The Effect of a Diving Mask on Intraocular Pressure in a Healthy Population

Purpose: Swimming goggles increase the intraocular pressure (IOP) via the periorbital frame pressure and suction effect. In comparison, diving masks have a larger frame rim and incorporate the nose. The exact effect(s) of diving masks on IOP is unknown. This study evaluates the influence of diving masks on IOP in normal, healthy subjects. Methods: Tonometry was performed in both eyes of all subjects with an AVIA®Tono-Pen by a single investigator. Measurements were taken at baseline without the diving mask and with the subjects wearing a small-volume, double-window diving mask, but with the mask lenses removed. Two IOP readings in each eye were measured, and an additional reading was measured if the difference between the initial 2 was ≥2 mm Hg. Central corneal thickness (CCT) was also measured in each eye, using a contact pachymeter (OcuScan®Alcon). Results: Forty eyes of 20 healthy volunteers (age 29.7 ± 9.3 years; range 21–52) were included. The mean CCT was 544.4 ± 43.5 µm. The mean IOP before the diving mask was worn had been 17.23 ± 2.18 mm Hg (n = 40). The IOP decreased by 0.43 mm Hg (p < 0.05) to 16.80 ± 2.57 mm Hg after the diving mask had been put on. There was no correlation between IOP change and age (r = 0.143, p = 0.337), gender (r = –0.174, p = 0.283) or CCT (r = –0.123, p = 0.445). Conclusion: There was no increase in IOP after the diving mask had been worn. A small but statistically significant decrease in IOP was observed. This study demonstrates that unlike swimming goggles, the strap tension and frame pressure on the periorbital tissue from a diving mask does not increase IOP. Diving masks may be a suitable alternative to swimming goggles for patients with advanced glaucoma or glaucoma filtration surgery.

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A comparative study of central corneal thickness (CCT) and intraocular pressure (IOP) in University of KwaZulu-Natal students of Black and Indian ethnicity*

African Vision and Eye Health ◽

10.4102/aveh.v71i4.83 ◽

2012 ◽

Vol 71 (4) ◽

Cited By ~ 2

Author(s):

Z. Sardiwalla ◽

D. Moodley ◽

T. Ndawonde ◽

A. Madikizela ◽

N. Ngobese ◽

...

Keyword(s):

Intraocular Pressure ◽

Ethnic Groups ◽

Black Males ◽

Central Corneal Thickness ◽

Corneal Thickness ◽

Total Sample ◽

Black Females ◽

The Mean ◽

The Difference ◽

The Right

Thisstudy compared central corneal thickness (CCT) and intraocular pressure (IOP) of Black and Indian students from the University of Kwa-Zulu-Natal. Two hundred (100 Black and 100 Indi-an) participants of both genders aged 18-25 years (mean and standard deviation; 20.1±1.6 years) participated in this study. CCT and IOP were measured for the right eye of each participant using a Tono-Pachymeter (NT530P) and a Goldmann applanation tonometer (GAT) respectively. Data was analyzed with descriptive, t-test and Pearson’s cor-relation statistics. In the total sample (N = 200), the mean CCT value was 519.5 ± 38.6 μm and CCT was higher in the Indians (526.5 ± 37.2 µm) than in the Blacks (512.4 ± 38.9 µm) (p = 0.01). Also, it was higher in the females (522.3 µm) than in males (516.7 µm), but the difference was insignificant (p = 0.07). The mean CCT was higher in the Indian males (520.1 µm) than in the Black males (513.2 µm), but the difference was insignificant (p=0.39). However, it was significantly higher in the Indian females (533 µm) than in the Black females (511.6 µm) (p = 0.003). In the total sample, the mean IOP was 14.6 mmHg and IOP was greater in Indiansthan Blacks (mean = 15.3 ± 2.9 mmHg and 13.8 ± 2.6 mmHg respectively) (p = 0.01). Also, the mean IOP (N = 200) value was slightly higher in the females (14.7 mmHg) than in males (14.5 mmHg) (p = 0.51). The mean IOP was higher in the Indian males (15.0 mmHg) than in the Black males (14.0 mmHg) (p = 0.07) and the mean IOP value was higher in the Indian females (15.7 mmHg) than in the Black females (13.6 mmHg) (p < 0.001). The higher mean IOP value in the Indian than Black participants was attributed to the higher mean CCT values. A positive, but inconsistent association between CCT and IOP was found in this study, the coefficient in the total sample (r = 0.382, p = 0.000), in the Blacks (r = 0.196, p = 0.05) and in Indians (r = 0.498, p = 0.000). A national population study comparing CCT and IOP in the various South African ethnic groups is recommended. Cognizance of these differences should be taken in the diagnoses of glaucoma in these ethnic groups. (S Afr Optom 2012 71(4) 171-177)

