Table 1 Comparison of the critical pressures to initiate iris buckling of different iris models with different material parameters, detailing the true value and the increased percentage ratio when compared with the normal undilated 5 mm iris.

From: Modelling floppy iris syndrome and the impact of pupil size and ring devices on iris displacement

Iris model

Iris initial critical buckling pressure

η = 0.6 (More floppy)

η = 0.8 (Mild floppy)

η = 1.0 (normal)

Value (mmHg)

Increase ratio (%)

Value (mmHg)

Increase ratio (%)

Value (mmHg)

Increase ratio (%)

With undilated pupil (diameter 5 mm)

18.04

−9.44

18.99

−4.67

19.92

–

With pupil dilated to 7 mm

23.86

19.78

25.92

30.12

28.00

40.56

With 7 mm M-ring (BC I)

28.39

42.52

31.49

58.08

34.58

73.59

With 7 mm M-ring (BC II)

28.27

41.92

31.39

57.58

34.51

73.24

  1. The increase ratio ‘R’ can be calculated by using the following equation:
  2. \(R = \frac{{P \, - \, P_N}}{{P_N}} \times 100\% ,\)
  3. where ‘P’ is the iris initial critical buckling pressure in different cases, and ‘PN’ is the initial critical buckling pressure of the normal undilated 5 mm iris model.
  4. BC boundary conditions.
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