The factors influencing peripapillary choroidal thickness in primary open-angle glaucoma

Comparison of Peripapillary Choroidal Thickness Between Primary Open-angle Glaucoma, Normal Tension Glaucoma, and Normal Eyes: A Systematic Review and Meta-analysis

TOPIC

To investigate differences in peripapillary choroidal thickness (PPCT) between primary open-angle glaucoma (POAG), normal tension glaucoma (NTG), and healthy eyes, additionally comparing differences between POAG and NTG eyes.

CLINICAL RELEVANCE

Peripapillary choroidal thickness is a well-established OCT parameter in eyes with glaucoma and other ocular pathologies. The relationship between PPCT and glaucoma, if better understood, may facilitate the development of PPCT as a potential diagnostic and monitoring metric for glaucoma. In particular, there has yet to be a synthesis that directly compares PPCT between POAG eyes and NTG eyes.

METHODS

A comprehensive literature search was performed on PubMed, EMBASE, and Cochrane Library, identifying studies from inception to December 2022. We included studies that measured PPCT using OCT in POAG, NTG, and healthy eyes. Mean difference (MD) among groups was calculated. Statistical analysis was performed using R version 4.2.0. Risk of bias of included studies was assessed using the Newcastle Ottawa Scale (NOS).

RESULTS

Eighteen studies were included in this meta-analysis, with a pooled total of 935 healthy control eyes, 446 NTG eyes, and 934 POAG eyes. There was a significant reduction of PPCT in POAG eyes compared with healthy eyes [MD = -16.32; 95% confidence interval (CI) (-27.55 to -5.09)]. Reduction in PPCT was also significant in NTG eyes compared with healthy eyes [MD = -34.96; 95% CI (-49.97 to -19.95)]. NTG eyes had significantly reduced PPCT compared with POAG eyes [MD = -26.64; 95% CI (-49.00 to -4.28)].

CONCLUSIONS

Glaucomatous eyes appear to have significantly reduced PPCT compared with normal healthy eyes. In addition, PPCT in NTG eyes appear significantly thinner compared with that in POAG eyes.

FINANCIAL DISCLOSURE(S)

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

Estrogen dysregulation, intraocular pressure, and glaucoma risk

Characterized by optic nerve atrophy due to retinal ganglion cell (RGC) death, glaucoma is the leading cause of irreversible blindness worldwide. Of the major risk factors for glaucoma (age, ocular hypertension, and genetics), only elevated intraocular pressure (IOP) is modifiable, which is largely regulated by aqueous humor outflow through the trabecular meshwork. Glucocorticoids such as dexamethasone have long been known to elevate IOP and lead to glaucoma. However, several recent studies have reported that steroid hormone estrogen levels inversely correlate with glaucoma risk, and that variants in estrogen signaling genes have been associated with glaucoma. As a result, estrogen dysregulation may contribute to glaucoma pathogenesis, and estrogen signaling may protect against glaucoma. The mechanism for estrogen-related protection against glaucoma is not completely understood but likely involves both regulation of IOP homeostasis and neuroprotection of RGCs. Based upon its known activities, estrogen signaling may promote IOP homeostasis by affecting extracellular matrix turnover, focal adhesion assembly, actin stress fiber formation, mechanosensation, and nitric oxide production. In addition, estrogen receptors in the RGCs may mediate neuroprotective functions. As a result, the estrogen signaling pathway may offer a therapeutic target for both IOP control and neuroprotection. This review examines the evidence for a relationship between estrogen and IOP and explores the possible mechanisms by which estrogen maintains IOP homeostasis.

Correlation between radial peripapillary vascular density and reduced central corneal thickness in glaucoma suspect patients

Background

Optical coherence tomography (OCT) angiography (OCTA) provides a quantitative assessment of the microcirculation of the retina and choroid. It may precede the retinal nerve layer (RNFL) and optic disc head defects. Retinal nerve fiber layer defects and reduced central corneal thickness (CCT) are important parameters in the assessment of a glaucoma suspect patients. The aim of this study is to investigate any possible relationship between the reduced central corneal thickness and the radial peripapillary capillary (RPC) density defect in glaucoma suspect.

Methods

In this cross sectional study, 92 eyes were incorporated. Peripapillary OCT angiography (4.5 mm) and Anterior segment OCT for corneal pachymetry were done. C/D Ratio, thickness of nerve fiber layer, the blood flow indices and central corneal thickness also were evaluated.

