Aim: To investigate the clinical and ophthalmological patterns associated with the onset and rapid progression of myopia in Ukrainian patients across different age groups. Materials and Methods: We analyzed data from 66 patients (132 eyes) with myopia, aged 6 to 17 years. In addition to a comprehensive ophthalmological examination, patients underwent OCT and OCT angiography (OCT-A), endothelial microscopy, assessment of corneal rigidity and scleral stiffness using the Sergienko–Shargorodska method, and a questionnaire survey. Results: Myopia onset occurred most frequently at 9-11 years of age (50% of cases) in the Ukrainian pediatric cohort. Gender did not influence disease onset or the rate of progression. Key clinical factors associated with rapid myopia progression (>1 D/year) included physical inactivity, vitamin deficiency, and parental smoking. Increased corneal rigidity (KER > 4.1) was detected as early as 6-8 years of age (67% of patients), preceding the first clinical peak of disease progression. At 9-11 years of age, rapid progression was associated with corneal endothelial decompensation, grade II–IV trabecular dysgenesis (91%), significant choroidal thinning (<190 μm; 91%), and anterior scleral thinning (TAST3 <500 μm; 79%), all of which may contribute to accelerated axial elongation. OCT-A confirmed ischemia in the peritemporal quadrant, whereas macular perfusion remained stable in most patients (88%). Conclusions: The development of myopia follows a staged pattern, progressing from refractive genesis (corneal and endothelial changes) in younger children to axial genesis (alterations of the scleral capsule) in adolescents aged 15-17 years. The preservation of macular perfusion despite peripheral ischemia suggests the presence of compensatory mechanisms during childhood.