The detection and dynamic monitoring of intraocular pressure have important clinical significance for the diagnosis and treatment of glaucoma. The current status of clinical intraocular pressure detection and dynamic intraocular pressure monitoring are reviewed. The technical challenges encountered, and the shortcomings of the existing technology are analyzed, in order to expect better intraocular pressure monitoring technology to be applied to patients.
Glaucoma/diagnosis* ; Humans ; Intraocular Pressure ; Technology ; Tonometry, Ocular

OBJECTIVE: To investigate accuracy of the currently used strategies for intraocular pressure measurements for reflecting actual 24-hour intraocular pressure fluctuations. METHODS: From September, 2018 to January, 2019, the patients with a suspected diagnosis of primary open angle glaucoma at our hospital were prospectively enrolled to receive 24-hour intraocular pressure monitoring using a Goldmann tonometer. With the intraocular pressure measurements at 0:00, 2:00, 5:00, 7:00, 8:00, 10:00, 11:00, 14:00, 16:00, 18:00, 20:00, and 22:00 as the gold standard (strategy 1), we compared the measurements taken at 5:00, 7:00, 10:00, 14:00, 18:00, and 22:00 (strategy 2) and at 8:00, 11:00, 14:00, and 16:00 (strategy 3) for their accuracy in reflecting 24-h intraocular pressure fluctuations. RESULTS: A total of 41 patients (82 eyes) were enrolled in this study. The peak intraocular pressures measured using the 3 strategies were 21.09±4.15 mmHg, 20.54±4.10 mmHg, and 19.91±4.38 mmHg, respectively, showing significant differences among them ( CONCLUSIONS For suspected cases of glaucoma, intraocular pressure measurements at 4 and 6 time points of a day can not precisely reflect the actual range of intraocular pressure fluctuations, and may lead to a missed diagnosis of glaucoma.
Glaucoma/diagnosis* ; Glaucoma, Open-Angle ; Humans ; Intraocular Pressure ; Prospective Studies ; Tonometry, Ocular

OBJECTIVE: To compare the corneal biomechanical properties among keratoconus, subclinical keratoconus and normal corneas by using CorVis ST, and to estimate the effect of these biomechanical indices in discriminating keratoconus and subclinical keratoconus from normal. METHODS: A total of 76 eyes of 67 subjects were enrolled and divided into three groups. Keratoconus group included 24 eyes from 17 patients, subclinical keratoconus group included 12 eyes from 12 patients and normal group included 40 normal eyes from 40 subjects．All the eyes were assessed with CorVis ST and ten biomechanical parameters, intraocular pressure (IOP) and central corneal thickness (CCT) were obtained from this machine. The discrimination of biomechanical characteristic of the three groups based on the all indices was reflected by discriminant analysis and the Fisher discriminant function was established. RESULTS: The values of corneal biomechanics of keratoconus, subclinical keratoconus, normal eyes were increased in sequence, except for three indices: the second applamation time (A2T), time taken to reach highest concavity (HCT) and maximum corneal velocity during the first applanation (Vin). Three sets of data were among a statistically significant difference (P<0.05). There were statistically significant differences (P<0.05) between any two groups by comparing with such two indices: radius value of central concave curvature at highest concavity (HCR) and CCT. The grades of the three groups were obvious, evaluated by the discriminant function. The accuracy of reevaluation was 85% by validation method. The biggest contribution of indices in discriminant function was given by such four indices in sequence: CCT, HCR, maximum deformation amplitude of highest concavity (HCDA) and maximum corneal velocity during the second applanation (Vout). CONCLUSION The corneal biomechanical properties of keratoconus and subclinical keratoconus were decreased compared with normal eyes. The biomechanical parameters based on CorVis ST showed a good performance for discriminating among keratoconus, subclinical keratoconus and normal corneas.
Biomechanical Phenomena ; Cornea ; Discriminant Analysis ; Humans ; Keratoconus ; Tonometry, Ocular

Increased intraocular pressure (IOP) during surgery is a risk factor for postoperative ophthalmological complications. We assessed the efficacy of systemically infused dexmedetomidine in preventing the increase in IOP caused by a steep Trendelenburg position, and evaluated the influence of underlying hypertension on IOP during surgery. Sixty patients undergoing laparoscopic surgery in a steep Trendelenburg position were included. Patients in the dexmedetomidine group received a 1.0 µg/kg IV loading dose of dexmedetomidine before anesthesia, followed by an infusion of 0.5 µg/kg/hr throughout the operation. Patients in the saline group were infused with the same volume of normal saline. IOP and ocular perfusion pressure (OPP) were measured 16 times pre- and intraoperatively. In the saline group, IOP increased in the steep Trendelenburg position, and was 11.3 mmHg higher at the end of the time at the position compared with the baseline value (before anesthetic induction). This increase in IOP was attenuated in the dexmedetomidine group, for which IOP was only 4.2 mmHg higher (P < 0.001 vs. the saline group). The steep Trendelenburg position was associated with a decrease in OPP; the degree of decrease was comparable for both groups. In intragroup comparisons between patients with underlying hypertension and normotensive patients, the values of IOP at every time point were comparable. Dexmedetomidine infusion attenuated the increase in IOP during laparoscopic surgery in a steep Trendelenburg position, without further decreasing the OPP. Systemic hypertension did not seem to be associated with any additional increase in IOP during surgery. (Registration at the Clinical Research Information Service of Korea National Institute of Health ID: KCT0001482)
Aged ; Dexmedetomidine/administration & dosage/*pharmacology ; Double-Blind Method ; Eye Diseases/surgery ; Female ; Head-Down Tilt ; Humans ; Hypnotics and Sedatives/administration & dosage/pharmacology ; Intraocular Pressure/*drug effects ; Intraoperative Complications/drug therapy/prevention & control ; Laparoscopy ; Male ; Middle Aged ; Prospective Studies ; Risk Factors ; Tonometry, Ocular ; Treatment Outcome

