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Marco Miranda, Gay Verdon-Roe, Ciara Bergin, Tony Redmond, David Crabb, David Garway-Heath; Exploration of the Dynamic Range of the Moorfields MDT to Assess Suitability to Monitor Glaucoma. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3915.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the dynamic range between stimuli employed in Standard Automated Perimetry, SAP, and in the Moorfields Motion Displacement Test, MMDT.
Frequency-of-seeing curves (FOS) were obtained from data collected at 8 locations of the visual field (VF) in 23 subjects with a range of pointwise sensitivities (0 - 35dB on the Humphrey VF analyzer, Carl Zeiss Meditec., SITA-Standard). Four locations of the VF in one eye per subject were tested. The method of constant stimuli was used for both SAP- and MMDT-like stimuli with 15 bins and 8 presentations per bin used to build the FOS curve. SAP was performed using Goldmann size III stimuli presented for 200msec. For the MMDT, vertical lines of areas ranging from 0.27 to 6.10mm2, depending on eccentricity, oscillated for 600msec. Both types of stimuli were presented on an EIZO GS521 monochromatic monitor (0.17mm/pixel) using the MMDT software (v.1.8.3). The Psignifit toolbox (v.3.0) was used to plot the curves and estimate the 50%-seen threshold. Results were analyzed using a multiple linear regression analysis (least squares).
SAP and MMDT thresholds were calculated from 184 FOS curves with truncation effects observed less frequently in SAP (7 cases) than in MMDT (19 cases). MMDT thresholds were measured across the range of SAP sensitivities from 36.8 to 7.8dB. The relationship between the two scales is significantly dependent (adjusted R2 = 0.76, p-value = 0.003; Figure 1) on the MMDT stimulus area and can be described by the formula: ThresholdSAP = − 0.65 × ThresholdMMDT − 0.63 × stimulus area + 36.61 (Eq.1)
A strong linear association between the values obtained with SAP and the MMDT was observed. Motion displacement threshold increased as VF sensitivity reduced. Although truncation of the FOS curves was more frequent with the MMDT, thresholds derived from staircase, as in clinical perimetry, would be more robust at this end of the scale. The results suggest that the MMDT has the potential to be used for monitoring glaucoma deterioration.
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