Central corneal thickness in patients with meibomian gland dysfunctiona

Does Dry Eye Affect Repeatability of Corneal Topography Measurements?

Objectives:

The purpose of this study was to assess the repeatability of corneal topography measurements in dry eye patients and healthy controls.

Materials and Methods:

Participants underwent consecutive corneal topography measurements (Sirius; Costruzione Strumenti Oftalmici, Florence, Italy). Two images with acquisition quality higher than 90% were accepted. The following parameters were evaluated: minimum and central corneal thickness, aqueous depth, apex curvature, anterior chamber volume, horizontal anterior chamber diameter, iridocorneal angle, cornea volume, and average simulated keratometry. Repeatability was assessed by calculating intra-class correlation coefficient.

Results:

Thirty-three patients with dry eye syndrome and 40 healthy controls were enrolled to the study. The groups were similar in terms of age (39 [18-65] vs. 30.5 [18-65] years, p=0.198) and gender (M/F: 4/29 vs. 8/32, p=0.366). Intra-class correlation coefficients among all topography parameters within both groups showed excellent repeatability (>0.90).

Conclusion:

The anterior segment measurements provided by the Sirius corneal topography system were highly repeatable for dry eye patients and are sufficiently reliable for clinical practice and research.

Differences in Central Corneal Thickness between Spectral Domain-Optical Coherence Tomography and Ultrasound Pachymetry in Patients with Dry Eye Disease

Purpose. To compare central corneal thickness (CCT) values via Spectral Domain-Optical Coherence Tomography (SD-OCT) and ultrasonic pachymetry in patients with severe dry eye disease (DED) to determine the level of agreement between these 2 methods. Methods. The paired samples t-test was used to compare CCT values in severe DED patients. Matching analysis between methods was performed using intraclass correlation coefficient (ICC). Intrasession reliability of the measurement methods was calculated via the concordance correlation coefficient (CCC), variation equivalent, and Pearson's correlation coefficient. The Bland-Altman procedure was used to graphically represent the differences between CCT values. Results. The study included 56 eyes of 24 female and 4 male patients. Mean age of the patients was 50.9 ± 11.3 years. Mean CCT via Cirrus SD-OCT was 523.82 ± 30.98 μm versus 530.050 ± 31.85 μm via ultrasonic pachymetry (paired samples t-test, P < 0.001). The Bland-Altman plot showed good agreement between the examiners. The ICC for repeatability was 0.974. The CCC between the 2 methods' CCT values was 0.973. The variation equivalent was 0.976 and Pearson's correlation coefficient was 99.3%, which also indicated high correlation between the 2 methods' measurements. Conclusions. The present findings show that in patients with severe DED Cirrus SD-OCT provides reliable intraobserver CCT values.

Reduced central corneal thickness in patients with isotretinoin treatment

CONTEXT

It is well known that oral isotretinoin treatment causes numerous ocular side-effects.

OBJECTIVE

To investigate the effect of systemic isotretinoin treatment on central corneal thickness (CCT) values due to meibomian gland disease (MGD).

PARTICIPANTS

In this prospective study, 47 patients (27 men, 20 women) with nodulocystic acne vulgaris treated with oral isotretinoin (0.8 mg/kg daily) were included.

METHODS

All patients were analyzed with the Pentacam Scheimpflug topography at baseline, on the 3rd and 6th month of treatment. Main outcome measures were MGD scores and CCT.

RESULTS

The mean age of patients was 25.1 ± 4.4 years. The mean MGD scores were significantly higher at 3rd month (1.3 ± 0.9) and 6th month (1.5 ± 1.0) of treatment compared with baseline (1.1 ± 0.9) (p < 0.001). The mean CCT value at baseline was 540.5 ± 22.1 µm; 536.9 ± 20.5 µm at 3rd month and 531.4 ± 22.2 µm at 6th month. The differences between baseline and 6th month CCT measurements were statistically significant (p < 0.001). There was negative correlation between mean MGD scores and CCT values at the 6th month of treatment which was statistically significant (p = 0.038, r = -0.221).

CONCLUSION

Isotretinoin treatment causes higher MGD scores. A statistically significant decrease in CCT due to MGD was detected at 6th month of treatment.

Evaluation of corneal topography and biomechanical parameters after use of systemic isotretinoin in acne vulgaris

Purpose. We report the effect of isotretinoin on corneal topography, corneal thickness, and biomechanical parameters in patients with acne vulgaris. Method. Fifty-four eyes of 54 patients who received oral isotretinoin for treatment of acne vulgaris were evaluated. All patients underwent a corneal topographical evaluation with a Scheimpflug camera combined with Placido-disk (Sirius), ultrasonic pachymetry measurements, and corneal biomechanical evaluation with an ocular response analyzer at baseline, in the 1st, 3rd, and 6th months of treatment, and 6 months after isotretinoin discontinuation. Results. The thinnest corneal thickness measured with Sirius differed significantly in the 1st, 3rd, and 6th months compared with the baseline measurement; there was no significant change in ultrasonic central corneal thickness measurements and biomechanical parameters (corneal hysteresis and corneal resistance factor) throughout the study. Average simulated keratometry and surface asymmetry index increased significantly only in the first month of treatment according to the baseline. All changes disappeared 6 months after the end of treatment. Conclusion. Basal tear secretion and corneal morphologic properties were significantly influenced during the systemic isotretinoin treatment and the changes were reversible after discontinuation. No statistical important biomechanical differences were found to be induced by isotretinoin.