Can Intravitreal Ranibizumab Alter Retrobulbar Circulation in Eyes with Age-Related Macular Degeneration?

Abstract

Purpose:

To determine the effect of a single intravitreal ranibizumab injection on retrobulbar circulation in cases with neovascular age-related macular degeneration (AMD).

Methods:

In this prospective and interventional study, 32 patients with neovascular AMD were enrolled. A single intravitreal ranibizumab dose was in only 1 eye per patient. Peak systolic velocity, end-diastolic velocity, resistive index and pulsatility index values in the common carotid artery, ophthalmic artery, central retinal artery, nasal posterior ciliary artery, and temporal posterior ciliary artery in both injected and uninjected healthy fellow eyes were measured using color Doppler ultrasonography at baseline and 1 week and 1 month after the injection of ranibizumab.

Results:

All measurements revealed no statistically significant difference among baseline, first week, and first month after injection measurements for all parameters measured in all arteries in both the injected and uninjected healthy fellow eyes.

Conclusion:

A single intravitreal injection of ranibizumab does not significantly affect on retrobulbar circulation of either the injected or the uninjected healthy fellow eyes with neovascular AMD.

Introduction

Age-related macular degeneration (AMD) is the most common cause of choroidal neovascular membranes (CNVM) and the most common cause of central visual loss and legal blindness in people over 65 years of age.^1,2 Although CNVM secondary to AMD accounts for only 10% of all cases, it is responsible for 90% of legal blindness.^3,4

Many treatment options are in use for the neovascular form of AMD, which proceeds progressively. Thermal laser photocoagulation, systemic drugs, various surgical methods, photodynamic treatment done with verteporfin and intravitreal drug applications are the treatment modalities that have been used until today and are still in use.

Vascular endothelial growth factor (VEGF) inhibitors have recently been put into use for the treatment of neovascular form of AMD as part of clinical studies.^5–7 Ranibizumab (Lucentis; Genentech, South San Francisco, CA) is a human anti-VEGF antibody fragment, which may bind to all isoforms of VEGF. It may inhibit all VEGF-A isoforms.⁷

In recent years, various studies have been done to evaluate the effect of anti-VEGF treatments on ocular hemodynamics; however, the number of the studies investigating the effect of ranibizumab on ocular blood flow is small.^8–11 The most commonly used method to evaluate the effect of these available anti-VEGF treatments on retrobulbar blood flow is color Doppler ultrasonography (CDU), which is a routine noninvasive diagnostic tool to detect hemodynamic changes in orbital vessels.^12–16 It has been used to successfully evaluate the hemodynamics in retrobulbar vessels in retinal diseases and healthy eyes.^14–17

In this study, we evaluated retrobulbar ocular hemodynamic changes with CDU in intravitreal ranibizumab treated eyes and in the healthy fellow eyes in patients with neovascular AMD.

Methods

Study population and design

This prospective and interventional study was carried out at the Beyoglu Eye Education and Research Hospital. The study followed the tenets of the Declaration of Helsinki and was approved by the local ethics committee. All participants received oral and written information about the study, and each participant provided written informed consent.

The study included patients with neovascular AMD for whom treatment with a single intravitreal injection of 0.5 mg of ranibizumab (Lucentis) in 0.05 mL was planned.

Exclusion criteria included patients with history of previous CNVM therapy, including thermal laser photocoagulation, photodynamic therapy, and intravitreal anti-VEGF agents, and patients with previous history of retinal vascular disease, retinal diseases of fellow eyes, glaucoma, ischemic optic neuropathy, ocular surgery, systemic hypertension, coronary artery disease, and diabetes mellitus.

Examination protocol and measurements

All of the patients underwent a complete examination, including Snellen best corrected visual acuity (BCVA), biomicroscopy, intraocular pressure (IOP) measured by the Goldmann applanation tonometry, and dilated fundus examination.

A fluorescein angiography, optical coherence tomography (OCT) (Stratus OCT; Carl Zeiss Meditec, Inc., Dublin, CA), and axial length measurements with the IOLMaster (Carl Zeiss Meditech, AG, Jena, Germany) were also performed in all patients.