Results

In eyes of glaucoma suspect patients; a significant positive correlation between CCT and total RPC density was detected (r = 0.38, P < 0.001). A strong positive correlation was also found between total RPC and peripapillary RNFL thickness (r = 0.55, P < 0.001).

Conclusion

Reduced central corneal thickness and peripapillary capillary density are two screening parameters for glaucoma suspect patients. The radial peripapillary capillary density is a valid diagnostic tool for glaucoma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-022-02628-z.

Determinants of vessel defects in superficial and deep vascular layers in normal-tension glaucoma using optical coherence tomography angiography

We investigated the characteristics of localized vessel density defects (VD) either in the deep or superficial vascular layer of normal-tension glaucoma patients using optical coherence tomography angiography (OCTA). In this retrospective, cross-sectional study, 74 eyes with localized retinal nerve fiber layer (RNFL) defect were included. The relationships between the widths of the VD in the superficial and deep layer and ocular factors were evaluated. Eyes with greater deep VD were significantly older (P = 0.023). The IOP measured at OCTA exam was significantly related to the width of the deep VD (P = 0.009). By contrast, average ganglion cell inner plexiform layer thickness (GCIPLT) was substantially related to the width of the superficial VD (P = 0.004). In logistic regression analysis, aging was noticeably associated with wider deep VD, whereas worse mean deviation (MD) had a significant association with wider superficial VD (P = 0.001, P = 0.003, respectively). In sum, while changes of the superficial layer seemed an overall ramification of glaucomatous damages, the deep layer was more likely to be affected by factors related to ocular microcirculation, such as IOPs and older age. Thus, looking into the deep vascular layer using OCTA could identify risk factors related to the disturbance in ocular microcirculation.

Comparison of the lamina cribrosa parameters in eyes with exfoliation syndrome, exfoliation glaucoma and healthy subjects

PURPOSE

This study aimed to compare lamina cribrosa (LC) parameters obtained by spectral-domain optical coherence tomography (SD-OCT) of eyes with exfoliation syndrome (PXS), exfoliation glaucoma (PXG) and healthy subjects.

METHODS

In this cross-sectional comparative study, 206 eyes of 206 subjects were included. The Bruch's membrane opening distance (BMOd), the anterior and posterior borders of the LC (LC thickness) and the anterior laminar depth (ALD) were imaged using the enhanced depth imaging (EDI) mode of SD-OCT.

RESULTS

There were 96 eyes in the PXG group, 55 eyes in the PXS group, and 55 eyes in the control group. The LC thickness was the thinnest in the PXG group (151.10 ± 51.18 μm), followed in the PXS group (158.76 ± 49.62 μm), and the thickest in the control group (181.00 ± 39.10 μm) (p = 0.002). In PXG cases where LC was observed in the deepest location, the ALD value was highest (423.92 ± 111.75 μm) in the PXG group, followed by the control group (403.08 ± 63.56 μm), and PXS group (357.43 ± 80.87 μm) (p < 0.001). The BMOd values were largest in the PXG group (1542.43 ± 152.99 μm), followed by the control group (1506.52 ± 169.09 μm) and PXS group (1435.74 ± 141.06 μm) (p < 0.001). In the PXG group, peripapillary retinal nerve fiber layer (pRNFL) thickness, BCVA, and cup to disc (C/D) ratio were also statistically different from the other groups (p < 0.001).

CONCLUSION

We found thinner LC thickness in PXG and PXS cases relative to the control group. Although its severity is associated with the diagnosis and severity of glaucoma, LC thinning can be encountered as an isolated condition in the presence of exfoliation.

EDI-OCT choroidal thickness in Posner-Schlossman syndrome

PURPOSE

To compare the choroidal thickness (CT) of the affected eyes with the contralateral eyes in the active period and in the remission period in Posner-Schlossman syndrome (PSS) using EDI-OCT.

PATIENTS AND METHODS

This prospective longitudinal study included 15 patients with PSS and 15 age- and sex-matched healthy subjects. All subjects underwent complete ophthalmologic examinations, and EDI-OCT was conducted to measure macular CT (mCT) at the subfoveal locations and at 0.5, 1.0 and 2.0 mm superior, inferior, nasal and temporal to the fovea. The mean measurements at each location were used for analysis. Linear regression analysis was performed to analyse the correlation between the choroidal thickness and IOP, and the correlation between the choroidal thickness and episode time.

