Purpose
To evaluate the effect of multiple intravitreal injections with ranibizumab and bevacizumab over time on macular GCC thickness in eyes with wet AMD compared to age-matched control eyes with dry AMD.
Methods
This was a retrospective, observational, case control study of consecutive patients diagnosed with AMD. 24 eyes treated with either ranibizumab or bevacizumab for newly-diagnosed wet AMD were enrolled along with 15 age-matched control eyes with dry AMD. All patients were followed by sequential macular imaging utilizing the RTVue® SD-OCT (Optovue, Inc., Fremont, CA) for a minimum of six months. Macular GCC thickness was defined as the combination of retinal nerve fiber, ganglion cell and inner plexiform layers. Measurements between the two groups were made at the initial and most recent follow-up exams. Eyes with a history of glaucoma or macular edema affecting the GCC were excluded.
Results
Average follow up for all patients was 22.1± 9.0 months .The treatment group received on average 11.5 injections. A decrease in the average GCC thickness was found across the parafoveal region (inner 3 mm) of 9.3±10.7 um and 1.5±4.3 um in the treatment and control groups respectively (p<0.05). A significant correlation was found between the number of injections and the average amount of GCC thinning in the parafoveal (r = 0.495, p < 0.05) and the perifoveal (r = 0.431, p < 0.05) regions, principally in the nasal and temporal quadrants.
Conclusions
Ranibizumab and bevacizumab can lead to significant GCC thinning over time that correlates with the number of injections. This may account for lack of visual improvement in some patients. Further large scale prospective studies are needed to validate these findings.
Keywords: 585 macula/fovea •
695 retinal degenerations: cell biology •
550 imaging/image analysis: clinical