Abstract
Purpose: :
To use optical coherence tomography (OCT) grading software to provide enhanced quantitative analysis regarding the longitudinal effects of ranibizumab on the morphology of the retina in patients with neovascular AMD.
Methods: :
Data from a consecutive series of 95 patients receiving intravitreal injections of ranibizumab for neovascular AMD were examined. Raw exported StratusOCT images were analyzed using custom software (OCTOR) which allows the grader to precisely position pre-specified boundaries on every B-scan. Changes in thickness/volume of the retina, subretinal fluid (SRF), subretinal tissue (SRT), and pigment epithelial detachments (PEDs) at week 1, and at months 1, 3, 6 and 9 post-treatment were calculated.
Results: :
StratusOCT images were available for analysis as follows: 15 patients at Week 1; 80 patients at Month 1; 84 patients at Month 3; 58 patients at Month 6; 37 patients at Month 9. Effect on Retina: The retina showed an average 44.83 µm decrease from baseline in FCP thickness by month 1 (P<0.001). This initial decrease lessened during the remainder of the study, with an average reduction of 30.55 µm at month 6 (P=0.0178), and 16.95 µm at month 9 (P=0.2642). Total retinal volume reached its nadir at month 1, with an average reduction of 0.43 mm3 (P<0.001). By month 9, this initial change had been reduced to a mean reduction of 0.32 mm3 (P=0.0011). Effect on SRF: The total volume of SRF reached its lowest level by month 1, with an average reduction from baseline of 0.24 mm3 (P<0.001). This reduction was maintained at month 3 but lessened subsequently, with an average reduction of 0.18 mm3 by month 9. Effect on SRT: The total volume of SRT was reduced by an average of 0.07 mm3 by month 1 (P=0.0159) and this reduction appeared to be maintained through the remainder of the study period, although subsequent changes were not statistically significant. Effect on PED: There was an average 0.3 mm3 decrease in total PED volume by month 1 (P<0.001), and this declined further during the study, to an average of 0.45 mm3 by month 9 (P=0.0014).
Conclusions: :
Although neurosensory retinal edema and SRF, showed an early reduction to nadir following initiation of ranibizumab therapy, the effect on the retina was attenuated over time, suggesting a possible tachyphylaxis. SRT and PEDs showed a slower but progressive and sustained reduction. Manual quantitative OCT subanalysis may be of value in clinical trials allowing a more precise understanding of anatomic outcomes and their correlation with visual acuity outcomes.
Keywords: age-related macular degeneration • imaging/image analysis: clinical • choroid: neovascularization