Correcting progressive myopia with bifocal contact lenses with central zone for distant vision: changes in accommodation and axial length (a preliminary report).

PURPOSE

To assess the state of accommodation and the dynamics of changes of ocular axial length in patients with progressive myopia who use bifocal soft contact lenses (BFSCLs).

MATERIAL AND METHODS

The main and control groups consisted of 50 children (100 eyes) each. Patients of the main group used BFSCLs with distance-oriented central zone and added power of 4 D on the periphery. Patients of the control group were corrected with spherical soft contact lenses (SSCLs). Baseline measurements included amplitude of accommodation (AA), positive relative accommodation (PRA) and the length of anterior-posterior axis of the eye. All patients were examined before wearing SCLs and every 3 months during the entire period of observation lasting 9 to 12 months.

RESULTS

Correction of myopia with contact lenses is accompanied by the increase of AA and RPA. The users of BFSCLs with distance-oriented central zone and added power of 4 D on the periphery, which induces myopic peripheral defocus, had their accommodative function normalize much faster than the patients wearing SSCLs. The average increase in the ocular axial length in the BFSCLs group appeared to be significantly smaller than in the SSCLs group (0.11 and 0.58 D, respectively), which can be attributed to the simultaneous formation of the central focus and induced peripheral myopic defocus.