Abstract
Purpose: :
Subretinal thickening in the foveal region on optical coherent tomography is often regarded as a poor visual prognostic indicator. In this study, we evaluated the changes in subretinal thickening over 12 months in patients on ranibizumab therapy for neovascular age related macular degeneration (nAMD) and its relation to the visual acuity and number of injections at 12 months.
Methods: :
Retrospective analysis of Spectralis OCT of 51 eyes of 51 patients undergoing ranibizumab treatment for nAMD were done. The data on clinic based visual acuity at baseline and 12 months and the total number of injections were recorded. The scan protocol used was Spectralis SD-OCT 20 x 20 volume cube with 60 scans at a spatial separation of 100µm. The subretinal thickening (SRT) was defined as a homogenous layer of hyper-reflectivity of band below the external limiting membrane (ELM) extending to the band that represents the retinal pigment epithelium. The height and chord length of the SRT was measured manually using the electronic callipers. The presence or absence of external limiting membrane (ELM) at the foveal dip was also was noted. Patients with any intraretinal or subretinal fluid in the subfoveal area that interfered with the measurements were excluded.
Results: :
The mean length of the SRT increased by 12 months but the height did not. The mean change of visual acuity at 12 months was 7.33 (SD 9.65). Both the length and the height of SRT did not influence the final visual outcome. The mean number of injections given over the period is 5.33 (SD 2.02). The thickness or the length of SRD did not correlate with the number of injections. However, eyes with no subfoveal ELM required significantly more injections (p=0.04). Final visual acuity did not correlate to the number of injections given.
Conclusions: :
SRT does not influence final visual outcome. Eyes with preservation of ELM required less number of injections.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • age-related macular degeneration