Abstract
Purpose:
To investigate SD-OCT selective layering assessment in diabetic patients with and without diabetic retinopathy(DR).
Methods:
110 subjects were enrolled: 90 were affected by diabetes mellitus and 20 normals served as controls. Proliferative DR, previous laser photocoagulation and intraocular surgery were the main exclusion criteria. 30 had no DR(noDR group), 30 patients had non proliferative DR without macular edema(DR group) and 30 had non proliferative DR with macular edema (DME group). Full ophthalmic examination, stereoscopic fundus photography and spectral domain-OCT(SD-OCT; macular region: 6 radial scans and dense volume) were performed. Automatic segmentation of retinal layers (inner limiting membrane plus retinal nerve fiber layer: ILM+RNFL; ganglion cell layer: GCL; inner plexiform layer: IPL; inner nuclear layer: INL; outer plexiform layer: OPL; outer nuclear layer: ONL; external limiting membrane: ELM; inner and outer segments of photoreceptors) was performed with manual refinement. Integrity of each layer was identified, and the thickness of individual layers was calculated. All measurement were performed twice by 2 independent graders.
Results:
No statistically significant differences were found for age among all groups, and for glycemic control between diabetics. A significant increase in thickness in all (except for outer)layers in DME group versus all groups (p<.002) and significant decrease of ILM+RNFL in noDR and DR group versus controls were found (p<.001). Increase of GCL in noDR group and decrease in DR group versus controls was found (p<.04)or decrease of IPL in noDR and DR group (p<.04) and INL and OPL in noDR group and their increase in DR group versus controls were found (p<.04). A progressive increase of ONL and no change in outer layers in all groups versus controls (p<.002) were found. The inter-grader agreement was at least substantial for all measurements.
Conclusions:
The thinning of inner retinal layers in diabetic patients without clinically detectable RD and with non proliferative RD without DME and the thickening of GCL and INL in noDR group and DR group respectively are confirmed in vivo. No change in outer layers among the groups was found. Automatic layering of the retina by SD-OCT is a useful tool to diagnose and monitor intraretinal changes in DR. Automatic retinal layering may contribute to the identification of selective layer changes in diabetic retinas.
Keywords: 499 diabetic retinopathy •
549 image processing •
688 retina