Prevalence, characteristics, and pathogenesis of paravascular inner retinal defects associated with epiretinal membranes.

Purpose: To investigate the prevalence, detailed characteristics, and pathogenesis of paravascular inner retinal defects (PIRDs) in eyes with epiretinal membranes (ERMs).

Methods: In this prospective observational case series, we included 81 eyes of 81 patients with idiopathic ERMs, without high myopia. The retinal structure surrounding the PIRDs was assessed using sequential thin sectioning of optical coherence tomography. The PIRDs were classified into three grades. Typical defects of the inner retinal tissue were defined as grade 3. Inner retinal cleavages with openings to the vitreous cavity and no apparent defect of the inner retinal tissue were defined as grade 2. Inner retinal cleavages or cystoid spaces with no connection to the vitreous cavity were defined as grade 1.

Results: Of 81 eyes with ERMs, 31 (38.3 %) had PIRDs along the temporal arcade vessels (grade 1 in six eyes, grade 2 in four eyes, and grade 3 in 21 eyes). PIRDs were frequently accompanied by broad defects of the inner retinal tissue (grade 3). Although some ERMs directly adhered to the edge of a PIRD or the retinal vessels, PIRDs were often located outside the area of adhesion to the ERM. In some OCT sections, vitreous traction on the inner retina seemed to contribute to the progression of PIRDs. Visual field abnormalities corresponded to the location of the PIRDs in 44.4 % of eyes with grade 3 PIRDs.

Conclusions: Deviation of retinal vessels due to the traction of the ERMs may contribute to the pathogenesis of PIRDs. PIRDs often cause visual field abnormalities corresponding to the location of the defect.