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ORIGINAL ARTICLE
Year : 2020  |  Volume : 33  |  Issue : 2  |  Page : 593-598

Changes of the choroid in preeclampsia and healthy pregnant women by using optical coherence tomography


1 Department of Ophthalmology, Faculty of Medicine, Shebin-El-kom Ophthalmology Hospital, Menoufia University, Menoufia, Egypt
2 Department of Ophthalmology, Shebin-El-kom Ophthalmology Hospital, Menoufia University, Menoufia, Egypt

Date of Submission16-Sep-2019
Date of Decision15-Oct-2019
Date of Acceptance20-Oct-2019
Date of Web Publication27-Jun-2020

Correspondence Address:
Mai A Mokhtar
Shebin El-Kom, Menoufia
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/mmj.mmj_297_19

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  Abstract 


Objective
The aim of the study is to evaluate choroidal thickness alteration in women with preeclampsia and compare with healthy pregnant and nonpregnant controls by using optical coherence tomography (OCT).
Background
Pregnancy is a predisposing factor for central serous chorioretinopathy. Choroidal thickness (CT) increases in central serous chorioretinopathy and this study evaluates changes in computed tomography (CT) during pregnancy and preeclampsia.
Patients and methods
This was a cross-sectional study conducted at Menoufia University Hospital Ophthalmology Department during the period from April 2018 to March 2019 on 66 eyes of 33 patients divided into groups. Each group had 22 eyes. Group 1 is the pregnant group and group 2 is the preeclampsia. Group 3 included healthy nonpregnant controls. Each of the patients underwent full ophthalmologic examination followed by OCT assessment and the procedure was achieved without pupillary dilatation. Macular thickness was determined automatically and was analyzed by OCT.
Results
The choroid thickness increases in both healthy pregnant women and preeclampsia women. Choroidal thickness in healthy pregnant women was significantly thicker than preeclampsia. The most likely mechanism for this increase is pregnancy-related fluid retention in the choroid layer. The choroidal thickness in preeclampsia was lower than healthy pregnant women. This lower rise in choroidal thickness can be generally attributed to the markedly increased systemic vascular vasospasm secondary to preeclampsia.
Conclusion
This study has shown that CT measured using OCT increased in women with preeclampsia and healthy pregnant women but the increase of CT in preeclampsia was lower than healthy pregnant controls.

Keywords: choroidal thickness, optical coherence tomography, preeclampsia, pregnant


How to cite this article:
Marey HM, Mokhtar MA, Ibrahim AM. Changes of the choroid in preeclampsia and healthy pregnant women by using optical coherence tomography. Menoufia Med J 2020;33:593-8

How to cite this URL:
Marey HM, Mokhtar MA, Ibrahim AM. Changes of the choroid in preeclampsia and healthy pregnant women by using optical coherence tomography. Menoufia Med J [serial online] 2020 [cited 2020 Oct 22];33:593-8. Available from: http://www.mmj.eg.net/text.asp?2020/33/2/593/287774




  Introduction Top


The choroid is the vascular layer of the eye containing connective tissue and lying between the retina and the sclera. It provides oxygen and nourishment to the outer layers of the retina. Choroid abnormalities such as thinning and loss of vascular tissue play a vital role in the pathophysiology of many diseases affecting the retina. Measurement of retinal thickness is important in the diagnosis, follow-up, and monitoring response to treatment of a number of eye diseases. Choroidal thickness can be measured in vivo using ultrasonography, MRI, and enhanced depth imaging optical coherence tomography (EDI-OCT)[1].

Preeclampsia is a multisystem pregnancy-specific syndrome and is a leading cause of maternal morbidity and mortality. It affects ∼5–7% of all pregnancies and is more prevalent when preexisting conditions such as hypertension, renal disease, obesity, or diabetes are present[2],[3]. Edema is a classic feature of the disease; however, it is no longer considered a diagnostic feature given its lack of sensitivity or specificity[4]. The exact pathophysiology of preeclampsia is not completely known.

Preeclampsia is characterized by an inadequate quality and quantity of the maternal vascular response to placenta and is associated with increased systemic vascular resistance. Systemic inflammatory response leading to generalized endothelial cell activation or dysfunction and inadequate trophoblast invasion of into spiral arteries appears to be mainly responsible in the pathogenesis of preeclampsia[5],[6]. Preeclampsia is a clinical syndrome complicated by dysfunction of various organs of the body.

Preeclampsia has various ocular manifestations. Blurred vision is the most common visual complaint. Focal or generalized arteriolar narrowing is the most common ocular finding in preeclampsia syndrome. Other ocular manifestations include photopsia, visual field defects, and sudden inability to focus, and in severe cases, complete blindness[5]. Fortunately, blindness due to occipital lesions is reversible and the lost vision is usually regained within 4 h to 8 days[6].