The blood pressure readings for systolic and diastolic blood pressure were obtained after the participant was seated for 10 min. The mean arterial blood pressure was calculated according to the formula, mean arterial blood pressure=2/3*diastolic blood pressure+1/3*systolic blood pressure. The mean ocular perfusion pressure was calculated as mean ocular perfusion pressure=2/3×mean arterial blood pressure−IOP.¹⁸

Intravitreal ranibizumab injection procedure

All injections were performed by the same vitreoretinal surgeon (K.Y.). The intravitreal ranibizumab was administered with topical anesthesia using proparacaine HCl 0.5% (Alcaine). After sterilization of the ocular surface and periocular area with 10% povidone iodine, an injection of 0.5 mg ranibizumab in 0.05 mL was administered using a 30 gauge needle through the pars plana. After the procedure, a topical antimicrobial agent was administered to all patients.

Ultrasound imaging

All color Doppler imaging examinations were performed by the same experienced radiologist (A.K.) using Toshiba Aplio SSA 770A equipment (Tochigi, Japan). Examinations were performed with patients in the supine position as described by Lieb et al.¹²

The radiologist was masked in terms of which was the treated eye. The pulsatility index (PI) and resistive index (RI) were calculated automatically by the scanner after measuring the peak systolic velocity (PSV) and end-diastolic (EDV) blood flow velocities of each vessel. CDU was performed with the gain adjusted to avoid artifactual color noise, thereby allowing detection of low velocities. The Doppler sample gate is then placed on the detected vessel to record blood flow signals. The angle between the Doppler beam and the long axis of each vessel was corrected to calculate actual flow velocities. The common carotid artery (CCA), ophthalmic artery (OA), central retinal artery (CRA), nasal posterior ciliary artery (NPCA), and temporal posterior ciliary artery (TPCA) of each patient were measured in both eyes within 1–3 days before (baseline) and 1 week, and 1 month after the injection of ranibizumab.

Statistical analysis

To achieve 95% confidence interval and 80% power of the study, 32 eyes were required to find a 3.5 cm/s difference with a standard deviation (SD) of 2.5 cm/s for CRA PSV value. The sample size was calculated using an alpha error of 0.05 and beta of 0.20. The statistical analyses were performed using Statistical Package for the Social Sciences (SPSS) version 16. The normality of the data was confirmed using the Shapiro–Wilk Test (P>0.05). Repeated measures analysis of variance was used for the comparison of all continuous variables. A P value of>0.05 was considered significant.

Results

A total of 34 patients were enrolled in the study. Two patients were then excluded because they did not return for the third CDU examination. Results for a total of 32 patients (15 women and 17 men) with mean age of (mean±SD) 64.2±11.2 years were analyzed.

Hemodynamic parameters measured in the CCA, OA, CRA, NPCA, TPCA injected eyes and uninjected eyes are shown in Table 1. There was no statistically significant difference among baseline, first week, and first month post-injection measurements for all parameters measured in CCA, OA, CRA, NPCA, TPCA, PSV, EDV, RI, and PI in the injected eyes.

Table 1.

