Surgical Clinical Trials

Surgical Clinical trials in ophthalmology (particularly vitreoretinal disease) have been a crucial aspect in forming management protocols and determining clinical outcomes. However, surgical trials in general are difficult to design and interpret because of varying surgical preferences, experience levels, and case heterogeneity. Below is a summary of several key trials in vitreoretinal surgery.

Protocol D evaluated the role of vitrectomy in 45 eyes with diabetic macular edema (DME) and vitreomacular traction (VMT).[1] Outcome measures were visual acuity, retinal thickening and surgical complications. Following vitrectomy performed for DME and VMT, retinal thickening was reduced in most eyes (nearly 70% of eyes experienced a greater than 50% reduction in thickness). This study informs surgeons that it is reasonable to consider vitrectomy surgery in eyes with reduced vision due to DME and VMT if intravitreal therapy has failed though it is significant to note that this study was designed in the pre anti-VEGF era.

The silicone oil study compared surgical outcomes in eyes with PVR retinal detachments where silicone oil was compared against SF6 and long acting gas (C3F8).[2,3] Inclusion criteria were patients with PVR of Grade C-3 or greater according to the Retina Society Classification and visual acuity of light perception or better. The outcome measures were evaluated with visual acuity of 5/200 or greater and macular reattachment for 6 months. Compared to SF6-treated eyes, a greater percentage of people randomized to silicone oil had an attached macula and a visual acuity greater than 5/200. However, no significant differences in visual acuity or rates of complete retinal reattachment, corneal abnormalities or glaucoma were found between the C3F8 and silicone oil groups. Patients in whom long-acting gas was used as tamponade agent had a higher risk of post-operative hypotony.

The scleral buckling versus primary vitrectomy in rhegmatogenous retinal detachments (SPR) study evaluated visual and anatomic outcomes in phakic and pseudophakic eyes using the two modalities. In phakic patients, SB achieved greater improvement in final VA than vitrectomy. Cataract progression was greater with vitrectomy. In the pseudophakic group, primary anatomical success rate was significantly higher in the primary vitrectomy group compared to scleral buckling. It should be noted that this report was published in 2007 prior to the widespread use of micro-incisional sutureless vitrectomy system (MIVS) and also before widefield intra-operative visualisation systems were broadly available worldwide.

More recently, the Primary Retinal Detachment Outcomes (PRO) studies have re-assessed the role of scleral buckle in the management of moderately complex primary rhegmatogenous retinal detachment in the era of MIVS and widefield visualisation systems.[5,6,7] One report from this series found that visual and anatomic outcomes were superior in phakic eyes treated with scleral buckle (solo procedure or combined with PPV) compared to eyes treated with vitrectomy alone. When pseudophakic eyes were assessed it was found that eyes treated with combined vitrectomy and buckle had superior single surgery anatomic success rates than eyes treated with vitrectomy alone. Visual outcomes were however similar for both groups.

The pneumatic retinopexy versus vitrectomy for the management of primary rhegmatogenous retinal detachment outcomes randomized trial (PIVOT) study evaluated visual and anatomic outcomes using the two techniques in a prospective fashion.[8] Primary anatomic success was greater in the vitrectomy group at 12 months (80.8% vs. 93.2%).  However, visual acuity was greater at 6 months in the pneumatic retinopexy group and rates of vertical metamorphopsia and cataract were lower.  This study provides good evidence that pneumatic retinopexy is a reasonable management option for patients with superior retinal detachments where the offending breaks are located above and between the 4 and 8 o’clock meridians.