Gender differences in corneal thickness values

The aim was to study gender differences in corneal thickness. We analysed the corneal thickness of 100 corneas of 100 healthy subjects (mean age 30.87±7.76 years; range, 19 to 54 years old) with the Orbscan Topography System II (Orbscan, Inc., Salt Lake City, UT. USA). The means of five consecutive measurements of the central and paracentral corneal thickness were obtained. No significant differences in mean corneal thickness between women and men at central (p=0.477), nasal (p=0.247), superonasal (p=0.242), inferonasal (p=0.554), temporal (p=0.538), superotemporal (p=0.524) and inferotemporal (p=0.860) corneal locations were found. In sum, there are no differences in mean central and paracentral corneal thickness values between women and men

Relationship Between Visual Field Sensitivity and Retinal Nerve Fiber Layer Thickness Measured by Scanning Laser Polarimetry and Optical Coherence Tomography in Normal, Ocular Hypertensive and Glaucomatous Eyes

Purpose: To evaluate the correlation between automated achromatic perimetry (AAP) and the output of two retinal nerve fiber layer (RNFL) analysers: scanning laser polarimetry (GDx-VCC) and optical coherence tomography (OCT). Methods: Quantitative RNFL measurements with GDx-VCC and Stratus-OCT were obtained in one eye from 52 healthy subjects, 38 ocular hypertensive (OHT) patients and 94 glaucomatous patients. All patients underwent a complete examination, including AAP using the Swedish interactive threshold algorithm (SITA). The relationship between RNFL measurements and SITA visual field global indices were assessed by means of the following methods: analysis of variance, bivariate Pearson's correlation coefficient, multivariate linear regression techniques and nonlinear regression models, and the coefficient of determination (r2) was calculated. Results: RNFL thickness values were significantly lower in glaucomatous eyes than in healthy and ocular hypertensive eyes for both nerve fiber analysers (P≤0.001), except for the inferior 120° average thickness in GDx-VCC. Linear regression models constructed for GDx-VCC measurements and OCT-derived RNFL thickness with SITA visual field global indices demonstrated that, for the mean deviation, the only predictor in the model was the nerve fiber indicator for GDx-VCC (r2=0.255), and for the pattern standard deviation, the predictors in the model were the nerve fiber indicator for GDx-VCC (r2=0.246) and the maximum thickness in the superior quadrant for Stratus-OCT (r2=0.196). The best curvilinear fit was obtained with the cubic model. Conclusions: Quantitative measurements of RNFL thickness using either GDx-VCC or OCT correlate moderately with visual field global indices in moderate glaucoma patients. We did not find a correlation between visual field global indices and RNFL thickness in early glaucoma patients. Further study is needed to develop new analytical methods that will increase RNFL analyser's sensitivity in early glaucoma patients

Morphometric differences between normal and dry eyes.

The aim of the study was to quantify the anatomic differences in central corneal thickness, anterior ocular chamber depth, lens thickness, vitreous chamber depth, and ocular axial length between normal and dry-eyes. Central corneal thickness (CCT), ocular anterior chamber depth (ACD), lens thickness (LT), vitreous chamber depth (VCD) and ocular axial length (AL) were measured in 70 normal subjects and in 58 subjects with dry-eyes. Central corneal thickness was measured with scanning-slit corneal topography while ocular anterior chamber depth, lens thickness, vitreous chamber depth and ocular axial length were measured with applanation ultrasound biometry. Central corneal thickness was 0.558±0.30 mm and 0.532±0.34 mm in normal and dry-eyes, respectively (p<0.001). Mean ocular anterior chamber depth was 3.17±0.23 mm and 2.93±0.35 mm in normal and dry-eyes, respectively (p=0.002). Lens thickness was 4.49±0.42 mm in the dry-eye patients and 4.71±0.32 mm in the normal subjects (p=0.022). Vitreous chamber depth was 16.75±1.75 mm and 15.54±1.34 mm in normal and dry-eyes, respectively (p=0.001). Ocular axial length was 24.58±1.73 in normal subjects and 23.07±1.48 in dry-eye subjects (p<0.001). We conclude that quantitative ocular anatomy values are lower in dry-eye subject

