Open angle except area of pigmented ciliary body lesion extending anteriorly/inferiorly into the angle around 8:00 clock hour, +peripheral anterior synechiae
OS
Non-pigmented trabecular meshwork
Open angle 360˚
Posterior segment exam
Cup-to-disc ratio 0.35 x 0.35 || 0.3 x 0.3
Disc flat, pink, no pallor || flat, pink, no pallor
Macula normal, both eyes
Vessels normal, both eyes
Periphery temporal chorioretinal atrophy || normal
Figure 1: External photo of the right eye prior to treatment demonstrates pigmented lesion from 7:00 to 9:00 clock hours (left). External photo of the right eye at current presentation demonstrates corectopia and decreased appearance of uveal melanoma from 7:00 to 9:00 clock hours, status-post brachytherapy 7 months prior (right).Figure 2: Slit-lamp photo of the right eye demonstrating deformation of iris at 7:00 clock hour, before treatment (left) and status-post brachytherapy 7 months prior (right).Figure 3: Example image of pigment on corneal endothelium (Krukenberg’s spindle), similar to what was seen on patient’s exam. (Photo courtesy of Sarwat Salim, MD, University of Tennessee).
Figure 4: Example gonioscopy images demonstrating heavily pigmented trabecular meshwork in the right eye (A) and non-pigmented trabecular meshwork in the left eye (B), similar to what was seen on the patient’s exam. (Yijie (Brittany) Lin, MD, & Joseph F. Panarelli, MD, 2015).
Differential Diagnosis
Open angle glaucoma
Secondary pigmentary glaucoma
Melanomalytic glaucoma
Direct infiltration of angle by untreated melanoma cells
Closed angle glaucoma
Secondary to peripheral anterior synechiae
Secondary to posterior synechiae with iris bombe
Secondary to anterior displacement of ciliary body
Secondary neovascular glaucoma
Additional Investigations
Figure 5: Ultrasound biomicroscopy image demonstrating uveal melanoma extending from ciliary body, prior to brachytherapy (top) and 7 months after brachytherapy (bottom).
Figure 6: OCT optic nerve head and retinal nerve fiber layer (RNFL) demonstrates a superotemporal RNFL defect in the right eye.
Figure 7: OCT demonstrates possible defect of ganglion cell/inner plexiform layer in the right eye.
Figure 8: OCT demonstrates possible defect of ganglion cell/inner plexiform layer in the right eye.
Diagnosis
Secondary pigmentary glaucoma
Pathophysiology
There are two proposed etiologies for pigmentary glaucoma secondary to uveal melanoma. In this case, the presumed etiology involves pigment release from a discohesive or necrotic tumor, which then clogs the trabecular meshwork and obstructs aqueous outflow. Since this pigment originates from the tumor, it is not associated with iris transillumination defects. Alternately, it is possible for the tumor to distort the anterior segment anatomy and induce iris rubbing with release of iris pigment, leading to a more classic pigmentary glaucoma.
Treatments
Topical/oral medication therapy
IOP did not decrease with trial of timolol/simbrinza
Ability to visualize trabecular meshwork may be limited by peripheral anterior synechiae
May incite further inflammation/scarring
Trabeculectomy
Concern for altered healing/failure/scarring in the setting of previously irradiated tissue
Risk of local metastasis
Probably does not increase risk of remote metastasis
Glaucoma drainage device
Ahmed glaucoma valve vs. Baerveldt shunt
Surgeon’s preference
To preserve vision in this patient, Ahmed valve is preferable due to ability to lower IOP immediately
Risk of local metastasis
Probably does not increase risk of remote metastasis
Enucleation
Offered to this patient; however, patient declined due to strong preference to preserve binocular vision.
Note, in this case, cyclodestruction was not considered as a viable treatment option due to concern for disruption of blood-ocular barrier.
Prognosis and Future Directions
The prognosis of glaucoma secondary to uveal melanoma is variable, depending on the size and location of the tumor, the oncologic treatment and the mechanism of secondary glaucoma.
When evaluating treatment options, it is important to consider patient preferences and risk tolerance, as well as the visual potential of the eye. In this case, after failure of medical therapy the patient declined enucleation and chose to proceed with incisional (Ahmed glaucoma valve) surgery despite the potential risk for local recurrence.
There is currently no consensus regarding the appropriate management of glaucoma secondary to uveal melanoma. Although there are multiple case reports, there is a paucity of evidentiary studies. Future prospective studies may provide useful evidence to guide treatment selection.
Mechanisms for glaucoma in uveal melanoma patients:
Neovascular Glaucoma
Retinal ischemia (chronic RD or radiotherapy)
Anterior segment ischemia
2 to 23 percent of patients undergoing brachytherapy
Anterior rotation of the ciliary body
Pigment clogging of the trabecular meshwork
Both iris melanomas and iris nevi
Posterior synechiae and iris bombe
Direct infiltration of the angle
Iris melanomas (tapioca, ring melanomas)
Tumor necrosis syndrome
Unrelated primary open angle glaucoma or narrow angle glaucoma
Glaucoma surgery in uveal melanoma patients:
Uveal melanoma is a common setting for glaucoma
Glaucoma surgery safest >2 years after brachytherapy
Good visual potential (20/100 or better)
Avoid trabeculectomy
Opposite quadrant
Overall risk of orbital spread is low but patients should be aware of the need for careful monitoring with orbital MRI
References
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