Hemodynamic Doppler Parameters at Baseline and After the Injection

	Injected eyes				Fellow eyes
	Baseline	First week	First month	P	Baseline	First week	First month	P
CCA
PSV, cm/s mean±SD	73.9±4.5	77.2±17.4	76.3±9.6	0.604	72.9±10.8	76.6±18.1	76.0±17.1	0.521
EDV, cm/s mean±SD	19.3±3	17.2±6.18	18.8±4.9	0.860	17.73±2.8	15.9±4.6	18.8±9.6	0.741
RI mean±SD	0.73±0.03	0.75±0.08	0.74±0.07	0.765	0.73±0.04	0.75±0.06	0.75±0.06	0.550
PI mean±SD	1.41±0.4	1.78±0.35	1.61±0.40	0.478	1.61±0.2	1.80±0.58	1.77±0.34	0.229
OA
PSV, cm/s mean±SD	51.0±7.5	55.2±14.6	52.4±21.4	0.873	53.6±11.2	57.1±8.3	57.9±16.7	0.390
EDV, cm/s mean±SD	13.45±4.1	15.35±6.7	13.98±8.7	0.845	13.2±4.6	15.6±6.8	14.8±6.3	0.279
RI mean±SD	0.7±0.08	0.71±0.08	0.73±0.07	0.588	0.73±0.06	0.70±0.1	0.72±0.06	0.724
PI mean±SD	1.44±0.3	1.53±0.56	1.54±0.38	0.820	1.54±0.3	1.56±0.65	1.50±0.23	0.637
CRA
PSV, cm/s mean±SD	17.68±6.6	16.8±3.4	15.8±4.40	0.466	17.6±4.9	18.4±4.98	14.4±3.3	0.124
EDV, cm/s mean±SD	4.07±0.9	4.50±1.72	3.91±1.10	0.778	4.2±1.46	4.56±1.77	3.98±1.40	0.709
RI mean±SD	0.70±0.08	0.65±0.05	0.70±0.07	0.971	0.68±0.1	0.7±0.08	0.64±0.09	0.411
PI mean±SD	1.36±0.30	1.22±0.21	1.41±0.31	0.694	1.34±0.43	1.34±0.33	1.19±0.31	0.263
NPCA
PSV, cm/s mean±SD	15.9±2.3	16.1±3.14	14.7±3.23	0.310	13.21±1.9	16.71±2.3	14.3±2.9	0.482
EDV, cm/s mean±SD	5.45±1.5	4.6±1.61	4.25±1.25	0.145	4.05±1.05	4.45±0.99	4.46±0.69	0.274
RI mean±SD	0.62±0.07	0.69±0.10	0.58±0.11	0.749	0.6±0.06	0.66±0.07	0.61±0.1	0.946
PI mean±SD	1.07±0.28	1.30±0.34	1.05±0.20	0.914	1.08±0.15	1.31±0.26	1.11±0.24	0.655
TPCA
PSV, cm/s mean±SD	17.66±4.7	15.9±4.53	15.46±3.4	0.148	17.5±4.5	17.1±3.95	16.1±3.8	0.549
EDV, cm/s mean±SD	4.77±1.6	4.43±0.65	4.90±1.78	0.876	4.6±1.5	4.5±1.6	4.77±1.2	0.683
RI mean±SD	0.60±0.09	0.65±0.08	0.60±0.06	0.963	0.6±0.07	0.65±0.09	0.64±0.08	0.867
PI mean±SD	1.05±0.23	1.18±0.23	1.09±0.19	0.731	1.21±0.3	1.19±0.25	1.18±0.24	0.676

CCA, common carotid artery; OA, ophthalmic artery; CRA, central retinal artery; NPCA, nasal posterior ciliary artery; TPCA, temporal posterior ciliary artery; PSV, peak systolic velocity; EDV, end-diastolic velocity; RI, resistive index; PI, pulsatility index; SD, standard deviation.

There was also no significant difference between baseline, and first week and first month post-injection values in the uninjected healthy fellow eyes.

The mean IOP (mmHg) before injection, 1 week post-injection, and 1 month post-injection was 12.7±2.6, 12.6±1.9, and 12.5±2.1 in the injected eyes (P=0.54) and 12.9±2.3, 12.6±1.9, and 12.8±2.4 in the healthy fellow eyes (P=0.35), respectively.

The mean before injection, 1 week post-injection, 1 month post-injection systolic blood pressure (mmHg) was 132±11.4, 136.8±11.3, and 135.8±12.7 and the mean baseline, 1 week post-injection, and 1 month post-injection diastolic blood pressure (mmHg) was 75±5, 78.5±6, and 77.5±6, respectively. There was no significant difference between the baseline, 1 week post-injection, and 1 month post-injection values of blood pressure.

Ocular perfusion pressure in the injected eyes and uninjected eyes are shown in Table 2. There was no significant difference between mean pre- and post-injection values of ocular perfusion pressure in both injected and healthy fellow eyes.

Table 2.

Ocular Perfusion Pressure at Baseline and After the Injection

	Injected eyes				Fellow eyes
	Baseline	First week	First month	P	Baseline	First week	First month	P
OPP mean±SD	49.9±2.1	52.6±3.0	49.9±3.3	0.845	49.0±2.0	52.1±3.0	49.0±3.3	0.864

OPP, ocular perfusion pressure.

Before injection, the axial length (mm) and BCVA in the injected eyes were 23.4±1.1 and 0.36±0.21, while after injection, BCVA in the injected eyes was 0.57±0.24.

