Sequential Anterior Ischemic Optic Neuropathy and Central Retinal Artery and Vein Occlusion after Ranibizumab for Diabetic Macular Edema

Monoclonal antibodies in diabetic retinopathy

INTRODUCTION

Diabetic retinopathy (DR), as one of the main complications of diabetes, is among the leading causes of blindness and visual impairment worldwide.

AREAS COVERED

Current clinical therapies include photocoagulation, vitrectomy, and anti-vascular endothelial growth factor (VEGF) therapies. Bevacizumab and ranibizumab are two monoclonal antibodies (mAbs) inhibiting angiogenesis. Intravitreal ranibizumab and bevacizumab can decrease the rate of blindness and retinal thickness, and improve visual acuity whether as monotherapy or combined with other treatments. They can increase the efficacy of other treatments and decrease their adverse events. Although administered intravitreally, they also might enter the circulation and cause systemic effects. This study is aimed to review our current knowledge about mAbs, bevacizumab and ranibizumab, in DR including superiorities, challenges, and limitations. Meanwhile, we tried to shed light on new ideas to overcome these limitations. Our latest search was done in April 2021 mainly through PubMed and Google Scholar. Relevant clinical studies were imported.

EXPERT OPINION

Future direction includes detection of more therapeutic targets considering other components of DR pathophysiology and shared pathogenesis of DR and neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease, the treat-and-extend regimen, and new ways of drug delivery and other routes of ocular drug administration.

In vivo evaluation of outer retinal function and structure after retrobulbar optic nerve crush by lateral orbitotomy in goats

Large animal model of optic nerve crush (ONC) plays an important role in translating novel therapeutic strategies developed in rodent model to clinical application. Due to the poor accessibility of the optic nerve (ON) in humans and large animals, lateral orbitotomy is needed to expose the retrobulbar ON. This study was to explore the effects of ONC and ON exposure with lateral orbitotomy (sham surgery) on the outer retinal function and structure in goats by using standard flash electroretinogram (FERG) and spectral-domain optical coherence tomography (SD-OCT). We found that ONC led to a transient reduction in FERG amplitudes at 1 week post injury (wpi), which recovered gradually over 2 months afterwards. Sham surgery alone also caused a similar pattern of amplitude reduction in FERG, although not as significantly as ONC did. Transient outer retinal thickening following ONC occurred at 4 wpi (when progressive thinning of the ganglion cell complex began), peaked at 8 wpi, then recovered gradually at 12 wpi. In contrast, outer retinal thickness remained unchanged statistically 3 months after sham surgery. Fundus fluorescein angiography showed that neither ONC nor ON exposure with lateral orbitotomy significantly caused any significant delay or absence of central retinal vascular filling. In summary, ONC with lateral orbitotomy affects outer retinal function and structure transiently.

Nonarteritic Anterior Ischemic Optic Neuropathy following Herpes Zoster Ophthalmicus and Steroid-Related Intraocular Pressure Spike

A 61-year-old woman presented with sudden vision loss from a left anterior optic neuropathy in the context of severely elevated intraocular pressure after starting topical steroids for anterior uveitis related to herpes zoster ophthalmicus (HZO). The strong temporal relationship between the vision loss and elevated IOP suggested the vision loss was related to nonarteritic anterior ischemic optic neuropathy (NAION). Anterior chamber paracentesis did not detect varicella zoster virus (VZV) and magnetic resonance imaging of the orbits was normal. Her vision remained stable and the optic disc edema resolved within 3 months. The occurrence of NAION following an acute elevation of intraocular pressure (IOP) is well-documented in the context of surgical procedures, glaucoma, uveitis and trauma. This case indicates that not every optic neuropathy in close temporal relationship with HZO is directly attributable to the virus. NAION may also occur after steroid-related IOP spikes and ophthalmologists should ensure that patients on topical steroids are closely monitored for ocular complications.

[Impact of antiangiogenic therapy on ocular blood flow and microcirculation in diabetic macular edema]

Today, diabetic macular edema (DME) is still one of the main causes of vision loss in patients with diabetes.