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A comparison of intraocular pressure values obtained with the Tono-Pachymeter NT530P, iCare® rebound tonometer and Goldmann applanation tonometer

African Vision and Eye Health ◽

10.4102/aveh.v70i3.109 ◽

2011 ◽

Vol 70 (3) ◽

Author(s):

N. Rampersad ◽

K. P. Mashige ◽

S. Jhetam

Keyword(s):

Intraocular Pressure ◽

Corneal Thickness ◽

Rebound Tonometer ◽

Correlation And Regression Analysis ◽

Goldmann Applanation Tonometer ◽

Bland Altman Method ◽

Applanation Tonometer ◽

The Mean ◽

The Difference ◽

The Right

The purpose of this study was to compare the intraocular pressure (IOP) values measured with the Tono-Pachymeter NT530P (Tonopachy™) and the iCare® rebound tonometer (iCare®) with those obtained by the Goldmann applanation tonometer (GAT). The right eyes of 105 subjects aged 18 to 82 years (mean age = 29.27 ± 14.67 years) were assessed with the three tonometers. Central corneal thickness (CCT) was measured first using the Tonopachy™ and then IOP was measured by Tonopachy™, iCare® and GAT. The data was analyzed with descriptive statistics, paired t-test, correlation and regression analysis. The Bland-Altman method of analysis was used to evaluate agreements between the sets of data from the three devices. The CCT values ranged from 440 µm to 606 µm (mean= 518.49 ± 33.01 µm). There was little or no correlation between CCT and IOP for any of the instruments used in this study (r = 0.29 for Tonopachy™, r = 0.22 for iCare®, r = 0.17 for GAT). The mean IOP measured with the Tonopachy™ was 14.31 ± 3.57 mmHg (range 8.7 mmHg to 31 mmHg) and 16.64 ± 4.38 mmHg (range 8 mmHg to 32 mmHg) using the iCare®. The mean IOP measured with the GAT was 14.79 ± 3.09 mmHg (range 8.7 mmHg to 29.7 mmHg). Using the Bland-Altman method, the upper and lower limits of agreement between the Tonopachy™ and GAT, iCare® and GAT, iCare® and Tonopachy™ were 5.1 mmHg and –4.2 mmHg, 8.6 mmHg and –4.9 mmHg, 7.5 mmHg and –2.8 mmHg respectively. In 79.1% of the eyes studied, the mean IOP difference between Tonopachy™ and GAT was less than 3 mmHg and in 20.9% of the eyes, the difference was greater than 3 mmHg. However, mean IOP differences of greater than 3 mmHg were obtained by iCare® in comparison with GAT (40%) and Tonopachy™ (34.3%) respectively. Findings of this study suggest that the Tonopachy™ yielded IOP readings that were consistent with those of GAT values while iCare® yielded higher IOP values compared to both GAT and Tonopachy™. (S Afr Optom 2011 70(3) 109-116)

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Comparison of intraocular pressure and central corneal thickness in non-glaucomatous North- East Indian tribals versus general Indians

Asian Journal of Ophthalmology ◽

10.35119/asjoo.v16i3.385 ◽

2019 ◽

Vol 16 (3) ◽

pp. 144-152

Author(s):

Tanie Natung ◽

Prasanta Kumar Goswami ◽

Avonuo Keditsu ◽

Wakaru Shullai

Keyword(s):