Serous retinal detachment (SRD) is an unusual cause of visual loss in preeclampsia, first described by von Greave in 1855. It involves separation of the neurosensory retina from the pigmented retinal epithelium and is one of the emergency situations in ophthalmology. The exact pathophysiology of SRD in cases of preeclampsia is not well known. It is usually present in patients with severe preeclampsia or eclampsia, and they are usually observed in the absence of significant retinal vascular abnormalities and retinal breaks. Hayreh et al.[6] suggested that SRD in preeclampsia may be caused by choroid ischemia secondary to accelerated hypertension.

The ocular symptoms and findings usually present in the third trimester and the visual system may be affected in 30–100% of pregnancies complicated with preeclampsia[7],[8]. Pathophysiology of these visual manifestations is similar to hypertensive retinopathy and it is associated with vasospasm, ischemia, increased microvascular permeability, and hemorrhage in the occipital cortex[8],[9].

OCT is a new diagnostic imaging modality that provides high-resolution, cross-sectional images of ocular structures with a longitudinal resolution of 3–10 mm[10]. OCT makes it possible to obtain noninvasive, rapid, objective, high-resolution, cross-sectional imaging of the retina and also permits direct, real-time imaging of ocular pathology that previously could not be visualized using traditional methods.

OCT provides images of the vitreous, retinal, and choroid structures that cannot be obtained by any other noninvasive diagnostic technique and its scans have been compared with histologic sections seen with light microscopy[11].

The aim of this study is to assess choroidal thickness in patients with preeclampsia by means of OCT and to compare these findings in healthy pregnant and healthy nonpregnant controls.


  Patients and Methods Top


This is a cross-sectional study that was conducted at the Ophthalmology Outpatient Clinic of Menoufia University Hospital.

All study procedures were carried out and approved by the Ethics Committee of Menoufia Faculty of Medicine and in accordance with the Declaration of Helsinki. Participant's names were kept on a password-protected database and linked only with a study identification number for this research. Written informed consent was obtained from each patient before his or her enrollment in the study.

Sample size based on past review of literature that assumed an effect size of 64.85 for choroid sample size has been calculated and it will be 22 eyes for every single group at a power of 80% and confidence interval of 95%.

An informed consent will be obtained from each patient and the study was approved by the ethics committee of the Faculty of Medicine Menoufia University.

Inclusion criteria of selected cases: for pregnant women with a single pregnancy in the third trimester and no refractive errors of more than −6 or +6 D for preeclampsia women as established by the National High Blood Pressure Education Program (NHBPEP) criteria will be included in the study group.

NHBPEP was established in 1972 by the National Institute of Health to translate research results on the health hazards into clinical and public health practice. Before 1900, high blood pressure was not generally recognized as a health problem. The goal of NHBPEP is to reduce death and disability through programs of professional, patient, and public education.

Gestational blood pressure elevation was defined as a blood pressure of 140 mmHg systolic or 90 mmHg diastolic in woman who was normotensive prior to 20 weeks of gestation. Patients excluded from the study were: smokers, those with drug abuse, significant cardiac disease systemic diseases including chronic systemic hypertension/diabetes mellitus, noticeable eye disorders such as glaucoma or retinopathy, or previous ocular surgery including refractive surgeries.

All patients underwent full ophthalmic examinations including a visual acuity test by LogMAR chart. Complete examination of the anterior segment in the form of from outside: (a) eye lids and lashes, (b) conjunctiva, (c) cornea, (d) anterior chamber, (e) iris and pupil, (f) lens and posterior chamber by using a slit lamp.

Complete examination of posterior segments by a Volk 90 D lens, intraocular pressure measurement by Goldman applanation tonometry, and spectral domain OCT by (Spectralis OCT, Heidelberg, Germany). To obtain images of the choroid, we adopted an EDI mode which was provided by the manufacturer (Heidelberg Engineering, Heidelberg, Germany).

Choroidal thickness was measured as the perpendicular distance between the hyperrefractive outer border of the retinal pigment epithelium, Bruch membrane layer is automatically detected by the SD-OCT device, and the sclera–choroid interface manually drawn by two experienced examiners.

Statistical analysis

All data were collected, tabulated, and statistically analyzed using IBM SPSS software package version 20.0 (IBM Corp., Armonk, New York, USA). Data were statistically described using number and percent. The Kolmogorov–Smirnov test was used to verify the normality of distribution. Quantitative data were described using range (minimum and maximum), mean, SD, and median. Significance of the obtained results was judged at the 5% level.

SPSS is short for Statistical Package for Social Sciences, and it is used by various kinds of researchers for complex statistical data analysis.

