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 Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 35  |  Issue : 3  |  Page : 1487-1492

Evaluation of retinal thickness in women using spectral-domain optical coherence tomography


Department of Ophthalmology, Faculty of Medicine, Menoufia University, Menoufia, Egypt

Date of Submission19-Mar-2022
Date of Decision17-Apr-2022
Date of Acceptance18-Apr-2022
Date of Web Publication29-Oct-2022

Correspondence Address:
Nissma M Shaheen
Shebin Elkawm
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/mmj.mmj_91_22

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  Abstract 


Objectives
To evaluate the macular, retinal nerve fiber layer (RNFL), and choroidal thickness alterations using spectral-domain optical coherence tomography (OCT) in postmenopausal, pregnant, and nonpregnant women.
Background
The choroid, also known as the choroidea or choroid coat, is a part of the uvea, the vascular layer of the eye. It contains connective tissues and lies between the retina and the sclera.
Patients and methods
A comparative study was conducted that included 75 eyes of 75 healthy women in the period from March 2021 to December 2021. They were divided into three groups: (a) nonpregnant women, (b) pregnant women, and (c) postmenopausal women. Each participant underwent a comprehensive ophthalmologic examination. Following this detailed ophthalmologic examination, the third-generation Spectralis OCT device (software version 5.6.3.0; Spectralis OCT) was used for the assessment of choroidal, macular, and RNFL thicknesses.
Results
The mean age of nonpregnant women was 29.64 ± 3.13 years, of pregnant women was 28.93 ± 3.89 years, and of postmenopausal women was 53.86 ± 1.75 years. There was no significant difference in all macular quadrants among the three study groups. Choroidal thickness was statistically significantly thicker in healthy pregnant women (333.36 ± 44.42) than in healthy nonpregnant women (326.93 ± 31.50) and significantly thinner in healthy postmenopausal women (282.64 ± 28.04) than in healthy nonpregnant women. There was no significant difference in RNFL thickness among the three study groups.
Conclusion
OCT has evolved over the past decade as one of the most important ancillary tests in ophthalmic practice. Pregnancy hormones may lead to an increase in fluid volume in many tissues of the body.

Keywords: choroidal thickness, macular thickness, postmenopause, pregnancy


How to cite this article:
Elghonemy K, Zaky M, Shaheen NM, Khairat N. Evaluation of retinal thickness in women using spectral-domain optical coherence tomography. Menoufia Med J 2022;35:1487-92

How to cite this URL:
Elghonemy K, Zaky M, Shaheen NM, Khairat N. Evaluation of retinal thickness in women using spectral-domain optical coherence tomography. Menoufia Med J [serial online] 2022 [cited 2024 Mar 28];35:1487-92. Available from: http://www.mmj.eg.net/text.asp?2022/35/3/1487/359533




  Introduction Top


The choroid is a pigmented vascular tissue that was first histologically examined in the 17th century and to date has been studied by various imaging methods. It extends from the ora serrata anteriorly to the optic nerve head posteriorly. According to histopathological examination, the choroid has a mean thickness of 0.15 mm anteriorly and 0.22 mm posteriorly; anatomically, it forms the posterior portion of the uveal tract, which continues anteriorly with the ciliary body and the iris. From retina to sclera, the choroid comprises Bruch's membrane, the choriocapillaris, the medium diameter choroidal vessels, and the large diameter choroidal vessels[1].

The macula or macula lutea (from Latin macula, 'spot'+lutea, 'yellow') is an oval-shaped highly pigmented yellow spot near the center of the retina. It has a diameter of around 6 mm and is often histologically defined as having two or more layers of ganglion cells. Near its center is the fovea centralis, a small pit that contains the largest concentration of cone cells in the eye and is responsible for central, high-resolution vision. The macula also contains the parafovea and perifovea.

The retinal nerve fiber layer (RNFL) or nerve fiber layer, stratum opticum, is formed by the expansion of the fibers of the optic nerve; it is thickest near the optic disc, gradually diminishing toward the ora serrata. As the nerve fibers pass through the lamina cribrosa sclerae, they lose their medullary sheaths and are continued onward through the retina as simple axis-cylinders.

When they reach the internal surface of the retina, they radiate from their point of entrance over this surface grouped in bundles and in many places arranged in plexuses[2].

