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RETINAL DISPLACEMENT, RETINAL VESSEL PRINTINGS AND INTEGRITY OF RETINAL REATTACHMENT AFTER RD SURGERY.

RETINAL DISPLACEMENT, RETINAL VESSEL PRINTINGS AND INTEGRITY OF RETINAL REATTACHMENT AFTER RD SURGERY.

In April 2020, JAMA Ophthalmology published a great paper written by Dr. Brosh1 and collaborators showing a higher rate of retinal displacement when performing vitrectomy (PPV) versus pneumatic retinopexy (PR) for the treatment of retinal detachment (RD). We encourage you to read this entire article to delve deeper into its results. However, today we want to take advantage of this blog to address terms that are not very familiar but that are well taught by this article.

How to assess retinal displacement?

What are retinal vessel printings?

Changes in the interdigitation zone in the OCT.

Retinal reattachment: high or low-integrity?

Occasionally, the neurosensory retina may not return to its exactly original position following RD surgery. This is called retinal displacement, which can be observed on fundus autofluorescence (FAF) by the presence of retinal vessel printings indicating the original position of retinal vessels prior to the RD. Both the deviation and direction of displacement can be measured (in millimeters). In this work1, median time from surgical procedure to FAF imaging was 3 months.

FAF image1 where you can observe the retinal vessel printings indicating where vessels were located prior to surgery (white arrows).

 

Changes in the interdigitation zone in the OCT.

In an OCT of a healthy macula, there are 4 hyperreflective bands in the outer retina. The third band (below the ellipsoid layer and above the RPE) is the interdigitation zone (corresponds to the phagosome zone). At this location, a process occurs at the outer segments of cones, which is essential for normal visual function.

OCT of a healthy macula where you can see the integrity of the third band.

 

In this work, they found that more than 95% of the patients with retinal displacement presented with abnormalities in the interdigitation zone. This finding was also associated with a higher probability of vertical metamorphopsia and worse VA.

OCT of a macula after RD surgery where disruption and abnormalities of the interdigitation area are seen1.

 

Retinal reattachment: high or low-integrity?

Surgical success following RD surgery is usually defined by achieving “retinal re-attachment”. However, by performing FAF and OCT imaging, we can further discuss about the quality of retinal reattachment as being of high or low-integrity based on the absence or presence of retinal vessel printings on FAF.

A high-integrity retinal reattachment means that the retina has been re-apposed as close as possible to its original location, without retinal vessel printings being observed on FAF. This presumably indicates that the alignment of the photoreceptors has occurred as close as possible to their original location with respect to their specific sites in the RPE. This will result in better functionality and less likelihood of vertical metamorphopsia compared to those with low-integrity.

In conclusion1, retinal displacement and low-integrity retinal reattachment appear to occur more frequently and to a greater extent with PPV vs PR. They hypothesize that the natural reabsorption of SRF by the RPE in PR, along with the presence of a smaller gas bubble that is in contact with a smaller area of the retina, induces less retinal displacement (Video 1). Conversely, the force exerted by a larger gas bubble after PPV can result in greater retinal displacement (Video 2 and Video 3).

These concepts can help us understand those cases where the retina has been successfully reattached but a patient’s vision has not improved as expected. Thanks to this work,1 we will now be able to assess whether retinal displacement and changes in the interdigitation zone are present in our own cases.

 

Beatriz Abadía MD PhD/ Pilar Calvo MD PhD

www.academiaretina.com

 

Video 1: Mechanism of retinal reattachment following pneumatic retinopexy.

https://edhub.ama-assn.org/jn-learning/video-player/18438379

 

Video 2: Mechanism of retinal displacement following pars plana vitrectomy.

https://edhub.ama-assn.org/jn-learning/video-player/18438381

 

Video 3: Coronal and cross-sectional views of the mechanism of retinal displacement following pars plana vitrectomy.

https://edhub.ama-assn.org/jn-learning/video-player/18438383

 

References:

1.