Correlations of Corneal Optical Densitometry, Endothelial Hexagonality Percentage, and Epithelium Thickness

Correlations of Corneal Endothelial Morphology and Corneal Thickness With Anterior Segment Parameters in Healthy Individuals

PURPOSE

The purpose of this study was to investigate the associations between central corneal endothelial cell density (ECD), endothelial morphology, and corneal thickness (central corneal thickness) with the anterior chamber depth, corneal volume (CV), white-to-white (WTW) distance, mean anterior chamber angle (CAmean), and gender in healthy individuals.

METHODS

This observational study included 136 healthy volunteers. The ECD, coefficient of variation of cell area, and hexagonal cell appearance ratio (%Hex) were measured by means of specular microscopy. The central corneal thickness, anterior chamber depth, CV, WTW distance, and the angle width of 12 points were taken by the Pentacam HR Scheimpflug anterior segment imaging. The arithmetical mean of the 12 points was considered as the CAmean. We used mixed effect linear regression model for the statistical analysis of the data.

RESULTS

ECD was positively correlated with CV ( P = 0.028), while after adjusting for age, it was negatively correlated with age ( P < 0.001). Coefficient of variation of cell area was positively correlated with CAmean ( P = 0.036), while after adjusting for age, it was positively correlated with age ( P < 0.001) and CAmean ( P = 0.005). Hex was negatively correlated with WTW ( P = 0.023) and CAmean ( P = 0.025), and after adjusting for age, this correlation remained the same ( P = 0.029 when correlated with WTW and P = 0.035 with CAmean).

CONCLUSIONS

There were significant changes in the morphology of the corneal endothelial cells in eyes with wider anterior chamber angle. Greater pleomorphism and polymegethism of the corneal endothelium was observed in healthy patients with wider CAmean. Deepening of the anterior chamber as myopia progresses could render the corneal endothelium more fragile and susceptible to mechanical stress, which is an area worthy of further study.

The comparison of corneal densitometry in cases with glaucoma following childhood cataract surgery and juvenile glaucoma

PURPOSE

To compare the corneal densitometry (CD) in pediatric cases with glaucoma following childhood cataract surgery and juvenile open-angle glaucoma (JOAG).

METHODS

This prospective comparative study involved 13 eyes with JOAG, 12 eyes with pseudophakic glaucoma, 13 eyes with aphakic glaucoma, and 15 control subjects. Pentacam HR Scheimpflug corneal topography was employed to evaluate corneal thickness (CCT) and CD values.

RESULTS

The mean intraocular pressure (IOP) and CCT were significantly higher in aphakic glaucoma cases than the other groups (p = 0.001). In aphakic eyes, the mean CD values were higher in most of the anterior, center, and posterior layers of 0-2 mm, 2-6 mm, 6-10 mm, and total zones (p < 0.001 for all). In pseudophakic eyes, the mean CD values were statistically similar with that of aphakic eyes and higher than that of JOAG and control eyes in all layers of 0-2 mm zone and in anterior layer of 10-12 mm and anterior and total layers of 2-6 mm zones (p < 0.05 for all). The CD values demonstrated significant correlations with CCT values in both aphakic and pseudophakic eyes. However, a significant correlation of CD values with IOP was only demonstrated in aphakic eyes (p = 0.01 for all).

CONCLUSION

The probable effects of childhood cataract surgery especially aphakia might cause corneal backscatter of light and increased CD in all layers in all zones of the cornea. Increased CD values and its correlation with CCT and IOP in aphakic glaucoma eyes may be of importance in clinical management.

Corneal optical density: Structural basis, measurements, influencing factors, and roles in refractive surgery

The cornea is the main refractive medium of the human eye, and its clarity is critical to visual acuity. Corneal optical density (COD) is an important index to describe corneal transparency. Intact corneal epithelial and endothelial cells, regular arrangement of collagen fibers in the stroma, and normal substance metabolism are all integral for the cornea to maintain its transparency. In the last two decades, the Pentacam Scheimpflug imaging system has emerged as a breakthrough for the measurement of COD (also called corneal densitometry). It has been found that a wide variety of factors such as age, refractive status, and corneal diseases can affect COD. Different corneal refractive surgery methods also change COD in different corneal regions and layers and affect visual acuity following the surgery. Thus, COD has gradually become a significant indicator to evaluate corneal health, one on which the attention of clinicians has been increasingly focused.

