Abstract
Purpose:
To evaluate thickness of the ganglion cell-inner plexus layer (GCIPL) in diabetic patients after resolution of macular edema, and in diabetic patients with no history of diabetic macular edema (DME), using Cirrus spectral-domain optical coherence tomography (OCT).
Methods:
This observational case-control cohort study group included 21 eyes from type 2 diabetic patients with previous history of DME, treated with intra-vitreal therapy or focal/grid laser therapy, resulting in the absence of fluid on OCT (cases), and a central macular thickness (CMT) < 315 µm. Controls were represented by 21 eyes from type 2 diabetic patients, matched by age, with no or mild non proliferative diabetic retinopathy, and without past or present macular edema. Average GCIPL thickness was measured from a macular cube scan performed with Cirrus HD-OCT. Primary outcome was the comparison between GCIPL thickness in cases and in controls. Secondary outcome was the correlation between best corrected visual acuity (BCVA) and GCIPL in each group.
Results:
Mean age was 61 ±9 years for cases, and 60 ±8 years for controls. In the cases group, median duration of edema was 36 ±18 months; 13 eyes (62%) had been treated with ranibizumab, 8 eyes had been treated with dexamethasone intravitreal implant and 11 eyes (52%) had undergone focal/grid laser therapy. The mean GCIPL thickness was 74 ±14 μm in cases group and 81 ±6 μm in control group (p=0.016). The mean minimum GCIPL thickness was 57 ±22 μm in cases group and 81 ±5 μm in control group (p=0.0001). In case group, mean BCVA was 0.41 ±0.25 LogMAR and BCVA was significantly correlated to mean GCIPL thickness (r=0.866; p<0.0001).
Conclusions:
Decreased GCIPL thickness in diabetic eyes after resolution of edema suggests the presence of inner retina damages, that could not be easily evaluated before fluid removal. Strongly significant correlation between GCIPL thickness and BCVA may partially explain visual loss despite restitution of foveal pit.
Keywords: 499 diabetic retinopathy •
531 ganglion cells •
550 imaging/image analysis: clinical