The predictive value of parameters of optic disk in evaluating the progression of myopia

Abstract

Aims/Purpose: To analyse the parameters of the optic nerve head (ONH) as markers of the progression of myopia with the usage of optical coherence tomography (OCT).Methods: 72 patients (144 eyes) aged 9–57 years with myopia were investigated. The standard OCT parameters of the ONH, the ovality index (OI), the zone of parapapillary atrophy (PPA), location of the lamina cribrosa (LC) of the sclera and the trunk of the central retinal vessels (CRV) were evaluated. Data was statistically approved.Results: A positive correlation between the axial length (AL) and the optic disc cup area, its horizontal and vertical diameters was found. Whilst the volume and the depth of the optic disc cup increased till the AL reached a certain critical value (26.3 mm) with subsequent reduction. An inverse correlation between the AL and the neuroretinal rim area, volume and rim/disc ratio was revealed. These changes in the ONH can be explained by scleral remodelling during elongation of the eye. Formation of γ‐zone PPA and an increase in the β‐zone PPA was accompanied by the tendency of thinning of the retinal nerve fibre layer (RNFL) in the inferior, nasal‐superior and superior sectors of the ONH. In 27.63% cases tilted optic discs were noted, of which 61.90% were vertically and 38.1% ‐ horizontally tilted. The direction of the tilt was determined by the location of the PPA zone with a tendency to thinning of the RNFL in the same sectors. A positive correlation between the AL of eye and the location of the LC of sclera was found. In 29.17% the superficial location of the LC was determined. In 54.17% elongation was accompanied by displacement of the trunk of the CRV on ONH in the nasal ‐ 71.79%, or in the superior‐nasal direction ‐ 28.21%.Conclusions: The revealed changes of optic disc cup, neuroretinal rim and the parapapillary zones; a superficial displacement of LC of sclera and ‘nasalization’ of the trunk of CRV; a decrease in the OI with growth in the AL; relationships of the PPA zone with a tendency to thinning of the RNFL and direction of the tilt can be useful as OCT markers in interpreting normative data in patients with myopia, predicting its progression, and also in differential diagnosis with glaucomatous optic neuropathy.