Peripapillary and macular choroidal thickness before and after phenylephrine instillation

Evaluation of Tropicamide-Phenylephrine Mydriatic Eye Drop Instillation on Choroidal Thickness

The purpose of this study is to evaluate choroidal thickness (ChT) at the subfoveal and peripheral level after the instillation of 0.5% tropicamide + 10% phenylephrine 9 hydrochloride eye drops by using OCT scans in enhanced depth image (EDI) mode. In total, 53 patients (30 males and 23 females) were involved, and the mean age was 25.62 ± 2.41 (age range: 23-36). The dominant eye was treated with tropicamide + phenylephrine (Visumidriatic Fenil 100 mg/mL + 5 mg/mL, Visufarma) while the nondominant eye was used as the control. An OCT analysis was performed on both eyes before and 30 min after the instillation of a drop of mydriatic in the dominant eye. The ChT was measured by using the OCT software measurement tool (Spectralis; Heidelberg Engineering; Heidelberg, Germany, version 6.0). The results showed a statistically significant ChT decrease (p = 0.009) in the temporal sector after the treatment with tropicamide + phenylephrine. In the subfoveal and nasal sectors, no statistically significant ChT changes were detected (p = 0.94; p = 0.85) following the administration of the mydriatic eye drops. The ChT thinning in the temporal sector following the instillation of the tropicamide + phenylephrine eye drops suggests that in the case of ChT studies, mydriatic administration should be avoided.

IMI-The Dynamic Choroid: New Insights, Challenges, and Potential Significance for Human Myopia

The choroid is the richly vascular layer of the eye located between the sclera and Bruch's membrane. Early studies in animals, as well as more recent studies in humans, have demonstrated that the choroid is a dynamic, multifunctional structure, with its thickness directly and indirectly subject to modulation by a variety of physiologic and visual stimuli. In this review, the anatomy and function of the choroid are summarized and links between the choroid, eye growth regulation, and myopia, as demonstrated in animal models, discussed. Methods for quantifying choroidal thickness in the human eye and associated challenges are described, the literature examining choroidal changes in response to various visual stimuli and refractive error-related differences are summarized, and the potential implications of the latter for myopia are considered. This review also allowed for the reexamination of the hypothesis that short-term changes in choroidal thickness induced by pharmacologic, optical, or environmental stimuli are predictive of future long-term changes in axial elongation, and the speculation that short-term choroidal thickening can be used as a biomarker of treatment efficacy for myopia control therapies, with the general conclusion that current evidence is not sufficient.

The retinal ganglion cell layer reflects neurodegenerative changes in cognitively unimpaired individuals

Background

To evaluate a wide range of optical coherence tomography (OCT) parameters for possible application as a screening tool for cognitively healthy individuals at risk of Alzheimer’s disease (AD), assessing the potential relationship with established cerebrospinal fluid (CSF) core AD biomarkers and magnetic resonance imaging (MRI).

Methods

We studied 99 participants from the Valdecilla Study for Memory and Brain Aging. This is a prospective cohort for multimodal biomarker discovery and validation that includes participants older than 55 years without dementia. Participants received a comprehensive neuropsychological battery and underwent structural 3-T brain MRI, lumbar puncture for CSF biomarkers (phosphorylated-181-Tau (pTau), total Tau (tTau), beta-amyloid 1–42 (Aβ 1–42), and beta-amyloid 1–40 (Aβ 1–40)). All individuals underwent OCT to measure the retinal ganglion cell layer (GCL), the retinal nerve fiber layer (RFNL), the Bruch’s membrane opening-minimum rim width (BMO-MRW), and choroidal thickness (CT). In the first stage, we performed a univariate analysis, using Student’s t-test. In the second stage, we performed a multivariate analysis including only those OCT parameters that discriminated at a nominal level, between positive/negative biomarkers in stage 1.

Results

We found significant differences between the OCT measurements of pTau- and tTau-positive individuals compared with those who were negative for these markers, most notably that the GCL and the RNFL were thinner in the former. In stage 2, our dependent variables were the quantitative values of CSF markers and the hippocampal volume. The Aβ 1–42/40 ratio did not show a significant correlation with OCT measurements while the associations between pTau and tTau with GCL were statistically significant, especially in the temporal region of the macula. Besides, the multivariate analysis showed a significant correlation between hippocampal volume with GCL and RNFL. However, after false discovery rate correction, only the associations with hippocampal volume remained significant.

