Correlation between pigmented arc and epithelial thickness (COPE) study in orthokeratology-treated patients using OCT measurements

Abstract

Purpose To determine the intensity of corneal pigmented arc in orthokeratology (ortho-k)-treated children, and its correlation with key epithelial thickness measurements obtained by anterior segment optical coherence tomography (AS-OCT). Methods This study is a retrospective case series. Medical records of children who received ortho-k treatment for myopia control in our hospital were reviewed. Intensity of ortho-k-associated pigmented arc and its correlation with key epithelial thickness parameters in the central 7-mm-diameter zone obtained by AS-OCT was examined. The subjects were further divided into apparent and unapparent pigmented arc groups for severity comparison. ResultsThe mean age of children was 11.4 years, and the incidence of corneal pigmented arc was 92.2% after lens wear for a mean duration of 21.2 months. Intensity of pigmented arc was found to be significantly correlated with key epithelial thickness parameters, including maximum and minimum epithelial thickness (Spearman's rank correlation coefficient (rs) = 0.404, P = 0.003; rs = − 0.426, P = 0.002, respectively), the difference between them (Min-Max) (rs = −0.624, P < 0.001) and standard deviation (rs = 0.659, P < 0.001). Significant correlation between intensity of pigmented arc and ortho-k target power (rs = 0.454, P = 0.001) was found. Comparison between the two groups showed significant difference in the same key epithelial thickness parameters. Conclusions Children receiving ortho-k treatment tended to develop pigmented arcs. Significant correlation between intensity of pigmented arc and key epithelial thickness parameters was observed. AS-OCT can be a useful tool for predicting intensity of pigmented arc in ortho-k-treated children.

Efficacy of Myopia Control and Distribution of Corneal Epithelial Thickness in Children Treated with Orthokeratology Assessed Using Optical Coherence Tomography

“…It has been shown that regular overnight wearing of ortho-k lenses elicits central corneal flattening and midperipheral steepening [1,13,14]. Kim et al demonstrated a consistent result obtained with the 6 mm-diameter ETM generated by the same model of spectral-domain OCT, showing that the mean changes in the CET of the central (2 mm in diameter), paracentral (2-5 mm annular ring), and midperipheral (5-6 mm annular ring) areas were −8.4, −1.4, and +2.7 µm, respectively [5].…”

“…With the development of anterior segment optical coherence tomography (AS-OCT), a noncontact technique for high-resolution cross-sectional imaging, we can accurately measure the epithelial changes in corneal tissues [13,14]. The newly available wide-field pachymetry scan pattern of the spectral-domain optical coherence tomography (SD-OCT) device (RTVue-XR Avanti, Optovue Inc., Fremont, CA, USA) has the ability to determine three-dimensional corneal epithelial structures of up to 9 mm-diameter and generate a wide epithelial thickness map (ETM) [13].…”

BCLA CLEAR - Orthokeratology

“…Pigmented corneal arcs or rings are increasingly reported in ortho-k lens wearers [100][101][102][103][104][105][106][107][108][109]. Although the composition of the pigmentation has not been confirmed, due to similarities in clinical appearance with other corneal iron depositions, it is presumed that the pigmented arc or ring is comprised of iron [102,105,106,110]. The pigmented arc typically originates in the inferior cornea, presumably in the epithelial layer, and has been observed as early as two weeks after commencing ortho-k [110].…”

“…any time of the day • Early morning aftercare every 6 months recommended (to assess ocular health, including corneal oedema) • Unscheduled aftercare: in case of unexpected symptoms Aftercare procedures [25,165] • Careful review of lens wear and care procedures (identify non-compliant behaviours); remind and re-educate where necessary • Regular aftercare procedures include measurements of: ○ Unaided visual acuity ○ Refraction/Over-refraction ○ Ocular health ○ Corneal topography ○ Lens condition ○ Axial length (to monitor effectiveness of myopia control therapy) (if available) • Particular attention to lens binding, corneal oedema, and corneal epithelial integrity at the 1 st aftercare Accessories • Use simple design (non-ridged wells), easy to clean lens cases [183,205] • Rinse lens case with saline or multipurpose solution and wipe with paper towel daily [205][206][207]; air-dry lens cases facing downward [207,208] • Avoid storing cases in bathroom and humid places [163,183,208] • Replace monthly [163,183] series of Taiwanese children wearing ortho-k lenses for an average period of almost two years [105,106].…”

Influence of Orthokeratology Lenses on the Structure of the Eye

“…было выявлено, что пигментная дуга встречается в 92,2 % случаев у детей школьного возраста, которые применяют ортокератологические линзы в среднем около 21,2 месяца. При этом интенсивность пигментации в значительной степени коррелировала с рефракцией линзы и с толщиной эпителия в 7-мм зоне [36].…”