The Impact of Intraocular Pressure Changes on Corneal Biomechanics in Primary Open-angle Glaucoma.
Xu Yunzhi, Ye Yiming, Chen Zidong, Xu Jiangang, Yang Yangfan, Zhang Yuning, Liu Pingping, Fan Yanmei, Chong Iok Tong, Yu Keming
AI Summary
This study found that lowering intraocular pressure significantly reduces corneal stiffness and modulus, and corneal biomechanics differ among glaucoma types, with normal-tension glaucoma corneas being the softest.
Abstract
Purpose
To investigate the relationship between intraocular pressure (IOP) changes and corneal biomechanical properties, determine the quantitative relationship between IOP changes and corneal biomechanical properties in patients with glaucoma and observe the differences among different types of glaucoma when the effects of high-level IOP were excluded.
Design
Prospective clinical cohort study.
Methods
Setting: Institutional.
Patients: Treatment-naive patients with primary open-angle glaucoma or ocular hypertension (OHT) were included.
Observation procedures: IOP was measured using a Goldmann applanation tonometer. Corneal biomechanics were evaluated using a corneal indentation device and corneal visualization Scheimpflug technology. Medication therapy was used for IOP reduction. Repeated measurements were taken at the baseline visit and each week thereafter within a month. Paired t tests were used to compare IOP and corneal biomechanical metrics before and after IOP-lowering therapy. One-way analysis of variance was employed to investigate potential differences across groups, with a Bonferroni post hoc correction administered for multiple intergroup comparisons.
Main outcome measures
Corneal biomechanical parameters following IOP changes.
Results
Eighty-one participants (mean age, 41.63 ± 17.33 years) were included in this study. The cohort comprised 20 patients with normal-tension glaucoma (NTG), 47 with high-tension glaucoma (HTG), and 14 with OHT. The baseline corneal stiffness (88.58 ± 18.30 N/m) and corneal modulus (0.71 ± 0.16 MPa) were greater than the post-IOP reduction values (67.15 ± 9.24 N/m and 0.54 ± 0.08 MPa, respectively; P < .001). The relationships between changes in IOP and changes in corneal biomechanical parameters were Δ corneal stiffness = 2.06*ΔIOP+6.47 (P < .001) and Δ corneal modulus = 0.017*ΔIOP+0.051 (P < .001). After IOP reduction, the mean corneal stiffness at the 4th week in the NTG group was significantly lower (60.97 ± 6.36 N/m) than that in the HTG (67.25 ± 9.01 N/m) and OHT (75.62 ± 6.52 N/m, P < .001) groups. Additionally, the stiffness of HTG patients was lower than that of OHT patients (P = .003).
Conclusions
Changes in IOP have an impact on corneal biomechanical parameters. Decreases in corneal stiffness and modulus were observed after IOP reduction. When the effect of high-level IOP was excluded, corneal biomechanics varied according to the type of glaucoma. The HTG corneas were softer than the OHT corneas, and the NTG corneas were even softer.
MeSH Terms
Shields Classification
Key Concepts4
In a prospective clinical cohort study of 81 participants (mean age, 41.63 ± 17.33 years) with primary open-angle glaucoma or ocular hypertension, the baseline corneal stiffness was 88.58 ± 18.30 N/m, and the corneal modulus was 0.71 ± 0.16 MPa. Following IOP reduction through medication therapy, these values decreased to 67.15 ± 9.24 N/m and 0.54 ± 0.08 MPa, respectively (P < .001).
In a prospective clinical cohort study of 81 participants with primary open-angle glaucoma or ocular hypertension, the relationship between changes in intraocular pressure (IOP) and changes in corneal biomechanical parameters was quantified as Δ corneal stiffness = 2.06*ΔIOP+6.47 (P < .001) and Δ corneal modulus = 0.017*ΔIOP+0.051 (P < .001).
In a prospective clinical cohort study of 81 participants with primary open-angle glaucoma or ocular hypertension, after intraocular pressure (IOP) reduction, the mean corneal stiffness at the 4th week in the normal-tension glaucoma (NTG) group was significantly lower (60.97 ± 6.36 N/m) than that in the high-tension glaucoma (HTG) group (67.25 ± 9.01 N/m) and the ocular hypertension (OHT) group (75.62 ± 6.52 N/m, P < .001).
In a prospective clinical cohort study of 81 participants with primary open-angle glaucoma or ocular hypertension, after intraocular pressure (IOP) reduction, the stiffness of high-tension glaucoma (HTG) patients was lower than that of ocular hypertension (OHT) patients (P = .003).
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