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D.V. Arlotte, R.V. North, N. Drasdo, D.R. Owens; A Modified Technique used to Assess Oscillatory Potentials in Patients with Diabetes Mellitus . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3972.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Oscillatory Potentials (OPs) are observed to be a sensitive measure in the progression of diabetic retinopathy, and are affected before signs are visible ophthalmoscopically. The ISCEV standard for recording OPs recommends 20 minutes dark adaptation (DA) followed by a conditioning flash (CF) of 5ms duration. In a clinical situation this technique of recording may be considered to be a lengthy process. The aim of this study was to investigate modified techniques in control subjects to obtain OPs of the same amplitude in a reduced time, and in patients with diabetes mellitus (DM). Methods: 10 patients with type 2 DM were recruited (mean age 61.8 +/- 10.16 (SD) years) with no visible signs of retinopathy, and 10 age matched healthy subjects (mean age 61.4 +/- 9.34 (SD) years). OPs were recorded using DTL electrodes and a mini Ganzfeld LED stimulator. Technique 1 - OPs were recorded after 20 minutes DA, a 12ms CF (549cd.m-2), followed by a further four white 12ms flashes at 15 second intervals. Technique 2 - From ambient room lighting, OPs were recorded following 2 minutes 37 seconds DA, and presented with four 12ms flashes at 15 second intervals. Technique 3 - Subjects were then adapted to a dim white background (0.06cd.m-2) for 2 minutes and OPs recorded using four flashes at 15 second intervals. Technique 4 – Following DA to the level of –3.5 log cd.m-2, measured using the Goldmann Weekers dark adaptometer, four 12ms white flashes were again presented at 15 second intervals. Techniques 1-4 were used for the control subjects, and techniques 2-4 for the diabetic patients. Results: Four distinct OPs were recorded using all four techniques, both in the control and diabetic groups. In the control group, OP summed amplitudes were significantly increased in techniques 3, and 4, when compared to the conventional method of 20 minutes DA (technique 1). Whereas, OPs recorded using technique 2 were not seen to be significantly different to those in technique 1. Summed amplitudes were reduced in the diabetic group, but were not significantly different to the controls (p>0.05). Amplitude of OP2 was significantly reduced in techniques 3 and 4, when compared to the controls. Implicit time of OP3 was significantly increased in the diabetic group in technique 3. Conclusions: Recording OPs using the modified techniques is much quicker when compared to the ISCEV recommendations of 20 minutes DA, and provides four distinct OPs. These new techniques may be a useful clinical tool in monitoring diabetic patients.
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