Pregnancy is a unique state involving changes in the hormonal profile, blood circulation, and metabolism. Several ocular changes may occur during pregnancy; however, most are transient and rarely cause problems. Pregnancy hormones may lead to increase in the fluid volume in many tissues of the body. The increase in the body fluids especially in the last trimester may cause an increase of retinal thickness[3]. Lately, the proportion of elderly women in the society has been increasing owing to success in increasing the life expectancy. This in turn is associated with increase in the number of postmenopausal women in the population[4].

Menopause is the permanent cessation of menstruation resulting from the loss of ovarian follicular activity that leads to a decline in endogenous estrogens and progesterone (P) production in aging women[5].

Menopause is also associated with ocular changes. An increase in the incidence of ocular pathologies and ocular symptoms has been observed during the postmenopausal period[6].

For decades, conventional imaging methods with low-resolution and low-accuracy rates have been used to evaluate ocular changes. Ultrasonography, fluorescein angiography, and indocyanine angiography did not provide such diagnostic possibilities as those presently offered by the EDI optical coherence tomography (OCT) examination[7].

The EDI-OCT examination is noninvasive, simple, and quick. This method makes it possible to precisely evaluate the macula, the choroid, and RNFL, including the measurement of their thickness providing high-resolution, cross-sectional images of ocular structures with a longitudinal resolution of 3–10 μm[8],[9].

The aim of this study was to evaluate the macular, RNFL, and choroid thickness alterations using spectral-domain (SD) OCT in postmenopausal, pregnant, and nonpregnant women.


  Patients and methods Top


This comparative study included 75 eyes of 75 women divided into three groups with 25 postmenopausal women, 25 pregnant women, and 25 nonpregnant women in the reproductive age. The study was done in the Ophthalmology Department of Menoufia University Hospital.

The certificate approval number was 1/2021 OPHT.

The inclusion criteria of this study were (a) postmenopausal women with at least 1 year after spontaneous menopause; (b) healthy nonpregnant women in the reproductive age, above 18 years old; and (c) healthy pregnant women. The exclusion criteria were (a) hormone replacement therapy, (b) history of any chronic disease or chronic medications, (c) previous ocular trauma or surgery, and (d) previous ocular disease affecting the posterior segment. All participants underwent thorough history taking, including personal information, history of any presenting complaint, systemic enquiry, past medical history, and family history. The clinical examination consisted of full ophthalmological examination, including uncorrected and corrected visual acuity by using Landolt C chart, refraction by autorefractometer, slit-lamp biomicroscopy with detailed fundus examination by 90 D Volk Lens, and IOP measurement by Goldman Applanation Tonometer. The third-generation Spectralis OCT device (software version 5.6.3.0; Spectralis OCT, Heidelberg Engineering, Dossenheim, Germany) was used for the assessment of the thickness of macula, RNFL, and choroid [Figure 1].
Figure 1: Spectralis OCT. OCT, optical coherence tomography.

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The examination procedure was achieved after full pupillary dilatation and under the same intensity of dim room lighting. Macular thickness was determined automatically and was analyzed by OCT software. Fast macular thickness map option was utilized for macular measurements. During assessments, macular thickness and volume analyses were used. The results obtained from the macular scan were classified by region. We selected the macular map analysis protocol on the Spectralis to display numeric averages of the measurements for each of nine subfields as defined by the Early Treatment Diabetic Retinopathy Study (ETDRS): CSF – central subfield, IIM – inferior inner macula, IOM – inferior outer macula, NIM – nasal inner macula, NOM – nasal outer macula, SIM – superior inner macula, SOM – superior outer macula, TIM – temporal inner macula, and TOM – temporal outer macula [Figure 2].
Figure 2: Early treatment diabetic retinopathy study subfield template used to derive macular thickness measurements from different regions of a high-density volume scan of the macula. Circles are 1, 3, and 6 mm in diameter.

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The peripapillary RNFL thickness parameters that were automatically calculated by the fast RNFL mode and divided into regions included temporal quadrant thickness, temporal superior quadrant thickness, nasal superior quadrant thickness, nasal quadrant thickness, nasal inferior quadrant thickness, temporal inferior quadrant thickness, and average thickness [Figure 3].
Figure 3: Sample RNFL report provided by SD-OCT. Numbers reflect individual mean RNFL thickness. Numbers in parentheses are the mean thickness of adults in the Spectralis normative database. Ts – temporal superior, Ns – nasal superior, N – nasal, Ni – nasal inferior, Ti – temporal inferior, G – average. RNFL, retinal nerve fiber layer; SD-OCT, spectral-domain optical coherence tomography.

