Impact of Hypothyroidism on Tomography and Biomechanics in Keratoconus – Cross-Sectional and Longitudinal Assessment within the Homburg Keratoconus Center at the Time of Inclusion and after 1 Year

Background and Purpose The etiology of keratoconus (KC) is probably multifactorial but remains essentially unknown. Previous scientific observations have suggested that hypothyroidism might play a role in the development and progression of KC. The purpose of this study was to analyze the tomographic and biomechanical parameters in KC patients with or without hypothyroidism. Methods Twenty-eight patients with KC and hypothyroidism (HT group) and fifty-six KC patients without thyroid dysfunction (WHT group) with matching gender and age were analyzed. Mean age was 40.3 years (range 14 – 57) in the HT group and 40.3 years (range 14 – 57) in the WHT group. Routine ophthalmic examinations consisted of corneal tomography and biomechanical parameters. We extracted the following KC parameters from the Pentacam (Pentacam HR, Oculus, Wetzlar, Germany): Keratoconus Index (KI), maximum keratometry (Kmax), astigmatism, and thinnest pachymetry (TP). From the ocular response analyzer (ORA, Reichert Ophthalmic Instruments, Depew, NY, USA), we extracted corneal hysteresis (CH), corneal resistance factor (CRF), and KC match index (KMI). Results The comparison of the tomographic and biomechanical values from cross-sectional and longitudinal analyses showed no significant differences between the HT and WHT groups. Conclusion The severity of KC based on tomographical and biomechanical parameters does not seem to depend on the presence of hypothyroidism.

Ocular Response Analyzer versus Goldmann Applanation Tonometer for Measurement of Intra-Ocular Pressure

Background Goldmann applanation tonometry (GAT) has been the gold standard for intraocular pressure(IOP) measurement ,since its appearance in clinical practice around 50 years ago.(1) In spite of being almost unchallenged, the last few years have become a sustained search for a new standard method for IOP measurement,. One such recently marketed instrument is the Ocular Response Analyzer (ORA), which able to detect the corneal biomechanics. Aim of the Work is to compare the IOP measurement estimated by Goldmann applanation tonometer to that of ORA and detect the effect of state of refraction, corneal topography and central corneal thickness (CCT) on these measurements. Patients and Methods This cross-sectional study was done from March 2018 to October 2018 on 65 eyes of patients visiting the outpatient clinic. Results The mean GAT IOP was 15.938 ± 6.041 while the mean ORA (IOPcc) and (IOPg) were 19.711 ± 7.59 and 17.242 ± 7.35 mm Hg respectively. There is a strong positive relationship between GAT IOP & ORA IOPg measurement (r = 0.880 – p = <0.001*). Also finding a weak yet significant correlation between IOPg and CCT (r = 0.385, p = 0.001). None of the pressure measurements was affected by refraction or corneal curvature significantly. Conclusion In conclusion, our results suggest that mean IOPs obtained by ORA were significantly higher than that of GAT with different influencing factors that are not completely understood. caution has to be sought when using the ORA, the values obtained ought not to be used interchangeably with the values obtained by 1 GAT, despite the presence of a positive correlation between these values. This underlines the importance of using one and only method of evaluation of the IOP for every patient in successive follow-up visits.

Comparison between different tonometers following intrastromal corneal ring segments implantation

Purpose: To compare different intraocular pressure (IOP) readings in corneas with intrastromal corneal ring segments (ICRS) taken by three different tonometers; Goldmann applanation tonometry (GAT), air puff tonometer, and ocular response analyzer (ORA) corneal-compensated IOP (ORA-IOPcc) and determine the relation of these measurements to different corneal parameters taken by Pentacam. Methods: An observational cross-sectional analytic study included patients who underwent ICRS keraring implantation at 3 months. In each eye, the two rings were placed using the femtosecond laser assisted technique 5.5 or 6 mm from the center. IOP was measured using three different tonometers; GAT, air puff tonometer, and ocular response analyzer (ORA) corneal-compensated IOP (ORA-IOPcc). Results: Fifty eyes of 30 patients (20 males and 10 females) aged 27.56 ± 6.38 years were included. IOP measurements by GAT, air puff tonometer, and ORA-IOPcc were 13.28 ± 2.13 mmHg, 10.47 ± 2.55 mmHg, and 13.19 ± 2.78 mmHg, respectively. Comparisons between air puff and each of GAT and ORA-IOPcc were statistically highly significant ( p-value <0.001). Conclusion: IOP measurements taken by air puff tonometer were significantly lower than those taken by GAT and ORA-IOPcc. These differences were not constant across the pressure range but increased as the pressure values determined using GAT and ORA increased. ORA-IOPcc and GAT showed similar readings. No correlation was found between any of the IOP readings taken by the three tonometers and the central corneal thickness.

Results of filtering bleb investigation by thermography method after glaucoma surgery

Thermography is the method of noninvasive registration of visible image of own infrared radiation of the human body surface by special devices. The results of filtration bleb investigation, carried out by thermography method are presented in patients with open angle glaucoma in different terms after glaucoma surgery. Purpose. To execute an investigation of a filtration bleb in patients with open angle glaucoma in different terms after glaucoma surgery by method of thermography. Material and methods. 35 patients (35 eyes) with open angle glaucoma were examined after 1, 7 days, after 1-3-6 months after minimally invasive sinustrabeculectomy. Authors used thermal imaging Тesto 875-2i with SuperResolution technology and telephoto lens 9° x 7°. The bleb area and temperature were evaluated With IRSoft and Universal Desktop Ruler programmes. Intraocular pressure (corneal compensated) (IOPcc) was measured with Ocular Response Analyzer®, ORA. Investigation protocol included 2 groups. Group №1 - 15 patients (15 eyes) with moderate glaucoma. Group №2 – 20 patients (20 eyes) with advanced glaucoma. All patients went through glaucoma surgery, microinvasive sinustrabeculectomy. Management and recurrent examinations were carried out in 1 and 7 day after glaucoma surgery; then in 1, 3 and 6 months after surgery. Results. The IOP level was credibly lowered in all patients in all terms of management in comparison with the baseline IOP level. High statistical correlation was determined in patients of 1 group between IOPcc and the index of temperature difference (between filtering bleb and surrounding conjunctiva temperatures), correlation coefficient >0,7, in all management terms after surgery (in 1, 3, 6 months). In 2 group there was determined statistical correlation between IOPcc and index of temperature difference between filtering bleb and surrounding conjunctiva temperatures (Δ Тsc - Тfb) in 1 week, in 1 and 3 months after surgery. The same correlation coefficient was determined between filtering bleb temperature and Δ Тsc- Тfb in 6 months after surgery. Conclusion. Thermography is a safe and noninvasive method, that credibly detects temperature elevation in surgery zone, indicates IOP level raise and can predict starting of filtering bleb scarring. This method defines the necessity of needling procedure execution in different terms after surgery treatment and allows to control its effectiveness. Key words: open angle glaucoma, filtering bleb, scarring, thermography, corneal compensated intraocular pressure, Ocular Response Analyzer.