|Year : 2019 | Volume
| Issue : 2 | Page : 678-682
The effect of hypertension on choroidal thickness measured by optical coherence tomography
Amin F Ellakwa, Asmaa M Ibraheem, Asela N Yousef
Department of Ophthalmology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
|Date of Submission||20-Dec-2017|
|Date of Acceptance||09-Feb-2018|
|Date of Web Publication||25-Jun-2019|
Asela N Yousef
Source of Support: None, Conflict of Interest: None
The aim of the study was to investigate the effect of hypertension on choroidal thickness using the enhanced-depth imaging mode of spectralis Heidelberg optical coherence tomography.
Hypertension is an important risk factor in developing systemic vascular disease and ocular vascular disease. The effect of hypertension on the retina and deeper retinal tissues is now a topic of great interest besides being a risk factor for ocular vascular disease. Recently, optical coherence tomography has been shown to be effective in evaluating choroidal thickness.
Patients and methods
We include in this study 100 participants (50 healthy normotensive and 50 hypertensive patients). Patients recruited from the internal medicine department and diagnosed with hypertension according to the guidelines of clinical hypertension criteria and controlled with treatment with no cardiac problems. We measured the choroidal thicknesses of the normotensive patients as a control group and the choroidal thicknesses of the hypertensive patients. Choroidal thickness measurements were taken at the fovea and at four more points which are located at, respectively, 500 μm nasal to the fovea, 1000 μm nasal to the fovea, 500 μm temporal to the fovea, and 1000 μm temporal to the fovea.
A significant difference was found for the choroidal thickness as the choroidal thickness decreases in hypertensive patients in comparison to normotensive participants.
The results of this study demonstrated that choroidal thickness decreases in patients with systemic arterial hypertension. This may be caused by arteriolar sclerosis and vascular contraction caused by high intravascular pressure in the choroid.
Keywords: choroidal thickness, enhanced-depth imaging, hypertension, optical coherence tomography, spectral domain optical coherence tomography
|How to cite this article:|
Ellakwa AF, Ibraheem AM, Yousef AN. The effect of hypertension on choroidal thickness measured by optical coherence tomography. Menoufia Med J 2019;32:678-82
|How to cite this URL:|
Ellakwa AF, Ibraheem AM, Yousef AN. The effect of hypertension on choroidal thickness measured by optical coherence tomography. Menoufia Med J [serial online] 2019 [cited 2020 Apr 2];32:678-82. Available from: http://www.mmj.eg.net/text.asp?2019/32/2/678/260938
| Introduction|| |
Hypertension is a health concern because it is a major risk factor for a number of cardiovascular diseases including stroke, atherosclerosis, type II diabetes, coronary heart disease, and renal disease. It affects 26% of adults worldwide; its prevalence is predicted to increase to 29% by 2025.
The wide prevalence of high blood pressure (BP) in the population explains why in a WHO report high BP has been listed as the first cause of death worldwide.
Cardiovascular diseases are the leading cause of death worldwide, more so in the economically developed countries and also in the developing world.
Retinal hemorrhage develops when necrotic vessels bleed in to either the nerve fiber layer (flame-shaped hemorrhage) or the inner retina (dot blot hemorrhage). Cotton wool spots are caused by ischemia to the nerve fiber layer secondary to fibrinoid necrosis and luminal narrowing. Ischemia to the nerve fibers leads to decreased axoplasmic flow. Nerve swelling and ultimately fluffy opacification exudates occur later in the course of the disease, surrounding the areas of hemorrhage, as a result of lipid accumulation. Papilledema is a result of both leakage and ischemia of the arterioles supplying the optic swelling and blurred disk margins, whereas leakage causes hemorrhage and disk edema.
In response to hypertension, the sympathetic nervous system will cause vasoconstriction, which may result in a thinner choroid, which was found in this study. However, the vasoconstriction may be overcome by a further increase in BP that leads to muscle layer and endothelial damage,. In addition, increased systemic arterial pressure and ophthalmic/ciliary artery vaso-occlusion may result in choroidal ischemia. That may also contribute to choroidal thinning.
Recently, optical coherence tomography (OCT) has been shown to be effective in evaluating choroidal thickness with current technological developments. New generation spectral domain optical coherence tomography (SD-OCT) devices with enhanced-scanning speed and special software programs like enhanced-depth imaging give the opportunity to achieve high-resolution images. Thus, the evaluation of deeper ocular tissues beyond the retina became possible, which could not be defined by time domain OCT.