PURPOSE: To investigate and compare the progression of medically treated primary open angle glaucoma according to the baseline intraocular pressure (IOP). METHODS: This study included a total of 345 eyes from 345 patients (mean follow-up period, 4.5 years). Eyes were classified into either conventional normal tension glaucoma (cNTG, < or =21 mmHg) or conventional high-tension glaucoma (cHTG, >21 mmHg) groups according to the conventional cut-off value of the IOP. Additionally, the median IOP (15 mmHg) was used to create two other groups (median NTG [mNTG] < or =15 mmHg and median HTG [mHTG] >15 mmHg). Using these values, 306, 39, 153, and 192 eyes were assigned to the cNTG, cHTG, mNTG, and mHTG groups, respectively. Glaucoma progression was determined either by optic disc/retinal nerve fiber layer photographs or serial visual field data. RESULTS: Mean reduction of IOP after medical treatment and of central corneal thickness was lower in the cNTG group, while the prevalence of disc hemorrhage and baseline visual field mean deviation did not differ between the cNTG and cHTG groups. A mean reduction in the IOP was observed after medical treatment, and central corneal thickness was lower in the mNTG group; disc hemorrhage was more frequent in the mNTG than in the mHTG group. Among the 345 analyzed eyes, 100 (29%) showed progression during the follow-up period. In the cHTG group, a higher baseline IOP (hazard ratio, 1.147; p = 0.024) was associated with glaucoma progression. Disc hemorrhage (hazard ratio, 15.533; p < 0.001) was also strongly associated with progression in the mNTG group. CONCLUSIONS: Baseline IOP was a significant risk factor for glaucoma progression in cHTG patients (10% of our total participants), while disc hemorrhage showed the strongest association with progression in the mNTG group, indicating that a cut-off value other than the conventional 21 mmHg is required to define true low-tension glaucoma in populations where NTG predominates among all glaucoma patients.
Aged ; Disease Progression ; Female ; Glaucoma, Open-Angle/*diagnosis ; Gonioscopy ; Humans ; Intraocular Pressure ; Low Tension Glaucoma/*diagnosis ; Male ; Middle Aged ; Nerve Fibers/pathology ; Optic Disk/pathology ; Optic Nerve Diseases/*diagnosis ; Photography/standards ; Retinal Ganglion Cells/pathology ; Retrospective Studies ; Tomography, Optical Coherence ; Tonometry, Ocular ; Vision Disorders/diagnosis ; Visual Field Tests/standards ; Visual Fields

Intraocular pressure detection has a great significance for understanding the status of eye health, prevention and treatment of diseases such as glaucoma. Traditional intraocular pressure detection needs to be held in the hospital. It is not only time-consuming to doctors and patients, but also difficult to achieve 24 hour-continuous detection. Microminiaturization of the intraocular pressure sensor and wearing it as a contact lens, which is convenient, comfortable and noninvasive, can solve this problem because the soft contact lens with an embedded micro fabricated strain gauge allows the measurement of changes in corneal curvature to correlate to variations of intraocular pressure. We fabricated a strain gauge using micro-electron mechanical systems, and integrated with the contact lens made of polydimethylsiloxane (PDMS) using injection molding. The experimental results showed that the sensitivity was 100. 7 µV/µm. When attached to the corneal surface, the average sensitivity of sensor response of intraocular pressure can be 125.8 µV/mm Hg under the ideal condition.
Contact Lenses, Hydrophilic ; Dimethylpolysiloxanes ; Glaucoma ; Humans ; Intraocular Pressure ; Tonometry, Ocular ; instrumentation

