Continuous 24-hour intraocular pressure monitoring in normal Chinese adults using a novel contact lens sensor system.

AIMS: To investigate the physiological nyctohemeral intraocular pressure (IOP) rhythms of normal Chinese adults using a novel contact lens sensor system (CLS) that can output IOP in millimetres of mercury (mm Hg) continuously. METHODS: Fifty-nine eyes of 59 normal Chinese adults completed 24-hour IOP monitoring using the novel CLS. A descriptive analysis was conducted on the 24-hour IOP mean, peak and acrophase, trough and bathyphase, fluctuation, and mean amplitude of intraocular pressure excursion (MAPE). The continuous data were analysed at several periods (diurnal period, 08:00-20:00 hours; nocturnal period, 22:00-06:00 hours; sleep time, 0:00-06:00 hours), and compared between right and left eyes, males and females, and different age ranges (<30, and ≥30), respectively. RESULTS: Normal adults had a lower peak, higher trough, smaller fluctuation and smaller MAPE (p<0.05 for all comparisons) but non-significantly different mean (p=0.695) in the nocturnal period or sleep time compared with the diurnal period. The 24-hour IOP peak and trough showed the frequency of occurrence ranging from 1.69% to 15.25% at an interval of 2 hours. No IOP parameter showed significant difference between right and left eyes (p>0.1 for all comparisons). The male group had larger 24-hour and diurnal IOP fluctuation and MAPE (p<0.05 for all comparisons). Subjects aged 30 or over had higher 24-hour and diurnal mean, higher peak, and larger MAPE (p<0.05 for all comparisons). CONCLUSION: Continuous 24-hour IOP output from the CLS in normal Chinese was stable with a comparable mean level between day and night, as well as scattered acrophase and bathyphase. The 24-hour IOP mean increased with age, and IOP variations were positively correlated to age and male sex.

A New Contact Lens Sensor System for Continuous Intraocular Pressure Monitoring: Evaluation of Safety and Tolerability.

PURPOSE: To assess the safety and tolerability of a new contact lens sensor (CLS) system for continuous 3- and 24-hr intraocular pressure (IOP) monitoring in human eyes. METHODS: Twenty-five subjects were recruited for 3-hr IOP measurement by CLS. Corneal fluorescein staining (CFS) scores were evaluated before and after measurement. Then, 30 participants (10 normal subjects and 20 glaucoma patients) were recruited for 24-hr IOP monitoring. Ocular surface disease index (OSDI) was assessed before and one day after measurement. Contact lens dry eye questionnaire-8 was assessed immediately after measurement. Visual analog scale of discomfort was measured before, immediately after, and one day after measurement. Best-corrected visual acuity (BCVA), tear break-up time (TBUT), and CFS were assessed before, immediately after, and 1 day after measurement. RESULTS: All participants completed 3- or 24-hr IOP measurement by CLS. Corneal fluorescein staining increased from 0.6±0.7 to 2.4±1.5 after 3-hr IOP measurement ( P <0.001). For participants undergoing 24-hr IOP monitoring, OSDI increased from 9.1±9.7 to 18.0±12.4 ( P =0.001). CLDEQ-8 score was 11.6±5.8. Visual analog scale increased from 11.1±14.2 to 35.2±21.8 after measurement ( P <0.001) and decreased to 26.7±18.4 one day later ( P <0.001 compared with baseline). BCVA decreased from 1.0±0.01 to 0.8±0.1 ( P <0.001) and returned to 0.9±0.1 after one day ( P <0.001 compared with baseline). TBUT decreased from 5.1±3.9 to 2.6±1.5 s ( P =0.001) and returned to 4.8±2.5 s ( P =0.465 compared with baseline). Corneal fluorescein staining increased from 0.7±0.9 to 4.3±0.8 ( P <0.001) and dropped to 0.8±0.7 ( P =0.599 compared with baseline). No significant difference was found for all variations of indicators between normal subjects and glaucoma patients ( P >0.1 for all comparisons). CONCLUSIONS: The CLS shows a great potential for a safe and tolerable 24-hr IOP monitoring in normal subjects and glaucoma patients. Clinical attention to the worsening signs and symptoms after measurement is required.

