Retrospective analysis of the effect of aflibercept loading dose on the retinal vessel diameters in patients with treatment-naive neovascular AMD

Retinal vascular structure independently predicts the initial treatment response in neovascular age-related macular degeneration

PURPOSE

Prediction of the early treatment response is important in neovascular age-related macular degeneration (nAMD). Hence, we aimed to test if non-invasive measurements of the retinal vascular structure were able to predict a successful outcome of initial intravitreal treatment.

METHODS

In 58 eyes of 58 patients with treatment-naïve nAMD, advanced markers of retinal vascular structure were measured by Singapore I Vessel Assessment prior to initial intravitreal treatment with three monthly injections of aflibercept with subsequently categorization of patients as full treatment responders (FTR) or non/partial treatment responders (N/PR), with the former defined as loosing fewer than five Early Treatment Diabetic Retinopathy Study letters and having no residual intra- or subretinal fluid or macular haemorrhage.

RESULTS

Of 54 eyes attending follow-up, 44.4% were categorized as FTR. Patients with FTR were older (81.5 vs. 77 years, p = 0.04), and prior to treatment those eyes had a lower retinal arteriolar fractal dimension (Fd) (1.21 vs. 1.24 units, p = 0.02) and venular length-diameter ratio (LDR) (7.3 vs. 15.9 units, p = 0.006), but did not differ with respect to other retinal vascular parameters. In multiple logistic regression models, a lower chance of FTR was independently predicted by a higher retinal venular LDR (odds ratio [OR] 0.91, 95% CI 0.82-0.99, p = 0.03, for each 1 unit increment) and marginally by a higher retinal arteriolar Fd (OR 0.83, 95% CI 0.68-1.00, p = 0.05, for each 0.01 unit increment).

CONCLUSION

Retinal venular LDR independently predicted the initial treatment response in nAMD. If confirmed by long-term, prospective studies, this might help to guide treatment.

Alterations in retinal arteriolar microvascular structure associate with higher treatment burden in patients with diabetic macular oedema: results from a 12-month prospective clinical trial

PURPOSE

This study was based on data from a 12-month prospective clinical trial and aimed to examine changes in retinal microvascular structure in eyes treated with intravitreal aflibercept in combination with focal/grid laser photocoagulation for diabetic macular oedema (DME).

METHODS

We included 32 treatment naïve eyes of 22 patients with centre involving DME. The treatment algorithm comprised a loading phase of three monthly injections of aflibercept and focal/grid laser photocoagulation [baseline (BL)-month 3 (M3)] followed by a pro re nata (PRN) aflibercept phase until month 12 (M12). Eyes were divided into groups with and without need for PRN treatment after loading. Parameters of retinal microvascular structure were measured in 45° optic disc centred fundus images at BL, M3 and M12 using a semi-automated software (VAMPIRE®, Vessel Assessment and Measurement Platform for Images of the Retina, Universities of Dundee and Edinburgh, UK).

RESULTS

A significant decrease in retinal arteriolar calibre was demonstrated at both M3 (-11.2 μm, p = 0.005) and M12 (-11.5 μm, p = 0.04) as compared to BL in eyes that needed PRN treatment during follow-up. In contrast, arteriolar calibre remained unchanged in eyes without need for PRN treatment (M3: -1.6 μm, p = 0.79 and M12: -7.0 μm, p = 0.22). For retinal venules, vessel calibre decreased both in eyes with and without need for PRN therapy at M3 (-9.5 μm, p = 0.01 and -11.6 μm, p = 0.01) as well as at M12 (-15.6 μm, p = 0.001 and -11.0 μm, p = 0.04).

CONCLUSION

Early changes in retinal arteriolar calibre are associated with an increased treatment burden during the first year of DME treatment.

Short-time effect of intravitreal injections on retinal vascular oxygenation and vessel diameter in patients with diabetic macular oedema or neovascular age-related macular degeneration

PURPOSE

To investigate the short-time effect of intravitreal injections (IVI) of the vascular endothelial growth factor inhibitors ranibizumab and aflibercept on retinal arterial and venous oxygen saturation (SO2a and SO2v), arteriovenous oxygen saturation difference (AVD) and vessel diameter (VDa and VDv) in patients with diabetic macular oedema (DME) and patients with choroidal neovascularization (CNV) due to age-related macular degeneration.

METHODS

Uncontrolled prospective observational study in 100 eyes. Retinal vessel oxygen saturation and diameters were assessed using a retinal oximeter before and minutes after IVI of ranibizumab or aflibercept.