PURPOSE: To assess the relationships between optic cup-to-disc ratio (CDR) and age, sex, and other demographic and health characteristics in the healthy Korean population. METHODS: The study design was retrospective and population-based. A total of 28,377 subjects who participated in the Korea National Health and Nutrition Examination Survey between 2008 and 2011 were enrolled in this study. Participants underwent structured interviews as well as systemic and ophthalmic examinations. Patients with glaucoma who were diagnosed using the International Society of Geographical and Epidemiological Ophthalmology classification were excluded. Changes in vertical CDR were examined by age in relation to systemic variables on multiple regression analysis. RESULTS: The mean vertical CDR was 0.34 +/- 0.12. The vertical CDR increased with age from subjects in their 20s to those in their 80s (p < 0.001). The mean CDR in males was significantly higher than that of females (p < 0.001). On multiple regression analysis, the vertical CDR was positively associated with age (p < 0.001), male sex (p < 0.001), diastolic blood pressure (p = 0.009), and intraocular pressure (p < 0.001) but was negatively associated with body mass index (p < 0.001). CONCLUSIONS: Greater vertical CDR was related to age, male sex, higher diastolic blood pressure, higher intraocular pressure, and lower body mass index in healthy Koreans.
Age Distribution ; Cross-Sectional Studies ; Female ; Glaucoma/diagnosis/*epidemiology ; Humans ; *Intraocular Pressure ; Male ; Morbidity/trends ; Optic Disk/*pathology ; Optic Nerve Diseases/diagnosis/*epidemiology ; *Population Surveillance ; Reference Values ; Republic of Korea/epidemiology ; Retrospective Studies ; Sex Distribution ; Tonometry, Ocular

PURPOSE: To investigate anterior segment parameters in obese patients in comparison to healthy individuals. METHODS: Thirty-four obese subjects and 34 age-sex-matched healthy subjects were enrolled in this prospective cross-sectional study. Ophthalmological examinations including intraocular pressure (IOP), central corneal thickness (CCT), anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), and axial length (AL) measurements were performed on each subject. Height and weight of all subjects were recorded and body mass index (BMI) was calculated. RESULTS: IOP was significantly higher in the obese group (p = 0.003). The mean ACD in obese subjects was significantly lower than that in control subjects (p = 0.036). AL, ACV, ACA and CCT were not significantly different between the groups. There was a positive correlation between BMI and IOP (r = 0.404, p < 0.001). ACD and ACA were negatively correlated with BMI. CONCLUSIONS: IOP was significantly higher and ACD was significantly lower in obese subjects. AL, ACV, ACA and CCT were not significantly different between the groups. The impact of obesity on anterior chamber parameters should be further investigated.
Adult ; Aged ; Anterior Chamber/*pathology/physiopathology ; Cross-Sectional Studies ; Female ; Humans ; Intraocular Pressure/*physiology ; Male ; Middle Aged ; Obesity/*diagnostic imaging ; Prospective Studies ; Tomography, Optical Coherence/*methods ; Tonometry, Ocular

Due to lack of the practical technique to measure the biomechanical properties of the ocular cornea in vivo, clinical ophthalmologists have some difficulties in understanding the deformation mechanism of the cornea under the action of physiological intraocular pressures. Using Young's theory analysis of the corneal deformation during applanation tonometry, the relation between the elasticity moduli of the cornea and the applanated corneal area and the measured and true intraocular pressures can be obtained. A new applanation technique has been developed for measuring the biomechanical properties of the ocular cornea tissue in vivo, which can simultaneously acquire the data of the applanation area and displacement of the corneal deformation as well as the exerted applanation force on the cornea. Experimental results on a rabbit's eyeball demonstrated that the present technique could be used to measure the elasticity moduli and creep properties of the ocular cornea nondestructively in vivo.
Animals ; Biomechanical Phenomena ; Cornea ; Elastic Modulus ; Intraocular Pressure ; Muscles ; Rabbits ; Tonometry, Ocular

OBJECTIVE: To compare the difference in intraocular pressure (IOP) readings as well as the tolerability between Icare rebound tonometer (Icare RBT) and Goldmann applanation tonometer (GAT), and to evaluate the application of Icare RBT in monitoring the intraocular pressure in children after congenital cataract surgery. METHODS: The IOP was measured with the Icare RBT and GAT respectively in 150 children (262 eyes) after congenital cataract surgery by two experienced ophthalmologists. Correlation and Bland-Altman analysis were used to assess the agreement in IOP readings between the two instruments. The influence of the central corneal thickness (CCT) adjusted for age on IOP readings was analyzed by linear regression analysis. The tolerance of the patients to Icare RBT and GAT measurement were surveyed. RESULTS: The mean age was (44.82 ± 11.56) months in 150 children, including 81 boys and 69 girls. The mean IOP readings by the Icare RBT and GAT were (16.08 ± 5.72) mmHg and (14.17 ± 5.05) mmHg, respectively. The mean difference between the Icare RBT and GAT was (1.91 ± 2.04) mmHg, which was significantly correlated with CCT (r=0.409, P<0.001). The IOP readings by Icare RBT was significantly correlated with that measured by GAT(r= 0.936, P<0.001). The 95% confidence interval of the difference between the two instruments was ?2.10 to 5.91 mmHg. The Icare RBT examination was well tolerated by the children compared to the GAT examination. CONCLUSION The Icare RBT is easy to use and well tolerated by the children after congenital cataract surgery. Compared to GAT, the value measured by the IOPs trends to be overestimated. The difference in readings between the 2 tonometers will magnify with the increase in CCT.
Cataract ; congenital ; Cataract Extraction ; Child, Preschool ; Female ; Humans ; Intraocular Pressure ; Male ; Tonometry, Ocular ; instrumentation