Analysis of corneal densitometry and endothelial morphometry in patients with psoriasis

BACKGROUND

To evaluate corneal endothelial properties and corneal densitometry values in patients with psoriasis and to compare the results with those of healthy controls.

METHODS

This prospective, comparative, and cross-sectional study included 106 eyes of 53 patients who were diagnosed with psoriasis and 106 eyes of 53 age-gender matched healthy controls. All patients were evaluated in terms of ocular surface tests such as Schirmer-1 and tear break-up time (TBUT). Corneal endothelial measurements were performed using noncontact specular microscopy. Corneal tomographic and densitometric measurements were obtained using the Scheimpflug imaging system. Measurements were also evaluated according to the psoriasis area and severity index (PASI) score.

RESULTS

The mean TBUT and Schirmer 1 test values were significantly lower in the psoriasis group than in the healthy controls (p = 0.02, p < 0.001, respectively). While the mean endothelial cell density was significantly lower in patients with psoriasis than the healthy controls (2389.9±314.9 cells/mm² vs. 2512.4±289.7 cells/mm², p = 0.02), the mean average endothelial cell area, standard deviation of cell area, coefficient of variation of cell area were significantly higher in patients with psoriasis (426.6±62.7 µm² vs. 403.2±46.1 µm², p = 0.01; 206.4±52.3 µm² vs. 183.2±43.8 µm², p = 0.006; and 48.1±6.3% vs. 45.7±6.7%, p = 0.04, respectively). Most of the densitometry measurements in concentric zones were higher in patients with psoriasis than in healthy controls, but none of the differences reached statistical significance.

CONCLUSIONS

A regular eye examination is crucial in patients with psoriasis because corneal structural and functional changes, particularly endothelial alterations, are of utmost importance in planning intraocular surgeries in patients with psoriasis.

Corneal densitometry and biomechanical properties in patients with primary congenital glaucoma

OBJECTIVE

To describe corneal densitometry, topographic measurements, and biomechanical properties in patients with primary congenital glaucoma (PCG) and healthy patients. To examine correlations between variables and determine their glaucoma diagnostic capacity.

METHODS

This was a cross-sectional, case-control study conducted in 50 eyes of 50 patients with PCG (G1) and 40 eyes of 40 healthy patients (G2). The variables determined in each participant were: intraocular pressure, best corrected visual acuity (BCVA), corneal densitometry, topographic data using the Pentacam HR-Scheimpflug imaging system (Oculus Optikgerate GmbH, Wetzlar, Germany), and corneal hysteresis (CH) and corneal resistance factor (CRF) using the Ocular Response Analyzer (Reichert Ophthalmic Instruments, Depew, NY).

RESULTS

Overall densitometry was significatively higher in the PCG group (G1: 17.94 ± 4.99 vs G2: 13.25 ± 1.96, p < 0.001). CH (G1: 8.02 ± 11.35 vs G2: 11.35 ± 1.42, p < 0.001) and CRF (G1: 9.48 ± 2.83 vs G2: 10.77 ± 1.34, p < 0.001) were lower in the glaucoma group. Mean posterior, central, and anterior elevation and mean keratometry were higher in G1 (p < 0.05). In the PCG group, overall densitometry showed significant correlation with CH (r = -0.321, p = 0.028) and with BCVA (r = -0.498, p = 0.002). AUCs (areas under the curve) for CH and overall densitometry were high (0.839 and 0.899 respectively) and the best overall densitometry; CH and CRF cutoffs were 14.0, 9.3 and 9.2 respectively.

CONCLUSION

Densitometry is increased, and biomechanical corneal properties are decreased in patients with PCG. Densitometry and visual acuity showed a negative and significant correlation, so this measurement could be used as an indirect parameter of BCVA in the clinical practice.