Corneal endothelial cell density decreases with age in emmetropic eyes

Purpose: To analyze the corneal endothelial cell density in healthy adult emmetropic subjects. Methods: We analyzed the corneal endothelial cell density of a group made up of 225 emmetropic subjects (n=225). As age-matched control groups we analyzed two other groups, one made up of myopic subjects (n=209) and the other made up of hyperopic subjects (n=203). We recorded the mean of three consecutive measurements of the corneal endothelial cell density using the Topcon SP-2000P non-contact specular microscope (Topcon Corp., Tokyo, Japan). Results: The mean age was 38.6±11.8 years, 40.7±12.2 years, and 39.2±10.5 years for emmetropic, myopic and hyperopic subjects respectively (p=0.994). No significant differences (p=0.920) in endothelial cell density values were found between emmetropic (2985±245 cells/mm2), myopic (2936±258 cells/mm2) and hyperopic eyes (2946±253 cells/mm2). Lower corneal endothelial cell density values were found in older emmetropic (p<0.001), myopic (p<0.001), and hyperopic subjects (p<0.001). A significant correlation between endothelial cell density and age was found in emmetropic (r= -0.958; p<0.001), myopic (r= -0.954; p<0.001) and hyperopic subjects (r= -0.948; p<0.001). Conclusions: In healthy emmetropic subjects there is a reduction in corneal endothelial cell density with age although there are no differences in corneal endothelial cell density values between emmetropic, myopic and hyperopic subjects

Quantitative ocular anatomy in vivo: comparison of axial length and anterior chamber depth values obtained by a single observer by means of optical biometry and immersion and applanation ultrasound biometry

The aim of the present work was to analyze and compare axial length and anterior chamber depth values obtained by means of IOLMaster ¿, immersion and applanation ultrasound. Axial length and the anterior chamber depth measurements were carried out by a single observer in 30 volunteers (n=30; mean age, 68±10.7 years of age; range 44 to 83 years) using IOLMaster¿ (Zeiss Humphrey System, CA, USA), immersion and applanation ultrasound biometry. Ultrasound measurements were carried out with the Compuscan A-B Storz (San Louis, MO, USA). The IOLMaster¿ provided axial length measurements that were 0.04 mm (p=0.936) and 0.13 mm (p=0.606) higher than those from immersion and applanation ultrasound respectively. The mean difference between the optical and applanation measurements was -0.11 mm, and -0.03 mm between the optical and immersion measurements. In conclusion, there are no significant differences between IOLMaster¿, immersion and applanation ultrasound axial length and anterior chamber depth values

Quantitative central corneal anatomy and anaesthetic eye drops effects: comparison between 0.4% oxybuprocaine and a combination of 0.1% tetracaine and 0.4% oxybuprocaine.

We aimed to analyse the changes in central corneal thickness values following the instillation of 0.4% oxybuprocaine eye drops and following a combination of 0.1% tetracaine and 0.4% oxybuprocaine eye drops. Orbscan pachymetry (Orbscan II Corneal Topography System; Orbscan, Inc., Salt Lake City, UT, USA) was carried out before and three minutes after the instillation of 0.4% oxybuprocaine eye drops, and before and three minutes after the instillation of a combination of 0.1% tetracaine and 0.4% oxybuprocaine eye drops in 35 healthy subjects (n=35; aged 20-30 years). After the instillation of 0.4% oxybuprocaine eye drops there was a mean increase in central corneal thickness of 25±11 microns. After the combination of 0.1% tetracaine and 0.4% oxybuprocaine eye drops it rose to 48±20 microns. The combination of 0.1% tetracaine and 0.4% oxybuprocaine anaesthetic eye drops causes higher increases in central corneal thickness values than 0.4% oxybuprocaine eye drops

The effect of a combination of 0.1% tetracaine HCl and 0.4% oxybuprocaine HCl on human central cornea thickness measurements.

A combination of 0.1% tetracaine HCl and 0.4% oxybuprocaine HCl is used when carrying out morphometrical corneal studies in vivo by means of ultrasound pachymetry. The aim of this was to determine the effect of a combination of 0.1% tetracaine HCl and 0.4% oxybuprocaine HCl anesthetic eye drops on central corneal thickness values. We carried out a prospective study involving 30 eyes of 30 healthy subjects. The mean age of the subjects was 26.13±2.62 years (age ranged from 20 to 30 years old). Central pachymetry was carried out prior to and three minutes after the instillation of two saline solution eye drops, and three minutes after the administration of a combination of 0.1% tetracaine HCl and 0.4% oxybuprocaine HCl anesthetic eye drops. The mean of three consecutive measurements of the central corneal thickness obtained with the Orbscan Topography System II (Orbscan, Inc., Salt Lake City, UT. USA) was used as the corneal thickness value. No significant differences were found (p=0.714) in the mean central corneal thickness values before and three minutes after saline solution eye drops had been instilled. Nevertheless, after anesthesia there was a significant increase in mean central corneal thickness (p<0.001). Increases ranged from 22 to 131 micrometers, with a mean of approximately 47 micrometers. Following the instillation of a combination of 0.1% tetracaine HCl and 0.4% oxybuprocaine HCl eye drops corneal thickness increase. Researchers must be aware of this effect of topical anesthetic eye drops on corneal morphometry in order to analyze corneal thickness results correctly