Visual fields correlate better than visual acuity to severity of diabetic retinopathy

Abstract

Aims/hypothesis: We compared the outcomes of perimetric and visual acuity tests in patients with diabetic retinopathy. Methods: We examined 59 diabetic patients with different degrees of retinopathy using stereo fundus photography in accordance with the Early Treatment of Diabetic Retinopathy Study (ETDRS) and fluorescein angiography. Conventional white-on-white perimetry (WWP) and short wavelength automated perimetry (SWAP) were performed and analysed with reference to normal values. Visual acuity was measured with ETDRS charts. Results: Regression analysis revealed that visual acuity was significantly associated with increasing severity of retinopathy according to the ETDRS scale when visual acuity was estimated by counting logarithm of minimum angle of resolution (LogMar) scores, but not when visual acuity was measured by the conventional reading of the smallest line that could be seen. Visual acuity decreased by 0.02 LogMar per ETDRS step (p=0.03). The degree of visual field loss was significantly associated with increasing severity of retinopathy according to the ETDRS scale, perimetric sensitivity decreasing by 0.44 dB per ETDRS step (p=0.0001) using WWP, and by 0.40 dB per ETDRS step (p=0.04) with SWAP. The size of the area of the foveal avascular zone and adjacent perifoveal intercapillary areas (PIAs) also affected the central visual field as obtained both by WWP (−2.6 dB/ mm 2 , p=0.03), and by SWAP (−7.9 dB/mm 2 , p=0.002), but did not affect visual acuity. The regression model fit for peripheral retinopathy according to the ETDRS scale was better using WWP than SWAP or visual acuity, while SWAP testing was superior to both WWP and visual acuity when measuring effects caused by enlarged foveal avascular zones and PIAs. Conclusions/interpretation: Perimetry can provide more useful information than visual acuity on functional loss in diabetic retinopathy, particularly when the perifoveal capillary network is damaged.

Visual acuity and perimetry as measures of visual function in diabetic macular oedema

“…However, Hudson and colleagues did not include eyes without oedema in their analyses and also did not characterise the perifoveolar capillary network. Although it cannot be excluded that the difference in results could depend on our use of a different classification of macular oedema, our multivariate analysis showed that FAZ and PIAs together was the only explanatory variable not only for SWAP but also for WWP defects, as previously described in more detail [9]. Similar observations on SWAP have been published by Remky et al [12].…”

“…Fields were evaluated in terms of the pattern deviation probability maps included in the Statpac interpretation tool [8]. Since no Statpac interpretation was available for SWAP 10-2, a normal database including 180 eyes of 90 healthy subjects was constructed for the generation of a Statpac program including pattern deviation probability maps [9]. In these maps, test point locations with significantly reduced differential light sensitivity are flagged as abnormal after elimination of effects of media opacities, such as cataract.…”

Diabetic Retinopathy

“…In fact, loss of oscillatory potentials on electroretinograms predicts the onset of proliferative retinopathy better than vascular lesions seen on fundus photographs or capillary nonperfusion visualized by fluorescein angiograms (40). Electroretinograms and psychophysical tests are primarily used in research settings, but recent reports using clinically available visual field test modifications (short-wave automated perimetry and frequency doubling perimetry) reveal field defects in patients with little or no vascular retinopathy (41,42), and visual fields predict the severity of retinopathy better than visual acuity (43). Together, these findings strongly suggest that functional tests are more sensitive indicators of retinal integrity than fundus photographs or optical coherence tomography and may serve as useful end points for clinical trials, but they must be validated first.…”

Diabetic Retinopathy—Update on Prevention Techniques, Present Therapies, and New Leads

“…[71][72][73] Most recently, tests of visual fields have also been reported to be more indicative of functional deficiency than visual acuity tests when determining retinopathy severity. 74 Frequency doubling technology (FDT) perimetry is now being used to investigate the neuronal consequences of early diabetic retinopathy by testing the visual field. Studies applying the technology have revealed severe impairment of retinal function, particularly affecting the inner retina and rod photoreceptors, even before visual acuity decline.…”