Effects of high-intensity light on early lens-induced myopia in chicks: optical coherence tomography assessment

To evaluate the impact of high-intensity light on ocular length and structural thickness in chick model of the early lens-induced myopia (LIM) by optical coherence tomography (OCT).

Four-day-old chicks were monocularly covered with −10 D lenses for a period of 2d, exposed to either high-intensity light (HL, 10000 lx) or normal-intensity light (NL, 500 lx) for 12h per day. A two-dimensional visualized swept-source OCT system was used to measure anterior chamber depth (ACD), lens thickness, vitreous chamber depth, axial length, retinal thickness and choroidal thickness. The refractive error was measured with retinoscopy.

After 2d of treatment, the LIM eyes under NL condition experienced a greater myopic shift (P=0.028) and greater axial elongation (P=0.033) than those exposed to HL. ACD significantly increased in LIM eyes under NL condition when compared with baseline, while no statistical difference of ACD was found between day 2 and day 0 in LIM eyes under HL condition. LIM eyes all experienced the thinning of retinal thickness and choroidal thickness (all P<0.05), with no statistically significant differences between NL and HL group.

HL could reduce the development of LIM at an early stage. Under NL, hyperopic defocus appears to induce a deepening of ACD at the early stage; this effect could potentially be mitigated by HL. At an early stage, HL may have no significant effects on the changes in retinal and choroidal thickness in LIM eyes.