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Choroid imaging was obtained by activating the EDI button.

The choroid was manually measured from the outer border of the hyper-reflective line corresponding to the retinal pigment epithelium to the inner surface of the sclera in subfoveal area [Figure 4].
Figure 4: Measurement of subfoveal choroidal thickness with EDI on Spectralis OCT. OCT, optical coherence tomography.

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Ethical approval: all patients signed the informed written consent form, and the study protocol was approved by the local Ethical Committee of Menoufia University Faculty of Medicine.

Statistical analysis

Data were collected, revised, coded, and entered into the Statistical Package for the Social Sciences (IBM SPSS) version 23 (SPSS Inc. Released 2015. IBM SPSS statistics for Windows, version 23.0; IBM Corp., Armonk, New York, USA).

The quantitative data were presented as mean, SDs, and ranges when parametric. Moreover, qualitative variables were presented as number and percentages.

The comparison between more than two independent groups with quantitative data and parametric distribution was done using one-way analysis of variance test followed by post-hoc analysis using the LSD test.

The confidence interval was set to 95% and the margin of error accepted was set to 5%. So, the P value was considered significant as follows:

  • P value more than 0.05: nonsignificant.
  • P value less than 0.05: significant.
  • P value less than 0.01: highly significant.


Spearman correlation was used to show correlation between two continuous non-normally distributed variables.


  Results Top


A total of 75 eyes of 75 patients with a mean age of 37.48 ± 12.10 years were included.

The mean age of nonpregnant women was 29.64 ± 3.13 years, of pregnant women was 28.93 ± 3.89 years, and of postmenopausal women was 53.86 ± 1.75 years.

The thicknesses of macula, choroid, and peripapillary RNFL obtained by the SD-OCT are displayed in [Table 1],[Table 2],[Table 3], respectively.
Table 1: Macular thickness in pregnant, postmenopause, and nonpregnant women

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Table 2: Choroid thickness in pregnant, postmenopausal, and nonpregnant women

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Table 3: Retinal nerve fiber layer thickness in pregnant, postmenopausal, and nonpregnant women

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Results showed that there was no significant difference in the thickness of macula or peripapillary RNFL in all of their quadrants among the three groups: pregnant, nonpregnant, and postmenopausal women. On the contrary, there was a significant difference in the choroid thickness among the three groups, where thickness was significantly thicker in pregnant women (333.36 ± 44.42) than in healthy nonpregnant ones (326.93 ± 31.50) and significantly thinner in healthy postmenopausal women (282.64 ± 28.04) than healthy nonpregnant ones [Table 1],[Table 2],[Table 3],[Table 4].
Table 4: Correlation between retinal thickness and choroidal thickness in each group

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  Discussion Top


Estrogen and progesterone receptors have been observed in different ocular tissues, such as the cornea, the conjunctiva, the Meibomian glands, the lens, the choroid, and the retina. The expression of estrogen and progesterone receptors in the eye is responsible for their ocular effects, and various studies were published in the literature about these receptors and their role in changing eye structures[10].

Pregnancy can affect the eyes. Nonpathological events occurring during pregnancy include reduced corneal sensitivity and increased corneal thickness related to the water retention. Choroidal thickness changes can be expected because of this water retention. There are some additional pathologic conditions that are reported to develop during pregnancy such as central serous chorioretinopathy[11]. However, few studies have investigated choroid thickness in pregnant women[12].

The reduction of blood pressure and systemic vascular resistance, which is observed particularly in the middle of pregnancy, may explain the increase in the choroid thickness in the second trimester[13].

Most researchers investigating choroid thickness in pregnant women interpret changes in the choroid thickness with reference to the hemodynamic and hormonal changes which occur in pregnancy[14]. Estrogen stimulates the activity of the renin–angiotensin–aldosterone system, which is the main cause of water retention.

A decrease in peripheral vascular resistance results from the effect of many active substances decreasing the vascular wall tone, including pregnancy hormones: estrogen, prolactin, placental lactogen, prostaglandin, or nitric oxide. Decreased vascular resistance may result in an increased blood flow through many organs, for example, the uterus, kidneys, and skin[15].

It is assumed that the choroid, as a tissue built mainly of blood vessels, in which the blood flow constitutes 85% of the blood flow through the eyeball, should respond by an increase in its thickness to an increase in blood flow and drop in the value of peripheral resistance. Some researchers have explained the increase in the choroidal thickness in pregnant women observed in their studies based on this assumption[13],[14].

