Published in Research

Could computer-aided orthokeratology fittings surpass standard methods?

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5 min read

New research published in Contact Lens & Anterior Eye compared the effectiveness and safety of computer-aided fitting methods for orthokeratology (ortho-k) compared to traditional lens fitting methods.

What are ortho-k lenses?

Ortho-k lenses are specially designed and fitted contact lenses that temporarily reshape the cornea to improve vision.

The most common condition these lenses are used to correct is myopia.

The lenses are typically worn at night, and while the improvements are reversible, they can be maintained if the lenses are worn regularly as directed.

How are ortho-k lenses fitted?

Traditionally, these lenses are fitted using a sequential process that requires a highly skilled optometrist to utilize a range of lenses by adjusting from the initial diagnostic lens to find the most suitable one for the patient.

What this involves: A large number of trial lenses and prolonged time of fitting.

Which brings us to …

In recent years, a new fitting method that utilizes computer-aided design (CAD) and computer-aided manufacturing (CAM) has emerged.

This method lessens the need for a large quantity of trial lenses and reduces the reliance on experienced optometrists.

Gotcha. Now, talk about this study.

Investigators conducted a multi-center, examiner-masked, randomized controlled trial (RCT) and recruited participants from May to December 2017.

The study was conducted at the following hospitals:

Who was included in the study?

Of the 280 patients enrolled, 215 were included in the analysis.

The participants were comprised of:

  • 109 in the trial group
    • 24.8% male (P < 0.01)
  • 106 in the control group
    • 44.3% male (P < 0.01)
  • For both groups:
    • Individuals with spherical equivalent (SE) ranging from −0.5D to −4.0D

Note: There were no significant differences between the groups regarding nationality, age, or body mass index (BMI).

How was the study conducted?

Researchers used stratified randomization to assign participants to the computer-aided ortho-k fitting group (trial group) or the traditional lens fitting group (control group).

The participants were stratified into three age groups with a minimum of 30 cases in each group:

  • Aged 8 to 13 years
  • Aged 13 to 18 years
  • Aged 18+ years


It was found that:

  • In both groups, compared to baseline data, the uncorrected visual acuity (UCVA) improved significantly, with SE reduced and central corneal curvature flattened greatly after wearing ortho-k lens
    • P < 0.05 for all

Compared to the control group, the trial group exhibited a:

  • Higher successful rate in correcting UCVA (93.6 % vs. 84.0 %, P = 0.03) and slightly better correction in refraction (77.1 % vs. 66.0 %, P = 0.07) at 1-month follow-up

Between the control and trial groups: No significant differences were observed in corneal changes or the incidence of adverse events.


A total of 65 (16.9%) participants—referred to as a “notable proportion”—were excluded from the final analysis, which created an insufficient number of participants.

  • Due to this insufficiency, there was no statistical difference observed in axial length elongation in the trial group compared to the control group.

Additionally, the axial elongation that the investigators observed in both groups was deemed unsatisfactory in children aged 8 to 13 years.

Expert opinion?

The authors noted that, while the computer-aided fitting method for ortho-k improved fitting efficiency and showed slightly better results in UCVA and temporary myopia reduction across age groups compared to traditional lens fitting, they may not offer an advantage over standard methods in all instances.

They stated: “However, it did not demonstrate statistically significant superiority in controlling axial elongation among younger participants (aged 8–13) and then may offer no advantage over traditional OK lenses, indicating the need for further investigation into its benefits in the wider population.”

Take home.

This research concluded that both traditional and computer-aided fitting methods for ortho-k methods are effective in reshaping the cornea to achieve good visual acuity and control myopia progression without significant or irreversible complications.

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