Assessment of the function of the central macula in diabetic maculopathy

Raj, A
(2016) Assessment of the function of the central macula in diabetic maculopathy. Doctor of Medicine thesis, University of Liverpool.

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Introduction: Neural degeneration of the retina has been demonstrated in diabetes mellitus (DM). Several studies have focused on retinal neural function in diabetic retinopathy (DR) but few have assessed function in diabetic maculopathy, the leading cause of visual disturbance in DM. Aim: To correlate, cross-sectionally and longitudinally, central macular function to diabetic maculopathy. Methods: Treatment-naïve subjects with DM were recruited to three groups: i) diabetic controls (no visible signs of DR); ii) early maculopathy (maculopathy not meeting criteria for clinically significant macular oedema (CSMO)); and iii) sight-threatening maculopathy (presence of CSMO and/or ischaemic maculopathy). A group of healthy controls was also recruited. Subjects underwent assessment of best correct visual acuity (BCVA), contrast sensitivity (CS), optical coherence tomography (OCT), microperimetry (MP), multifocal electroretinography (mfERG), oscillatory potential (OP) and systemic risk factors (HbA1c, serum cholesterol and blood pressure). Subjects with DM were invited to follow-up at 6 months and 12 months where assessments were repeated. One-way ANOVA and ANCOVA were used for cross-sectional and longitudinal analysis, respectively (SPSS, Version 22). Results: Eighty-nine subjects with DM (diabetic controls, n=24; early maculopathy, n=24; sight-threatening maculopathy, n=41) and 29 healthy controls were recruited. Compared to both healthy and diabetic controls, subjects with sight-threatening maculopathy showed significant worsening in CS (10-15% reduction, p<0.01), MP central ring sensitivity (23-29% reduction, p<0.01), mfERG central ring amplitude (45% reduction, p<0.01), mfERG implicit time (7% prolongation, p<0.01) and OP sum amplitude (35% reduction, p≤0.01), and a 20-25% increase in mean central subfield thickness(CSFT) on OCT (p<0.01). Subjects with early maculopathy showed a trend towards worsening in mfERG amplitude (23% reduction, p<0.05), CS (7% reduction, p<0.05) and MP sensitivity (p=0.06) compared to healthy controls. Function was non-significantly reduced in diabetic controls compared to healthy controls. Sixty-one subjects were invited for follow-up, with 39 and 31 subjects attending at 6 and 12 months respectively. At 12 months, there was a trend towards worsening OP sum amplitude (p=0.03); conversely, MP sensitivity improved (p<0.01). There were no significant or trend associations with other assessments, most notably best corrected distance visual acuity. There was no correlation between change in mean central subfield thickness on OCT and change in mfERG, MP and OP (p>0.10 for all comparisons). Conclusions: Central macular function is reduced in diabetic maculopathy despite reasonable visual acuity. Assessment of neural function alongside clinical examination may provide the clinician with a clearer picture of central macular status and aid in clinical decision making.

Item Type: Thesis (Doctor of Medicine)
Additional Information:
Divisions: Faculty of Health and Life Sciences > Faculty of Health and Life Sciences
Depositing User: Symplectic Admin
Date Deposited: 18 Dec 2017 10:54
Last Modified: 02 Apr 2021 08:28
DOI: 10.17638/03009729