Intraocular Pressure ◽

Central Corneal Thickness ◽

Linear Regression Analysis ◽

Corneal Thickness ◽

Cross Sectional Study ◽

Cross Sectional ◽

East Indian ◽

North East ◽

The Mean ◽

The Difference

Purpose: To compare the intraocular pressure (IOP) and central corneal thickness (CCT) of non-glaucomatous North-East (NE) Indian tribals and general Indians. Materials and methods: In a prospective, cross-sectional study, the IOP and CCT of non-glaucomatous NE Indian tribals (n = 50) and non-glaucomatous general Indians (n = 50) were compared. Glaucoma was ruled out by history, detailed ocular examinations, and investigations. Results: There was very good correlation between the CCT and IOP values of right and left eyes (p = 0.940 and 0.847, respectively). The difference in the IOP values in the two groups was not statistically significant (p = 0.312 for Oculus Dexter [OD], p = 0.400 for Oculus Sinister [OS]). Similarly, the difference in the CCT values in the two groups was not statistically significant (p = 0.736 for OD and 0.613 for OS). The mean CCT and IOP OD for the whole population was 530.50 ± 35.42 μm and 13.80 ± 2.760 mmHg, respectively. By linear regression analysis, the IOP OD of the whole population had good correlation with CCT OD of the whole population (adjusted r2 = 0.084, p = 0.002), but not with age (adjusted r2=0.000, p=0.314) and sex (adjusted r2 = 0.010, p = 0.163). Similarly, CCT OD for the whole population did not have good correlation with age (adjusted r2 = -0.009, p = 0.762) and sex (adjusted r2 = -0.007, p = 0.603). Conclusions: In this study of individuals with normal corneas and without glaucoma, no racial variation was found in the CCT and IOP values of the two groups. The IOP OD of whole population had good correlation with CCT, but not with age and sex. There was good correlation between OD and OS values of IOP and CCT.

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Corneal Biomechanical Parameters and Central Corneal Thickness in Glaucoma Patients, Glaucoma Suspects, and a Healthy Population

Journal of Clinical Medicine ◽

10.3390/jcm10122637 ◽

2021 ◽

Vol 10 (12) ◽

pp. 2637

Author(s):

Mª. Ángeles del Buey-Sayas ◽

Elena Lanchares-Sancho ◽

Pilar Campins-Falcó ◽

María Dolores Pinazo-Durán ◽

Cristina Peris-Martínez

Keyword(s):

Central Corneal Thickness ◽

Corneal Thickness ◽

Mean Difference ◽

The Other ◽

Control Group ◽

Healthy Population ◽

Diagnostic Categories ◽

Significant Difference ◽

Biomechanical Parameters ◽

The Mean

Purpose: To evaluate and compare corneal hysteresis (CH), corneal resistance factor (CRF), and central corneal thickness (CCT), measurements were taken between a healthy population (controls), patients diagnosed with glaucoma (DG), and glaucoma suspect patients due to ocular hypertension (OHT), family history of glaucoma (FHG), or glaucoma-like optic discs (GLD). Additionally, Goldmann-correlated intraocular pressure (IOPg) and corneal-compensated IOP (IOPcc) were compared between the different groups of patients. Methods: In this prospective analytical-observational study, a total of 1065 patients (one eye of each) were recruited to undergo Ocular Response Analyzer (ORA) testing, ultrasound pachymetry, and clinical examination. Corneal biomechanical parameters (CH, CRF), CCT, IOPg, and IOPcc were measured in the control group (n = 574) and the other groups: DG (n = 147), FHG (n = 78), GLD (n = 90), and OHT (n = 176). We performed a variance analysis (ANOVA) for all the dependent variables according to the different diagnostic categories with multiple comparisons to identify the differences between the diagnostic categories, deeming p < 0.05 as statistically significant. Results: The mean CH in the DG group (9.69 mmHg) was significantly lower compared to controls (10.75 mmHg; mean difference 1.05, p < 0.001), FHG (10.70 mmHg; mean difference 1.00, p < 0.05), GLD (10.63 mmHg; mean difference 0.93, p < 0.05) and OHT (10.54 mmHg; mean difference 0.84, p < 0.05). No glaucoma suspects (FHG, GLD, OHT groups) presented significant differences between themselves and the control group (p = 1.00). No statistically significant differences were found in the mean CRF between DG (11.18 mmHg) and the control group (10.75 mmHg; mean difference 0.42, p = 0.40). The FHG and OHT groups showed significantly higher mean CRF values (12.32 and 12.41 mmHg, respectively) than the DG group (11.18 mmHg), with mean differences of 1.13 (p < 0.05) and 1.22 (p < 0.001), respectively. No statistically significant differences were found in CCT in the analysis between DG (562 μ) and the other groups (control = 556 μ, FHG = 576 μ, GLD = 569 μ, OHT = 570 μ). The means of IOPg and IOPcc values were higher in the DG patient and suspect groups than in the control group, with statistically significant differences in all groups (p < 0.001). Conclusion: This study presents corneal biomechanical values (CH, CRF), CCT, IOPg, and IOPcc for diagnosed glaucoma patients, three suspected glaucoma groups, and a healthy population, using the ORA. Mean CH values were markedly lower in the DG group (diagnosed with glaucoma damage) compared to the other groups. No significant difference was found in CCT between the DG and control groups. Unexpectedly, CRF showed higher values in all groups than in the control group, but the difference was only statistically significant in the suspect groups (FHG, GLD, and OHT), not in the DG group.