One patient had transient raised IOP and 2 patients had subconjuctival hemorrhage as a complication of intravitreal ranibizumab injection. No other ocular or systemic complications were seen.

Discussion

AMD, a progressive degenerative disease whose etiology is not fully understood, is one of the most important causes of irreversible visual loss in the aged population (65 years and above) in developed countries.^19–21 In neovascular type AMD, which is responsible for 90% of AMD-related blindness, angiogenesis triggered for an unknown reason results in CNVM formation.^22,23 VEGF inhibitors are being used for the treatment of CNVM. Of them, pegabtanib sodium, ranibizumab, and bevacizumab are used effectively today. Ranibizumab, a monoclonal antibody developed particularly for ocular use, acts by binding to all isoforms of VEGF-A and inactivating them.⁷ The efficacy of ranibizumab has been studied in 2 published clinical trials. These are Minimally Classic/Occult Trial of the Anti-VEGF Antibody Ranibizumab in the Treatment of Neovascular AMD (MARINA) and Anti-VEGF Antibody for the Treatment of Predominantly Classic Choroidal Neovascularization in AMD (ANCHOR). The findings of these 2 large clinical trials showed significant improvements in visual acuity or preservation of visual acuity among patients with neovascular AMD treated with ranibizumab.²⁴ However, the effect of intravitreal anti-VEGF drugs on choroidal and retinal hemodynamics is not yet fully known. CDU has been used in various studies to evaluate this effectiveness and its efficacy has been shown.^14–17 Spectral domain OCT and Fourier domain OCT are some of the other techniques used to evaluate ocular blood flow.^25–28

Many studies have been done to evaluate the effectiveness of bevacizumab an off-label drug used as a VEGF inhibitor in CVNM treatment on ocular blood flow.^8,10,11,29 A study by Hosseini et al. performed to evaluate the effect of bevacizumab on ocular blood flow, detected that bevacizumab reduced PSV and EDV values in CCA and posterior ciliary artery and increased the RI value.¹¹ Bonnin et al. measured mean blood flow velocities in the CRA, TPCA, and OA by using ultrasound imaging before and 4 weeks after a single intravitreal injection of 1.25 mg of bevacizumab. Four weeks after injection, the mean blood flow velocity decreased in the CRA, TPCA, and OA, respectively.⁸ Mete et al. also investigated the effects of intravitreal bevacizumab on retrobulbar circulation in 33 eyes of 30 patients with neovascular AMD. They reported that the PSV and EDV in the NPCA and the PSV of the TPCA decreased significantly 1 day after intravitreal injection of bevacizumab.¹⁰ Mete et al. evaluated the effect of intravitreal ranibizumab on ocular blood flow using CDU and compared ocular blood flow velocity of the patients before and 1 day after intravitreal ranibizumab injection. They detected that EDV values increased in NPCA and TPCA, and the RI value decreased in TPCA 1 day after the injection compared to the values before the injection.⁹

Our clinical study investigated the effect of a single intravitreal ranibizumab treatment in neovascular AMD patients on ocular hemodynamic parameters at 1 week and 1 month after the injection in the injected and noninjected eyes. We found that in the CCA, OA, CRA, NPCA, and TPCA, all the values were not statistically significant in the injected eyes at 1 week and 1 month after injection of ranibizumab. There was no significant difference between baseline, 1 week post-injection, and 1 month post-injection values in the uninjected healthy fellow eyes. We also found that ocular perfusion pressure after intravitreal ranibizumab, which has not been previously investigated, was not significantly changed after the procedure.

Many imaging modalities can be used for evaluation of ocular blood flow, including fluorescein and indocyanine green angiography, CDU, laser speckle imaging, retinal vessel analysis, and laser Doppler flowmetry. CDI has an important advantage over the other techniques, it is noninvasive, not affected by poor ocular media, and it requires no contrast or radiation.

