Department%20of%20ophthalmology,

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Department of ophthalmology, Yonsei University,
college of medicine Tae-im Kim, Sang Woo Kim,
Byung Jin Ha, Eung Kweon Kim
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Introduction
Vistech VCTS (Vision Contrast Test System)
6500 - under normal room lighting (30-60 ft L) -
recommanded distance Far - 10 feet (3m) -
measure with best optical correction
contrast changes Average in 0.25 log unit step
5 different spatial frequencies (1.5, 3, 6, 12,
18 cpd)
each stimulus has 15 tilted sine wave
criterion dependent method right, left, up and
blank
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Introduction
Optec 6500 Stero Optical co., Inc. Chicago,
IL, USA Microprocessor-controlled and
continually calibrated light levels Target
illumination with 3.0 cd/m² for night or 85 cd/m²
for day Compliance with the ANSI Contrast
sensitivity slide package F.A.C.T sine
wave or C.A.T letter Near and Far testing
capability Binocular glare testing Eyeview
software Data base for research
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Introduction
F.A.C.T (Functional Acuity Contrast Test) 201 -
consists of the circular stimuli in 5 rows and 8
columns - recommended distance Far - 10 feet
(3m) - measure with best optical correction
contrast changes Average in 0.15 log unit step
5 different spatial frequencies (1.5, 3,
6, 12, 18 cpd)
Larger patch size than VCTS 1.7 degrees
each stimulus has 15 tilted sine wave
3 Alternative forced choice right, left, up
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Purpose
To investigate the repeatability and sensitivity
of Optec 6500 for contrast sensitivity
measurement, comparing with commonly used Vistec
VCTS 6500 chart in normal, healthy subjects
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Methods

• Subjects
• 40 eyes of young healthy volunteers, (14 male
  and 6 female) (total)
• age 27.5 (26 34 years old)
• BCVA of all subjects 0.8 or better
• Excluding criteria
• - any ocular pathology (cataract, glaucoma,
  retinal disease etc)
• - any previous ocular surgery
• - any neurological problem
• - any systemic disease
• - insufficient mental ability to perform
  the test
• - physical disability which make it
  difficult to perform the test

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Methods
Procedure measurements done twice with1 week
interval with optimal refractive correction and
natural pupil 1. Measurements of CST with
Vistech VCTS 6500 ( Group 1 ) under
room luminance (?120 cd/m2), working distance of
3m 2. Measurements of CST with Optec 6500 (
Group 2 ) under continually controlled
luminance 85 cd/m2 using F.A.C.T 201 chart Data
and Statistics 1. Numericalized CST values,
using conversion chart 2. Contrast sensitivity
were compared at all frequencies
Sensitivity T test, Repeatability Bland and
Altman plot
Coefficient of Repeatibility (COR) 3.
STSS v 10.1 for windows (SPSS Inc., Chicago, IL,
USA)
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Results
CST of VCTS and Optec 6500 (mean, 95 CI)
Contrast sensitivity
Range of VCTS
Range of Optec
Spatial Frequency (cpd)
T test, plt0.001, n80 for each frequency
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Results
Table. Mean and Standard deviation of CST between
test and retest
Test (Mean (SD)) Retest (Mean (SD))
Vistech 1.5 cpd 74.13 (19.96) 75.00 (24.49)
3.0 cpd 126.86 (48.28) 140.85 (47.58)
6.0 cpd 162.13 (49.82) 173.25 (43.54)
12 cpd 135.53 (33.48) 129.98 (28.39)
18 cpd 62.50 (15.61) 60.90 (18.69)
Optec 6500 1.5 cpd 45.3 (20.86) 47.6 (21.15)
3.0 cpd 90.73 (48.01) 87.60 (29.09)
6.0 cpd 100.70 (47.56) 92.78 (41.97)
12 cpd 49.23 (21.17) 47.73 (22.90)
18 cpd 19.28 (12.51) 15.60 (9.41)
n40
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Results

• Maximal contrast sensitivity was observed at
  6 cpd and was significant higher if compared to
  1.5, 12 and 18 cpd in both test using two
  different machine.
• The distributions of the score of contrast
  sensitivity test are similar in both test.
• The scores of contrast sensitivity of Optec 6500
  are relatively low.
• The discrepancy of repeated test is also less
  prominent in Optec 6500.

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Discussion

• Contrast sensitivity (CS) describes the ability
  to distinguish differences in luminance
• There are several commercially available
  clinical testers
• The Vistech CS chart series are popular
• but, reported not to warrant repeatability
  in several papers
• Optec 6500 Vision Tester
• based on the Functional Acuity Contrast
  Test (FACT)
• multifunctional instrument
• measurement of visual acuity, contrast
  sensitivity, disability glare
• as well as stereo- and color vision.

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Conclusions

• Sensitivity of contrast sensitivity test with
  Vistec VCTS is better than that Optec 6500 in
  normal eye.
• 2. Testing results using Optec 6500 improved
  accuracy in analysis of contrast sensitivity with
  narrow range score, accurate CST, and adopting
  strict 3 alternative forced choice method for
  analysis
• Repeatability of each test using Optec 6500 is
  better than that of Vistec VCST
• Measurement of contrast sensitivity with Optec
  6500 might be comparable or better in studies to
  compare the quality of implanted lenses or
  refractive surgery outcome than Vistec VCTS