Corneal Stiffness and Modulus of Normal-Tension Glaucoma in Chinese.

PURPOSE: To assess and compare the corneal biomechanics of normal-tension glaucoma (NTG), high-tension glaucoma (HTG), and normal controls based on stiffness and modulus. The correlations among central corneal thickness (CCT), visual field, retinal nerve fiber layer (RNFL) thickness, and corneal biomechanics in glaucoma eyes were also evaluated. DESIGN: A prospective, cross-sectional, comparative study. METHODS: This study included 334 eyes of 108 NTG patients, 113 HTG patients, and 113 control subjects at Zhongshan Ophthalmic Center, Sun Yat-Sen University. Corneal biomechanics were evaluated using a corneal indentation device (CID) and corneal visualization Scheimpflug technology (Corvis ST). Visual field and RNFL thickness were obtained using standard automated perimetry and spectral-domain optical coherence tomography. One-way analyses of variance with Bonferroni post hoc tests and a multivariable linear regression analysis with adjustment were conducted. Correlations among corneal biomechanical parameters, CCT, visual field, and RNFL thickness were analyzed. RESULTS: The corneal stiffness of the NTG patients (71.0 ± 10.9 N/m) was significantly lower than that of the HTG patients (77.3 ± 15.6 N/m; P = .001) and the CCT- and IOP-matched normal controls (75.6 ± 11.0 N/m; P = .023). The patients in the NTG group had lower corneal stiffness than those in the control group (ß = -4.88, 95% CI -9.002, -0.758; P = .020) after adjusting for confounders. Stiffness was positively correlated with CCT in the NTG group (P = .028) but not in the HTG group (P = .509). There was no significant correlation (P > .05) between corneal biomechanics, visual field, or RNFL thickness. CONCLUSIONS: The corneas of NTG patients were softer than those of HTG patients and controls, as assessed by CID, which were associated with thinner CCT. These might suggest different ocular biomechanical properties in NTG and HTG.

A Novel Indentation Assessment to Measure Corneal Biomechanical Properties in Glaucoma and Ocular Hypertension.

Purpose: To evaluate the ability of the new in vivo corneal indentation device (CID) to measure corneal biomechanical properties. Methods and Results: In total, 186 eyes from 46 healthy subjects, 107 patients with primary open-angle glaucoma, and 33 patients with ocular hypertension were enrolled in a cross-sectional study. Measurements were performed using corneal visualization Scheimpflug technology (Corvis ST) and the CID. The deformation amplitude (DA), inward applanation time, inward applanation velocity (A1V), outward applanation time (A2T), outward applanation velocity (A2V), highest concavity time, DA ratio, max inverse radius (MIR), integrated radius, and stiffness parameter A1 were included as Corvis ST parameters, and stiffness and modulus were included as CID parameters. Associations between the Corvis ST and CID parameters and correlations between central corneal thickness and corneal biomechanical parameters were analyzed. The stiffness was significantly correlated with all the Corvis ST parameters (P < 0.05). The modulus was significantly correlated with the DA, A1V, A2T, A2V, highest concavity time, and MIR (P < 0.05). The DA, inward applanation time, A1V, A2T, A2V, DA ratio, MIR, integrated radius, and stiffness parameter A1 values and both CID-derived values were significantly correlated with central corneal thickness (P < 0.05). Conclusions: Parameters derived from the CID and Corvis ST demonstrated agreement in the measurement of corneal biomechanical properties. The stiffness and modulus can characterize in vivo corneal biomechanical properties. Translational Relevance: Agreeing with the Corvis ST regarding the assessment of corneal biomechanical properties, the CID can be a novel clinical tool for biomechanical evaluation of the cornea.