare 2 methods for optimizing the final central vault of a collagen copolymer posterior chamber phakic intraocular lens (pIOL) (Visian Implantable Col lamer Lens) in eyes with keratoconus and myopia. SETTING: Private practice, Beverly Hills, California, USA. DESIGN: Comparative interventional study. METHODS: The length of the pIOL to implant in keratoconic eyes with myopia was selected based on the white-to-white (WTW) distance or the sulcus-to-sulcus (STS) distance using the pIOL manufacturer's protocol. The final central vault distance was compared a minimum of 3 months postoperatively. RESULTS: The pIOL length was based on WTW measurements in 8 eyes of 6 patients and on STS measurements in 8 eyes of 5 patients. There was no significant difference between the 2 groups in the mean preoperative WTW distance, STS distance, or manifest refraction spherical equivalent (MRSE) (P = .22, P = .37, and P = 1.00, respectively). The mean postoperative vault was 1.03 corneal thickness +/- 0.72 (SD) in the WTW group and 1.18 +/- 0.35 corneal thickness in the STS group (P = .61). The vault distance was less than 1.0 corneal thickness in 3 eyes (37.5%) in the WTW group and 1 eye (12.5%) in the STS group. A small postoperative vault was associated with a high preoperative MRSE (P = .03). CONCLUSIONS: The WTW and STS methods both provided adequate final central pIOL vault in keratoconic eyes with myopia. The STS calculations gave greater final vault and higher vault predictability, although the difference between the 2 methods was not statistically significant.