Purpose: In several case-studies improved outcomes have been reported after switching from a pro-re-nata (PRN)- to a treat-and-extend (T&E)-based therapeutic approach in cases of neovascular age-related macular degeneration (nAMD). We therefore wished to compare the effects of instigating 2 different protocols in newly-diagnosed nAMD undergoing treatment with Ranibizumab.
Methods: The outcomes of a PRN- and a T&E-based regime were retrospectively compared in treatment-naïve eyes under therapy with Ranibizumab for minimally 12 months in a routine clinical setting. The primary outcome measures included the proportion of the eyes with intraretinal fluid in OCT and visual stability after the initial drug-loading phase.
Results: The comparative case-series included 107 eyes (PRN: 68; T&E: 39). During the 2-year follow-up period, a similar number of clinical examinations were performed in the 2 groups (PRN: 14.0 ± 6.2; T&E 13.4 ± 4.4; P = 0.97), whereas the number of injections that were administered differed for the first (PRN: 5.5 ± 2.0 vs. T&E 6.8 ± 2.4; P = 0.008) and the second year (PRN: 1.9 ± 2.0 vs. T&E 3.8 ± 2.3; P = 0.002). The proportion of eyes with intraretinal fluid after the initial drug-loading phase remained stable (PRN: from 33.8% to 36.4%; T&E: from 25.6% to 29.0%); so, too, did the central retinal thickness and the visual acuity.
Conclusion: Despite a limited sample size, this retrospective analysis revealed the anatomical and the functional improvements during the 2-year follow-up period to be not roughly different for the 2 strategies. However, when the PRN-approach is instigated, the risk of under-treatment due to lapses in visits or to over-extensions in the intervals between treatments may be underestimated.
Keywords: PRN; Ranibizumab; intravitreal injections; pro-re-nata; treat-and-extend; wet age-related macular degeneration.