Various pathogenetic mechanisms have been described in iatrogenic heterochromia. Except for those related to topical antiglaucoma therapy, which are brought about by histological changes,1, 2 all the other cases have been attributed to surgical complications.3, 4, 5 We present an unusual case of acquired unilateral iris heterochromia following bilateral placement of Baerveldt glaucoma drainage implant (GDI) for the treatment of refractory glaucoma.
A 56-year-old Caucasian man with bilateral high myopia, surgical aphakia, and primary open-angle glaucoma was evaluated for uncontrolled intraocular pressure (IOP) increase in spite of maximal antiglaucoma medical therapy. Subsequently, the patient underwent a bilateral non-simultaneous superotemporal placement of a Baerveldt 350-mm2 GDI, with a 14-day interval between surgical operations, modified with an occlusive 7-0 external absorbable ligature and a 5-0 nylon intraluminal suture, which was tucked under the conjunctiva.
The ophthalmological examination disclosed a new unilateral heterochromia of the iris in the right eye (RE), with a change from blue to green (Figure 1), seven days after the Baerveldt GDI placement. Both the eyes presented a clear cornea, absence of cells or flare in the anterior chamber, and an IOP value of 10 mmHg. The fundoscopy confirmed the absence of cells in the vitreous cavity. The echographic evaluation revealed a peripheral flat serous-haemorrhagic choroidal detachment in the RE, which was restricted to the superonasal part of the eye, anterior to equator, extended from 1:00 to 3:00 o'clock meridians, without haemorrhage in the vitreous (Figure 2).
The cause for the temporary iris heterochromia, which regressed spontaneously after 33 days, remained unclear. It may have been a consequence of the persistent choroidal bleeding with iron deposition on the iris even if blood cells in anterior chamber or vitreous cavity have never been found during ophthalmological evaluations. A toxic effect of Baerveldt GDI, which could lead to the alteration in pigmentation, has not been considered because the patient received a bilateral GDI placement. The presence of a serous-haemorrhagic choroidal detachment should be considered after unexplainable iris colour change and looked for with an echographic evaluation especially to detect the peripheral and flat forms.