Abstract
Purpose::
To determine the frequency of optical coherence tomography (OCT3) machine boundary line misplacements (BLM) of inner and outer macula and to compare OCT machine versus manual measurement of retinal thickness in eyes with neovascular age-related macular degeneration (AMD).
Methods::
Charts and OCT scans of patients who had been evaluated for the diagnosis of subfoveal choroidal neovascularization secondary to AMD were retrospectively reviewed. OCT scans were processed using the fast macular thickness (FMT) analysis protocol (retinal thickness map) and measures for the desired regions were obtained from corresponding A-scan results. Subsequently, 2 manual measurements of the retinal thickness at the same points were performed using the manual caliper function of the OCT3 analysis software. Frequency of BLM at the fovea (central) and outside the foveal region (elsewhere) was determined. BLM were classified according to OCT appearance. All results from AMD eyes were compared to eyes with diabetic macular edema (DME) as controls.
Results::
100 eyes of 100 patients with neovascular AMD and 25 eyes of 25 patients with DME were included in the study. For AMD group, 30 patients were male and 70 were female. The average age was 78.9 (+/- 7.03). OCT BLM rate in the AMD group was 70% versus 24% in DME control group. BLM occurred in the presence of intraretinal cystic fluid (IRF) in 21.4%, 12.9% with subretinal thickening (SRT), 11.4% with both IRF+SRT, 7.1% with subretinal fluid (SRF), and 5.7% with pigment epithelium detachment (PED). Average retinal thickness for machine reading and manual measurement was 280 +/-98.2 µm and 269 +/-85.7 µm (p=0.058), respectively, while in DME control group was 355+/-113 µm and 343+/-111 µm (p=0.95), respectively. BLM was associated with lower signal strength, better visual acuity, and greater standard deviation of machine retinal thickness measurement.
Conclusions::
The frequency of BLM was higher in eyes with neovascular AMD than DME. BLM was more likely to occur in presence of IRF then SRT and both together. OCT3 machine retinal thickness readings were not as accurate as that for DME. Given these findings, manual readings of retinal thickness should be used in the eyes with neovascular AMD with BLM with the current software program.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • age-related macular degeneration • retina