Adjustable valve for IOP control with reed valve

1. A drainage device for implantation in an eye of a patient to treat an ocular condition, comprising:

an implant body portion comprising a valve portion, the valve portion comprising a flexible membrane disposed and arranged in a manner to affect flow of aqueous humor through the implant body portion; and

a reed valve disposed downstream of the flexible membrane, the reed valve being configured to prevent backflow of aqueous humor toward the membrane and configured to stabilize flow by affecting pressure at the flexible membrane, wherein the reed valve comprises:

a fluid passageway;

a flexible reed arranged so that pressure in the fluid passageway acts across substantially an entire length of the flexible reed to crack the reed valve, the flexible reed being deflectable to increase and decrease a size of the fluid passageway; and

a hard stop disposed adjacent the flexible reed and that is disposed to limit the range of deflection of the flexible reed into the fluid passageway of the aqueous humor.

2. The drainage device of claim 1 , wherein the reed valve is configured to create backpressure at the membrane that affects the rate of flow at the flexible membrane.

3. The drainage device of claim 1 , wherein the hard stop extends from a wall of the fluid passageway.

4. The drainage device of claim 1 , wherein the hard stop includes a first portion extending substantially perpendicular to the direction of flow and a second portion extending downstream from the first portion.

5. The drainage device of claim 1 , wherein the hard stop extends more than half the distance across the fluid passageway.

6. The drainage device of claim 1 , wherein the reed and the hard stop are balanced to provide a maximum open condition when the IOP is less than 15mmHg.

7. The drainage device of claim 1 , wherein the reed valve comprises a reed having a uniform thickness.

8. The drainage device of claim 1 , wherein the drainage device comprises a reed having a tapering thickness.

9. The drainage device of claim 1 , wherein the reed is configured and disposed to have a cracking pressure between about 0.25mmHg and 8mmHg.

10. The drainage device of claim 1 , wherein the hard stop limits deflection of the reed when pressure exceeds at least 8mmHg.

11. The drainage device of claim 1 , further comprising a drainage tube extending from the implant body portion and having a distal body configured to extend to and fit within the anterior chamber of the eye.

12. A drainage device for implantation in an eye of a patient to treat an ocular condition, comprising:

an implant body portion comprising a flexible membrane disposed and arranged in a manner to affect flow of aqueous humor through the implant body portion;

a passage portion disposed downstream from the flexible membrane; and

a reed valve disposed in the passage portion, the reed valve comprising a flexible reed having a first end and a second end, the first end being fixed to the passage portion and the second end being displaceable as a cantilever from a first position substantially restricting flow to a second position permitting relatively increased flow, the reed valve being configured to stabilize flow by creating back-pressure at the flexible membrane,

wherein the reed valve comprises a hard stop disposed adjacent the flexible reed and that is disposed to limit the range of deflection of the flexible reed into passage portion, the hard stop including a first portion extending substantially perpendicular to the direction of flow and a second portion extending downstream from the first portion.

13. The drainage device of claim 12 , wherein the hard stop extends from a wall of the passage portion.

14. A drainage device for implantation in an eye of a patient to treat an ocular condition, comprising:

an implant body portion comprising a valve portion, the valve portion comprising a flexible membrane disposed and arranged in a manner to affect flow of aqueous humor through the implant body portion; and

a reed valve disposed downstream of the flexible membrane, the reed valve being biased to a closed position that prevents the passage of aqueous humor past the valve, the reed valve having a cracking pressure in the range of about 0.25mmHg and 8mmHg and being configured to prevent backflow of aqueous humor toward the membrane and configured to stabilize flow by affecting pressure at the flexible membrane, wherein the reed valve comprises:

a flexible reed that deflects to increase and decrease a size of a fluid passageway and has a cross-sectional area that varies along a length of the reed, wherein the flexible reed is a single reed extending across the fluid passageway.

15. The drainage device of claim 14 , comprising a hard stop disposed adjacent the flexible reed and that is disposed to limit the range of deflection of the flexible reed into the fluid passageway.

16. The drainage device of claim 14 , wherein the hard stop extends from a wall of the fluid passageway.

17. The drainage device of claim 14 , wherein the hard stop includes a first portion extending substantially perpendicular to the direction of flow and a second portion angled from the first portion.