SAFE, PERMANENT EYE-COLOR CHANGE

Transcription

1 SAFE, PERMANENT EYE-COLOR CHANGE Prepared by Gregg Homer JSD (PhD) February 1, 2012

2 THE PIGMENTARY GLAUCOMA ISSUE

3 Glaucoma Defined Glaucoma is currently defined as a disturbance of the structural or functional integrity of the optic nerve that causes characteristic atrophic changes in the optic nerve, which may also lead to specific visual field defects over time. This disturbance usually can be arrested or diminished by adequate lowering of intraocular pressure (IOP). Source: Medscape Reference at <

4 Normal Aqueous Flow In a normal eye, the aqueous humor originates in the ciliary body, then flows along the posterior iris, through the pupil, into the anterior chamber, then out through a spongy tissue along the perimeter of the anterior iris called the trabecular meshwork or TM and into a drainage canal called the Schlemm s Canal.

5 Zonular Fibers The lens is encased in the lens capsule. Zonular fibers run from the ciliary muscles to the lens capsule. To focus, the ciliary muscles relax or contract, thereby retracting or relaxing the shape of the lens capsule and thus the shape of the encased lens.

6 Iris Pigment Back of Eye Front of Eye This is an OCT image of a brown iris. Notice the thick layer of pigment covering the posterior (back) of the iris, as compared to the relatively thin layer covering the anterior (front) of the iris.

7 Pigmentary Glaucoma In the case of pigmentary glaucoma or PG, the anterior zonular fibers rub against the posterior iris, dislodging pieces of pigment. The aqueous flow then carries these pieces of pigment into the anterior chamber.

8 Pigmentary Glaucoma The smaller pieces of pigment pass easily through the TM and out the Schlemm s canal. The larger pieces, however, become lodged in the TM and inhibit the normal outflow of aqueous humor.

9 Pigmentary Glaucoma As a result, intraocular pressure or IOP builds up inside the eye, which, if left untreated for a long enough period of time, can lead to glaucoma.

10 THE STRŌMA PROCEDURE

11 The Blue Eye In a blue eye, the stroma fibers of the iris scatter incoming white light, creating a translucent, blue-gray appearance.

12 The Brown Eye In a brown eye, a thin layer of brown pigment covers the anterior iris, preventing light creating an opaque brown iris.

13 Strōma Laser The Strōma laser is a Q-Switched Nd:YAG, which produces a highly discriminatory, photo-absorbed frequency.

14 Strōma Procedure The Strōma laser fires a series of small, computerguided pulses across the iris to photo-disrupt stromal melanocytes. Because of its photo-absorption properties, the energy passes through the clear cornea and selectively targets the brown melanocytes, leaving the cornea and posterior iris stroma undisturbed.

15 Pigment Elimination Photo-disrupted melanocytes release cytokine protein molecules into the aqueous humor of anterior chamber. The cytokine signal recruits macrophages (Greek for big eaters ), which engulf and digest photodisrupted melanocytes as cellular debris. Complete elimination of melanocytes takes 1-4 weeks.

16 The Outcome The final outcome is the removal of the brown stromal pigment and the emergence of the underlying natural blue stroma.

17 DISTINCTIONS BETWEEN PIGMENTARY GLAUCOMA AND STROMA

18 1. Pigment Density Recall that in PG, the pigment originates from the thicker layer covering the posterior iris, as compared to the far thinner layer covering the anterior iris. The larger pieces dislodged from the posterior iris are thus likely to be far larger than any pieces dislodged from the anterior iris. Back of Eye Front of Eye

19 2. Abrasion v. Digestion: PG Recall that in PG, pigment is dislodged by the abrasion of zonular fibers against the posterior iris, resulting in the passage of both larger and smaller pieces of pigment into the anterior chamber.

20 2. Abrasion v. Digestion: Strōma In the Strōma procedure, however, the photo-disrupted melanocytes release cytokines, which, in turn, recruit macrophages that engulf and digest these melanocytes as common microscopic cellular debris. These microscopic particles pass easily through the TM and out the Schlemm s canal, without creating any increase in IOP.

21 3. Dispersion Time PG occurs after many years of untreated pigmentary abrasion, TM occlusion, elevated IOP. The Strōma procedure, however, takes only seconds, and the macrophagic digestion and elimination process occurs over 2 to 4 weeks. Any increase in IOP should be quickly detected and treated in follow-up visits, before any nerve damage occurs.

22 4. IOP Ranges: PG Normal IOP ranges from 10 mm Hg to 21 mm Hg. Average IOP is about 16 mm Hg. The risk of developing glaucoma does not rise significantly until IOP exceeds 21 mm Hg. The average IOP of patients with PG is about 29 mm Hg.* * Siddiqui, et al., What is the risk of developing pigmentary glaucoma from pigment dispersion syndrome? 135 Am J Ophthalmol (2003).

23 4. IOP Ranges: Strōma Patient Low High Pre-Op Post-Op * Patients were excluded because energy density was insignificant. In Strōma's human studies to date, all patients remained within the normal IOP range at all times. Post-op IOP never rose above pre-op IOP, and in most cases, IOP actually fell (by as much as 35%).

24 5. Treatment Options: PG Treatment options for PG include topical IOPlowering medications (such as latanoprost, which dilates the Schlemm s canal and expands the TM) and laser treatments (such as SLT, which selectively targets and disperses pieces of pigment trapped in the TM).

25 5. Treatment Options: Strōma Even if pigment were to become lodged in the TM of a Strōma patient, it would be quickly detected and treated in follow-up exams. Because Strōma pigment digestion occurs over such a short period of time, short-term treatment with a topical medication should suffice. If a case were resistant to topical medication, a single, noninvasive SLT treatment would be available.

26 Conclusions The causes of PG are entirely different from the effects of the Strōma procedure: The density of the posterior iris pigment dispersed in PG is far higher than the density of the anterior iris pigment dispersed in Strōma. In PG, pigment is abraded from the posterior pigment in large and small pieces; in Strōma, pigment is photo-disrupted and eliminated as micro-particles through the normal macrophagic digestive process and aqueous outflow. In PG, pigment dispersion occurs over the life of the patient; in Strōma, dispersion is completed within 4 weeks. The average IOP range is 10 mm HG to 21 mm Hg, and the average of PG patients is about 29 mm Hg. The IOP range of Strōma patient was 12 mm Hg to 20 mm Hg. In Strōma's human studies, post-op IOP never rose above pre-op IOP, and in most cases, IOP actually fell (by as much as 35%). Even if pigment appeared in the TM of a Strōma patient, it would be quickly detected and easily treated in follow-up exams with short-term topical medication.