The current study has some limitations. First, the blood flow measurements were taken 1 week and 1 month after the ranibizumab injection. For this reason, what happened to the blood flow measurements in the immediate post-injection period could not be evaluated. This limitation makes it difficult to draw a complete picture of the events occurring in the retrobulbar circulation after the ranibizumab injection. Second, this study is limited by the reproducibility of CDU. Stalmans et al. found long-term fluctuations of CDU by examining the intertest variability of measurements over a 1-month time interval.³⁰ It has also been shown that training significantly improves reproducibility.³¹ Harris et al. initially found that reproducibility was good in the CRA and OA, but had a higher variability in the PCA.³² The higher variability of hemodynamic variables among PCA is caused by the small size of these vessels and by their irregular and tortuous course.³³ Third, correlations between CDU parameters and clinical outcomes were not evaluated.

In conclusion, our results showed no changes in blood flow velocities in all arteries after a single intravitreal ranibizumab injection. However, further randomized, prospective, clinical trials with larger numbers of patients are needed to research the long-term effects of repeated injections of intravitreal ranibizumab on retrobulbar circulation.

Footnotes

Author Disclosure Statement

No author has a financial or proprietary interest in any material or method mentioned.

References

Schmidt-Erfurth

, Miller

J.W.

, Sickenberg

et al. Photodynamic therapy with verteporfin for choroidal neovascularization caused by age-related macular degeneration: results of a single treatment in a phase I and II study. Arch. Ophthalmol., 117:1177–1187. 1999.

Klein

, Klein

B.E.

, Linton

K.L.

Prevalence of age-related maculopathy. The Beaver Dam Eye Study. Ophthalmology, 99:933–943. 1992.

Bird

A.C.

, Bressler

N.M.

, Bressler

S.B.

et al. An international classification and grading system for age-related maculopathy and age-related macular degeneration. Surv. Ophthalmol., 39:367–374. 1995.

Ferris

F.L.

, Fine

S.L.

, Hyman

Age-related macular degeneration and blindness due to neovascular maculopathy. Arch. Ophthalmol., 102:1640–1642. 1984.

Kaiser

P.K.

Antivascular endothelial growth factor agents and their development: therapeutic implications in ocular diseases. Am. J. Ophthalmol., 142:660–668. 2006.

Bhisitkul

R.B.

Vascular endothelial growth factor biology: clinical implications for ocular treatments. Br. J. Ophthalmol., 90:1542–1547. 2006.

Rosenfeld

P.J.

, Schwartz

S.D.

, Blumenkranz

M.S.

et al. Maximum tolerated dose of a humanized anti-vascular endothelial growth factor antibody fragment for treating neovascular age-related macular degeneration. Ophthalmology, 112:1048–1053. 2005.

Bonnin

, Pournaras

J.A.C.

, Lazrak

et al. Ultrasound assessment of short-term ocular vascular effects of intravitreal injection of bevacizumab (Avastin(®)) in neovascular age-related macular degeneration. Acta ophthalmol., 88:641–645. 2010.

Mete

, Saygili

, Mete

, Gungor

, Bayram

, Bekir

Does ranibizumab (Lucentis®) change retrobulbar blood flow in patients with neovascular age-related macular degeneration?

Ophthalmic Res., 47:1415. 2012.

10.

Mete

, Saygili

, Bayram

, Bekir

Effects of intravitreal bevacizumab (Avastin) therapy on retrobulbar blood flow parameters in patients with neovascular age-related macular degeneration. J. Clin. Ultrasound., 38:66–70. 2010.

11.

Hosseini

, Lotfi

, Esfahani

M.H.

et al. Effect of intravitreal bevacizumab on retrobulbar blood flow in injected and uninjected fellow eyes of patients with neovascular age-related macular degeneration. Retina., 32:967–971. 2012.

12.

Lieb

W.E.

, Cohen

S.M.

, Merton

D.A.

Color Doppler imaging of the eye and orbit: technique and normal vascular anatomy. Arch. Ophthalmol., 109:527–531. 1991.

13.

Erickson

S.J.

, Hendrix

L.E.

, Massaro

B.M.

et al. Color Doppler flow imaging of the normal and abnormal orbit. Radiology, 173:511–516. 1989.

14.

Williamson

T.H.

, Harris

Color Doppler ultrasound imaging of the eye and orbit. Surv. Ophthalmol., 40:255–267. 1996.

15.

Lieb

W.E.

, Flaharty

P.M.

, Ho

, Sergott

R.C.

Color Doppler imaging of the eye and orbit: a synopsis of a 400 case experience. Acta Ophthalmol., 70:50–54. 1992.

