Relationship between Intraocular Pressure Fluctuation and Visual Field Progression Rates in the United Kingdom Glaucoma Treatment Study

The impact of intraocular pressure fluctuations on the progression of glaucoma and associated factors

Background

In recent years, remarkable advancements in the comprehension of glaucoma pathophysiology have highlighted the necessity of looking beyond the conventional focus on mean intraocular pressure (IOP) levels. IOP fluctuations have been identified as a potential factor that could exert a substantial impact on the progression of glaucoma.

Main text

IOP exhibits dynamic variations throughout a 24-h cycle. Glaucoma patients exhibit substantially more pronounced IOP fluctuations compared to healthy individuals, even when the mean IOP remains within the normal range. This implies that IOP fluctuations may play a role in glaucoma progression through mechanisms independent of elevated mean IOP. In this review, an exhaustive examination of studies spanning the past decade was conducted to analyze the relationship between IOP fluctuations and disease progression in primary open-angle glaucoma (POAG), ocular hypertension (OHT), normal tension glaucoma (NTG), and primary angle-closure glaucoma (PACG). While a few studies present conflicting results, the majority of research supports the notion that elevated IOP fluctuations significantly contribute to disease progression in POAG patients. This association has also been confirmed in PACG patients. However, in NTG or OHT patients, other risk factors may outweigh IOP fluctuations in disease progression or glaucoma conversion. Additionally, we summarized common factors affecting IOP fluctuations to provide a basis for the identification of patients prone to significant daily IOP variations. Finally, the efficacy of various IOP-lowering interventions in modulating IOP fluctuations is concisely summarized, offering insights for the formulation of comprehensive treatment strategies that incorporate IOP fluctuation management.

Conclusions

IOP fluctuations play a significant role in disease progression in POAG and PACG. Individuals with certain systemic or ocular characteristics are more predisposed to pronounced and recurrent IOP fluctuations. Consequently, a comprehensive assessment of IOP fluctuation that transcends mean IOP values, as well as the integration of IOP fluctuations management into glaucoma treatment strategies are of paramount importance.

Risk for ocular hypertension progression to early glaucoma: A predictive model and key predictors

BACKGROUND

Ocular hypertension (OHT) is the most significant risk factor for glaucoma. We aimed to develop a model for predicting OHT progression to early glaucoma and to identify key predictors.

METHODS

Patients with OHT with at least two follow-up visits within 3 years were categorized into non-progressive and progressive groups based on optic nerve morphology and/or functional changes during follow-up. Data were split into training and testing sets (8:2 ratio). Least absolute shrinkage and selection operator regression and logistic regression were used to select predictors. Machine learning models were constructed using the selected predictors as input and evaluated using area under the receiver operating characteristic (AUC) and precision-recall (AP) curve values. The optimal model was further evaluated using 10-fold cross-validation and a validation set. The Shapley additive explanations method was applied to interpret the predictors.

RESULTS

Overall, 395 eyes from 395 patients were included (non-progressive: n=295; progressive: n=100). The random forest model outperformed all others, achieving AUC values of 0.881 (95% confidence interval [CI]: 0.835-0.926) in the training set and 0.937 (95% CI: 0.884-0.991) in the testing set. In the independent validation set (n=82), the AUC and AP values were 0.865 (95% CI: 0.782-0.947) and 0.707, respectively. Key predictors were baseline intraocular pressure, rim area, ganglion cell-inner plexiform layer (GCIPL) inferior-temporal thickness difference, and GCIPL superior-temporal thickness difference. Family history and male sex also contributed.

CONCLUSIONS

The developed model could effectively predict the risk for OHT progression to early glaucoma and may aid devising individualized treatment plans and follow-up protocols.

Relationship Between Intraocular Pressure and the True Rate of Functional and Structural Progression in the United Kingdom Glaucoma Treatment Study

Purpose

To investigate the effect of average intraocular pressure (IOP) on the true rate of glaucoma progression (RoP) in the United Kingdom Glaucoma Treatment Study (UKGTS).

Methods

UKGTS participants were randomized to placebo or Latanoprost drops and monitored for up to two years with visual field tests (VF, 24-2 SITA standard), IOP measurements, and optic nerve imaging. We included eyes with at least three structural or functional assessments (VF with <15% false-positive errors). Structural tests measured rim area (RA) with Heidelberg retina tomography (HRT) and average peripapillary retinal nerve fiber layer (pRNFL) thickness with optical coherence tomography (OCT). One eye of 436 patients (222 on Latanoprost) was analyzed. A Bayesian hierarchical model estimated the true RoP of VF and structural metrics, and their correlations, using sign-reversed multivariable exponential distribution. RA and pRNFL measurements were converted to a dB scale, matching the VF metric (mean deviation [MD]). The effect of average IOP on the true RoPs was estimated.