RESULTS

40 eyes with CNV and 34 eyes with DME were included in the analysis. At baseline, SO2a and SO2v were significantly higher in DME (p = 0.043 and p = 0.009, respectively). After IVI, SO2a significantly decreased in CNV and DME eyes by 2.6% (p = 0.016) and 4.6% (p = 0.002) and SO2v decreased by 14.0% (p = 0.004) and 12.4% (p = 0.017), respectively. However, a significant increase in AVD was only found in CNV (15.7%, p = 0.001). VDa decreased significantly only in DME by 5.7% (p = 0.010). No medication-specific disease effect was found and vice versa.

CONCLUSIONS

The observed changes can be interpreted as signs of increased metabolic demand during the physiological stress after an IVI. The abnormal arterial constriction and the abolished increase in AVD seen only in eyes with DME indicate an impairment of vascular autoregulation and oxygen distribution and a reduced neuroretinal metabolism in the diabetic retina with a significant impact on inner retinal oxygen consumption shortly after IVI.

Short-term effect on the ocular circulation induced by unilateral intravitreal injection of aflibercept in age-related maculopathy

Purpose

Intravitreal injection of anti‐vascular endothelial growth factor (anti‐VEGF) is the standard treatment for neovascular age‐related macular degeneration (AMD). As VEGF is a physiological key player for regulating retinal vascular tone, questions have been raised whether the application of anti‐VEGF could induce alterations in ocular perfusion.

Methods

The study included 20 eyes from 20 Caucasian patients with unilateral neovascular AMD and 20 fellow eyes. All eyes were treated with standard intravitreal injection of aflibercept (IVA). Measurements of blood flow at the optic nerve head (ONH) and the choroid were performed with laser speckle flowgraphy (LSFG). The intraocular pressure (IOP), systolic and diastolic blood pressure, heart rate, mean arterial pressure (MAP) and ocular perfusion pressure (OPP) were analysed. Measurements were performed at baseline and repeated immediately after the injection and 30 and 45 min later.

Results

Mean time between injection of aflibercept and first follow‐up was 8:56 ± 4:25 min. The injection led to significant rise in IOP. In the injected eyes, mean blur rate (MBR, i.e. a relative measure of perfusion and the main outcome parameter of LSFG) within the major vessels of the ONH as well as at the entire ONH region decreased significantly (p < 0.001). No change in MBR was observed in the fellow eye. Choroidal blood flow was maintained stable in both eyes.

Conclusion

Intravitreal injection of aflibercept (IVA) led to a short‐term reduction in perfusion only in the treated eye. This was independent from IOP, indicating a direct pharmacological effect. No changes in choroidal perfusion were observed during the first 45 min after the injection.

Retinal metabolic and structural alterations in response to aflibercept treatment in neovascular age-related macular degeneration

PURPOSE

Non-invasive retinal markers of disease activity could pave the way for individualized treatment in neovascular age-related macular degeneration (nAMD). We aimed to evaluate if retinal vascular oxygen saturation and calibres could predict the initial treatment response after a loading phase of intravitreal aflibercept in nAMD.

METHOD

A total of 149 eyes were included (nAMD, n = 76; dry AMD, n = 30; normal eyes n = 43). Of these, 57 treatment-naïve eyes with nAMD received three monthly injections with 2.0 mg aflibercept and were subsequently stratified according to functional and structural response according to development in best-corrected visual acuity and macular retinal thickness. The retinal vascular oxygen saturation and calibres were measured prior to treatment and 1 month after the third injection.

RESULTS

Patients with nAMD and dry AMD had higher retinal arteriolar oxygen saturation as compared to normal eyes (94.3% versus 95.2% versus 92.6%, p = 0.04). Thirty-nine (68.4%) and 12 (21.1%) eyes with nAMD were functional and structural responders. After the loading phase, structural nonresponders developed a higher retinal arteriolar (95.3% versus 93.3%, p = 0.03) and venular (64.7% versus 59.4%, p = 0.02) oxygen saturation, and responders developed a lower retinal arteriolar calibre (118.0 versus 114.3 μm, p < 0.01). In a multiple logistic regression model, increasing retinal venular oxygen saturation associated with a negative structural treatment outcome (odds ratio 1.17 for each 1% increment after the loading phase, 95% confidence interval 1.01-1.36, p = 0.03).

CONCLUSION

Changes in the retinal venular oxygen saturation associate independently with initial treatment response in nAMD, but functional and structural retinal measurements prior to treatment could not predict the treatment response.