A new treatment algorithm for the management of myopic choroidal neovascularization using intravitreal ranibizumab

Field: Medicine (Health Sciences)

Despite extensive use of antivascular endothelial growth factor (anti-VEGF), the optimal treatment for choroidal neovascularization associated with pathologic myopia (mCNV) is still a matter of debate, centring on a Pro re nata regimen (PRN, initial single dose plus additional doses in case of CNV activity) and a loading dose+PRN regimen (three consecutive monthly injections+PRN). However, one protocol is not clearly superior to the other in terms of efficacy or safety (Neelam et al. 2012). This 18-month prospective study evaluated the outcomes of a treatment algorithm guided by the initial response to the first ranibizumab injection. The loading dose was given in cases of persistent CNV activity at the 1-month examination, with a PRN strategy reserved for silent CNV. CNV activity was defined as persistent leakage on fluorescein angiography, persistent intraretinal/subretinal fluid on optical coherence tomography, visual acuity loss of at least five ETDRS letters or increased metamorphosia. The research adhered to the tenets of the Declaration of Helsinki and was approved by the institutional review board. Fifteen patients were included in the PRN Group and 12 in the LOAD+PRN Group (Table 1). The median BCVA improved in the PRN group from its baseline value over the subsequent 3 months, registering a continuous statistically significant BCVA gain, which was preserved thereafter. The LOAD+PRN Group failed to maintain the improvement registered at 1 month, with the gains stabilizing from the 3-month examination on. At the 18-month examination, a greater proportion of eyes with an improvement of >1 and >3 lines was registered in the PRN group (86% versus 58%, 73% versus 25%, Chi-square test, p: 0.02). Statistically significant reductions in the CMT and CNV areas were noted in both groups from the 1-month examination on. The baseline features of the two groups differed significantly in median age at the time of inclusion, symptom duration and CNV area. The mean number of injections administered was 1.3 ± 0.5 in the PRN Group and 4.4 ± 1 in the LOAD+PRN Group. During the follow-up, five patients received 1 additional injection in the PRN Group, whereas 10 patients required additional injections after the loading dose (5, 3 and 2 eyes requiring 1, 2 and 3 injections, respectively). These results are consistent with recent studies of IVRI, showing a mean visual improvement from 1.5 to 4 lines (Vadalà et al. 2011; Iacono et al. 2012). The difference between the two groups in BCVA outcomes, baseline characteristics, mean number of injections administered and high retreatment rate noted in the LOAD+PRN Group are likely the result of the treatment algorithm, which included eyes with higher CNV activity in the LOAD+PRN Group. As already highlighted in the studies employing anti-VEGF therapy for mCNV, the most favourable functional results are generally obtained in patients under 55, with shorter symptom duration and smaller CNV (Ruiz-Moreno et al. 2013) – all characteristics encountered in patients in the PRN Group. A continuous statistically significant improvement in the BCVA occurred during the first 3 months, whereas it was not seen in the LOAD+PRN Group. Our data cast some doubt on the reinforcing effect of the loading dose, as previously described by other authors (Kung et al. 2014). On the contrary, the importance of treating early-stage, small CNV seems crucial. The main shortcomings of this study are the small sample size and the short-term follow-up. It was not designed to establish the superiority of the PRN strategy over the loading dose followed by a Pro re nata treatment. In essence, our data confirm that an early diagnosis is associated with a small CNV with reduced activity, allowing a simple PRN strategy in a subgroup of younger patients and avoiding potential overtreatment through the loading phase.