The Impact of Changes in Corneal Back Surface Astigmatism on the Residual Astigmatic Refractive Error following Routine Uncomplicated Phacoemulsification

Table 1

Calculated change in the astigmatic power (DC, diopters) and axis (°) with reference to the results obtained during objective refraction and Orbscan II analysis of the corneal back surface (CBS) over 3 and 5 mm central zones.

	1 and 2 months (n = 52)	2 and 3 months (n = 24)
Objective refraction, power (DC)	0.98 (0.67), 0.79–1.17	1.06 (0.61), 0.80–1.31
FSA, 3 mm	1.31 (1.08), 1.01–1.60	0.71 (0.62), 0.45–0.97
BSA, 3 mm	2.96 (2.41), 2.29–3.63	2.56 (1.90), 1.76–3.36
FSA, 5 mm	1.83 (1.50), 1.04–1.74	1.20 (1.10), 0.73–1.66
BSA, 5 mm	4.44 (3.32), 3.52–5.36	3.58 (3.58), 2.07–5.09
Objective refraction, axis (°)	98.6 (56.5), 82.9–114.3	88.1 (59.6), 62.9–113.2
FSA, 3 mm	95.1 (62.3), 73.3–111.9	106.3 (50.3), 85.1–127.5
BSA, 3 mm	80.0 (57.2), 64.1–95.9	86.2 (49.3), 65.4–107.0
FSA, 5 mm	98.4 (52.5), 81.7–117.0	78.5 (66.7), 50.3–106.7
BSA, 5 mm	91.2 (48.9), 77.6–104.8	90.7 (59.5), 65.6–115.8

The mean (±SD) and the lower and upper limits of the 95% confidence interval are shown for those cases where vector analysis revealed the change in astigmatism determined by subjective refraction was ≥0.50 DC over the course of the noted periods. FSA = change in front surface astigmatism, over central 3 and 5 mm optical zones. BSA = change in back surface astigmatism, over central 3 and 5 mm optical zones.