Abstract
Purpose:
A new grading protocol for diabetic macular edema (DME) was presented previously based on optical coherence tomography (OCT) and fluorescence angiography (FA). Aim of this study was to correlate visual acuity to several different subtypes of DME based on this grading protocol.
Methods:
71 eyes of 50 patients with clinically significant DME were examined with macular map OCT scans and fluorescence angiography using Spectralis HRA and OCT (Heidelberg Engineering©). Visual acuity was performed according to the ETDRS protocol (early treatment of diabetic retinopathy study) on the same day. All imaging data was evaluated by 2 readers according to a grading protocol abbreviated “SAVE” that was previously presented, whereas “S” stands for “subretinal fluid”, “A” for “area” (planimetric dimension), “V” for “vitreo-retinal abnormalities” and “E” for edema type (focal, non-focal, ischemic, degenerative). The aim of the grading protocol is to describe all categories by numbers followed by the central millimetre retinal thickness in µm (e.g. S0A5V1E2 537). All imaging and functional test results were correlated.
Results:
There was a good inter-grader agreement regarding the graded categories of the SAVE grading protocol. Subretinal fluid did not show a significant correlation with visual acuity, nor did edema expansion (category A). However, there was a correlation between the edema subtype (category E) and visual acuity. Visual acuity was significantly better in patients with edema type 1 (focal edema) than in type 3 (ischemic) or 4 (degenerative). The significance of the correlation between visual acuity and central retinal thickness depended on the morphologic sub-type.
Conclusions:
Apart from describing the individual type and amount of alteration of DME, the SAVE grading protocol based on OCT and FA images reveals the correlation between retinal morphology and function. These findings are relevant not only for diagnosis in daily clinical routine, but also for treatment decisions and the definition of inclusion criteria in clinical trials.
Keywords: 499 diabetic retinopathy •
550 imaging/image analysis: clinical •
542 grouping and segmentation