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Keywords:

  • age-related macular degeneration;
  • clinical methods;
  • optical coherence tomography;
  • reproducibility of results

Abstract.

Purpose:  To determine the intersession repeatability of Stratus optical coherence tomography (OCT) measures of retinal thickness in patients with age-related macular degeneration (AMD).

Methods:  Measurement of retinal thickness was performed over four sessions over 12 weeks using a standardized OCT protocol with the fast macular thickness map in 67 non-treated eyes of 67 patients with AMD enrolled in a clinical trial. The intrapatient standard deviation (Sw) and 95% coefficient of repeatability (CR) (inline image), expressed in μm and as a percentage of mean retinal thickness, were calculated to estimate intersession repeatability.

Results:  The CR was 32 μm for the average retinal thickness in the central 1 mm A1 subfield [95% confidence interval (CI) 31–33 μm] and 53 μm (95% CI 51–55 μm) for the centre-point thickness (CPT). When expressed as a percentage, the CR was 15% (95% CI 14–16) for the central 1 mm A1 subfield and 29% (95% CI 27–30) for the CPT measure.

Conclusion:  The average central 1 mm (A1) subfield retinal thickness measure shows good intersession repeatability in patients with stable, early AMD with poorer repeatability for the CPT measure. The results suggest that a change in Stratus OCT retinal thickness of more than 32 μm in the central A1 subfield is more indicative of true clinical change in these patients.