How well does orthokeratology work over long periods of time?

Paper title: Efficacy, predictability and safety of long-term orthokeratology: An 18-year follow-up study

Authors: Joan Gispets (1), Pilar Yébana (1), Núria Lupón (1), Genis Cardona (1), Joan Pérez-Corral (1),

Jaume Pauné (2), Bernat Cortilla (3)

1. Department of Optics and Optometry, Universitat Politècnica de Catalunya, Violinista Vellsolà, 37, E08222 Terrassa, Spain
2. Paunevision, Contactología Avanzada, Spain
3. Centre de la Visió, Spain

Date: Nov 2021

Reference: Gispets J, Yébana P, Lupón N, Cardona G, Pérez-Corral J, Pauné J, Cortilla B. Efficacy, predictability and safety of long-term orthokeratology: An 18-year follow-up study. Cont Lens Anterior Eye. 2022 Feb;45(1):10153 [Link to open access paper]

Corneal staining has been found to be a common adverse response with orthokeratology,^1-7 with some studies finding associations with higher myopic powers⁴ and younger children.⁵

This prospective, observational study investigated the long-term safety, efficacy, and refractive correction predictability of orthokeratology for adults and children and the association between adverse effects and parameters such as refractive error and corneal topography.

Data on 300 orthokeratology wearers (34% of which were children) was gathered from across 3 optometric centres in Barcelona between 1997 and 2015. Information on demographics, refraction and visual acuity, adverse effects and anterior segment parameters was examined.

Predictability of refractive change was defined in terms of spherical refraction values within 0.50D or less of the target refraction of emmetropia (myopia control effects were not considered). Efficacy was defined as the ratio of post-ortho-k uncorrected distance visual acuity and pre-ortho-k distance corrected visual acuity.

The age range of the case histories was from 7 to 53yrs old, with 34% of the patients being under 17yrs when ortho-k treatment was started. The treatment period was a mean of 37 months with most patients using their lenses on a nightly basis.

For adults and children who wore ortho-k lenses for at least a year, the predictable visual outcomes were 95.9% and 88.7%, respectively. The efficacy for adults was 1.01 and for children 0.98. More children were complication-free (65.7%) compared to adults (55.4%). One single event of microbial keratitis occurred only in an adult, which equated to 6.8 cases per 10,000 patient-years.

Approximately one-third of the ocular complications had occurred within the first month of treatment and another third occurred between the 13^th and 217^th month. At the 1-year mark, complications were slightly more frequent in children (35%) than in adults (29%).

Corneal staining was the most common ocular finding, with a higher incidence for adults, higher myopia, higher corneal eccentricity, and smaller corneal horizontal radius.

The authors found that orthokeratology had good predictability and efficacy and a low incidence of serious ocular events for both children and adults. This makes it a safe, long-term option for correcting and managing myopia.

Corneal staining was found frequently (73% of the ocular complication episodes found) for these wearers

• Of these corneal staining events, the central corneal region was the most affected for 78% of children and 65% of adults
• The staining was more frequent for adults and patients who were required to add a protein removal step into their cleaning procedure. It was also more common for those with higher myopia, higher corneal eccentricity, and smaller corneal horizontal radius

This provides an insight into possible staining causes for ortho-k wearers. It is also an opportunity for eye care practitioners to periodically remind patients of the importance of lens care, particularly if the incidence of complications starts to increase for children at the 1-year stage of treatment.

This study collected data from case histories over an 18-yr period which likely encompassed evolving practices, cleaning regimes and lens designs. These may be less relevant to current ortho-K fitting and management approaches. Future studies using a prospective, longitudinal design could avoid these potential inconsistencies.

Title: Efficacy, predictability and safety of long-term orthokeratology: An 18-year follow-up study

Authors: Joan Gispets, Pilar Yébana, Núria Lupón, Genis Cardona, Joan Pérez-Corral, Jaume Pauné, Bernat Cortilla

Purpose: To determine the efficacy, predictability and safety of long-term orthokeratology in children and adults.

Methods: Case histories of 300 orthokeratology patients (596 eyes; 34.3% children; 65.7% adults) were reviewed to collect information on demographics, corneal and refractive parameters, visual acuity, residual refraction and adverse effects. Predictability was defined as the percentage of eyes with absolute values of spherical equivalent refraction ≤ 0.5 D of emmetropia, and efficacy as the ratio of post-orthokeratology uncorrected and pre-orthokeratology corrected distance visual acuity.

Results: Median duration of treatment was 37 and 28.5 months in children and adults, respectively (p = 0.022). During the first year, 17.2% of children and 33% of adults ceased lens wear (p < 0.001). For children and adults with a successful ortho-k treatment of at least one year of duration, 88.7% and 95.9% of eyes had a predictable refractive outcome, and efficacy was 0.98 and 1.01, respectively. A larger percentage of children (65.7%) were free of complications than of adults (55.4%) (p = 0.015). One event of microbial keratitis occurred in adults (6.8 cases per 10,000 patient-years) and none in children. Corneal staining was the most frequent complication, with a higher incidence in adults (p = 0.007) and in higher myopia (p < 0.001), higher anterior corneal eccentricity (p = 0.019) and smaller anterior horizontal radius (p = 0.027).

Conclusions: Orthokeratology is a safe and predictable long-term procedure in children and adults, with a low incidence of serious adverse effects. Corneal staining episodes are relatively frequent throughout the course of the treatment, thus highlighting the relevance of education of experienced users.

[Link to open access paper]