Glaucoma drainage devices (GDD) are safe and effective in the management of silicone oil–induced glaucoma and may pose less of a risk than diode laser cyclophotocoagulation (CPC), a study in the Journal of Glaucoma suggests. Although CPC has the advantage of shorter operative times and repeatability, this option carries a higher risk of failure, blindness and phthisis, the researchers noted.

Glaucoma surgery in silicon-oil filled eyes can be challenging, and no consensus exists on the preferred surgical option, the research team from Saudi Arabia noted. They compared the effectiveness of GDD and CPC in 56 eyes of patients with refractory glaucoma following vitrectomy with silicone oil injection.

Seventeen eyes had GDD implants and 39 eyes underwent CPC. Risk factors for the development of ocular hypertension included diabetes mellitus in 19 patients, axial myopia in 13 patients, history of trauma in 15 patients, use of scleral buckles in 10 patients, history of previous ocular surgery in 13 patients and associated uveitis in two patients. Only six patients had pre-existing glaucoma before silicon oil injection.

All patients had a complete ophthalmic exam and IOP measurement at baseline with follow ups at one day, one week, one month, three months, six months and 12 months postoperatively. The investigators considered rates of complete and qualified success of IOP as being between ≥5mm Hg and ≤21mm Hg.

The preoperative IOP was 35.7±7.9mm Hg and 27.8±8.4mm Hg in the CPC and GDD groups, respectively, with a worse baseline visual acuity and higher proportion of silicon oil-filled eyes in the CPC group.

At one year, both groups achieved a reduction in IOP (23.5±11.5mm Hg in the CPC group compared with 15.3±5.9mm Hg in the GDD group) and number of medications taken. However the GDD group had a much higher success rate of 94.1% (16/17) vs. just 53.8% (21/39) in the CPC group. Additionally, five eyes in the CPC group lost light perception compared with just one eye in the GDD group.   

The re-operation rate and larger proportion of eyes going blind in the CPC group also contributed to the higher surgical failure: in the CPC group, five eyes required

additional procedures. In the GDD group, none of the eyes required additional surgery. Six eyes in the GDD group had received prior CPC whereas only one in the CPC group had received a prior GDD.

Although the researchers noted the comparison of surgical success between the two groups could be viewed as unfair, given the study limitations, “the finding also adds weight to the result that a significant proportion of eyes that have an initial CPC have uncontrolled glaucoma and require subsequent surgery,” the researchers wrote in their paper.

The investigators suggested CPC could be reserved for eyes with poorer visual potential and those with greater risk of retinal re-detachment after silicone oil removal.