Laser Scleral Elastomodulation For Pressure Reduction In Glaucoma

Glaucoma is a leading cause of blindness worldwide, and current topical and laser therapies are limited in their cost, efficacy, longevity and ease of use.  A novel laser approach for reducing IOP without tissue destruction involves a mid-infrared laser that minimally alters the sclera to achieve a therapeutic effect.  In this study, we seek to enhance aqueous outflow with a low cost, portable, laser scleral therapy.

Senogen GmbH, Palo Alto, CA, USA

A 1.55 um battery operated diode laser can be mounted onto a slit lamp for non-contact delivery of a laser annulus pattern (4 quadrants, 12-18 mm) onto the anterior sclera.  Finite element modeling of scleral shrinkage and increasing scleral compliance are tested on multiple pig and cadaver eyes with OCT imaging, histology, aqueous angiography and OCE (elastography) to verify structural and functional efficacy of primary and uveoscleral outflow. Clinical validation with a 2.1 um precursor wavelength in 150 normotensive eyes using a similar pattern was performed with ethics approval to demonstrate clinical safety and efficacy in IOP reduction with one year follow up. Further clinicals with the 1.55 um laser wavelength are underway.

At a 1.55 um laser wavelength, OCT and histology show a 4-degree, full circumferential increase in the iridocorneal angle with uniform deepening of the scleral tissue, reflected in specular changes, microvacuoles, but without tissue damage. OCE indicates a 40% decrease in scleral stiffness. Aqueous angiography reveals a 20% improvement in primary outflow; riboflavin fluorescence tests show a 50% increase in uveoscleral outflow due to enhanced scleral tissue flexibility and porosity, plus increased supraciliary space. IOP reduced from 40 to 15 mm Hg, averaging a 30% decrease using real-time sensors. At a 2.1 um laser wavelength, no negative effects were observed in 150 patients, with an average IOP reduction of 22% sustained for 12 months.

Laser Scleral Elastomodulation with a 1.55 um slit lamp mounted laser demonstrates potential as a promising alternative for treating glaucoma. Altered primary and uveoscleral outflow due to an increased angle anatomy, and scleral tissue compliance and porosity without focal thermal damage confirms the feasibility of non-destructive (repeatable) ab externo laser scleroplasty for IOP reduction.