Effect of intravitreal bevacizumab on subfoveal choroidal thickness in eyes with diabetic macular edema

Haitham Y Al-Nashar

doi:10.4103/1110-9173.195248

ORIGINAL ARTICLE

Year : 2016 | Volume : 17 | Issue : 3 | Page : 157-161

Effect of intravitreal bevacizumab on subfoveal choroidal thickness in eyes with diabetic macular edema

Haitham Y Al-Nashar MD
Department of Ophthalmology, Faculty of Medicine, Zagazig University, Zagazig, Egypt

Date of Submission	26-May-2016
Date of Acceptance	14-Jul-2016
Date of Web Publication	6-Dec-2016

Correspondence Address:
Haitham Y Al-Nashar
Department of Ophthalmology, Faculty of Medicine, Zagazig University, Zagazig 44519
Egypt

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/1110-9173.195248

Abstract

Purpose
The purpose of this study was to evaluate the changes in subfoveal choroidal thickness (SFCT) in eyes with diabetic macular edema (DME) after intravitreal bevacizumab (IVB) injection.
Patients and methods
Thirty eyes diagnosed as nonproliferative diabetic retinopathy with DME were included in this prospective study. All eyes received an intravitreal injection of 1.25 mg/0.05 ml bevacizumab. Best-corrected visual acuity, SFCT, and central macular thickness were measured and recorded before the IVB injection and 1 month after the injection. The choroidal thickness was measured using enhanced depth imaging technique of Heidelberg Spectralis-optical coherence tomography.
Results
The mean age of the patients was 55.63±4.6 years, with a mean duration of diabetes of 8.26±1.96 years. The mean preinjection SFCT was 214.3±7.9 μm. The mean SFCT after 1 month of IVB injection was 215.5±6.8 μm, with no significant difference from the preinjection value (P=0.56). The mean change in the SFCT 1 month after intravitreal injection was 1.1±9.5 μm, with 0.5% change ratio. The correlation between change in SFCT and changes in central macular thickness and best-corrected visual acuity were 0.24 and −0.3, respectively, which were insignificant (P=0.2 and 0.09, respectively).
Conclusion
The IVB injection has no effect on the SFCT in eyes with DME.

Keywords: bevacizumab, choroidal thickness, diabetic macular edema

How to cite this article:
Al-Nashar HY. Effect of intravitreal bevacizumab on subfoveal choroidal thickness in eyes with diabetic macular edema. Delta J Ophthalmol 2016;17:157-61

How to cite this URL:
Al-Nashar HY. Effect of intravitreal bevacizumab on subfoveal choroidal thickness in eyes with diabetic macular edema. Delta J Ophthalmol [serial online] 2016 [cited 2021 Oct 16];17:157-61. Available from: http://www.djo.eg.net/text.asp?2016/17/3/157/195248

Introduction

Diabetic macular edema (DME) is a serious condition that may affect vision in eyes with diabetic retinopathy [1]. Disturbance of the outer and inner blood–retinal barriers plays an important role in the pathogenesis and development of DME, with subsequent accumulation of fluid in the subretinal space and intraretinal tissue [2],[3]. One of the main factors that cause disruption to the inner blood–retinal barrier is the vascular endothelial growth factor (VEGF) [4],[5].

Many pathological changes are present in the choroid of eyes with diabetic retinopathy. These changes include dilatation of choroidal vessels with increased tortuosity, formation of microaneurysms, and the presence of areas of choroidal nonperfusion [6],[7]. Many studies demonstrated that the choroid has an important role in the pathogenesis of diabetic retinopathy. Different types of inflammatory cells and choroidal microvasculature dropout were found in the early stage of diabetic retinopathy [8].

Treatment with intravitreal corticosteroid or anti-VEGF drugs was recommended in eyes with DME [9].

Many studies found that in eyes with DME there is a decrease in the choroidal thickness, and these studies concluded that tissue hypoxia will result from decreased choroidal thickness and volume with subsequent increase in the level of VEGF, resulting in disturbance of the blood–retinal barrier active transport and development of DME [10],[11].

Recently, enhanced depth imaging technique of spectral-domain optical coherence tomography (EDI SD-OCT) was used frequently in choroidal examination and analysis [12],[13].

The aim of this study was to evaluate whether the treatment with anti-VEGF agents is associated with changes in choroidal thickness in eyes with DME.

Patients and methods

Thirty eyes of 19 patients were included in this prospective study.

Inclusion criteria

Eyes with nonproliferative diabetic retinopathy associated with DME diagnosed clinically and with fluorescein angiography were included in this study.

Exclusion criteria

Patients who had a history of previous panretinal or macular laser photocoagulation, or use of intraocular or periocular steroids or anti-VEGF drug injection, were excluded from the study. In addition, exclusion criteria included macular diseases other than DME, proliferative diabetic retinopathy, ocular inflammation, vitreoretinal, and ocular surgeries.

Methods

All patients underwent ocular examination, including best-corrected visual acuity (BCVA), slit-lamp biomicroscopic examination, measurement of intraocular pressure, dilated fundus examination, and fluorescein angiography.

All eyes received an injection of 1.25 mg/0.05 ml bevacizumab [intravitreal bevacizumab (IVB), Avastin; Genentech Inc., USA]. Topical anesthesia was induced by 0.4% benoxinate eye drops before the injection. After disinfection and draping, 0.05 ml containing 1.25 mg of bevacizumab was injected into the vitreous cavity. A 27-G needle was used in intravitreal injection, which was administered 4 mm from the limbus. Paracentesis with aqueous humor removal was performed after the injection to avoid an increase of the intraocular pressure.

