A novel 8-mm Schlemm's canal scaffold reduces outflow resistance in a human anterior segment perfusion model.
OBJECTIVE
To study the effect on outflow facility and outflow resistance of a nitinol microstent implanted into Schlemm's canal.


METHODS
Using a constant pressure perfusion method, outflow facility and outflow resistance were measured in 26 pairs of dissected anterior segments from donated human eyes. Measurements were made at perfusion pressures of 10, 20, 30 and 40 mm Hg. The Hydrus Microstent was placed in Schlemm's canal of one eye and the contralateral eye underwent a sham procedure. Outflow facility and outflow resistance were measured again after the microstent implantation or sham procedure.


RESULTS
The Hydrus Microstent significantly increased outflow facility from 0.33 ± 0.17 μL/min/mm Hg to 0.52 ± 0.19 μL/min/mm Hg (P < 0.001). Outflow resistance was significantly reduced from 4.38 ± 3.03 mm Hg/μL/min at baseline to 2.34 ± 1.04 mm Hg/μL/min (P < 0.001) with the microstent. There was a linear correlation between outflow resistance at baseline and decrease in outflow resistance with the microstent (R(2) = 0.89, P < 0.0001).


CONCLUSIONS
The increase in outflow facility and decrease in resistance supports the potential use of the Hydrus Microstent as a surgical option to reduce intraocular pressure (IOP). The IOP-lowering effect may be higher in eyes with higher outflow resistance (and IOP) as compared with eyes with lower outflow resistance (and IOP).
Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE 68198, USA.
Vikas
V
Gulati
Shan
S
Fan
Cassandra L
CL
Hays
Thomas W
TW
Samuelson
Iqbal Ike K
II
Ahmed
Carol B
CB
Toris
D000368:Aged; D000704:Analysis of Variance; D000867:Anterior Chamber / Q000601:surgery*; D001082:Aqueous Humor / Q000378:metabolism*; D005260:Female; D020327:Glaucoma Drainage Implants; D005902:Glaucoma, Open-Angle / Q000601:surgery; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008954:Models, Biological; D010477:Perfusion / Q000379:methods; D014129:Trabecular Meshwork / Q000033:anatomy & histology / Q000601:surgery