PURPOSE

To identify changes in the ocular blood flow and microvascular network of the macular zone in patients with DME after antiangiogenic therapy.

MATERIAL AND METHODS

In the course of the study, 25 patients (50 eyes) with monolateral clinically significant DME aged 67.5±3.85 years were examined. Control group consisted of 75 healthy subjects (150 eyes). All patients underwent ultrasound examination of the eyes and orbits (in Color Doppler Imaging (CDI) and Pulse-Doppler modes) and OCT-angiography (OCT-A) before the intravitreal injection of ranibizumab, as well as 3 days, 2 weeks, and 1 month after the treatment.

RESULTS

According to OCT-A, the initial values of microvascular network parameters were significantly below the norm (p<0.05). After intravitreal ranibizumab injection (IRI), no significant changes in the density of microcapillaries or in the parameters of foveal avascular zone (FAZ) were recorded. However, a transient increase of the FAZ area was revealed 2 weeks after the injection, as well as an increase of microcapillaries density in the central quadrant together with a decrease of density in the peripheral quadrants 1 month after IRI. By the end of the follow-up period, a decrease in the initially raised maximum systolic velocity (Vsyst) and resistance index (RI) in the ophthalmic artery (OA) of the affected eye were documented. Additionally, an increase in Vsyst and 2-fold increase in end-diastolic velocity (Vdiast), as well as a decrease in RI in the central retinal artery (CRA) on the affected and paired eyes were detected.

CONCLUSION

The study revealed no negative effects of the angiogenesis inhibitor ranibizumab on retinal microcirculation or ocular blood flow. The registered changes in blood flow may indicate improvement of hemodynamic parameters after resorption of macular edema.

Rubeosis iridis in patients with diabetes: not forgetting oculoischaemic syndrome as a differential

This case illustrates an oculoischaemic syndrome presenting with iris neovascularisation in a patient with established diabetic retinopathy. It highlights the importance of considering the differential diagnosis of rubeosis in all patients, including those with an underlying vascular pathology. Moreover, it urges clinicians to consider the sequelae of a compromised vascular system, such as the iatrogenic central retinal artery occlusion as a result of intravitreal injections. Early diagnosis not only informs correct ophthalmic treatment, but is crucial in preventing ischaemic stroke and, therefore, reducing the risk of systemic morbidity and mortality.

Sudden visual loss in the untreated eye of a patient with neovascular glaucoma following an intravitreal bevacizumab injection: A case report

The current study presents the case of a patient with a rare adverse event characterized by sudden vision loss in the untreated eye following an intravitreal injection of bevacizumab for neovascular glaucoma (NVG). The patient was diagnosed with NVG refractory to Ahmed glaucoma valve implantation and a vitreous hemorrhage in the right eye, which was treated with 1.25 mg intravitreal bevacizumab. Ten days after the bevacizumab injection, the left eye exhibited sudden visual loss. The patient's best-corrected visual acuity (BCVA) decreased from 80 to 25 letters [Early Treatment Diabetic Retinopathy Study (ETDRS) chart]. A fundus examination revealed a swollen optic disk with unclear boundaries, retinal hemorrhages and thinning retinal vessels. Fundus fluorescein angiography (FA) identified hyperfluorescence in the optic disk and an enlarged foveal avascular zone. The visual field revealed quadrantal defects that confirmed the diagnosis of anterior ischemic optic neuropathy associated with ischemic maculopathy. Six months later, following medical treatment, the patient's BCVA was increased to 44 letters. However, a clinical examination found neovessels with one papilla disk (PD) above the disk. Laser photocoagulation treatment was administered immediately. The area of neovessels above the disk was reduced to 1/4 PD at the last follow-up. In conclusion, although intravitreal anti-vascular endothelial growth factor (Bevacizumab) is an effective treatment for neovascular ocular diseases, its adverse effects must be taken into consideration for the treatment of NVG. Photocoagulation remains an effective treatment for proliferative diabetic retinopathy.

Effects of multiple intravitreal anti-VEGF injections on retinal nerve fiber layer and intraocular pressure: a comparative clinical study

AIM

To determine the effect of multiple injections of ranibizumab or bevacizumab on retinal nerve fiber layer (RNFL) and intraocular pressure (IOP) in patients with age-related macular degeneration (AMD).

