Quantitative subanalysis of optical coherence tomography after treatment with ranibizumab for neovascular age-related macular degeneration

Abstract

Purpose: To investigate the effects of ranibizumab on retinal morphology in patients with neovascular age-related macular degeneration (AMD) using optical coherence tomography (OCT) quantitative subanalysis.

Methods: Data from 95 patients receiving intravitreal ranibizumab for neovascular AMD were collected. StratusOCT images were analyzed using custom software that allows precise positioning of prespecified 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 after treatment were calculated.

Results: Total retinal volume reached its nadir at month 1, with an average reduction of 0.43 mm(3) (P < 0.001). By month 9, this initial change had been reduced to a mean reduction of 0.32 mm(3) (P = 0.0011). Total SRF volume reached its lowest level by month 1, with an average reduction of 0.24 mm(3) (P < 0.001). This reduction lessened subsequently, to 0.18 mm(3), by month 9. There was an average 0.3-mm(3) decrease in total PED volume by month 1 (P < 0.001), and this later declined further, to 0.45 mm(3), by month 9 (P = 0.0014). Total SRT volume was reduced by an average of 0.07 mm(3) at month 1 (P = 0.0159) and subsequently remained constant.

Conclusions: Although neurosensory retinal edema and SRF showed an early reduction to nadir after the initiation of ranibizumab therapy, the effect on the retina was attenuated over time, suggesting possible tachyphylaxis. PED volume showed a slower but progressive reduction. Manual quantitative OCT subanalysis may allow a more precise understanding of anatomic outcomes and their correlation with visual acuity.

Figure 1

Optical coherence tomography B-scan of an eye demonstrating subretinal fluid (SRF) accumulation and pigment epithelial detachment (PED). The clinically relevant boundaries (internal limiting membrane, outer photoreceptor border, retinal pigment epithelium [RPE], and the estimated normal position of the RPE layer [A]) are graded using “OCTOR” (computer-assisted manual grading) software, which then computes the volumes of the spaces (retina, SRF, and PED) defined by these boundaries (B).

Figure 2

Neurosensory retina outcomes as provided by “OCTOR” (computer-assisted optical coherence tomography grading software). A, Mean change from baseline in thickness of the neurosensory retina at the foveal center point (FCP). B, Mean change from baseline in total volume of the neurosensory retina. Vertical lines, 1 standard error of the mean. *P<0.05, **P<0.01.

Figure 3

Subretinal outcomes as provided by “OCTOR” (computer-assisted optical coherence tomography grading software). A, Mean change from baseline in total volume of subretinal fluid. B, Mean change from baseline in total volume of subretinal tissue. Vertical lines, 1 standard error of the mean. *P<0.05, **P<0.01.

Figure 4

Mean change from baseline in total volume of pigment epithelial detachment as provided by “OCTOR” (computer-assisted optical coherence tomography grading software). Vertical lines, 1 standard error of the mean. *P<0.05, **P<0.01.

Figure 5

“Height from RPE” outcomes as provided by “OCTOR” (computer-assisted optical coherence tomography grading software). A, Mean change from baseline in “Height from RPE” at foveal center point (FCP). B, Mean change from baseline in total volume of “Height from RPE”. Vertical lines, 1 standard error of the mean. *P<0.05, **P<0.01.