Abstract
Purpose::
Anti-VEGF-therapy induces characteristic effects on retinal morphology and function most intensively during the first months following treatment initiation with consecutive monthly injections. The morphologic changes in retina, retinal pigment epithelium (RPE) and choroidal neovascularization (CNV) were analyzed using high-resolution OCT and correlated with functional parameters.
Methods::
30 patients with CNV secondary to age-related macular degeneration (AMD) received monthly intravitreal injections with ranibizumab (Lucentis®). OCT examinations using the STRATUS as well as a HR-Raster OCT prototype (Zeiss) as well as BCVA testing and microperimetry were performed on days 0, 8, 30, 60 and 90. FA (HRA 2) examinations were done on day 0 and 90. Results were evaluated regarding morphologic and volumetric changes in OCT/HR-OCT and correlated with retinal function.
Results::
The initial monthly regimen of intravitreal ranibizumab induced a significant decrease in central retinal thickness and mean retinal thickness within one week (-88±84µm; p<0.01). Simultaneously, the overall mean retinal volume indicating the total amount of intraretinal fluid decreased markedly, but less than the retinal thickness in the fovea. This morphologic change correlated with a significant improvement in visual acuity (+5.1±4.0 letters; p<0.01) at this early point in time. At month one, a distinct decrease in height (-113µm; p=0.03) and diameter (-756µm; p=0.07) of RPE detachment was noted. At month three, a complete resolution of intra- and subretinal fluid was seen in all eyes accompanied by a further increase in BCVA (+6.2±5.8 letters; p<0.01). The morphological lesion origin remained detectable, but appeared flatter and smaller mostly maintaining the initial configuration. In contrast to retinal changes, alterations at the level of the RPE or the CNV had little impact on visual acuity. Changes in retinal volume correlated well with changes in microperimetry demonstrating recovery of photoreceptors in the entire macular region.
Conclusions::
Effects of monthly intravitreal ranibizumab injections can be observed as early as after one week. Particularly within the initial three months, there is a strong correlation between morphologic retinal changes observed with OCT/HR-OCT and functional improvement. Structural changes at the level of the RPE and CNV are more prolonged and have a less immediate impact on retinal function.
Keywords: imaging/image analysis: clinical • age-related macular degeneration • retinal pigment epithelium