As the choroid is an important moderator of ocular physiology in the current study we aimed to analyze the effect of hypertension on choroidal thickness with SD-OCT.
| Patients and Methods|| |
This was a prospective, observational, clinical study carried out on 100 participants (50 hypertensive patients recruited from the internal medicine department and diagnosed with hypertension according to the guidelines of clinical hypertension criteria and controlled with treatment with no cardiac problems and 50 healthy normotensive patients) at the Ophthalmology Department in Menoufia University in the period between January 2017 and August 2017.
Informed consent is obtained from all of the study participants.
Inclusion criteria were clear media, nonocular or systemic diseases other than hypertension, systolic BP greater than 140 mmHg, diastolic BP greater than 90 mmHg according to the 2013 European Society of Hypertension/European Society of Cardiology Guide for the Management of Arterial Hypertension.
Exclusion criteria were diabetic retinopathy; macular edema from ocular inflammatory disease, for example, uveitis, pars planitis, Bechet's syndrome, toxoplasmosis, and HIV-related cytomegalovirus uveitis, postoperative cataract surgery, central and branch retinal vein occlusion, and retinal vascular disease, following injury to the eye and in association with choroidal tumors; any type of intraocular intervention such as previous retinal treatment, macular laser photocoagulation, and vitrectomy; intravitreal steroids or antiangiogenic drugs for the treatment of any retinal problem; history of any intraocular surgery; refractive error of more than 3D; glaucomatous or ocular hypertension patients; uveitis or other retinal diseases,; and media opacities such as cataract.
Full ophthalmoscope examination including refractive error best corrected visual acuity, anterior segment finding, intraocular pressure (Goldman applanation tonometry), axial length by ultrasonography and 90D lens funduscopy, and SD-OCT scans were performed.
Examination of patients
All patients were examined with SD-OCT after pupillodilation with Tropicamide 1%. Measurement of choroidal thickness: macular line raster scan was used to evaluate choroidal thickness. It enables depth penetration with good quality. The choroidal thickness was measured as the perpendicular distance between the hyperrefractive outer border of the retinal pigment epithelium Bruch's membrane layer automatically detected by the SD-OCT device and the sclerachoroidal interface manually drawn by two experienced examiners (F.A.-S.T.) who conducted diagnoses of the participants. The choroidal thickness was measured at five different points at the subfovea and at 500, 1000 μm superior subfovea and inferior to the subfovea.
Approval by Ethics Committee of Menoufia Faculty of Medicine was obtained for performing the study and consents from all patients were taken after explanation of all steps of the study.
Results were collected, tabulated, and statistically analyzed by an IBM compatible personal computer with SPSS statistical package version 20 (SPSS Inc., Released 2011. IBM SPSS statistics for windows, version 20.0; IBM Corp., Armnok, New York, USA).
Two types of statistical analysis were done:
- Descriptive statistics was expressed in number, percentage
- Analytic statistics were as follows:
- Student's t-test is a test of significance used for comparison of quantitative variables between two groups of normally distributed data
- Analysis of variance test was used for comparison of quantitative variables between more than two groups of normally distributed data with least significant difference test as the post-hoc test
- Pearson's correlation was used to study the correlation between two quantitative variables.
A P value of less than 0.05was considered statistically significant.
| Results|| |
This was a prospective, observational, clinical study carried out on 100 participants (50 hypertensive patient recruited from the internal medicine and diagnosed with hypertension according to the guidelines of clinical hypertension criteria and controlled with treatment with no cardiac problems and 50 healthy normotensive participants) at the Ophthalmology Department in Menoufia University in the period between January 2017 and August 2017.
The selected participants were divided into two groups:
- Group 1: included 50 hypertensive patients
- Group 2: included 50 healthy normotensive participants as a control group.
Patient characteristics of the studied groups: the mean value of age, among the study groups, it is 52.28 ± 9.08 years for the hypertensive group (range: 50–70 years), and for the normotensive group, it was 52.90 ± 9.37 (range: 50–70 years), which was not statistically significant at a P value of less than 0.36 [Table 1].
|Table 1: Effect of age, visual acuity, and intraocular pressure on choroidal thickness in normal and hypertensive patients|
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There was no statistical difference between the studied participants regarding the sex as all the cases are men.
