Banu Oncel

Diurnal variation of the tear osmolarity in normal subjects measured by a new microchip system

Purpose To show the diurnal variation of tear osmolarity in normal subjects. Methods Thirty volunteers were recruited. Tear osmolarity was measured with TearLab osmolarity system at 3-hour regular intervals between 8:00 AM and 5:00 PM. One-way analysis of variance test was used for statistical analysis. Results Thirty healthy volunteers (all men) with a mean age of 29.6±4.3 years (range 18-45) were recruited. The difference between measurements at 8:00 AM and 11:00 AM, 8:00 AM and 2:00 PM, 8:00 AM and 5:00 PM, 11:00 AM and 2:00 PM, 11:00 AM and 5:00 PM, and 2:00 PM and 5:00 PM were not statistically significant (one-way analysis of variance test, p>0.05). Conclusions In normal subjects, tear osmolarity seems to have a stable profile during the daytime.

Assessment and comparison of anterior chamber dimensions using various imaging techniques.

BACKGROUND AND OBJECTIVE To assess and compare the horizontal dimensions of the anterior chamber by different anterior segment imaging techniques. PATIENTS AND METHODS Eighty eyes of 40 patients without any ocular disease or previous ocular surgery were recruited and three consecutive measurements of internal anterior chamber diameter and white-to-white distance (WTW) parameters were determined. RESULTS Mean internal anterior chamber diameter was 11.80 +/- 0.39, 11.56 +/- 0.47, and 11.61 +/- 0.58 mm with Visante-OCT, SL-OCT, and Pentacam, respectively. Mean WTW distance was 11.87 +/- 0.35 and 11.65 +/- 0.32 mm by IOLMaster and OrbscanIIz, respectively. There was no significant difference between Visante-OCT and Pentacam, IOLMaster, and OrbscanIIz (P = .125, .918, and .314). However, detection of mean internal anterior chamber diameter was significantly greater by Visante-OCT than SL-OCT (P = .026). All devices displayed a high intrasession repeatability (repeated measured ANOVA, P > .05). CONCLUSION Internal anterior chamber diameter measurements using Visante-OCT, SL-OCT, and Pentacam, and WTW measurements using IOLMaster and OrbscanIIz were easy to handle and demonstrated good repeatability. Although similar results of horizontal anterior chamber diameter were determined by Visante-OCT, Pentacam, IOLMaster, and OrbscanIIz, the inter-device differences should be considered during clinical practice.

Tear osmolarity in unilateral pseudoexfoliation syndrome.

Purpose:  The aim was to evaluate tear osmolarity of patients with clinically unilateral pseudoexfoliation (PEX) syndrome and to compare the values with otherwise normal subjects.

Comparison of non-contact methods for the measurement of central corneal thickness

BACKGROUND AND OBJECTIVE This study examined the repeatability of and agreements between central corneal thickness measurements obtained by four different non-contact pachymetry devices. PATIENTS AND METHODS Seventy-eight eyes of 39 subjects were included. Central corneal thickness of each eye was measured by Visante optical coherence tomography (OCT) (Carl Zeiss Meditec Inc., Dublin, CA), Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany), Orbscan IIz topography (Bausch & Lomb Surgical Inc., San Dimas, CA), and slit-lamp OCT (SL-OCT) (Heidelberg Engineering GmbH, Heidelberg, Germany). Inter-device agreements and correlations and repeatability of each device were examined. RESULTS All measurement methods correlated well with each other with a correlation coefficient greater than 0.90 and P value of less than .001 for all comparisons. However, Pentacam overestimated central corneal thickness: 546.7 ± 38.2, 535.5 ± 42.7, 531.7 ± 37.6, and 531.2 ± 36.0 μm for Pentacam, Orbscan IIz, Visante OCT, and SL-OCT, respectively (P < .001 for all comparisons versus Pentacam). Despite good correlation, magnitude of differences was high and this bias was proportional (ie, not constant across a range of corneal thickness values) for the following pairs: Orbscan versus Visante OCT, Orbscan versus SL-OCT, and Orbscan versus Pentacam (P < .001 for all comparisons). CONCLUSION Although measurements obtained by various non-contact methods correlate well, numerical agreement of the results may not be sufficient for their interchangeable use in clinical practice.