Retinal vessel movement measurable in eyes with epiretinal membrane

Issue: June 2013

Retinal vessel movement associated with an epiretinal membrane is measurable and may correlate with worsening best corrected visual acuity, according to a study.

“We hypothesized that retinal tangential movement played a significant role in progression of disease as the epiretinal membrane convolutes the neurosensitive tissue. This was most evident in patients with worsening of symptoms in whom excessive retinal tangential movement was present in the absence of increased central macular thickness or decreased best corrected visual acuity,” Mads Kofod, MD, and colleagues said in the study, which was published in Ophthalmology.

Study results

The retrospective, comparative case series included 206 eyes of 113 patients; 142 eyes had an epiretinal membrane (ERM) and 64 fellow eyes were healthy.

All ERM eyes were divided into two subgroups — unchanged symptoms or worsening systems — based on the patient’s description of his or her change in metamorphopsia.

“The method used in this study could be called, presumably, a poor proxy measure for metamorphopsia,” Kofod told Ocular Surgery News in a subsequent interview. “With increased metamorphopsia, the small details in the visual acuity test could become increasingly difficult to identify. Our belief is that there is increasing metamorphopsia with increasing retinal vessel movement.”

Baseline and follow-up fundus images of each eye were used to measure retinal vessel movements. The fundus images were divided into five equal parts horizontally and vertically, with retinal vessel movement being measured in the nine central squares.

“Our method of viewing aligned images is immediately available to clinicians, but the measuring of retinal vessel movements is quite time-consuming,” Kofod said. “The clinician can view the flickering image to easily identify changes to traction over time, but he won’t get a number to state the distance the retinal vessels have moved.”

Analysis of this area showed significantly greater retinal tangential movement in eyes with an ERM compared with healthy eyes (P < .001). In addition, there was a correlation between increased retinal tangential movement and a reduction in BCVA (P = .024), as well as a correlation with an increase in central macular thickness (P < .001).

Kofod and colleagues also found a correlation between retinal tangential movement and the amount of time in between examinations (P < .001).

Application of study data

Kofod said he hopes study data will allow clinicians a “fresh look” on contraction changes between screening visits.

“For clinicians, an excessive retinal vessel movement can give more assurance of disease activity, which helps to determine indication for surgery if the clinical findings are inconclusive as to why the patient is experiencing a worsening of symptoms,” he said.

Kofod and colleagues are also currently investigating how retinal vessels unfold following surgery, which, he believes, will shed more light on how far and at what rate retinal vessels unfold after the retinal membrane has been peeled.

“Hopefully clinicians will be able to use this method to evaluate retinal vessel movement and look at this as a sign of progression in disease analysis, along with increased retinal thickness or BCVA changes,” Kofod said. – by Ashley Biro

Reference:
Kofod M, et al. Ophthalmology. 2012;doi:10.1016/j.ophtha.2012.03.022.
For more information:
Mads Kofod, MD, can be reached at Department of Ophthalmology, Glostrup Hospital, Nordre Ringvej 57, DK-2600 Glostrup, Denmark; +61-3-9929-8371; fax: +61-3-9662-3859; email: madkof01@glo.regionh.dk.

Disclosure: Kofod has no relevant financial disclosures.