Orthokeratology and the choroid

The choroid is a multifunctional,highly vascular,and dynamic tissue which contributes to ocular homeostasis and the regulation of eye growth in both animals and humans.Although challenging to reliably measure,recent advances in ocular imaging(particularly optical coherence tomography)has expanded the current understanding of the role of the choroid in ageing and refractive error development during childhood.This commentary considers recent advances in the field,particularly the impact of orthokeratology on choroidal thickness and contour in myopic children,and the potential use of choroidal metrics as a biomarker for future eye growth.

Modelling ocular ageing in adults with well-controlled type I diabetes

Purpose:To develop a paraxial eye model based on a previously collected cohort of adults with well-controlled type 1 diabetes mellitus(DM1)and a limited range of refractive errors.Methods:The study used the previously published biometric data of 72 participants(Age:41.5
12.4 years)with DM1.Measurements included objective refraction,anterior and posterior corneal radii of curvatures,and internal distances.Moreover,phakometry was used to determine the lens radii of curvature and lens equivalent indices,from which the lens powers were calculated.A multivariate linear regression was performed for each biometric parameter with respect to current age(Age),the time since the onset of diabetes(Tdb),and current levels of glycated hemoglobin(HbA1c).The vitreous chamber depth was determined from other distances,and lens equivalent index was chosen to balance the models.These were compared with an existing model for nondiabetic eyes.Results:Some dependent parameters were not affected by the independent variables(spherical equivalent,anterior corneal radius of curvature,central corneal thickness),some were affected by time since onset(the lens radii of curvatures,anterior chamber depth)and others were affected by both age and time since onset(posterior corneal radius of curvature,lens thickness,axial length).None of the dependent parameters were affected by current levels of HbA1c.Conclusions:The proposed model accurately describes the age-related changes in the eyes of people with DM1.In this description the age of diabetes onset plays an important role,especially if the diabetes onset occurred during childhood.