Could Children's Myopization Have Been Avoided during the Pandemic Confinement? The Conjunctival Ultraviolet Autofluorescence (CUVAF) Biomarker as an Answer

Abstract

Background: The objective of this study was to evaluate the association of the presence of conjunctival ultraviolet autofluorescence (CUVAF) with the level and progression of myopia and the impact of reduced sunlight exposure during the COVID-19 pandemic confinement (PC).

Methods: A retrospective observational study was carried out using three cohorts, children (9-17 years old), young adults (18-25 years old), and adults (>40 years old) with myopia (≤0.75D) and at least three annual eye examinations (before and after PC). All participants underwent an automatic objective refraction and CUVAF area analysis. All the participants filled out a questionnaire regarding lifestyle and myopia history.

Results: The 298 recruited participants showed that during the PC, children's and young adults' myopia progression rate increased on average by -0.50 and -0.30 D/year, respectively, compared with the pre-pandemic level (p < 0.0001 and p < 0.01). A significantly greater progression was observed in those with low baseline myopia compared to those with moderate or high myopia (p < 0.01). CUVAF shows its protective effect associated with outdoor activity (OA) with regard to the age of onset of myopia and mean diopters (p < 0.01). In fact, although there were no differences in the increase in diopters between children with and without CUVAF during the PC, those who had CUVAF started with lower gains (-0.3 D/year) compared to those who did not (-0.5 D/year; p < 0.05). The myopia treatments (atropine drops, Ortho-K, and MiSight^® contact lenses) showed a reduction effect in myopic progression rate post-PC in comparison with non-treated children (p < 0.0001, p < 0.0001 and p < 0.01, respectively).

Conclusions: The strict restriction of OA during PC led to the rate of myopia progression doubling among children and young adults. This progression occurred mainly in children with previously low myopia, and CUVAF, as a biomarker of OA, reflects its potential to provide benefits in the form of recommended behavioral changes to protect against the development of myopia.

Keywords: COVID-19; CUVAF; confinement; myopia; outdoors.

Figure 1

(A) In vivo demonstration of corneal focusing of peripheral light coming from the temporal side of the eye onto the limbus and nasal conjunctiva with higher light intensity compared to the temporal side. (B) Optical representation of the peripheral light-focusing effect that leads to a concentration of the incoming rays of light, passing through the anterior chamber, onto the contralateral limbo-conjunctival surface of the eye. (C) CUVAF negative (no conjunctival hyperautofluorescent area is seen) in a color photograph taken under UV light (peak wavelength of 365 nm). (D) CUVAF positive (demonstrates an area of hyperautofluorescence in the right nasal interpalpebral region) in a color photograph taken under UV light (peak wavelength of 365 nm). (E) CUVAF negative (no conjunctival hyperautofluorescent area is seen) in a photograph taken using the BAF mode of the Heidelberg Spectralis HRA + OCT (peak wavelength of 488 nm). (F) CUVAF positive (demonstrates a triangular conjunctival hyperautofluorescent area with limbal base and temporal apex) in a photograph taken using the BAF mode of the Heidelberg Spectralis HRA + OCT (peak wavelength of 488 nm). Image courtesy of Gutierrez-Rodriguez et al [6].

Figure 2

Calculation of myopia progression rate pre- and post-PC to obtain the difference in progression rate due to PC.

Figure 3

Association between baseline refractive error and outdoor activities measured by CUVAF (A–C) and questionnaires (D–F). (A,D): Children aged 6–17 years. (B,E): Young adults aged 18–25 years. (C,F): Association between age of myopia diagnosis and outdoor activity measured by CUVAF and questionnaires. C: CUVAF (conjunctival ultraviolet autofluorescence). h/OA: hours spent doing outdoor activity (weekly). DX: age of myopia diagnosis. Significance p < 0.05. * p < 0.05, ** p < 0.01.

Figure 4

Rate of myopia progression (diopters/year) pre- and post-PC. (A): Children aged 6–17 years. (B): Young adults aged 18–25 years. (C): Middle-aged adults >40 years. PC: pandemic confinement. Significance p < 0.05. ** p < 0.01, **** p < 0.0001.

Figure 5

(A,B): Comparison of the difference in the rate of myopia progression after PC regarding the presence or absence of CUVAF. (A): Children aged 6–17 years. (B): Young adults aged 18–25 years. (C,D): Comparison of the myopia progression rate (D/year) in pre- and post-PC in relation to the presence of CUVAF. (C): children aged 6–17 years. (D): young adults aged 18–25 years. C: CUVAF (conjunctival ultraviolet autofluorescence). PC: pandemic confinement. Significance p < 0.05. * p < 0.05, ** p < 0.01, **** p < 0.0001.

Figure 6

Myopia progression rate (D/year) after COVID-19 confinement regarding myopia classification and outdoor activity (measured by CUVAF) in children. (A): Difference in myopia progression rate after PC in M1, M2, and HM groups. (B): Myopia progression rate pre- and post-PC among M1, M2, and HM groups. (C): Percentages of CUVAF (+) and CUVAF (-) children in M1, M2, and HM. (D): Difference in myopia progression rate after PC among M1, M2, and HM groups and the presence of CUVAF. C: CUVAF (conjunctival ultraviolet autofluorescence). PC: pandemic confinement. Significance p < 0.05. * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001, ns; non-significant.

Figure 7

Differences in myopia progression rates after COVID-19 confinement regarding different types of myopia treatments in children. Atropine drops; MiSight^®, and Ortho-K contact lenses. Significance p < 0.05. ** p < 0.01, *** p < 0.001, **** p < 0.0001.