16.

Harris

, Joos

, Kay

et al. Acute IOP elevation with scleral suction: effects on retrobulbar haemodynamics. Br. J. Ophthalmol., 80:1055–1059. 1996.

17.

Lieb

W.E.

, Flaharty

P.M.

, Sergott

R.C.

et al. Colour Doppler imaging provides accurate assessment of orbital blood flow in occlusive carotid artery disease. Ophthalmology, 98:548–552. 1991.

18.

Gherghel

, Orgul

, Gugleta

, Gekkieva

, Flammer

Relationship between ocular perfusion pressure and retrobulbar blood flow in patients with glaucoma with progressive damage. Am. J. Ophthalmol., 130:597–605. 2000.

19.

Vingerling

J.R.

, Dielemans

, Bots

M.L.

, Hofman

, Grobbee

D.E.

, de Jong

P.T.

Age-related macular degeneration is associated with atherosclerosis. The Rotterdam Study. Am. J. Epidemiol., 142:404–409. 1995.

20.

Friedman

D.S.

, O'Colmain

B.J.

, Muñoz

et al. Eye Diseases Prevalence Research Group. Prevalence of age-related macular degeneration in the United States. Arch. Ophthalmol., 122:564–572. 2004.

21.

Ambati

, Ambati

B.K.

, Yoo

S.H.

, Ianchulev

, Adamis

A.P.

Age-related macular degeneration: etiology, pathogenesis, and therapeutic strategies. Surv. Ophthalmol., 48:257–293. 2003.

22.

Tezel

T.H.

, Bora

N.S.

, Kaplan

Pathogenesis of age related macular degeneration. Trends Mol. Med., 10:417–420. 2004.

23.

Distler

, Neidhart

, Gay

R.E.

, Gay

The molecular of angiogenesis. Int. Rev. Immunol., 21:33–49. 2002.

24.

Kourlas

, Abrams

Ranibizumab for the treatment of neovascular age-related macular degeneration: a review. Clin. Ther., 29:1850–1861. 2007.

25.

Wang

, Fawzi

, Tan

, Gil-Flamer

, Huang

Retinal blood flow detection in diabetic patients by Doppler Fourier domain optical coherence tomography. Opt. Express., 17:4061–4073. 2009.

26.

Nassif

N.A.

, Cense

, Park

B.H.

et al. In vivo high-resolution video-rate spectral-domain optical coherence tomography of the human retina and optic nerve. Opt. Express., 12:367–376. 2004.

27.

Wang

, Bower

B.A.

, Izatt

J.A.

, Tan

, Huang

Retinal blood flow measurement by circumpapillary Fourier domain Doppler optical coherence tomography. J. Biomed. Opt., 13:064003. 2008.

28.

Wojtkowski

, Srinivasan

V.J.

, Ko

T.H.

, Fujimoto

J.G.

, Kowalczyk

, Duker

J.S.

Ultrahighresolution, high-speed, Fourier domain optical coherence tomography and methods for dispersion compensation. Opt. Express., 12:2404–2422. 2004.

29.

Avery

R.L.

, Pieramici

D.J.

, Rabena

M.D.

, Castellarin

A.A.

, Nasir

M.A.

, Giust

M.J.

Intravitreal bevacizumab (Avastin) for neovascular agerelated macular degeneration. Ophthalmology, 113:1695. 2006.

30.

Stalmans

, Siesky

, Zeyen

, Fieuws

, Harris

Reproducibility of color Doppler imaging. Graefes Arch. Clin. Exp. Ophthalmol., 247:1531–1538. 2009.

31.

Stalmans

, Vandewalle

, Anderson

D.R.

et al. Use of colour Doppler imaging in ocular blood flow research. Acta Ophthalmol., 89:609–630. 2011.

32.

Harris

, Williamson

T.H.

, Martin

et al. Test/retest reproducibility of color Doppler imaging assessment of blood flow velocity in orbital vessels. J. Glaucoma., 4:281–286. 1995.

33.

Galassi

, Sodi

, Ucci

, Renieri

, Pieri

, Baccini

Ocular hemodynamics and glaucoma prognosis: a color Doppler imaging study. Arch. Ophthalmol., 121:1711–1715. 2003.