The study included wet AMD patients divided into 3 subgroups. AMD patients with Type 1 membranes (under RPE) consisted of 25 patients (9 men, 16 women) with a mean age of 72.9 ± 10.8 years (median: 70.2 years; range: 57.7 – 88.5 years). The Type 2 AMD patients group comprised of 11 patients (6 man and 5 women) with a mean age of 81.11 ± 12.3 years (median: 87.0 years; range: 67.1 – 89.3 years). The last groups were the 6 patients with RAP (1 man, 5 women) with a mean age of 68.9 ± 10.3 00 years (median: 68.2 years; range: 57.7 – 68.5 years).
All the groups were examined with Fluorescein angiography (FA), structural OCT and OCTA. According to the OCTA the neovascular membranes can be divided into 3 main types such as:
-Type 1 CNV situated under the RPE
-Type 2CNV situated above the RPE in which the vessels originate from the choroid and transverse the RPE
- Type 3 CNV with retino-choroidal anastomoses coming from the deep retinal plexus and corresponding to RAP lesions.
With the use of OCTA and the whole complex of diagnostic tools we were able to study the structure of neovascular membranes of our patients.
In the first group of 25 AMD patients we had a Type 1 neovascular membrane, in which the new vessels originated from the choroid and transverse the Bruch’s membrane and were located underneath the RPE.
In 50% of the cases (12) the neovascular membranes were with the shape of “medusa” or coral-form with multiple radial branching vessels, emerging from main feeding one ( Fig. 1).
In some of the cases it was very difficult to detect the neovascularistion as it was situated underneath the RPE. Only in the images trough the choroid we were able to detect the emerging new vessels and see their structural characteristics. All other segmentations of OCT A gave normal images.
In 7 patients – 2% of this group-- the new vessels were very large in caliber, rough looking with numerous branches, forming a network of small capillaries or looking like a broom. These types of CNV were usually prone to progression and they were the ones that did not respond to the therapy (Fig.2). In about 1 % of the patients with CNV Type I the vascular membranes lacked distinct smaller vessels, although we were able to outline the big feeding one.
The Type 2 AMD patients group comprised of 11 . The lesions emerged from the choroid, traversed the RPE and formed a membrane located between the RPE and neurosensory retina. These are the classic type CNVs found in the FA. These lesions had well outlined borders on the OCT-A and typical shape. In 7 patients ---- the OCTA characteristics were that of “ glomeruli” like shape with multiple branching little vessels with different hyporeflectivity ( Fig.3).
In some of the cases peripheral arcades with several branches at the end on the neovascular membrane were seen on the OCTA images. They were considered to be a hallmark of activity and of further progression of the neovascular membranes.
The last groups were the 6 patients with RAP (1 man and 5 women). In the RAP lesions the new vessles originally emerged from the deep retinal plexus. OCT-A gave us the opportunity to see the lesions in the superficial and deep retinal plexus and its junctions with the vessels of the choroid, where they formed retino-choroidal anastomoses. ( Fig.4). CNV type 3 was characterized by a tuff shaped high –flow vascular network arising from the deep capillary plexus in the outer retinal layer. In all eyes, a feeder vessel was seen connecting the CNV with the deep retinal capillary plexus. About 80% of lesions we found were associated with pigment epithelial detachment.
All of the patients in the 3 different groups were treated intravitreally with Eylea (Aflibercept) in dose 2 mg (0.05 ml). The mean number of intravitreal injections was 7 (SD 3.4). All the patients were followed for a period of one year. The injections were done following the Treat and extend protocol. In that scheme the pateints had 3 initial loading doses every 4 weeks and later on in patients without activity of the disease the injection interval was extended with 2 weeks. The shortest interval in our patients was 4 weeks.
The mean VA of our patients was 0.1 (SD 0.2) for the three groups. After the application of the treatment the VA increases averedgedly with 6±2 letters by the end of the year follow up. The mean improvement of the VA was up to 0.3 (SD0.4: P<0.001). We established also significant reduction of the central retinal thickness. From initial mean retinal thickness of (400 ± 130 μm) by the end of the year the reduction of the retinal thickness was up to (294 ± 75 μm).
In the 7 patients from the first group with typical very large vessels of the membranes on the OCTA no improvement of the VA has been found. The mean VA of 0.1(SD 0.2) remained unchanged and even in 2 patients reduced to 0.05. The central retinal thickness was very slightly changed after the treatment from (395 ± 110 μm) up to ( 300 ± 75 μm ). We can say that particular subgroup was resistant to therapy.
However overall, all patients showed decrease in the density of the small branching vessels of the neovascular membranes after the anti- VEGF therapy. In this subgroup that decrease in the density was the smallest but still existed.
Our study gave us the opportunity to outline the main criteria on OCTA showing and predicting progression, which can be an indicator for starting anti-VEGF treatment. Patients with neovascular membranes which on the OCT A are with “ medusa” like shape or lace with rough large vessels and numerous branching capillaries have been the ones with quick progression and resistant to therapy. Another risk factor for progression is the presence of anastomoses between the vessels. The new active vessels are usually large in caliber, branching and forming a network. In the 3 groups of patients we had 7 such patients who progressed further in the period of 1 year. The RAP patients were also difficult to treat and they preserved the initial visual acuity but with maximal number of injections.