Ocular Rigidity and Outflow Facility in Nonproliferative Diabetic Retinopathy

Purpose. To determine if Friedenwald’s technique for estimating the coefficient of corneal rigidity (Ko, units mmHg/μL), could differentiate between the cornea in keratoconus, normal eyes, and after crosslinking (CXL). Methods. Two operators (1 and 2) independently measured Ko in three groups (keratoconus, normal, and post-CXL corneas), and repeated the procedure in some where their care remained unchanged and others after routine CXL (>28 days postop, epi-off treatment, 3.0 mW/cm2, 30 min). The data were subsequently used to quantify interoperator error, test-retest/intersessional reliability for estimation of Ko, the significance of intergroup differences, and the effect of CXL on Ko. Results. The major findings were: (i) Ko values were not normally distributed; (ii) mean (±sd, 95% CI) interoperator error was -0.002 (±0.019, −0.006 to 0.003, n = 95) and the limit of agreement between the operators was ±0.039; (iii) RMS differences in the intersessional estimation of Ko values were 0.011 (operator 1) and 0.012 (operator 2); (iv) intergroup differences in Ko were not significant ( p > 0.05 ); (v) intersessional change in Ko (y) was linearly related to Ko estimated (x) at 1st session (for operator 2 y = 1.187x−0.021, r = 0.755, n = 16, p < 0.01 ); and (vi) change in Ko (y1) after CXL was linearly related to Ko (x1) at preop (for operator 2 y1 = 0.880x1−0.016, r = 0.935, n = 20, p < 0.01 ). Conclusion. Friedenwald’s technique for estimating the Ko is prone to substantial interoperator error and intersessional differences. According to the technique, the change in Ko following CXL is on par with the expected intersessional change observed in controls.

PURPOSE. Ocular rigidity (OR) is an important biomechanical property, thought to be relevant in the pathophysiology of open-angle glaucoma (OAG). This study aims to evaluate the relationship between OR and neuroretinal damage caused by glaucoma. METHODS. One hundred eight subjects (22 with healthy eyes, 23 with suspect discs, and 63 with OAG) were included in this study. OR was measured using a noninvasive optical coherence tomography (OCT)-based method developed by our group. We also measured central corneal thickness (CCT), corneal hysteresis (CH), and corneal resistance factor (CRF). Pearson and partial correlations were performed to evaluate the relationship between OR and glaucomatous damage represented by ganglion cell complex (GCC), retinal nerve fiber layer (RNFL) thicknesses, and neuroretinal rim area.

ABSTRACT Introduction and Objectives: Diabetes mellitus (DM) is known to have a biomechanical effect on tissue. High blood glucose concentrations that lead to increased production of free radical intermediates causes ocular rigidity (OR) changes. This change can effect intraocular pressure (IOP) in patients with type 2 DM. This study to determine correlation between ocular rigidity with IOP in patients with type 2 DM. Methods: A cross-sectional study with a correlation test design of OR with IOP in type 2 DM patients was conducted in RSUP dr. Mohammad Hoesin Palembang from January until June 2018. Eighty eye samples consist of 60 type 2 DM and 20 control group. IOP examination was performed using a Goldmann applanation tonometer and OR measurements using schiotz tonometer with two loads then assessed in Friedenwald differential tables. Result: There was a significant correlation between diabetic retinopathy and OR (p=0,000). There was a significant correlation between OR and IOP in NPDR and PDR group (p=0,000). There was a significant relationship between patient age with OR and IOP (p<0,05). Conclusion: There is a significant correlation between ocular rigidity and IOP in people with type 2 DM.