An 89-year-old man presented for a routine glaucoma follow-up complaining of decreased vision in the right eye. The patient denied any acute changes but insisted that the vision in the right eye was gradually deteriorating. He had a history of prior fluctuations in vision, and the clinical significance of his complaint was not clear.

Medical History
The patient had a past medical history of atrial fibrillation, aortic aneurysm, hypertension, hyperlipidemia, type 2 diabetes mellitus, myocardial infarction and arthritis. He was pseudophakic OU and had been treated for 25 years for primary open-angle glaucoma. In 1985, a cyclodialysis cleft was surgically induced for glaucoma management in the right eye. Additionally, the glaucoma in the left eye was treated with argon laser trabeculoplasty in 1994 and trabeculectomy with mitomycin-C in 1995. The patient was taking the following ocular medications: dorzolamide-timolol b.i.d. OS, bimataprost q.h.s. OS and preservative-free artificial tears. The family history and social history were non-contributory.

Best-corrected visual acuity was 20/25 in the right eye and 20/30 in the left eye with no pinhole improvement. Extraocular motility was normal and confrontation visual fields were full in both eyes. The pupils were sluggish with no relative afferent papillary defect. Intraocular pressure by applanation was 2 mmHg in the right eye and 15 mmHg in the left eye. Anterior examination was unremarkable with PCIOLs bilaterally. 
Asymmetric cup/disc ratios were noted, with a Disc Damage Likelihood Scale score of 1/10 in the right eye and 4/10 in the left eye. Visual fields were obtained showing a superior arcuate defect in the left eye but full field in the right eye. Ultrasound biomicroscopy was obtained and showed the postoperative cyclodialysis cleft in the right eye (See Figure 1).

What is your differential diagnosis? What further workup would you pursue?