Sclera as the target tissue in progressive myopia.

UNLABELLED

Introduction: The aim of the study was to study the eye corneoscleral shell and connective tissue (CT) system in children with acquired and congenital progressive myopia, and to identify the informative diagnostic criteria of weakened supporting function of the sclera.

MATERIAL AND METHODS

155 children aged 9-17 were examined: 18 had emmetropia or hyperopia, 20--low, 32--moderate and 85--high myopia. 32 children had complicated myopia (CM) due to peripheral retinal degeneration (PRD). Corneal hysteresis (CH), scleral acoustic density (SAD), X-ray vertebral topography, plantography, joint hypermobility, serum cortisol (SC), and autonomic balance were measured.

RESULTS

Corneal hysteresis, mmHg and SAD, rel. units (mean ± SE) were lower if myopia was higher: in low myopia, CH was 13.0 ± 0.3, in moderate myopia, 11.9 ± 0.3#, in high myopia, 10.7 ± 0.3#; SAD was resp. 215.9 ± 5.2, 204.9 ± 3.7# and 192.8 ± 5.8# (#: p < 0.05 with regard to low myopia). The lowest CH (10.3 ± 0.4) and SAD (186.5 ± 7.3) were found in acquired CM. Congenital myopia with PRD showed CH and SAD greater than in acquired CM (p < 0.05). Serum cortisol (nmol/L) in hyperopia was 335.8 ± 40.9 and dropped with higher myopia: in low myopia--290.7 ± 58.6, in moderate--250.9 ± 26.4, in high--243.9 ± 20.5. The lowest SC was found in acquired CM, consistent with CH and SAD. Connective tissue dysplasia progressed with higher myopia: it was found in 76.9% of children with low, 82.4% with moderate, 89.2% with high acquired myopia, and 91.7% with congenital myopia. Biomechanical defects of CT and hormonal imbalance were combined with vegetative nervous system (VNS) imbalance: in high myopia only 20.5% of children were eutonic, 61.5%--sympathicotonic and 17.5% parasympathicotonic.

CONCLUSIONS

School age children with progressive myopia showed biomechanical abnormalities of the corneosclera, along with CT dysplasia, decreased SC and imbalanced VNS, more pronounced in acquired complicated myopia. Our findings contribute to the understanding of myopia pathogenesis and to the diagnostic/prognostic evaluation of myopic children, in particular when deciding whether sclera-strengthening intervention is needed.