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Intraocular Pressure Changes Following Different Keratoplasty Techniques and Association with Cornea Parameters and anterior Chamber Depth

10.21203/rs.3.rs-254015/v1 ◽

2021 ◽

Author(s):

Gülşah Gümüş ◽

cigdem altan ◽

yusuf yildirim ◽

nilay kandemir besek ◽

selim genç ◽

...

Keyword(s):

Intraocular Pressure ◽

Anterior Chamber ◽

Corneal Thickness ◽

Anterior Chamber Depth ◽

Early Postoperative Period ◽

Lamellar Keratoplasty ◽

Deep Anterior Lamellar Keratoplasty ◽

Anterior Lamellar Keratoplasty ◽

The Difference ◽

Pressure Changes

Abstract Purpose To evaluate early intraocular pressure (IOP) changes following different keratoplasty techniques and to investigate the relationship between corneal thickness (CT), keratometry values, anterior chamber depth (ACD) and IOP changes. Methods We included patients who underwent penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK). ACD, CT, and keratometry measurements were repeated postoperatively at hour 24, week 1, and month 1. IOP measurements were repeated at postoperative hours 6 and 24, week 1, and month 1 by Tono-Pen XL. Results Twenty-two patients underwent PK, 12 patients underwent DALK, and 19 patients underwent DMEK. The difference between the IOP preoperatively and 6 hours postoperatively and between the IOP preoperatively and 24 hours postoperatively were statistically significant in the three types of surgery (p < 0.05 for each). The difference between preoperative and postoperative week 1 IOP was statistically significant only in the PK group (p = 0.023). When the IOP was compared between the three types of surgeries, the IOP at postoperative week 1 in the PK group was significantly higher than the DALK and DMEK groups (p = 0.021). There was no correlation between ACD, corneal thickness, K values, and IOP in any group. Conclusion IOP may increase in all types of keratoplasty during the first hours after surgery, but PK has a risk of high IOP longer in the early postoperative period. PK patients should be followed more carefully during postoperative week 1 to check for an increase in IOP.

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Age distribution and associated factors of cornea biomechanical parameter stress-strain index in Chinese healthy population

BMC Ophthalmology ◽

10.1186/s12886-020-01704-6 ◽

2020 ◽

Vol 20 (1) ◽

Author(s):

Guihua Liu ◽

Hua Rong ◽

Ruxia Pei ◽

Bei Du ◽

Nan Jin ◽

...

Keyword(s):

Intraocular Pressure ◽

Axial Length ◽

Corneal Thickness ◽

Age Distribution ◽

Partial Least Square ◽

Healthy Population ◽

Corneal Curvature ◽

Stress Strain ◽

Strain Index ◽

Biomechanical Parameter

Abstract Background To investigate the new cornea biomechanical parameter stress-strain index (SSI) in Chinese healthy people and the factors associated with SSI. Methods A total of 175 eyes from 175 participants were included in this study. Axial length was measured with the Lenstar LS-900. Pentacam measured curvature of the cornea and anterior chamber volume (ACV). Cornea biomechanical properties assessments were performed by corneal visualization Scheimpflug technology (Corvis ST). Student’s t-test, one-way ANOVA, partial least square linear regression (PLSLR) and linear mixed effects (LME) model were used in the statistical analysis. Results The mean (±SD) SSI was 1.14 ± 0.22 (range, 0.66–1.78) in all subjects and affected by age significantly after age of 35 (P < 0.05). In LME models, SSI was significantly associated with age (β = 0.526, P < 0.001), axial length (AL) (β = − 0.541, P < 0.001), intraocular pressure (IOP) (β = 0.326, P < 0.001) and steepest radius of anterior corneal curvature (RsF) (β = 0.229, P < 0.001) but not with ACV, biomechanical corrected intraocular pressure (bIOP), flattest radius of anterior corneal curvature (RfF) or central corneal thickness (CCT) (P > 0.05 for each). Conclusions SSI increased with age after the age of 35. In addition to age, SSI was positively correlated with RsF and IOP, while negatively correlated with AL.

