Differences in choroidal responses to near work between myopic children and young adults.

BACKGROUND: Near work is generally considered as a risk factor for myopia onset and progression. This study aimed to investigate the choroidal responses to a brief-period of near work in children and young adults. METHODS: Thirty myopic medical students (aged 18-28 years) and 30 myopic children (aged 8-12 years) participated in this study. The submacular total choroidal area (TCA), luminal area (LA), stromal area (SA), choroidal vascularity index (CVI) and choriocapillaris flow deficit (CcFD), as well as subfoveal choroidal thickness (SFCT) were measured with swept-source optical coherence tomography/optical coherence tomography angiography (SS-OCT/OCTA) before and immediately after 20 min, 40 min, 60 min of near work at a distance of 33 cm. RESULTS: In adults, 20 min of near work induced a significant reduction in SFCT (- 5.1 ± 6.5 µm), LA [(- 19.2 ± 18.6) × 103 µm2], SA [(- 8.2 ± 12.6) × 103 µm2] and TCA [(- 27.4 ± 24.9) × 103 µm2] (all P < 0.01). After 40 min of near work, LA was still reduced [(- 9.4 ± 18.3) × 103 µm2], accompanied with a decreased CVI (- 0.39% ± 0.70%) and an increased CcFD (0.30% ± 0.78%) (all P < 0.05). After 60 min of near work, CVI was still reduced (- 0.28% ± 0.59%), and CcFD was still increased (0.37% ± 0.75%) (all P < 0.05). In children, 20 min of near work induced a significant increase in CcFD (0.55% ± 0.64%), while 60 min of near work induced increases in SA [(7.2 ± 13.0) × 103 µm2] and TCA [(9.7 ± 25.3) × 103 µm2] and a reduction in CVI (- 0.28% ± 0.72%) (all P < 0.05). Children exhibited lower near work-induced LA and TCA reduction than adults, with a mean difference of - 0.86% and - 0.82%, respectively (all P < 0.05). CONCLUSIONS: The temporal characteristics and magnitude of changes of choroidal vascularity and choriocapillaris perfusion during near work was not identical between children and adults. The initial response to near work was observed in choriocapillaris in children, whereas it was observed in the medium- and large-sized vessels in adults. TRIAL REGISTRATION: Clinical Trial Registry (ChiCTR), ChiCTR2000040205. Registered on 25 November 2020, https://www.chictr.org.cn/bin/project/edit?pid=64501 .

Choroidal vasculature act as predictive biomarkers of long-term ocular elongation in myopic children treated with orthokeratology: a prospective cohort study.

BACKGROUND: Despite receiving orthokeratology (ortho-k), the efficacy of retarding ocular elongation during myopia varies among myopic children. The current study aimed to investigate the early changes of choroidal vasculature at one month after ortho-k treatment and its association with one-year ocular elongation, as well as the role of such choroidal responses in predicting the one-year control efficacy of ortho-k treatment. METHODS: A prospective cohort study was conducted in myopic children treated with ortho-k. Myopic children aged between 8 and 12 years who were willing to wear ortho-k lenses were recruited consecutively from the Eye Hospital of Wenzhou Medical University. Subfoveal choroidal thickness (SFCT), submacular total choroidal luminal area (LA), stromal area (SA), choroidal vascularity index (CVI), choriocapillaris flow deficit (CcFD) were evaluated by optical coherence tomography (OCT) and OCT angiography over a one-year period. RESULTS: Fifty eyes from 50 participants (24 males) who finished one-year follow-ups as scheduled were included, with a mean age of 10.31 ± 1.45 years. The one-year ocular elongation was 0.19 ± 0.17 mm. The LA (0.03 ± 0.07 mm2), SA (0.02 ± 0.05 mm2) increased proportionally after one-month of ortho-k wear (both P < 0.01), as did the SFCT (10.62 ± 19.98 µm, P < 0.001). Multivariable linear regression analyses showed that baseline CVI (ß = - 0.023 mm/1%, 95% CI: - 0.036 to - 0.010), one-month LA change (ß = - 0.009 mm/0.01 mm2, 95% CI: - 0.014 to - 0.003), one-month SFCT change (ß = - 0.035 mm/10 µm, 95% CI: - 0.053 to - 0.017) were independently associated with one-year ocular elongation during ortho-k treatment after adjusting with age and sex (all P < 0.01). The area under the receiver operating characteristic curve of prediction model including baseline CVI, one-month SFCT change, age, and sex achieved 0.872 (95% CI: 0.771 to 0.973) for discriminating children with slow or fast ocular elongation. CONCLUSIONS: Choroidal vasculature is associated with ocular elongation during ortho-k treatment. Ortho-k treatment induces increases in choroidal vascularity and choroidal thickness as early as one month. Such early changes can act as predictive biomarkers of myopia control efficacy over a long term. The utilization of these biomarkers may help clinicians identify children who can benefit from ortho-k treatment, and thus has critical implications for the management strategies towards myopia control.