Based upon the repeated intervisit measurements of these 104 eyes, the resulting ICC, intervisit SD, and CV values for each method and region are summarized in the
Table and
Figure 3. The overall ICC was 0.98 (95% CI: 0.97–0.99) for the Iowa algorithm and 0.95 (95% CI: 0.93–0.97) for the Cirrus algorithm; the overall intervisit SDs were 1.55 μm (Iowa) and 2.45 μm (Cirrus); and the CVs were 2.2% (Iowa) and 3.5% (Cirrus),
P < 0.0001. Sector-based regional ICCs ranged from 0.94 to 0.99 (Iowa) and 0.64 to 0.95 (Cirrus). Regional ICCs were significantly better using the Iowa approach except for the superior region. Sector-based regional intervisit SDs ranged from 1.53 to 2.74 μm (Iowa) and 2.96 to 7.51 μm (Cirrus); and sector-based regional CVs ranged from 2.2% to 4.0% (Iowa) and 4.2% to 10.7% (Cirrus),
P < 0.0001 for all comparisons. The mean ± 1.96 SD differences in overall GCL+IPL thicknesses across visits were 0.0 ± 4.3 μm (Iowa) and 0.5 ± 6.8 μm (Cirrus), as shown in the Bland-Altman plots of
Figure 4. The mean ± 1.96 SD differences in sectoral GCL+IPL thicknesses across visits were 0.0 ± 7.6 μm (Iowa, SN sector), 0.1 ± 12.5 μm (Cirrus, SN sector), −0.2 ± 7.6 μm (Iowa, S sector), −0.1 ± 8.2 μm (Cirrus, S sector), −0.3 ± 7.4 μm (Iowa, ST sector), 0.4 ± 14.1 μm (Cirrus, ST sector), 0.1 ± 4.4 μm (Iowa, IT sector), 1.0 ± 12.6 μm (Cirrus, IT sector), 0.5 ± 4.2 μm (Iowa, I sector), 0.9 ± 12.4 μm (Cirrus, I sector), 0.2 ± 4.8 μm (Iowa, IN sector), and 0.8 ± 20.8 μm (Cirrus, IN sector), as shown in the Bland-Altman plots of
Figure 5.