SURGICAL PEARLS

Posterior Vitreous Detachment in Primary Retinal Detachment

BY FLAVIO REZENDE, MD, PHD

Recent studies have demonstrated that pseudophakic eyes appear to have better outcomes with pars plana vitrectomy (PPV) over scleral buckling (SB) for the repair of the primary rhegmatogenous retinal detachment (RRD)^1,2 and that combining encircling SB doesn’t seem to improve RRD repair outcomes.³ For phakic patients, however, these studies demonstrate a benefit of SB over PPV.^1,2 So some surgeons have suggested combining PPV with cataract/lens extraction and IOL implantation (phaco+IOL) to potentially improve surgical outcomes.⁴

How can a young VR surgeon build an algorithm to help chose the surgical procedure for a primary RRD repair?

Although a recent meta-analysis failed to demonstrate any significant difference,⁵ the above-mentioned studies suggest that lens status does play a role in surgical success.^1,2 The prognostic factors shown to influence success rates in RRD repair include the area of detached retina, the presence of hypotony, choroidal detachment, size and number of retinal breaks.^1,6

Although the role of posterior vitreous detachment (PVD) in the pathophysiology of retinal tear-related RRD is well known, the status of the posterior hyaloid is rarely considered when making a decision regarding the surgical technique.

Around 40% of eyes with RRD present with partial PVD. The presence of partial PVD has been shown by our group to have an impact on surgical outcomes for pneumatic retinopexy (PR) and scleral buckling in phakic RRD eyes.⁷

The analysis of the posterior hyaloid status in phakic RRD eyes is not simple. Spectral-domain OCT is rarely useful due to vitreous opacities and obscuration by macula-off detachments, so we base our judgment of PVD stage on the dynamic B-scan ultrasonography. The more the retina is detached, the harder it is to determine if PVD is complete or partial. To simplify, complete PVD definition is given when a definite collapsed PVD is seen (Figure 1). If one is not sure, don’t use this parameter to help choosing the technique.

Figure 1. Illustration and corresponding B-scan ultrasonography of eyes with phakic RRD in the presence of partial (left top and left bottom) and total PVD. Posterior hyaloid adhesion or separation from optic disc is highlighted (*).

Distinguishing atrophic holes versus retinal-tear related RRD is also important because their pathophysiology is distinct. The recent European Vitreo-Retinal Society (EVRS) study showed that in phakic RRD eyes with atrophic holes, PR and SB had similar results, but in the presence of retinal tears, SB was superior to PR.² The PVD status was not documented though.

Based on our results, in the presence of complete PVD (collapsed PVD on B-scan), PR had a 90% primary success rate in phakic RRD eyes with retinal tears (360º laser not performed). In the presence of partial PVD, only 35% succeeded with PR.⁷

Surgical trick: If you still wish to try PR in the presence of partial PVD, aim the needle deep towards the mid vitreous to avoid the gas bubble being trapped between the partially detached hyaloid and the retina.

If SB is considered in a phakic RRD, in the presence of complete PVD, segmental buckling or suprachoroidal buckling could be considered. But if partial PVD is present, encircling buckle is preferred (Figure 2). In this situation, if new tears occur due to continuous traction generated by the partially detached posterior hyaloid, they most likely will occur in the buckled area and laser retinopexy should suffice.

Figure 2. Suggested algorithm for primary RRD repair.

If PPV is the technique you are most comfortable with, the recent PACORES data suggests that combined phaco+IOL and PPV do provide similar results to SB in phakic RRD eyes.

So now, when you see a new patient with uncomplicated phakic RRD, consider performing a B-scan and include the PVD status in your surgical decision-making. With the current data, we can reach similar surgical results with all techniques available according to patient’s characteristics at presentation.

Good luck! NRP

REFERENCES

Dr. Rezende is chief of the retina division and an associate professor in the Department of Ophthalmology at the University of Montreal, where he also heads the vitreoretinal fellowship program.