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Analysis of reproducibility, evaluation, and preference of the new iC100 rebound tonometer versus iCare PRO and Perkins portable applanation tonometry

European Journal of Ophthalmology ◽

10.1177/1120672119878017 ◽

2019 ◽

Vol 30 (6) ◽

pp. 1349-1355 ◽

Cited By ~ 1

Author(s):

Mercedes Molero-Senosiaín ◽

Laura Morales-Fernández ◽

Federico Saenz-Francés ◽

Julian García-Feijoo ◽

Jose María Martínez-de-la-Casa

Keyword(s):

Intraocular Pressure ◽

Visual Analogue Scale ◽

Analogue Scale ◽

Normal Subjects ◽

Applanation Tonometry ◽

Rebound Tonometer ◽

The Mean ◽

The Difference ◽

The Comparative Study ◽

Mean Time

Objectives: To analyze the reproducibility of the new iC100 rebound tonometer, to compare its results with the applanation tonometry and iCare PRO and to evaluate the preference between them. Materials and methods: For the study of reproducibility, 15 eyes of 15 healthy Caucasian subjects were included. Three measurements were taken each day in three separate sessions. For the comparative study, 150 eyes of 150 Caucasian subjects were included (75 normal subjects and 75 patients with glaucoma). Three consecutive measurements were collected with each tonometer, randomizing the order of use. The discomfort caused by each tonometer was evaluated using the visual analogue scale. Results: No statistically significant differences were detected between sessions. In the comparison between tonometers, the measurements with iC100 were statistically lower than those of Perkins (−1.35 ± 0.417, p = 0.004) and that iCare PRO (−1.41 ± 0.417, p = 0.002). The difference between PRO and Perkins was not statistically significant ( p = 0.990). The mean time of measurement (in seconds) with iC100 was significantly lower than with Perkins (6.74 ± 1.46 vs 15.53 ± 2.01, p < 0.001) and that PRO (6.74 ± 1.46 vs 11.53 ± 1.85, p < 0.001). Visual analogue scale score with iC100 was lower than Perkins (1.33 ± 0.99 vs 1.73 ± 1.10, p < 0.05). In total, 61.7% preferred iC100 against Perkins. Conclusion: The reproducibility of this instrument has been proven good. iC100 underestimates intraocular pressure compared to applanation tonometry at normal values and tends to overestimate it in high intraocular pressure values. Most of the subjects preferred iC100 tonometer.

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Self-measurement with Icare HOME tonometer, patients’ feasibility and acceptability

European Journal of Ophthalmology ◽

10.1177/1120672118823124 ◽

2019 ◽

Vol 30 (2) ◽

pp. 258-263 ◽

Cited By ~ 3

Author(s):

Barbara Cvenkel ◽

Makedonka Atanasovska Velkovska ◽

Vesna Dimovska Jordanova

Keyword(s):

Intraocular Pressure ◽

Central Corneal Thickness ◽

Corneal Thickness ◽

Pressure Data ◽

Limits Of Agreement ◽

Goldmann Applanation Tonometer ◽

Applanation Tonometer ◽

Perception Of Self ◽

The Mean

Purpose: To evaluate and compare the accuracy of self-measurement of intraocular pressure using Icare Home rebound tonometer with Goldmann applanation tonometer and assess acceptability of self-tonometry in patients with glaucoma and ocular hypertension. Methods: In the study, 117 subjects were trained to use Icare Home for self-measurement. Icare Home tonometer readings were compared with Goldmann applanation tonometer, including one eye per patient. Agreement between the two methods of measurement was evaluated by Bland and Altmann analysis. Questionnaire was used to evaluate patients’ perception of self-tonometry. Results: One hundred and three out of 117 patients (88%) were able to measure their own intraocular pressure and 96 (82%) fulfilled the requirements for certification. The mean (SD) difference Goldmann applanation tonometer minus Icare Home was 1.2 (2.4) mmHg (95% limits of agreement, –3.4 to 5.9 mmHg). The magnitude of bias between the two methods depended on central corneal thickness, with greater bias at central corneal thickness <500 µm. In 65 out of 96 subjects (67.7%), Icare Home results were within 2 mmHg of the Goldmann applanation tonometer. Seventy-three out of 93 (78.5%) felt that self-tonometry was easy to use and 75 patients (80.6%) responded that they would use the device at home. Conclusion: Icare Home tonometry tends to slightly underestimate intraocular pressure compared to Goldmann applanation tonometer. Most patients were able to perform self-tonometry and found it acceptable for home use. Measurements using rebound self-tonometry could improve the quality of intraocular pressure data and optimize treatment regimen.