Conclusions

We found a significant correlation between Tau (pTau) and neurodegeneration biomarkers (tTau and hippocampus volume) with GCL degeneration and, to a lesser degree, with damage in RFNL. OCT analysis constitutes a non-invasive and unexpensive biomarker that allows the detection of neurodegeneration in cognitively asymptomatic individuals.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13195-022-00998-6.

Effect of Mydriatic Administration On Retinal Hemodynamics in Glaucoma: An Optical Coherence Tomography Angiography Study

PRCIS

Pupillary dilation with 0.5% tropicamide and 2.5% phenylephrine resulted in a statistically significant decrease in foveal avascular zone (FAZ) metrics in glaucoma eyes. This observation emphasizes the critical role of pupillary status in interpreting glaucomatous vascular alterations detected by OCTA.

PURPOSE

To evaluate the influence of mydriatic eye drops on optical coherence tomography angiography (OCTA) parameters in patients with primary open-angle glaucoma (POAG).

METHODS

A total of 20 POAG eyes and 20 control eyes were recruited in the study. The imaging area on the fundus was visualized by AngioPlex (Cirrus 5000 HD-OCT; Carl Zeiss Meditec) using en face view of 3×3▒mm and 6×6▒mm preview scans. Images were generated before and after the instillation of topical 0.5% tropicamide and 2.5% phenylephrine. Optic nerve head (ONH) perfusion, ONH flux index, macular perfusion density, macular vessel density, and foveal avascular zone (FAZ) measurements were consecutively obtained for each session. Differences between the pre-and post-dilation measurements were evaluated in POAG patients and controls.

RESULTS

POAG eyes showed a statistically significant decrease in the FAZ area from a mean of 0.29▒mm2to 0.25▒mm2(P=0.037) and FAZ perimeter from a mean of 2.27▒mm to 2.09▒mm (P=0.045) in the OCTA 6×6▒mm scan area after tropicamide/phenylephrine instillation. Pre-and post-dilation measurements of ONH perfusion and ONH flux index were significantly lower in the glaucoma group compared to controls (P<0.05, for all).

CONCLUSION

Topical pupillary dilation with 0.5% tropicamide and 2.5% phenylephrine results in a statistically significant reduction in the FAZ area and FAZ perimeter in POAG eyes. Further OCTA studies are needed for the diagnostic value of vascular changes due to pupil dilation in glaucoma.

Choroidal Thickness Profile in Chorioretinal Diseases: Beyond the Macula

Enhanced depth imaging optical coherence tomography (EDI-OCT) and swept-source OCT (SS-OCT) have emerged as essential diagnostic tools in the study and management of various chorioretinal diseases. Evidence from early clinical studies using EDI-OCT and SS-OCT indicates that choroidal dysfunction plays a major role in the pathogenesis of chorioretinal diseases. Measurement of choroidal thickness (CT) has already become a major research and clinical method, and CT is considered as an indicator of choroidal status in a variety of ophthalmic diseases. Recently, CT measurement has also been proposed as a non-invasive marker for the early detection and monitoring of various systemic diseases. Among the several possible CT measurement locations, subfoveal CT has rapidly become a reliable parameter for measuring CT in healthy and diseased eyes. Moreover, recent advancements in OCT technology have enabled faster and wider imaging of the posterior part of the eye, allowing the various changes in CT as measured outside the macula to be shown accordingly. In this review, we first provide an overview of the results of clinical studies that have analyzed the healthy macular choroid and that in various chorioretinal diseases, and then summarize the current understanding of the choroid outside the macula. We also examine the CT profile as an index that encompasses both within and outside of the macula. Furthermore, we describe the clinical applications of ultrawide OCT, which enables visualization of the far periphery, and discuss the prospects for the development of more reliable choroidal parameters that can better reflect the choroid's characteristics.

Evaluation of choroidal thickness in prodromal Alzheimer's disease defined by amyloid PET

Objective

To assess and compare the involvement of choroidal thickness (CT) in patients with mild cognitive impairment (MCI) and dementia due to Alzheimer’s disease (AD) defined by amyloid PET and healthy controls (HC).

