Relationship among corneal biomechanics, refractive error, and axial length.
OBJECTIVE
To evaluate the relationship between different ocular and corneal biomechanical parameters in emmetropic and ametropic healthy white children.


METHODS
This study included 293 eyes of 293 healthy Spanish children (135 boys and 158 girls), ranging in age from 6 to 17 years. Subjects were divided according to the refractive error: control (emmetropia, 99 children), myopia (100 children), and hyperopia (94 children) groups. In all cases, corneal hysteresis (CH) and corneal resistance factor (CRF) were evaluated with the Ocular Response Analyzer system. Axial length (AL) and mean corneal power were also measured by partial coherence interferometry (IOLMaster), and central corneal thickness (CCT) and anterior chamber depth were measured by anterior segment optical coherence tomography (Visante).


RESULTS
Mean (±SD) CH and CRF were 12.12 (±1.71) and 12.30 (±1.89) mm Hg, respectively. Mean (±SD) CCT was 542.68 (±37.20) μm and mean (±SD) spherical equivalent was +0.14 (±3.41) diopters. A positive correlation was found between CH and CRF (p < 0.001), and both correlated as well with CCT (p < 0.0001). Corneal resistance factor was found to decrease with increasing age (p = 0.01). Lower levels of CH were associated with longer AL and more myopia (p < 0.001 and p = 0.001, respectively). Higher values of CH were associated with increasing hyperopia. Significant differences in CH were found between emmetropic and myopic groups (p < 0.001) and between myopic and hyperopic groups (p = 0.011). There were also significant differences in CRF between emmetropic and myopic groups (p = 0.02). Multiple linear regression analysis showed that lower CH and CRF significantly associated with thinner CCT, longer AL, and flatter corneal curvature.


CONCLUSIONS
The Ocular Response Analyzer corneal biomechanical properties seem to be compromised in myopia from an early age, especially in high myopia.
*PhD †MSc Departments of Optics (IB-G, AG-S) and Surgery (EE-G), University Hospital La Fe (EE-G), University of Valencia, Valencia, Spain; Fundación Oftalmológica del Mediterráneo, Valencia, Spain (AL-A); Foundation for the Visual Quality (Fundación para la Calidad Visual, FUNCAVIS), Alicante, Spain (DPP-L); and Department of Optics, Pharmacology, and Anatomy, University of Alicante, Alicante, Spain (DPP-L).
Inmaculada
I
Bueno-Gimeno
Enrique
E
España-Gregori
Andres
A
Gene-Sampedro
Aitor
A
Lanzagorta-Aresti
David P
DP
Piñero-Llorens
D000293:Adolescent; D000867:Anterior Chamber / Q000033:anatomy & histology; D058452:Axial Length, Eye / Q000473:pathology*; D001696:Biomechanical Phenomena; D002648:Child; D003315:Cornea / Q000502:physiology*; D003430:Cross-Sectional Studies; D004547:Elastic Tissue / Q000502:physiology; D005260:Female; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D012030:Refractive Errors / Q000503:physiopathology*; D012044:Regression Analysis; D041623:Tomography, Optical Coherence; D014792:Visual Acuity / Q000502:physiology