Implantable contact lens for moderate to high myopia: relationship of vaulting to cataract formation

Abstract

Purpose: To study cataract formation in eyes with an implantable contact lens (ICL) used for moderate to high myopia.

Setting: University Eye Hospital, Lausanne, Switzerland.

Methods: An ICL (model V3 or V4, Staar Surgical AG) was implanted in 75 eyes. Three months after surgery and again at the last follow-up examination, the transparency of the crystalline lens was assessed on transilluminated photographs and the vaulting of the ICL over the crystalline lens was evaluated. Central vaulting was measured precisely on digitized photographs taken with a 75 SL Zeiss slitlamp camera, while peripheral vaulting was estimated on photographs obtained with a Scheimpflug camera. The minimum follow-up was 12 months; the mean was 21.8 months.

Results: At the last follow-up, 20 of the 75 eyes (27%) had an ICL-induced anterior subcapsular cataract (ASCC). The number of cataracts increased with the duration of the follow-up. Cataracts developed more commonly in older patients than in younger patients. All 20 cataracts occurred when the central vaulting was equal to or less than 0.09 mm. In 26 eyes with the same range of vaulting (among which 11 had no vaulting), the lenses were clear at the last visit. The 20 patients with cataract and the 26 patients with clear lenses matched in age and duration of follow-up but not in myopia. No touch between the ICL and the crystalline lens was encountered when the central vaulting was equal to or greater than 0.15 mm. Vaulting showed a slight decrease over time. No statistically significant difference in vaulting was found between models V3 and V4.

Conclusion: Central and/or peripheral contact between the ICL and the crystalline lens may be responsible for the high incidence of ASCC formation in this study. Central vaulting greater than 0.09 mm appears to protect the crystalline lens from cataract formation. However, we recommend aiming for higher central vaulting (0.15 mm) to avoid contact between the ICL and the crystalline lens. This should be attainable by implanting longer ICLs.