RESULTS

The mean mCT was significantly thinner in affected eyes than in contralateral eyes in the acute phase (p = 0.010) but were not different in the remission phase (p = 0.404). The mean mCT was significantly increased in the remission phase compared to that in the acute phase in the affected eyes (p = 0.000). The mCT of healthy subjects was significantly thicker than in the affected eyes (p = 0.020) and similar to the fellow eyes of PSS patients (p = 0.357) in the acute phase. Linear regression analyses show negative correlations between the mCT changes and IOP changes in the affected eyes compared to those in the fellow eyes in the acute period (R² = 0.396, p = 0.033) and between the mCT changes and IOP changes from the acute period to the remission period in the affected eyes (R² = 0.372, p = 0.027). Linear regression analyses show positive correlations (age- and sex-matched) between the CT changes and episode time from the affected eyes to the fellow eyes in the acute period (R² = 0.492, p = 0.012).

CONCLUSIONS

The mCT values of the PSS-affected eyes were significantly thinner than those of the fellow eyes in the acute phase and in the remission phase, and this change was correlated with IOP reduction and episode time.

Factors Influencing Optical Coherence Tomography Peripapillary Choroidal Thickness: A Multicenter Study

Purpose

To quantify peripapillary choroidal thickness (PCT) and the factors that influence it in healthy participants who represent the racial and ethnic composition of the U.S. population.

Methods

A total of 362 healthy participants underwent optical coherence tomography (OCT) enhanced depth imaging of the optic nerve head with a 24 radial B-scan pattern aligned to the fovea to Bruch's membrane opening axis. Bruch's membrane, anterior scleral canal opening (ASCO), and the anterior scleral surface were manually segmented. PCT was measured at 100, 300, 500, 700, 900, and 1100 μm from the ASCO globally and within 12 clock-hour sectors. The effects of age, axial length, intraocular pressure, ethnicity, sex, sector, and ASCO area on PCT were assessed by ANOVA and univariable and multivariable regressions.

Results

Globally, PCT was thicker further from the ASCO border and thinner with older age, longer axial length, larger ASCO area, European descent, and female sex. Among these effectors, age and axial length explained the greatest proportion of variance. The rate of age-related decline increased further from the ASCO border. Sectorally, the inferior-temporal sectors were thinnest (10.7%-20.0% thinner than the thickest sector) and demonstrated a higher rate of age-related loss (from 15.6% to 20.7% faster) at each ASCO distance.

Conclusions

In healthy eyes, PCT was thinnest in the inferior temporal sectors and thinner PCT was associated with older age, European descent, longer axial length, larger ASCO area, and female sex. Among these associations, age had the strongest influence, and its effect was greatest within the inferior temporal sectors.

Evaluation of Prelaminar Region and Lamina Cribrosa with Enhanced Depth Imaging Optical Coherence Tomography in Pseudoexfoliation Glaucoma

Objectives:

To analyze optic nerve head images of pseudoexfoliative glaucoma (PXG) patients and healthy volunteers obtained with enhanced depth imaging spectral domain-optical coherence tomography (SD-OCT).

Materials and Methods:

Seventy patients with PXG and 68 age- and gender-matched healthy subjects were included in this prospective study. The prelaminar tissue and lamina cribrosa were imaged using spectralis OCT with the enhanced depth imaging technique. PXG disease stage was determined with visual field to evaluate relationships between prelaminar tissue thickness (PTT), lamina cribrosa thickness (LT) and disease severity.

Results:

There was no significant difference between the PXG group and control group with regard to age, gender, central corneal thickness, or axial length. The mean PTT (93.1±44.5 μm, p<0.05) and LT (206.3±33.6 μm p<0.05) values of the PXG group were significantly lower compared to the control group in enhanced depth imaging OCT measurements. The PXG patients were divided into stages according to visual field defect severity. While a significant difference was not detected in PTT based on disease stage (p>0.05), a statistically significant difference was detected between stages for LT (p<0.05).

Conclusion:

A thinner PTT was correlated with the presence of PXG but not with the severity of glaucoma. In addition, LT has a stronger relationship with disease severity and progression compared to PTT.