Choroidal thickness measurement

All SD-OCT examinations were performed using Heidelberg Spectralis-OCT (Heidelberg Engineering, Heidelberg, Germany) using line scan (30°) centered on the fovea. The choroidal thickness was measured using EDI-OCT technique, by positioning the SD-OCT equipment closer to the eye than the ordinary; with this practice, the sensitivity of imaging in the deeper layers of tissue is increased.

The choroidal thickness was measured manually using the cursor in the software of the instrument. The measure extends from the hyper-reflective layer of the retinal pigment epithelium to the hyporeflective line corresponding to the choroidal scleral junction.

Follow-up software in OCT machine was used to measure the same line that passes through the fovea before and after injection.

All patients gave an informed consent according to the tenets of the Declaration of Helsinki.

Outcome measures

These included BCVA, subfoveal choroidal thickness (SFCT), and central macular thickness (CMT) measured with the same OCT instrument. All these data were collected and recorded before the IVB injection and after 1 month of the injection.

Statistical analysis

Statistical analysis of the collected data was performed using SPSS (IBM SPSS statistics 14.0; IBM, Chicago, Illinois, USA). A P-value less than 0.05 was considered statistically significant.

Results

A total of 30 eyes of 19 patients were included in this study. The mean age of patients was 55.63±4.6 years, and 11 patients were male and eight were female. The mean duration of diabetes was 8.26±1.96 years. No history of ocular disease other than diabetic retinopathy was reported in any patient ([Table 1]).

Table 1 Patients' demographic data

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The preinjection baseline value of the mean SFCT was 214.3±7.9 μm (range: 201–225 μm). The mean SFCT after 1 month of IVB injection was 215.5±6.8 μm (range: 205–228 μm), with no significant difference from the preinjection value (P=0.56) ([Table 2] and [Figure 1]).

Table 2 Changes in subfoveal choroidal thickness, central macular thickness and best-corrected visual acuity

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Figure 1 Subfoveal choroidal thickness (SFCT) measurement before and 1 month after intravitreal bevacizumab injection.

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The mean change in the SFCT after 1 month of intravitreal injection was 1.1±9.5 μm (range: −15 to +22 μm), and it was expressed as the ratio to baseline. After 1 month of IVB injection, the ratio of the SFCT was insignificantly decreased to 0.5% of the baseline value ([Figure 2]).

Figure 2 Changes in subfoveal choroidal thickness (SFCT) 1 month after intravitreal bevacizumab injection

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Before IVB injection, the mean CMT was 486.5±27.3 μm (range: 452–558 μm) and mean BCVA was 0.12±0.04 (range: 0.05–0.2), and 1 month after IVB injection they were 337.03±14.5 μm (range: 315–365 μm) and 0.5±0.14 (range: 0.16–0.7), respectively, with significant statistical difference (P≤0.001) ([Figure 3]).

Figure 3 Enhanced depth imaging-optical coherence tomography measurement of subfoveal choroidal thickness: (a) before injection and (b) 1 month after injection.

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The mean change in CMT after 1 month of IVB injection was −149.43±31.2 μm, with change ratio of 30.7%. The mean change in BCVA after IVB injection was 0.39±0.1, with a change ratio of 325% ([Table 2]).

The correlation between change in SFCT and changes in both CMT and BCVA was calculated. There was no significant correlation between changes in SFCT and CMT (r=0.24, P=0.2). In addition, there was no statistically significant correlation between the change in SFCT and change in BCVA (r=−0.3, P=0.09), suggesting that changes in CMT and BCVA are not directly related to change in SFCT ([Table 3]).

Table 3 Correlation between the postinjection subfoveal choroidal thickness and both central macular thickness and best-corrected visual acuity

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Discussion

Systemic hyperglycemia and increased level of free radicals in the eye are important factors in the pathogenesis of DME, as they cause activation and increased level of VEGF [14].

A normal choroidal function with normal structure of its blood vessels is essential for a normal retinal function. Abnormality of choroidal volume or decreased blood flow may cause dysfunction of photoreceptors with subsequent damage and death. Histological examination of the eye had demonstrated the role of blood vessels of the choroid in the pathological changes that affect the retina in diabetic patients [15],[16].

Histological examination of the choroid in patients with diabetic eye disease revealed the presence of areas of localized dilatation of the blood vessels with increased vascular tortuosity. In addition, areas of localized vascular narrowing are seen with capillary dropout in advanced cases [17],[18].Querques et al. [19] in their study to investigate the changes in macular choroidal thickness in eyes with diabetic retinopathy concluded that there was a generalized thinning of the choroid on EDI examination technique of SD-OCT. Decreased choroidal circulation and thickness results in disturbance of blood–retinal barrier because of increased level of VEGF.

The results of the present study showed that the SFCT of DME eyes was insignificantly changed from the baseline after IVB, as the SFCT baseline level was 214.3±7.9 μm and after 1 month of IVB injection it was 215.5±6.8 μm.

Sonoda et al. [20] in their study compared the effect of intravitreal triamcinolone acetonide (IVTA) and IVB on SFCT in eyes with DME, and they found that there was no significant difference in the SFCT after IVB, whereas the SFCT was reduced significantly after IVTA. They concluded that the decrease in choroidal thickness in eyes with DME after IVTA suggests that the choroidal pathological changes in diabetic maculopathy may be steroid sensitive. They also concluded that VEGF had a lower effect on choroidal pathological changes in DME.

The results of this study showed that changes in CMT did not correlate with SFCT. IVB has a different effect on macula and choroid, and thus it is considered that the macula is more affected by IVB than the choroid. This may be because of the slow and difficult movement of bevacizumab to the choroidal vasculature. However, the exact mechanism is still unclear.

Conclusion

This study demonstrated that IVB injection has no effect on the SFCT in eyes with DME.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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