Methods

Sixty-three eyes from 34 AD patients [12 eyes (19.0%) with dementia and 51 eyes (80.9%) with MCI], positive to ¹¹C-labelled Pittsburgh Compound-B with positron emission tomography (¹¹C-PiB PET/CT), and the same number of sex- and age-paired HC were recruited. All participants underwent enhanced depth imaging optical coherence tomography (EDI-OCT) assessing CT at 14 measurements from 2 B-scans. Paired Student t-test was used to compare CT measurements between MCI, dementia and sex- and age-paired HC. A univariate generalized estimating equations model (GEE) test was performed to compare MCI and dementia individually with all HC included.

Results

Compared with HC, eyes from patients with positive ¹¹C-PiB PET/CT showed a significant CT thinning in 5 selected locations (in foveal thickness in vertical scan, in temporal scan at 1500μm, in superior scan at 500μm and in inferior scan at 1000μm and 1500μm, p = 0.020–0.045) whilst few significant CT reduction data was reported in MCI or dementia individually versus HC. However, the GEE test identified significant CT thinning in AD compared with all HC included (p = 0.015–0.046).

Conclusions

To our knowledge, the present study is the first measuring CT in eyes from MCI and dementia eyes positive to ¹¹C-PiB PET/CT reporting a significant trend towards CT thinning in MCI patients which became more pronounced in dementia stage. We support further investigation involving larger and prospective OCT studies in AD population characterized with available biomarkers to describe whether choroidal vascular damage occurs specifically in prodromal stages of AD.

Effects of different mydriatics on the choroidal vascularity in healthy subjects

PURPOSE

To evaluate choroidal vasculature changes after the instillation of mydriatic parasympatholytic and sympathomimetic agents in healthy subjects.

METHODS

A total of 95 healthy subjects were enrolled in this prospective, randomized comparative study. Study participants were divided into three different groups depending on the drug to be administered: tropicamide (1%) group (n = 31), tropicamide (0.5%) + phenylephrine (10%) group (n = 30) and control group receiving artificial tears (n = 34). All participants underwent a complete ophthalmological examination including best corrected visual acuity, refractive status and axial length. Subfoveal choroidal thickness (CT), total choroidal area (TCA), luminal and stromal choroidal area (LCA and SCA) and choroidal vascularity index (CVI) were measured before and after eye drops instillation.

RESULTS

All the baseline characteristics were matched between the three groups (all P > 0.05). Before the mydriatic instillation, there were no significant differences of CT, TCA, LA, SCA, and CVI among the three groups (all P > 0.05). After drug administration, CT, TCA, LCA, SCA, and CVI did not show any significant change as well (respectively, P = 0.265; P = 0.483; 0.573; P = 0.405 and P = 0.708).

CONCLUSIONS

Instillation of mydriatic eye drops did not induce significant changes of the choroidal vasculature, suggesting that their use do not alter CT and CVI evaluation.

Choroidal spatial distribution indexes as novel parameters for topographic features of the choroid

The purpose of the study is to propose choroidal spatial distribution indexes (CSDIs) to represent choroidal topographic features, establish a normative database for CSDIs, and identify factors associated with CSDIs in healthy eyes. Retrospective data analysis of 363 healthy eyes from a single-center, prospective, cross-sectional, non-interventional study. Subjects were evaluated using spectral domain OCT with enhanced depth imaging. Choroidal volume and average thickness were measured with OCT in nine macular subfields defined by the Early Treatment Diabetic Retinopathy Study. Vertical CSDI was defined as the natural logarithm of superior choroidal volume divided by inferior choroidal volume. Horizontal CSDI was defined as the natural logarithm of temporal choroidal volume divided by nasal choroidal volume. The overall distributions of vertical and horizontal CSDIs was analyzed. Linear regression analyses were used to identify ocular and systemic factors associated with vertical and horizontal CSDIs. The average vertical CSDI was 0.062 ± 0.206, and average horizontal CSDI was 0.138 ± 0.226. Both vertical and horizontal CSDIs followed normal distribution. Increasing age was significantly associated with greater vertical CSDI (choroidal volume distribution tilted toward the superior region), and longer axial length and thinner subfoveal choroidal thickness were significantly associated with greater horizontal CSDI (choroidal volume distribution tilted toward the temporal region).