Research suggests that both trial lens fitting and software fitting approaches are effective in temporarily reducing myopia, providing good uncorrected visual acuity (UCVA) and delaying the elongation of axial length for moderate and high myopic adolescents. They note that the two approaches can be combined when fitting orthokeratology (OK) lenses.

In this one-year follow-up study, 100 myopic patients who received vision correction with OK lenses were divided into the trial fitting group and the software fitting group. The team of researchers assessed the UCVA, refractive error, ocular health status and fitting situation of the right eye of each subject at baseline and one week, one month, three months, six months and 12 months of lens wear. They also measured the axial length and corneal endothelium cells (CECs) at baseline and 12 months.

The study found that, compared with baseline measurements, the spherical equivalent refraction, UCVA and central corneal curvature changed significantly after OK lens wear. When comparing these parameters between both groups, the researchers found the differences were insignificant at each time point. The study notes that axial length and CECs did not change significantly during the first year of OK treatment, and the rate of corneal staining between both groups did not change over the treatment period.

While both methods are effective, the researchers note trial fitting helps to check if OK lens wear is acceptable for the patients, and software fitting can improve the fitting efficiency and reduce the training difficulties. However, because the study was limited to patients with low to moderate corneal toricity (i.e., less than 1.50D, with-the-rule), patients who may need more curves or a larger optic zones may do better with a trial fitting approach than software fitting. “Both the two approaches can be combined in OK lens fitting,” the researchers conclude.

Lu D, Gu T, Lin W, et al. Efficacy of trial fitting and software fitting for orthokeratology lens: one-year follow-up study. Eye Contact Lens. July 25, 2018. [Epub ahead of print].