Liu et al.[14] performed a meta-analysis in which (despite many differences occurring between the studies included in the meta-analysis) they found a statistically significant difference in the choroid thickness between pregnant and nonpregnant women. The same relationship was also confirmed in their own study, where the choroidal thickness in pregnancy was statistically significantly higher.

Apart from the meta-analysis available, studies on the choroid thickness concern small groups of examined women. The study in which the largest number of women was examined from the perspective of choroid thickness was conducted by Sayin et al.[13], who compared choroid thickness in 100 pregnant women (at week 15 and 38 of pregnancy) and 100 women who were not pregnant. The results indicated that the choroid thickness was statistically significantly higher in pregnancy; however, a statistically insignificant relationship was noted between the choroid thickness and gestational age.

Owing to the increase in life expectancy and the constant age at menopause, women are spending longer periods of their life in a hypo-estrogenic state. In the postmenopausal period, many organs and systems of the body are susceptible to postmenopausal sex hormone deficiency. Eye is one of the organs affected by menopause. Thus, menopause may cause major ocular changes.

Because of the presence of sex steroid hormone receptors in various ocular tissues, sex steroid hormones may have a significant effect on ocular physiology and structure[16].

A study by Ciccone et al.[17] showed that administration of single-dose nasal 17-β-estradiol increases ophthalmic artery perfusion.

On the contrary, Atalay et al.[18] investigated ocular hemodynamic parameters using Doppler. They concluded that hormone replacement therapy with estradiol 17-valerate 2 mg plus cyproterone acetate 1 mg improves ocular vascular Doppler indices, which may be a reflection of cerebral vascular status. We can speculate that the decrease in choroidal thickness in postmenopausal women may indicate a reduced estrogen-dependent vasodilatory effect in ophthalmic artery secondary to menopausal estrogen deficiency.

Many techniques have been developed to monitor choroidal blood flow; nevertheless, these measurements are especially difficult because the choroidal vessels are 'hidden' beneath the retinal pigment epithelium, and blood flow is assessed mainly indirectly. To assess whether an increase or decrease in choroidal thickness occurs during pregnancy or postmenopause respectively in response to the ongoing hemodynamic and hormonal changes, choroidal thickness was examined using a new imaging technique, EDI-OCT[13]. The heretofore choroidal imaging by means of SD-OCT was limited, mainly due to the difficulties with transmission of the signal through the retinal pigment epithelium. The EDI-OCT, which is the modification of the standard OCT, provides resolution to ∼3–4 μm and deeper scanning, which allows visualization and dimensioning of the choroid[19].


  Conclusion Top


There was no statistically significant difference in macular thickness and RNFL thicknesses among the three study groups. Choroid thickness was statistically significant thicker in healthy pregnant than in healthy nonpregnant and significant thinner in healthy postmenopausal women than healthy nonpregnant ones.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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2.
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Gupta PD, Johar KSr, Nagpal K, Vasavada AR. Sex hormone receptors in the human eye. Surv Ophthalmol 2005; 50:274–284.  Back to cited text no. 10
    
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Sayin N, Kara N, Pirhan D, Vural A, Araz Ersan HB, Tekirdag AI, et al. Subfoveal choroidal thickness in preeclampsia: comparison with normal pregnant and nonpregnant women. Semin Ophthalmol 2014; 29:11–17.  Back to cited text no. 13
    
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Liu R, Kuang GP, Luo DX, Lu XH. Choroidal thickness in pregnant women: a cross-sectional study. Int J Ophthalmol 2016; 9:1200.  Back to cited text no. 14
    
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Siesky BA, Harris A, Patel C, Klaas CL, Harris M, McCranor LJ, et al. Comparison of visual function and ocular hemodynamics between pre- and post-menopausal women. Eur J Ophthalmol 2008; 18:320–323.  Back to cited text no. 16
    
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Ciccone MM, Cicinelli E, Giovanni A, Scicchitano P, Gesualdo M, Zito A, et al. Ophthalmic artery vasodilation after intranasal estradiol use in postmenopausal women. J Atheroscler Thromb 2012; 19:1061–1065.  Back to cited text no. 17
    
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Atalay E, Karaali K, Akar M, Ari ES, Simsek M, Atalay S, et al. Early impact of hormone replacement therapy on vascular hemodynamics detected via ocular colour Doppler analysis. Maturitas 2005; 50: 282–288.  Back to cited text no. 18
    
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

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



 

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