Sagittal Height Simulation Software Shows Promise For Orthokeratology Lens Fitting

Optometrist inserting contact lens into girl's eye
Credit: Getty Images
Clinicians may eventually be able to achieve trial-free fitting of orthokeratology lenses using a novel sagittal height fitting algorithm, according to a report.

A sagittal height simulation software can determine the alignment curve (AC) value of orthokeratology contact lenses, according to a study published in Eye & Contact Lens. 

Investigators included 103 eyes of 103 pediatric patients (57 boys, 46 girls, mean age 10.6±2.0 years) with myopia in the randomized control study. Patients with amblyopia, keratoconus, glaucoma, or prior history of ocular trauma were excluded from the analysis. 

Researchers separated participants into 2 groups. They calculated the AC radius of group 1 via the novel fitting algorithm, and determined the AC radius of group 2 using flat K readings and eccentricity values. Investigators recorded the number of lens trials per patient and determined the consistency of AC radius between the initial and final trial lenses using Pearson Correlation and Bland-Altman plots. 

The researchers found that the number of trials for groups 1 and 2 were 1.2±0.4 and 1.4±0.5, respectively, indicating a statistically significant difference between the 2 groups (t =2.404, P =.018). The difference in AC value between the initial and final lenses for groups 1 and 2 was 0.000±0.020 mm and 0.003±0.028 mm, respectively, with no statistically significant difference noted between the 2 methods (t =0.748, P =.456). 

Investigators look to continue advancing this novel technology. “Next, we will add eyelid traction and surface tension asymmetry correction modules into the software, and further evaluate whether the simulation software can be used to achieve the trial-free fitting of the orthokeratology contact lens.” 

Study limitations include a single center design, ethnic homogeneity among participants, and the use of only 1 brand of orthokeratology lens. 


Yi Z, Jing S, Wenhua W, Qian L, Ningli W. Evaluation of orthokeratology lens fitting assisted by sagittal height simulation software. Eye Cont Lens. 2022;48(2):78-82 doi:10.1097/ICL.0000000000000861