The used tests were: F test (analysis of variance), for normally distributed quantitative variables, to compare between more than two groups and post-hoc test (Tukey) for pairwise comparisons. Kruskal–Wallis test, for abnormally distributed quantitative variables, to compare between more than two studied groups and posthoc (Dunn's multiple comparison test) for pairwise comparisons


  Results Top


There was no significant difference among groups 1, 2, and 3 as regarding intraocular pressure, age, and visual acuity [Table 1].
Table 1: Comparison between the different studied groups according to age

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Significant positive correlation was present between choroidal thickness and systemic blood pressure [Table 2].
Table 2: Comparison between the different studied groups according to systemic blood pressure

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Mean subfoveal choroidal thickness was the highest in pregnant group followed by the preeclampsia group which was statistically significant (P ≤ 0.001) [Table 3] and least in healthy nonpregnant controls.
Table 3: Comparison between the different studied groups according to subfoveal choroidal thickness

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Mean foveal thickness was the highest in the pregnant group followed by the preeclampsia group, which was statistically significant (P = 0.041) [Table 4] and was least in healthy nonpregnant controls.
Table 4: Comparison between the different studied groups according to foveal thickness

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There was significant positive correlation between foveal thickness and subfoveal choroidal thickness ([Table 5] and [Figure 1], [Figure 2]).
Table 5: Correlation between foveal thickness with subfoveal choroidal in each group

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Figure 1: Comparison between the different studied groups according to subfoveal choroidal thickness.

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Figure 2: Comparison between the different studied groups according to foveal thickness.

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  Discussion Top


To date, there is no gold standard method in evaluating choroidal thickness[12]. Since the introduction of Fourier spectral domain OCT in 2006, high scanning speeds and high resolution have enabled accurate imaging and investigation of the choroid[13]. As a highly vascular ocular structure, the choroid is directly influenced by intraocular and perfusion pressure.

Choroid function and structure are known to play a role in the pathogenesis of several ocular disorders[14]. Spectral domain OCT is a noninvasive painless pupillary imaging modality used to diagnose, make treatment decisions, and monitor many retinal diseases[15].

Obtaining choroidal thickness measurements is useful for evaluating choroid thickening and thinning diseases. A new method for visualizing the choroid, enhanced depth imaging OCT, has been reported[16],[17].

This study was done on 66 participants: 22 healthy pregnant women and 22 preeclampsia women and 22 healthy nonpregnant women to evaluate the effect of pregnancy and preeclampsia on choroidal thickness by EDI and compare the changes with the healthy group.

In the current study we noted that choroidal thickness in healthy pregnant women was significantly thicker than women with preeclampsia. The most likely mechanism for this increase is pregnancy-related fluid retention in the choroid layer. This lower rise in choroidal thickness of preeclampsia women can be generally attributed to the markedly increased systemic vascular vasospasm secondary to preeclampsia.

In a study by Demir et al.[18], it was found that foveal thickness was increased particularly in the last trimester and this increase was thought to be due to pregnancy-related fluid retention in the retinal tissue[18].

Foveal thickness alterations in healthy pregnant women were first described by Cankaya and colleagues. This study conducted by Cankaya and colleagues showed that foveal retinal thickness was significantly higher in healthy pregnant women in their second and third trimesters[19],[20].

However, in these previous studies choroidal thickness which may be the most susceptible layer to be affected by preeclampsia had not been examined.

Our study did not agree with Gök et al.[21] which found no significant correlation between systemic hypertension and choroidal thickness[21].

Our study did not agree with Gök et al.[21], which found a decrease in choroidal thickness in patients with systemic arterial hypertension[21].

In our study we found that there is significant correlation between intraocular pressure, systemic blood pressure, and subfoveal choroidal thickness and foveal thickness which did not agree with Ulusoy[22], which found that macular thickness was inversely associated with systemic hypertension at most macular subfields except for the fovea[22].

In our study, we found no significant correlation between visual acuity and subfoveal choroidal thickness and foveal thickness.

Similarly, systemic hypertension was inversely associated with macular thickness in most macular subfields, particularly in patients 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 is significantly thinner in patients with systemic hypertension in comparison to patients without this condition. In a recent article Kong et al.[23] studied choroid thickness changes after acute diabetic control in type 2 diabetic patients. The authors reported significantly increased choroid thickness 2 weeks after a eucaloric diet, glucose control, and blood pressure control. They also found a statistically significant correlation between the changes in systolic blood pressure, diastolic blood pressure, 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[23].

In conclusion, we found an increase in foveal thickness and choroid thickness in healthy pregnant women than preeclampsia groups (P < 0.001).


  Conclusion Top


This study has shown that choroid thickness measured by OCT increased in women with preeclampsia and healthy pregnant women more than normal healthy nonpregnant women, but this increase in preeclampsia was lower than the healthy pregnant controls.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Branchini L, Regatieri CV, Flores-Moreno I, Baumann B, Fujimoto JG, Duker JS. Reproducibility of choroidal thickness measurements across the three spectral domain optical coherence tomography systems. Ophthalmology 2012; 119 :119–123.  Back to cited text no. 14
    
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    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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