Abstract
Purpose :
In vivo measurement of thickness in individual retinal layers provides important information on the relationship between refractive development, eye growth and retinal morphology. In our lab, we previously studied how the overall retinal thickness (RT) changes with age in marmoset eyes. The purpose of this study was to evaluate the change in thickness in individual retinal layers in relation to the change in refractive error (Rx) and vitreous chamber depth (VCD) in marmoset eyes.
Methods :
Twenty-two eyes of 14 marmosets were treated for 10 weeks with negative (-5/-10D) and positive (+5D) soft contact lenses to induce myopia and hyperopia respectively. VCD, cycloplegic Rx and RT were measured using a high frequency A-scan ultrasound, Nidek autorefractor and Bioptigen SD-OCT (12x12mm2, 100B-scans, 1000A-scans/B-scan) respectively at baseline (≈70 days) and end of treatment (≈150 days). VCD measurement and SD-OCT were performed under anesthesia (alfaxan, 1.5mg/kg, im). Automatic thickness segmentation and quantification was performed with the Iowa Reference Algorithms v3.8.0 (Iowa Institute for Biomedical Imaging) and presented in the 9 ETDRS subfields
Results :
At the end of treatment, 14 of the 22 eyes experienced a myopic shift (mean±SD:-2.38±2.43D, -0.19 to -7.71D) while the remaining 8 had a hyperopic shift (mean±SD:-1.15±1.05D, +0.15 to +3.10D). Eyes that experienced myopic shift exhibited a relative overall retinal thinning (-3.13±11.25µm), whiles eyes that experienced hyperopic shift had a relative retinal thickening (0.50±13.24µm; p>0.05). The overall retinal thinning for the eyes that experienced the myopic shift occurred at the temporal, inferior and superior ETDRS areas and correlated with VCD change (R2=0.21, p<0.05). When each retinal layer was evaluated individually, this same correlation was observed in the retinal nerve fiber layer (RNFL: R2=0.24, p<0.05) and ganglion cell layer (GCL: R2=0.19, p<0.05).
Conclusions :
In marmoset eyes with various degrees of lens-induced eye growth, the overall RT decreased with increasing axial growth. These changes appeared due to a thinning of the RNFL and GCL. If the thinning of these layers is confirmed in myopes, RNFL and GCL thickness analysis could represent early retinal changes associated with myopia development and can be used to guide early interventions and help provide answers to clinically relevant questions about the development of degenerative myopia
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.