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Effects of SMILE Surgery on Intraocular Pressure, Central Corneal Thickness, Axial Length, Peripapillary Retinal Nerve Fiber Layer, and Macular Ganglion Cell Complex Thickness

Journal of Ophthalmology ◽

10.1155/2020/4934196 ◽

2020 ◽

Vol 2020 ◽

pp. 1-6

Author(s):

Zhanlin Zhao ◽

Sylvain Michée ◽

Jean-François Faure ◽

Christophe Baudouin ◽

Antoine Labbé

Keyword(s):

Intraocular Pressure ◽

Ganglion Cell ◽

Nerve Fiber ◽

Axial Length ◽

Central Corneal Thickness ◽

Corneal Thickness ◽

Ganglion Cell Complex ◽

Fiber Layer ◽

Rnfl Thickness ◽

The Mean

Purpose. To evaluate the change in intraocular pressure (IOP), central corneal thickness (CCT), axial length, peripapillary retinal nerve fiber layer (RNFL) thickness, and macular ganglion cell complex (GCC) thickness after small incision lenticule extraction (SMILE) surgery. Methods. This prospective observational study was conducted in Espace Nouvelle Vision, Ophthalmological Clinic, Paris, France. Fifty eyes of 25 patients were enrolled in this study and underwent SMILE surgeries. IOP, central corneal thickness (CCT), axial length (AL), peripapillary RNFL thickness, and macular GCC thickness were measured before and at 3 months after SMILE. Results. The mean preoperative spherical equivalent was −3.15 ± 1.50 diopters (D), and the mean postoperative value was 0.15 ± 0.28 D. After SMILE surgery, IOP decreased from 15.03 ± 2.79 mmHg to 11.02 ± 2.73 mmHg and 10.02 ± 2.21 mmHg at 1 and 3 months, respectively ( P < 0.01 for both comparisons). The mean decrease in measured IOP as a function of ablation depth was 0.065 ± 0.031 mmHg/μm. CCT decreased from 545.98 ± 26.61 μm to 478.40 ± 30.26 μm after SMILE surgery ( P < 0.01 ). AL decreased from 24.80 ± 0.84 mm to 24.70 ± 0.83 mm ( P < 0.01 ). There was no statistically significant change in mean peripapillary RNFL or mean GCC thickness after SMILE surgery. Conclusions. SMILE surgery modified IOP measurement, CCT, and AL but did not change peripapillary RNFL and macular GCC thicknesses. The postoperative drop in measured IOP might be explained by the decreased CCT. An accurate re-evaluation of AL should be performed before cataract surgery among post-SMILE patients.

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Age Distribution and Associated Factors of Cornea Biochemical Parameter Stress-Strain Index in Chinese Healthy Population

10.21203/rs.3.rs-56107/v1 ◽

2020 ◽

Author(s):

Guihua Liu ◽

Hua Rong ◽

Ruxia Pei ◽

Bei Du ◽

Nan Jin ◽

...

Keyword(s):

Intraocular Pressure ◽

Axial Length ◽

Regression Models ◽

Corneal Thickness ◽

Age Distribution ◽

Biochemical Parameter ◽

Healthy Population ◽

Corneal Curvature ◽

Stress Strain ◽

Strain Index

Abstract Background: To investigate the new cornea biochemical parameter stress-strain index (SSI) in Chinese healthy people and the factors associated with SSIMethods: A total of 175 eyes from 175 participants were recruited in this study. Axial length was measured with the Lenstar LS-900. Pentacam was used to measure curvature of the cornea and ACV and cornea biomechanical properties were measured by corneal visualization Scheimpflug technology (Corvis ST). Student’s t-test, one-way ANOVA, univariate and multivariate linear regression were used in the statistical analysis.Results: The mean (±SD) SSI was 1.14 ± 0.22 (range, 0.66–1.78) in all subjects and affected by age significantly after age of 35 (P < 0.05). In univariate regression models, SSI did not vary with biomechanical intraocular pressure (bIOP) (P=0.989), steepest radius of anterior corneal curvature (RsF) (P=0.984) or central corneal thickness (CCT) (P=0.651). In multivariate regression models, SSI was significantly associated with age (β=0.557, P<0.001), axial length (AL) (β=-0.550, P<0.001), intraocular pressure (IOP) (β=0.377, P<0.001) and flattest radius of anterior corneal curvature (RfF) (β=0.222, P<0.001) but not with anterior chamber volume (ACV).Conclusions: SSI was increased by age after the age of 35. In addition to age, SSI and RfF, IOP is positively correlated and negatively correlated with AL.

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