The Relationship Between Corneal Hysteresis and Retinal Ganglion Cells - A Step Forward in Early Glaucoma Diagnosis.

BACKGROUND Glaucoma is a major cause of irreversible visual field (VF) loss across the world. Many studies have assessed the accuracy of glaucoma diagnostic tests for a more precise diagnosis to quickly identify patients with higher risk of progression. MATERIAL AND METHODS We conducted a study that included 214 eyes divided into 3 groups: 79 eyes from patients diagnosed with primary open-angle glaucoma (POAG), 68 eyes from patients diagnosed with ocular hypertension (OH), and 67 eyes from normal individuals (normal eyes, NE). All patients included in the study received a complete checkup. RESULTS In POAG patients, means of central corneal thickness (CCT), corneal hysteresis (CH), corneal resistance factor (CRF), mean defect (MD), visual field index (VFI), peripapillary retinal nerve fiber layer (pRNFL), and ganglion cell complex (GCC) are lower than in OH patients, and in NE are higher than in both groups. Also, we found a statistically significant direct correlation between CH and GCC thickness. Further statistical analysis revealed that both pRNFL thickness and GCC thickness are significantly influenced by CH value in a precise manner. CONCLUSIONS The first cell type affected in glaucoma is the retinal ganglion cell. We found a positive correlation between GCC thickness and CH, suggesting that CH might be a parameter to consider in the evaluation of all glaucoma patients from their first examination. Moreover, both pRNFL thickness and GCC thickness are influenced by CH, suggesting the utility of monitoring the value of CH at every checkup to detect its decrease in glaucoma patients.

The importance of corneal biomechanics in assessing first degree family members of keratoconus patients.

Aim: to determine the values of biomechanical parameters (corneal hysteresis - CH, corneal resistance factor - CRF and keratoconus match index - KMI) in patients with keratoconus and their first degree family members. The purpose of the present study was to investigate the importance of assessing corneal biomechanics in subjects at risk of developing the primary ectasia. Materials and methods: 48 participants divided into three groups were analyzed in an observational study after a complete ophthalmological exam with the primary focus on Ocular Response Analyzer. Results: The mean values of CH, CRF, and KMI in the group of relatives were lower compared with the controls but higher when compared with keratoconus patients. We noted significant differences of CH and CRF between all three groups, while in the case of KMI, only the keratoconus group presented statistically significant differences compared with the relatives, respectively with the healthy subjects. Conclusions: the decreased values of CH and CRF may raise the question whether corneal biomechanics could be an adjuvant tool in the screening of a first-degree family member of a keratoconus patient in the attempt of the early detection of a possible forme fruste keratoconus.

Overexpression of Tear Inflammatory Cytokines as Additional Finding in Keratoconus Patients and Their First Degree Family Members.

Keratoconus is a progressive corneal ectasia that may lead to severe visual impairment due to the irregular astigmatism caused by corneal thinning. In addition to its association with atopy, eye rubbing, or genetic component, late reports suggest the involvement of inflammation in the pathogenesis of the disease. Our aim was to determine the concentration of IL-4, IL-6, IL-10, RANTES, IFN gamma, and TNF alpha in the tear film of patients with keratoconus and their first degree family members. We analyzed forty-eight participants in an observational cross-sectional study. The diagnosis of keratoconus had to be confirmed in addition to a minimum of 47 D corneal refractive power by corneal topography readings provided by a Placido-based topography system and analysis of the pattern: irregular astigmatism with an asymmetric "bow-tie." As for the other groups, the most important diagnosis criteria were a normal topographic pattern with a regular astigmatism. 17 keratoconus patients, 16 relatives, and 15 controls were recruited after clinical assessment as part of the research. The cytokine's mean values were similar in the keratoconus group and the relatives' samples but significantly higher compared to the controls. Important differences were found in IL-4 levels between keratoconus patients and relatives and between relatives and controls (mean difference of 302.42, p < 0.0016 and 219.16, p < 0.033, Tukey's HSD procedure). In the keratoconus group, using the CORR procedure, we found statistically strong correlations of IL-6 lacrimal concentrations with the disease stage (r = 0.56, p < 0.01), keratometry (r = 0.55, p < 0.02), pachymetry (r = -0.64, p < 0.048), and corneal hysteresis (r = -0.53, p < 0.02). Cytokine overexpression may be relevant for the inflammatory etiology of keratoconus. In conclusion, in the case of some first degree family members, the elevated tear biomarkers may represent a supplementary risk factor.