There was statistically significant reduction in hypertensive patients in comparison with normotensive participants in comparison with the basal line [Table 2] and [Figure 1] and [Figure 2].
|Table 2: Comparison of choroidal thickness in normal and hypertensive patients|
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|Figure 1: Choroidal thickness measurements by optical coherence tomography (enhanced-depth imaging) in normal participants.|
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|Figure 2: Choroidal thickness measurements by optical coherence tomography (case 1) in hypertensive patients.|
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Correlation between foveal thickness and choroidal thickness at different locations in hypertensive patients [Figure 3] and [Figure 4].
| Discussion|| |
To date, there is no gold standard method in evaluating choroidal thickness. Since the introduction of Fourier SD-OCT in 2006, high scanning speeds and high resolution have enabled accurate imaging and investigation of the choroid. As a highly vascular ocular structure, the choroid is directly influenced by intraocular and perfusion pressure.
Therefore, real-time high-definition images of the choroid are more likely to demonstrate the real-time vascular status of this tissue in vivo. Choroidal function and structure are known to play a role in the pathogenesis of several ocular disorders. SD-OCT is a noninvasive non contra trans pupillary imaging modality used to diagnose, make treatment decisions, and monitor many retinal diseases.
Obtaining choroidal thickness measurements is useful for evaluating choroidal thickening and thinning diseases. A new method for visualizing the choroid, enhanced-depth imaging OCT, has been reported.
The current study was done on 100 participants, 50 healthy normotensive and 50 hypertensive patients. The patients were recruited from the internal medicine department and were diagnosed with hypertension according to the guidelines of clinical hypertension criteria and controlled with treatment with no cardiac problems to evaluate the effect of hypertension on choroidal thickness by enhanced-depth imaging.
We included healthy participants with normal blood parameters, including complete blood count, clinical chemistry, and thyroid function test.
In the current study, the results of this study demonstrated that choroidal thickness decreases in patients with systemic hypertension in comparison to healthy normotensive participants. This may be caused by arteriolar sclerosis and vascular contraction caused by high intravascular pressure in the choroid in agreement with the study by Akay et al. which found a decrease in patients with systemic arterial hypertension.
Our study did not agree with Gok et al. that found no significance correlation between systemic hypertension and choroidal thickness.
Our study showed no significant correlation between foveal thickness and choroidal thickness in normal and hypertensive patients in agreement with the study by Kong et al., which found that macular thickness was inversely associated with systemic hypertension at most macular subfields except for the fovea.
Similarly, systemic hypertension was inversely associated with macular thickness in most macular subfields, particularly in participants with elevated fasting glucose level. This finding suggests that it may be necessary to consider the presence of hypertension when macular thickness and pericentral choroidal thickness are significantly thinner in patients with systemic hypertension in comparison to patients without this condition. In a recent article, Jo et al. studied choroidal thickness changes after acute diabetic control in type 2 diabetic patients. The authors reported significantly increased choroidal thickness 2 weeks after a eucaloric diet, glucose control and BP control. They also found statistically significant correlation between the changes in systolic BP, diastolic BP, mean arterial pressure, and mean ocular perfusion pressure. The finding in that study cannot be compared with our findings because of the potentially confounding effect of diabetes and acute diabetic control.
Our study did not agree with Niknam et al. who found that systemic hypertension does not seem to have a larger effect on choroidal circulation in hypertensive patients that are controlled by antihypertensive drugs.
In the current study, we found no significance correlation between intraocular pressure, visual acuity, age, and sex in relation to choroidal thickness in normal and hypertensive patients. Arteriovenous crossing was significantly higher in hypertensive patients than normal participants.
To the best of our knowledge, our study is the first to evaluate the correlation between foveal thickness and choroidal thickness at different locations in hypertensive patients and there was significant positive correlation between foveal thickness and both choroidal thickness at 500 and 1000 μm.
In conclusion, we found a decrease in choroidal thickness in patients with systemic arterial hypertension in comparison with normotensive participants and this may be caused by arteriolar sclerosis and vascular contraction caused by high intravascular pressure in the choroid.
| Conclusion|| |
In conclusion, we found a significant decrease in choroidal thickness due to hypertension caused by arteriolar sclerosis and vascular contraction caused by high intravascular pressure in the choroid.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2]