Results

True RoP at the mean average IOP (17 mm Hg) was faster (P < 0.001) for VF-MD (-0.59 [-0.73, -0.48] dB/year) than HRT-RA (-0.05 [-0.07, -0.03] dB/year) and OCT-pRNFL (-0.08 [-0.11, -0.06] dB/year). The proportional acceleration of RoP per mm Hg increase was, however, not significantly different (smallest P = 0.15). Accounting for the structural floor-effect largely eliminated the differences in RoPs (smallest P = 0.25).

Conclusions

VF appeared to deteriorate at a faster rate than structural measurements. However, this could be explained by the floor-effect from nonfunctional tissue. IOP induced a similar acceleration in RoP per mm Hg increase.

Intraocular pressure and optical coherence tomography concerning visual field outcomes in "green" patients: An observational study

This study investigates the relationship between intraocular pressure (IOP), optical coherence tomography (OCT) parameters, and visual field (VF) outcomes in 'Green' patients-those with normal OCT findings but potential VF abnormalities. Understanding this relationship is crucial for improving early detection and management strategies for glaucoma, especially in patients who show functional loss despite normal structural findings on OCT. A cross-sectional study was conducted at Taipei City Hospital, Renai Branch, Taiwan, from July 1, 2015, to July 1, 2023. Participants were referred for suspected glaucoma and included based on normal OCT parameters ('green' coding) and completed VF tests. Patients with any ocular disease that could confound results were excluded. Logistic regression models were used to assess relationships between IOP, OCT parameters (rim area, disc area, retinal nerve fiber layer thickness, cup-to-disc ratios, and cup volume), and VF outcomes. Age, sex, and IOP status (normal or ocular hypertension) were also included in the analysis. All data were analyzed using Statistical Package for the Social Sciences version 23.0. Larger disc area was a significant predictor of VF abnormalities, with an adjusted OR of 3.72 (95% confidence interval [CI], 1.14-12.15). Neither normal IOP nor ocular hypertension significantly predicted VF loss (adjusted OR = 0.89; 95% CI, 0.27-2.96). Female sex was associated with a higher likelihood of VF abnormalities (adjusted OR = 5.68; 95% CI, 1.03-31.25). Other OCT parameters, including retinal nerve fiber layer thickness and cup-to-disc ratios, were not significantly associated with VF outcomes. Disc area plays a critical role in predicting VF abnormalities in "green" patients, suggesting the importance of integrating disc size into screening and monitoring protocols. These findings challenge the reliance on IOP alone for predicting VF loss and support the need for more comprehensive assessments. Future research should explore longitudinal studies to further assess the predictive value of disc area and investigate additional factors, such as vascular and biomechanical influences, that may contribute to VF deterioration in this population.

Intraocular Pressure Response to Perceived Stress in Juvenile-Onset Open Angle Glaucoma

PRCIS

High perceived stress from academic pressure is associated with intraocular pressure (IOP) elevation and reduced fluctuation in juvenile-onset open angle glaucoma patients. Personalized stress assessment and relief strategies may serve as an adjunct therapy in glaucoma.

OBJECTIVE

To evaluate the effect of higher perceived stress, resulting from academic pressure, on IOP in juvenile-onset open angle glaucoma (JOAG) patients compared with healthy individuals.

METHODS

The study included 48 university students aged 18-27 years, comprising 24 JOAG patients on antiglaucoma eyedrops and 24 healthy controls. In an examiner-blind pretest-posttest design, participants' IOP was measured weekly using Goldmann tonometry during three follow-up visits at the beginning and end of the academic semester. Perceived Stress Scale (PSS) scores were also evaluated at these 2-time points to capture the contrast in perceived stress between periods of low and high academic pressure.

RESULTS

The baseline PSS score at the semester's start was lower in both groups (14.1±1.9 in glaucoma vs. 13.5±2.4 in control) and significantly increased by the end of the semester (29.2±2.1 vs. 28.5±1.3; P <0.001), indicating increased perceived stress. Concurrently, IOP rose from 22.01±5.87 to 25.08±5.84 mm Hg in the glaucoma group and from 11.36±2.03 to 13.65±2.11 mm Hg in the control group. Factorial analysis revealed a significant interaction between stress and JOAG ( F(1,94) =15.94, P =0.001), partial η 2 =0.08, with stress having a greater increase on IOP in the glaucoma group (+3.10 mm Hg) compared with the control group (+2.23 mm Hg) ( t(94) =4.457, P <0.001).

