Endocrine Regulation of Ocular Growth in Childhood and Adolescence: A Critical Narrative Review of the Growth Hormone–Insulin-like Growth Factor 1 Axis and Related Hormonal Systems

Abstract

The postnatal eye enlarges under tight optical control, coordinating corneal power, lens change and axial elongation so that the retinal image remains focused as the globe grows. Because this process unfolds during the same years in which the somatotropic axis drives somatic growth, it is biologically plausible that growth hormone (GH) and insulin-like growth factor 1 (IGF-1) participate in ocular growth, yet the strength and specificity of that relationship remain contested. This critical narrative review evaluates the evidence linking the developing eye to the GH-IGF-1 axis and to the wider endocrine system in children and adolescents. Literature was identified through structured searching of Europe PMC and the Crossref metadata database, complemented by targeted author and citation searches, with every cited source and Digital Object Identifier verified before inclusion. The review distinguishes three tiers of confidence. The role of IGF-1 in retinal vascular development is well supported: low circulating IGF-1 in preterm infants is mechanistically and clinically associated with arrested retinal vascularisation, providing the clearest example of an endocrine growth factor governing an ocular developmental process. Evidence that ocular tissues are GH-responsive and IGF-1-responsive is moderate, resting largely on anterior-segment, scleral, retinal and choroidal changes observed in acromegaly, on structural findings during paediatric GH replacement, and on the ocular phenotype of hereditary IGF-1 resistance. Evidence that the axis drives physiological axial elongation and myopia is weak and inconsistent: genetic associations at the IGF1 locus are of small effect and not always replicated, mechanistic support derives chiefly from animal and cell models using non-physiological insulin exposure, and clinical correlations between body size and eye size are confounded by shared somatic growth. Thyroid hormone and sex steroids exert defined but incompletely quantified effects on retinal and corneal development. The principal unresolved questions concern whether longitudinal IGF-1 trajectories predict axial growth independently of stature, whether GH therapy alters refraction, and how local and systemic IGF-1 signalling are partitioned within ocular tissues. Prospective, endocrinologically phenotyped cohorts are required before causal claims are justified.