Abstract
Purpose: :
As part of a randomised controlled trial investigating the effectiveness of low vision intervention for patients with diabetic eye disease, we have conducted an observational study of the impact of visual impairment on self-reported visual ability. Here we present baseline visual ability and visual function data in relation to disease severity.
Methods: :
Eligible patients with diabetic eye disease were recruited from diabetic clinics at Moorfields Eye Hospital, London into 4 severity groups: 1: background retinopathy, 2: preproliferative retinopathy, 3: preproliferative retinopathy with maculopathy and 4: advanced diabetic eye disease. All participants completed a visual function assessment including acuity, contrast sensitivity, reading performance, color vision, binocular fields, fixation stability and microperimetry. A visual ability questionnaire, the Massof Activity Inventory was administered to all participants within 1 week of enrolment, providing a measure of visual ability.
Results: :
82 patients (29 female, 53 male) were enrolled, 21 with type 1 and 61 with type 2 diabetes. 20 patients were recruited to group 1, 20 to group 2, 17 to group 3 and 25 to group 4. Disease severity was significantly associated with visual ability score (r=0.37, p=0.01), with significantly greater ability reported in groups 1 and 2 (3.29 and 3.39 logits) than in groups 3 and 4 (1.54 and 1.96 logits). Several aspects of visual function including acuity, contrast sensitivity, critical print size, peripheral visual fields and macular sensitivity were also related to disease severity (r=0.33-0.45, p<0.03). We found no association between disease severity and color vision (r=0.11, p>0.05) or fixation stability (r=0.44, p>0.05). After controlling for confounding factors (age and sex) and adjusting for loss of visual function (distance and near acuity and central and peripheral field loss) there was no significant difference in ability scores (p=0.22).
Conclusions: :
Increasing severity of diabetic eye disease is associated with reduced visual ability. This is largely explained by visual function changes, such as reduced acuity and central and peripheral field loss. Future work will examine those aspects of visual function most closely related to visual ability and determine the effectiveness of low vision intervention in this patient population.
Clinical Trial: :
http://www.isrctn.org ISRCTN91672666
Keywords: low vision • diabetic retinopathy • diabetes