title: Test-retest variability of microperimetry using the Nidek MP1 in patients with macular disease.
abstract: OBJECTIVE
  To determine the test-retest variability of the retinal sensitivity of the Nidek MP1 microperimeter in patients with macular disease.
  
  
  METHODS
  In this prospective study, 50 patients were enrolled with a range of macular diseases. One examiner performed two consecutive microperimetry tests for all patients using the same test strategy. Test-retest variability for mean sensitivity (MS), mean deviation (MD), point-wise sensitivity (PWS), local defect classification (LDC), average sensitivity for the central macula (CMS, 16 loci inside 10 degrees ), paracentral macular sensitivity (PMS, 52 loci in the 10 to 20 degrees ring), and dense scotoma size (DSS) were analyzed by calculating the 95% coefficients of repeatability or percentage agreement.
  
  
  RESULTS
  Mean (SD) age and visual acuity were 61 (15) years and 0.34 (0.32) logMAR, respectively. The mean difference in MS between tests 1 and 2 was +0.2 dB (SD, 0.9 dB; P = 0.127). The coefficients of repeatability for MS, MD, CMS, and PMS were 1.81, 2.56, 2.13, and 1.93 dB, respectively. The mean (SD) of coefficients of repeatability for PWS across all 68 loci was 5.56 (0.86) dB. Of all test loci in all patients 76% had perfect agreement in LDC, and 94% of patients had a change in DSS of four or fewer test loci.
  
  
  CONCLUSIONS
  Test-retest variability was lowest for MS and highest for PWS. However, MS does not provide spatial information. The authors recommend the use of CMS and PMS for monitoring macular function and consider a change of greater than 2.56 and 2.31 dB (the upper limit of the 95% confidence interval of their coefficients of repeatability), respectively, to exceed test-retest variability.
authors.affiliation: Moorfields Eye Hospital, London, United Kingdom. fkchen02@yahoo.com
authors.forename: Fred K
authors.initials: FK
authors.lastname: Chen
authors.forename: Praveen J
authors.initials: PJ
authors.lastname: Patel
authors.forename: Wen
authors.initials: W
authors.lastname: Xing
authors.forename: Catey
authors.initials: C
authors.lastname: Bunce
authors.forename: Catherine
authors.initials: C
authors.lastname: Egan
authors.forename: Adnan T
authors.initials: AT
authors.lastname: Tufail
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Coffey
authors.forename: Gary S
authors.initials: GS
authors.lastname: Rubin
authors.forename: Lyndon
authors.initials: L
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