SCIENTIFIC REPORT

Exaggerated relative nasal-temporal asymmetry of macular capillary blood flow in patients with clinically significant diabetic macular oedema

C Hudson^1,2, J G Flanagan^1,2, G S Turner¹, H C Chen¹, M H Rawji² and D McLeod¹

¹ University Department of Ophthalmology, Royal Eye Hospital, Manchester M13 9WH, UK
² School of Optometry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada and Department of Ophthalmology, University of Toronto, Toronto, Ontario M5T 2S8, Canada

Correspondence to:
Correspondence to:
Chris Hudson PhD
School of Optometry, University of Waterloo, 200 University Avenue East, Waterloo, Ontario N2L 3G1, Canada; chudson{at}sciborg.uwaterloo.ca

Aims: To compare the macular capillary blood flow of patients with clinically significant diabetic macular oedema (DMO) with that of non-diabetic subjects and to determine the relation between blood flow and capillary leakage in patients with DMO.

Methods: The sample comprised 45 non-diabetic subjects (mean age 59 years) and 18 type 2 patients with clinically significant DMO (mean age 60 years). Macular capillary blood flow measurements were acquired using the Heidelberg retina flowmeter (HRF) and a 10°x2.5° scan field centred on the fovea. Fluorescein angiography was undertaken on each of the diabetic patients after the completion of HRF measurements.

Results: Temporal macular capillary blood flow was significantly lower for the patients with clinically significant DMO compared with age matched non-diabetic subjects (ANCOVA, p = 0.0011) while relative nasal-temporal asymmetry of macular capillary blood flow was significantly higher (p = 0.0125). Nasal-temporal asymmetry of macular capillary blood flow was significantly higher for the patients with DMO and capillary leakage within the scan area (two tailed t test, p = 0.0071). Macular capillary blood flow was always lower in areas of DMO and capillary leakage.

Conclusion: Capillary blood flow was reduced in areas of DMO and capillary leakage, suggesting the presence of a localised perturbation of capillary blood flow regulation.

Abbreviations: DMO, diabetic macular oedema; FAZ, foveal avascular zone; FFA, fundus fluorescein angiography; HRF, Heidelberg retina flowmeter; SLDF, scanning laser Doppler flowmetry

Keywords: diabetic macular oedema; retinal thickening; capillary blood flow

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