Assessment of ocular responce analyzer advantages for IOP measurements in children with progressive myopia

Abstract

Abstract Purpose To study IOP in children with progressive myopia and myopic adults 4‐9 years after photorefractive keratectomy (PRK) using ORA (Reichert) and to assess the influence of corneoscleral biomechanics on IOP measurement results. Methods Corneal‐compensated IOP (IOPcc), corneal hysteresis (CH), factor of corneal resistivity (FCR), IOP by Goldman (IOPG), corneal thickness and axial length were measured in 34 children (75 eyes) with low (27 eyes), moderate (31 eyes) and high (17 eyes) progressive myopia and 8 patients (16 eyes) with emmetropia or low hyperopia aged 7‐17, and 17 adults (28 eyes) with moderate and high myopia 6.5±0.2 years after PRK and 8 adults (16 eyes) of the same age (36.6±2.0 years) and myopia degree who had no refractive surgery. Results An insignificant (within the age norm) relative increase of IOPcc has been detected in children with moderate (17.6±0.7 mmHg) and high myopia (17.8±0.8 mmHg) as compared with low myopia (16.4±0.6). Values of IOPcc seem to provide a more exact reflection of the ophthalmic tonus in myopic eyes than IOPG. CH proved to be lower in moderate (10.9±0.3 mmHg) and high myopia (10.7±0.4 mmHg) than in low myopia (11.2±0.3 mmHg) and emmetropia (12.4±0.7 mmHg), while FCR remains practically unchanged. So, CH is related to biomechanical properties of sclera. In the late period after PRK, IOPcc (14.9±0.4 mmHg) and FCR (8.9±0.2 mmHg) are lower than without refractive surgery (resp. 18.4±0.8 and 10.5±0.4 mmHg), while CH shows an identical drop in both cases (resp. 9.4±0.2 and 9.8±0.4 mmHg) compared to norm, which testifies to surgically induced biomechanical changes of the cornea. Conclusion ORA reduces the impact of corneoscleral biomechanical properties on IOP measurements.