Influence of intraocular pressure in anterior lamina cribrosa depth – a prospective observational study in a healthy Portuguese population

Abstract

PurposeTo investigate the association between anterior lamina cribrosa depth (ALCD) determined with enhanced depth imaging spectral‐domain optical coherence tomography (EDI‐OCT) and IOP in a healthy Portuguese population.MethodsProspective observational study conducted between January and April 2015 of 44 subjects with a irrelevant ophthalmologic history. EDI‐OCT of optic nerve head (ONH) was performed in all participants (2 cross scans: vertical and horizontal). ALCD was defined as the perpendicular distance between the line connecting both edges of Bruch's membrane and the anterior border of the lamina cribrosa, at the maximum depth point. An experienced operator manually segmented ALCD and a mean of the two consecutive blinded measurements was computed. To guarantee observations’ independence, only one eye was considered per subject. Only high‐quality images were accepted. The tenets of the Declaration of Helsinki were followed. Statistical analyses were performed using STATA 13.0.ResultsStudied population included 44 subjects (26 women), with a mean age of 62.9 ± 14.3 years. Mean vertical and horizontal maximum ALCD was 453.3 ± 88 μm and 436.1 ± 78.7 μm, respectively. Neither gender nor age were associated with these ALCD scans (p > 0.05). When controlling for gender, age and spherical equivalent, maximum vertical and horizontal ALCD increased, respectively, by 8.8 μm (95% confidence interval [CI], 0.6–17.0 μm; p = 0.04) and 8.1 μm (95% CI, 0.4–15.7 μm; p = 0.04) per mmHg increase in IOP.ConclusionsOur sample of healthy subjects presented a statistically significant positive linear relation between IOP and ALCD, when controlling for possible confounding factors. Our results may trigger furthers studies to better elucidate the role of IOP in morphological and functional dynamics of the ONH.