Population: 17 patients (23 eyes) aged 67,30 ± 20 (13 women, 4 men) affected by central scotoma were tested. Mean Visual Acuity was .81 ±.29. logMAR (range ...
CENTRAL VISUAL FIELD ASSESSMENT: CCVFT COMPARED TO MP-1, A PRELIMINARY STUDY Scherlen A-C. (1), Faure G. (2), Goldschmidt M. (3), Vital-Durand F. (4), Fays A. (5), Lepoivre J-P. (6), Miege C.(1) (1)
Essilor International, Vision Institute, Paris, France, (2) Low Vision Clinic, Hôpital La Timone, Marseille, France, (3) CPHV, Lausanne, Switzerland, (4) Inserm U 846, Université Claude Bernard, Lyon 1, France, (5) CHU Dijon, France
Objectives
Visual field charts
Assessment of visual field defects is a critical step in the planning of rehabilitation of visual function in low vision centers. Simple methods have already been proposed by MackEben (1999, 2008), Trevino (2008). Here we compared two methods of central visual field evaluation: 1- the California Central Visual Field Test 2- Microperimeter (MP-1) (CCVFT)©, Mattingly Low Vision, Inc Nidek©.
Methodology
Example 1: CCVFT yields smaller scotomas [MP1: 101,9 deg2 ; CCVFT: 63,6 deg2]
Population: 17 patients (23 eyes) aged 67,30 ± 20 (13 women, 4 men) affected by central scotoma were tested. Mean Visual Acuity was .81 ±.29 logMAR (range 1.4 -.3). Procedure: Monocular assessments of the size, shape and location of the scotoma were performed by a trained professional. The size of the absolute scotoma was measured in deg2. CCVFT was proposed first before MP-1. Fixation stability was estimated by the experimenter during the CCVFT session. It was recorded by the MP-1 and classified in 2 categories: “stable” , within 2°, or “unstable”, more than 2°. Data processing: For each patient, the ratio between MP-1 and CCVFT surfaces was calculated. An overestimation of CCVFT compared to MP-1 would yield a ratio 1. Example 2: CCVFT yields similar scotomas [CCVFT: 64 deg2, MP1: 67 deg2]
Results CCVFT procedure took an average of 8,6 minutes, MP-1 took 20,7 minutes. The distribution of scotoma surfaces measured with MP-1 and CCVFT showed an average size of absolute scotomas of 51.61 deg2 for MP-1 and 43.6 deg2 for CCVFT. NS (p=0.6) (Figure 1) The surface ratios of the scotoma obtained from both instruments were compared taking MP-1 data as reference. Mean value of the ratio between the 2 surfaces (MP-1/CCVFT) was 1.33± 0.71. CCVFT underestimates by 33% the surface of absolute scotoma, but the global pattern is similar.
Scotoma surfaces (deg2) measured with the CCVFT
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In addition, the surface ratios were dependent on the scotoma size (F(1.18)=6.58; p