METHODS

This retrospective study includes 35 eyes of 35 patients treated with intravitreal bevacizumab (IVB, 1.25mg/0.05mL) and 30 eyes of 30 patients with intravitreal ranibizumab (IVR, 0.5mg/0.05mL) who had Fast RNFL analysis (Stratus™); IOP measurements were taken 30 minutes and 24 hours after each injection.

RESULTS

The mean ages were 68.0±7.5 and 69.1±7.7 years in the IVR and IVB groups, respectively (P=0.55). They underwent (6.3±1.9) and (5.1±1.3) injections (P=0.07) over (13.6±2.1) and (14.05±2.6) months (P=0.45) in the IVR and IVB groups, respectively. Changes in overall and temporal RNFL thickness in IVR-treated eyes (105.3±6.9µm and 74.4±11.2µm) were not different from those in untreated eyes in the IVR group (104.6± 8.4µm and 75.1±12.6µm) (P=0.57 and P=0.41, respectively). Similarly, overall and temporal RNFL thickness in IVB-treated eyes (105.8±8.1µm and 74.5±11.8µm) were not different from those in untreated eyes in the IVB group (104.6±8µm and 74.8±12.9µm) (P=0.42 and P=0.80, respectively). The frequencies of IOP rise (P=0.60) and changes in RNFL thickness from baseline (P=0.16) were comparable between groups.

CONCLUSION

Repeated intravitreal injection of ranibizumab or bevacizumab does not seem have adverse effects on RNFL thickness or IOP in wet AMD patients.

Evaluation of retrobulbar blood flow by color doppler ultrasonography after intravitreal ranibizumab injection in patients with neovascular age-related macular degeneration

PURPOSE

This study aimed to evaluate the changes in retrobulbar blood flow by using color Doppler sonography in patients who had undergone intravitreal ranibizumab injection for neovascular age-related macular degeneration (AMD).

METHODS

The study comprised 37 AMD patients who had undergone intravitreal 0.5 mg ranibizumab injection. The ophthalmic artery, central retinal artery, and short lateral posterior ciliary artery of both eyes of patients were evaluated by color Doppler sonography. Peak systolic velocity, end-diastolic velocity, and resistance index were calculated before injection, and after injection on day 7 and day 30. The pre- and postinjection values were compared using Wilcoxon signed rank test.

RESULTS

In a comparison with the preinjection values of peak systolic velocity, end-diastolic velocity, and resistance index, the postinjection values at both day 7 and day 30 showed no statistically significant difference in ophthalmic artery, lateral posterior ciliary artery, and central retinal artery (p > 0.05). Similarly, for the same parameters, pre- and postinjection values in the uninjected fellow eye showed no statistically significant difference (P > 0.05).

CONCLUSIONS

Intravitreal ranibizumab injection for neovascular AMD does not cause a significant change in the retrobulbar blood flow in either the injected eye or the fellow eye.

Vascular endothelial growth factor promotes progressive retinal nonperfusion in patients with retinal vein occlusion

OBJECTIVE

Central retinal vein occlusion (CRVO) or branch retinal vein occlusion (BRVO) causes hypoperfusion, high levels of vascular endothelial growth factor (VEGF), macular edema, and loss of vision. Many patients also show areas of complete closure of retinal vessels (retinal nonperfusion [RNP]) that increase over time. The objective was to assess the effect of blocking VEGF on progression of RNP.

DESIGN

Retrospective analysis of prospectively collected data from 2 randomized, sham injection-controlled, double-masked, multicenter clinical trials.

PARTICIPANTS

A total of 392 and 397 patients with macular edema due to CRVO or BRVO.

METHODS

An independent reading center measured the area of RNP on fluorescein angiograms (FAs) in 2 phase III trials investigating the effect of ranibizumab (RBZ; Lucentis; Genentech, Inc, South San Francisco, CA) in patients with CRVO or BRVO.

MAIN OUTCOME MEASURES

The percentage of patients with no posterior RNP at months 0, 3, 6, 9, and 12.

