RESUMO
PURPOSE: To quantify and assess the reproducibility of the corneal stromal thickness profiles captured by the SD-OCT. Secondly, we correlated the zonal thicknesses to the age, gender and axial length. METHODS: We included 227 normal eyes of 227 patients with a maximum hypermetropia of +5 and myopia of -6 diopters (D). Subjects with an intraocular pressure exceeding 22 mm Hg, evidence of cataract formation, history of ophthalmic surgery or disease were excluded. Lastly, reproducibility was evaluated in a subset of 50 participants by means of an identical scan protocol repeated by 2 different OCT operators. RESULTS: Stromal values were consistently thicker in the peripheral cornea (p<0.001). Age was negatively correlated with approximately every sector of the stroma with notable exceptions of the center (r=0.117, p=0.088) and the superior inner (r=0.057, 0.409), middle (r=0.086, p=0.209) and outer locations (r=0.120, p=0.079). There was no statistical significance in most sectors when looking at the axial length, gender and K1/K2. This method was highly reproducible in terms of both the ICC and COV. CONCLUSION: Corneal stromal mapping is highly reproducible and shows a negative correlation to age. Additionally, the periphery of the stroma is consistently thicker to the center. Other variables like gender and axial length show no relationship to the corneal stroma.
RESUMO
Purpose To understand the influence of tomographic corneal characteristics on the epithelium of normal eyes. Methods We scanned a total of 98 eyes of 98 individuals using anterior segment tomography and a spectral-domain optical coherence tomography (OCT) epithelial mapping tool. Only eyes with no previous pathology were included, with a refractive range of +5 diopters (D) to -6 D, intraocular pressure of < 22 mmHg, and no evidence of dry eye (Schirmer's test 2 value > 5 mm). Corneal curvature metrics were statistically correlated with regional epithelial thickness parameters. Results The anterior and posterior corneal surface flat and steep axis, the maximum and minimum curvature, corneal topographic astigmatism, astigmatism polar values, and corneal volume had no statistically significant correlation (p>0.05) with the epithelial thickness. Similarly, anterior corneal surface asphericity had no significant correlation. Posterior surface asphericity had a statistically significant moderate correlation with the epithelium in all areas. Similar results were seen in the multivariate analysis. Conclusions None of the front or back surface parameters had any influence on the corneal epithelium except for the posterior surface asphericity. This statistically significant yet clinically insignificant correlation may be enhanced in diseased populations like keratoconus and could indicate epithelial remodeling with early posterior corneal changes.
RESUMO
PURPOSE: To quantify and view the possible influence of demographic variables on normal macular layers. Additionally, we wanted to assess the reproducibility using the Spectralis SD-OCT. METHODS: A Spectralis SD-OCT machine using a commercially available algorithm was used to scan 242 healthy subjects in an outpatient setting. We examined retinal thicknesses in seven layers: retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL) and retinal pigment epithelium (RPE). Combined retinal thicknesses were expressed as inner retinal layer (IRL), photoreceptor layer (PL) and total retinal thickness (TRT). Measurements were taken from each of the nine sectors defined by the Early Treatment Diabetic Retinopathy Study; the center was the fovea, the inner circle (IC) was 1-3 mm away, and the outer circle (OC) was 3-6 mm away. RESULTS: The TRT was thickest inferiorly in the IC, and superiorly in the OC. The RNFL (P=0.030), GCL (P=0.006), IPL (P=0.006), IRL (P=0.030), PL (P<0.001) and TRT (P=0.001) were found to be thicker in males. The GCL (r=0.078, P=0.001), IPL (r=0.079, P=0.001), IRL (r=0.072, P=0.002), PL (r=0.076, P=0.001) and TRT (r=0.090, P<0.001) were found to decrease with age. The INL (r=0.060, P=0.010), ONL (r=0.078, P=0.001), and RPE (r=0.066, P=0.004) were inversely related to axial length. Excellent reproducibility was observed in all layers. CONCLUSION: Our study shows differences in various retinal layers according to age, gender, and axial length. Additionally, we demonstrate excellent reproducibility of this algorithm using the Spectralis SD-OCT.