title: Optical Defocus Rapidly Changes Choroidal Thickness in Schoolchildren.
abstract: The current study aimed to examine the short-term choroidal response to optical defocus in schoolchildren. Myopic schoolchildren aged 8-16 were randomly allocated to control group (CG), myopic defocus group (MDG) and hyperopic defocus group (HDG) (n = 17 per group). Children in MDG and HDG received additional +3D and -3D lenses, respectively, to their full corrections on the right eyes. Full correction was given to their left eyes, and on both eyes in the CG. Axial length (AXL) and subfoveal choroidal thickness (SFChT) were then measured by spectral domain optical coherence tomography. Children wore their group-specific correction for 2 hours after which any existing optical defocus was removed, and subjects wore full corrections for another 2 hours. Both the AXL and SFChT were recorded hourly for 4 hours. The mean refraction of all subjects was -3.41 ± 0.37D (± SEM). SFChT thinned when exposed to hyperopic defocus for 2 hours but less thinning was observed in response to myopic defocus compared to the control group (p < 0.05, two-way ANOVA). Removal of optical defocus significantly decreased SFChT in the MDG and significantly increased SFChT in the HDG after 1 and 2 hours (mean percentage change at 2-hour; control vs. hyperopic defocus vs. myopic defocus; -0.33 ± 0.59% vs. 3.04 ± 0.60% vs. -1.34 ± 0.74%, p < 0.01). Our results showed short-term exposure to myopic defocus induced relative choroidal thickening while hyperopic defocus led to choroidal thinning in children. This rapid and reversible choroidal response may be an important clinical parameter in gauging retinal response to optical defocus in human myopia.
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, PR China.|Laboratory of Experimental Optometry, Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hong Kong, PR China.|Hainan Eye Hospital, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Haikou, PR China.
authors.forename: Danyang
authors.initials: D
authors.lastname: Wang
authors.affiliation: Laboratory of Experimental Optometry, Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hong Kong, PR China.
authors.forename: Rachel Ka Man
authors.initials: RK
authors.lastname: Chun
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, PR China.
authors.forename: Manli
authors.initials: M
authors.lastname: Liu
authors.affiliation: Laboratory of Experimental Optometry, Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hong Kong, PR China.
authors.forename: Roger Pak Kin
authors.initials: RP
authors.lastname: Lee
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, PR China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, PR China.
authors.forename: Ting
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Laboratory of Experimental Optometry, Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hong Kong, PR China.
authors.forename: Chuen
authors.initials: C
authors.lastname: Lam
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, PR China.|Laboratory of Experimental Optometry, Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hong Kong, PR China.
authors.forename: Quan
authors.initials: Q
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, PR China.|Laboratory of Experimental Optometry, Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hong Kong, PR China.
authors.forename: Chi Ho
authors.initials: CH
authors.lastname: To
mesh_terms: D000293:Adolescent; D002648:Child; D002829:Choroid / Q000000981:diagnostic imaging / Q000473:pathology*; D005139:Eyeglasses; D006801:Humans; D009216:Myopia / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D041623:Tomography, Optical Coherence