RESULTS

There was no difference among treatment groups at baseline, but at the month 6 primary end point the percentage of patients with CRVO and no RNP was significantly greater in the RBZ groups (0.3 mg, 82.0%, P = 0.0092; 0.5 mg, 84.0%, P = 0.0067) versus the sham group (67.0%). Reperfusion of nonperfused retina was rare (1%) in sham-treated patients with CRVO, but occurred in 6% to 8% of patients with CRVO treated with RBZ (30% of those who had RNP and could improve). Results in patients with BRVO mirrored those in patients with CRVO. Crossover to 0.5 mg RBZ from sham at month 6 halted the progression of RNP and resulted in improvement in both CRVO and BRVO.

CONCLUSIONS

Treatment with RBZ did not worsen RNP in patients with RVO, but rather reduced its occurrence compared with sham. These data provide an important new insight regarding the pathogenesis of RVO; the initial vein occlusion is a precipitating event that causes baseline ischemia and release of VEGF, which then contributes to progression of RNP and thus worsening of ischemia. Timely, aggressive blockade of VEGF prevents the worsening of RNP, promotes reperfusion, and eliminates a positive feedback loop.

Insight into 144 patients with ocular vascular events during VEGF antagonist injections

AIM

To record ocular vascular events following injections of vascular endothelium growth factor (VEGF) antagonists.

METHODS

Collaborative multicenter case series (48 cases), literature reviews (32 cases), and reports to the FDA (64 cases) of patients that had vascular occlusions during anti-VEGF therapy were collected and analyzed.

RESULTS

A total of 144 cases of ocular vascular events were identified, with these diagnosed a median of 15 days after anti-VEGF injection. The majority of patients had pre-existing risk factors for cardiovascular events and nine patients had a prior history of glaucoma. Mean visual acuity dropped by 6.4 lines with severe visual loss after injection to NLP (five eyes), LP (six eyes), and HM (two eyes). The overall risk of ocular vascular events following a VEGF antagonist injection was 0.108% in the general population and 2.61% in the diabetic population. Mean retinal arterial constriction after intravitreal bevacizumab in 13 eyes was 21% (standard deviation = 27%), and mean retinal venous constriction was 8% (standard deviation = 30%).

CONCLUSION

Ocular vascular events are rare during anti-VEGF therapy, but can lead to severe visual loss and may be caused by a number of factors including the vasoconstrictor effect of the drug, a post-injection rise of intraocular pressure, patient stress as a result of the procedure, and the patient's natural history of underlying ocular or systemic diseases. The diabetic population appears to have a tendency towards ocular vascular occlusions.

Retinal blood flow in response to an intravitreal injection of ranibizumab for neovascular age-related macular degeneration

PURPOSE

To assess the hemodynamic response of retinal arterioles and venules following a single intravitreal injection of ranibizumab in neovascular age-related macular degeneration (NV-AMD) patients and to assess the influence of the number of prior injections on this response.

METHODS

Fifteen NV-AMD patients were prospectively recruited and grouped according to the dosage of ranibizumab previously received. Group 1 NV-AMD patients (n = 7) had previously received 1.50 mg or less, and group 2 patients (n = 8) had received more than 1.50 mg in the study eye. A group of 12 non-NV AMD patients were also recruited for control comparison. Vessel diameter, centreline blood velocity and blood flow were assessed with the Canon Laser Blood Flowmeter immediately prior to an injection and at a mean follow-up of 37.7 and 36.7 days for group 1 and group 2 patients, respectively.

RESULTS

The NV-AMD patients as a whole and the group 1 cohort had a significantly greater arteriolar diameter at baseline than the non-NV AMD patients. There was a significant reduction in arteriolar diameter, velocity and blood flow in group 1 but not in group 2 NV-AMD patients at follow-up. There was only an insignificant decrease in measured parameters of the retinal venules. At follow-up, there was no difference in the diameter, velocity or flow between AMD patients.

CONCLUSION

Intravitreal ranibizumab treatment for NV-AMD induces a reduction in arteriolar diameter, velocity, and blood flow in patients who have received <1.50 mg of ranibizumab.