CONCLUSIONS

Higher perceived stress significantly increases IOP, especially in JOAG patients, suggesting personalized stress management as a potential adjunct therapy for patients.

Visual Field Outcomes in the Primary Tube Versus Trabeculectomy Study

PURPOSE

To describe visual field outcomes in the Primary Tube Versus Trabeculectomy (PTVT) Study.

DESIGN

Cohort analysis.

PARTICIPANTS

A total of 155 eyes (155 subjects) randomly assigned to treatment with tube shunt surgery (n = 84) or trabeculectomy with mitomycin C (n = 71).

METHODS

The PTVT Study was a multicenter randomized clinical trial comparing the safety and efficacy of trabeculectomy and tube shunt surgery in eyes without previous intraocular surgery. Subjects underwent standard automated perimetry (SAP) at baseline and annually for 5 years. Standard automated perimetry tests were deemed reliable if the false-positive rate was ≤ 15%. Tests were excluded if visual acuity was ≤ 20/400 or loss of ≥ 2 Snellen lines from baseline because of a nonglaucomatous etiology. Linear mixed-effects models were used to compare rates of change in SAP mean deviation (MD) between the 2 groups. Intraocular pressure (IOP) control was assessed by percentage of visits with IOP < 18 mmHg and mean IOP.

MAIN OUTCOME MEASURES

Rate of change in SAP MD during follow-up.

RESULTS

A total of 730 SAP tests were evaluated (average of 4.7 tests per eye). The average SAP MD at baseline was -12.8 ± 8.3 decibels (dB) in the tube group and -12.0 ± 8.4 dB in the trabeculectomy group (P = 0.57). The mean rate of change in SAP MD was -0.32 ± 0.39 dB/year in the trabeculectomy group and -0.47 ± 0.43 dB/year in the tube group (P = 0.23). Eyes with mean IOP 14 to 17.5 mmHg had significantly faster rates of SAP MD loss compared with eyes with mean IOP < 14 mmHg (-0.59 ± 0.13 vs. -0.27 ± 0.08 dB/year; P = 0.012), and eyes with only 50% to 75% of visits with IOP < 18 mmHg had faster rates than those with 100% of visits with IOP < 18 mmHg (-0.90 ± 0.16 vs. -0.29 ± 0.08 dB/year; P < 0.001). Multivariable analysis identified older age and worse IOP control as risk factors for faster progression in both treatment groups.

CONCLUSIONS

No statistically significant difference in mean rates of visual field change was observed between trabeculectomy and tube shunt surgery in the PTVT Study. Worse IOP control was significantly associated with faster rates of SAP MD loss during follow-up. Older patients were also at risk for faster progression.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Association of Long-Term Intraocular Pressure Variability and Rate of Ganglion Complex Thinning in Patients With Glaucoma

PURPOSE

To evaluate the association of mean intraocular pressure (IOP) and IOP variability (IOP fluctuation [SD of IOP] and the IOP range) with the rate of ganglion cell complex (GCC) layer thinning over time in patients with glaucoma.

DESIGN

Prospective cohort study.

METHODS

Participants with at least 4 visits and 2 years of follow-up of optical coherence tomography tests were included. A linear mixed-effect model was used to investigate the association of IOP parameters with the rates of GCC thinning. Subgroup analyses were conducted for eyes with early (MD ≥ -6 dB), and moderate to advanced stage (MD < -6 dB) at baseline.

RESULTS

The cohort consisted of 369 eyes of 249 glaucoma patients (282 early glaucoma and 87 moderate to advanced glaucoma) with mean (standard deviation [SD]) age of 68.2 (10.7) years over 5.1 years of follow-up. The mean rate of GCC change was -0.59 (95% confidence interval [CI], -0.67 to -0.52) µm per year. In multivariable models, faster annual rate of GCC thinning was associated with a higher IOP fluctuation (-0.17 [95% CI, -0.23 to -0.11] µm per 1-mmHg higher, P < .001) or higher IOP range (-0.07 [95% CI, -0.09 to -0.05] µm per 1-mmHg higher, P < .001) after adjustment for mean IOP and other confounding factors. Similar results were found for early and moderate to advanced stages of glaucoma.

CONCLUSIONS

IOP variability showed an independent association with macular change in patients with glaucoma regardless of severity at baseline, even after adjustment for mean IOP, supporting its potential value as a therapeutic target for clinical decision-making.