Table 1. The focal VMT classification tool: WISPERR.

Letter	Feature classified	Description of measurement technique or feature	Units of measurement or graded categories
W	Width of vitreomacular attachment	Width of the longest measurable vitreomacular adhesion extent on any scan that is connected to the foveal centre—if there are multiple areas of adhesion, the longest single one should be used	Measurement in microns
I	Interface between retina and vitreous cavity	Surface membrane	(0) None (1) Hyper-reflective inner retinal signal on the VMA itself compared with adjacent retina (indicative of thickened ILM and can include thickened ILM alone and/or pre-ILM material, which has not met criteria for an ERM) (2) Any ERM on any part of the area of retina encompassed by the OCT (signified by a discrete line anterior to ILM surface, retinal corrugations, and discrete areas of high signal on ILM) (3) Any ERM within the central 1-mm ETDRS circle or contiguous with the zone of VMT
S	Shape	Foveal shape based on foveal profile and position as compared with surrounding retina	(0) Normal (1) Abnormal profile with loss of smooth contour e.g. notch formation, concave with loss of depression relative to other side, asymmetry of depression, or flat profile (2) Clear eversion of the central foveola with a convex profile of the central fovea
P	Pigment epithelium	Presence of RPE abnormalities in central ETDRS 1-mm diameter circle	(0) Not present (1) Present (could include drusen and/or RPE atrophy)
E	Elevation of retinal surface from RPE	Height of maximum central retinal thickness in central 1-mm diameter ETDRS circle—measured from inner surface of RPE to the point of lowest vitreoretinal adhesion and therefore including any SRFa	Measurement in micronsa
R1	Inner retina	Inner retinal changes within central 3-mm ETDRS circle	(0) Normal (1) Inner retinal cysts or cleavage
R2	Outer retina	Outer retinal changes within central 3-mm ETDRS circle	(0) None (1) Focal outer retinal abnormality (including ‘cotton ball' sign, IS/OS/ELM disruption/fragmentation) without SRF, or dehiscence (2) SRF with outer retinal separation of the photoreceptors from the RPE with upward displacement of IS/OS and ELM lines (including with hypo- or hyper-reflective filling of the resultant space). Usually associated with irregularity of photoreceptor outer segments but no actual defects or dehiscence (3) Outer retinal dehiscence, that is, sharply defined defect in the outer retina involving at least the ellipsoid zone and ELM secondary to photoreceptor separation with a layer of intact inner retina. Size of defect measured as base diameterb (4) Full-thickness macular hole and ‘maximum minimum' horizontal linear dimensionc

Abbreviations: ELM, exterior limiting membrane; ERM, epiretinal membrane; ETDRS, Early Treatment Diabetic Retinopathy Study, ILM, inner limiting membrane; IS, inner segment; OCT, optical coherence tomography; OS, outer segment; RPE, retinal pigment epithelium; SRF, subretinal fluid; VMA, vitreomacular adhesion; VMT, vitreomacular traction.

^aMany OCT systems measure this in an automated way but it is best measured manually to avoid segmentation errors. In cases where there is a partially avulsed flap of retina or an oblique highest point, the height to the lowest point of contiguous vitreoretinal adhesion should be used.

^bThe maximum base diameter should be measured horizontally from the two junctions of the outer retina with RPE. A dense scanning protocol should be followed to avoid missing small eccentric full-thickness macular holes.

^cThe maximum of the minimum linear diameter is measured—this is defined as the narrowest hole diameter in the approximate mid-retina using a line drawn parallel to the RPE. The narrowest part of hole should be measured other than that involving the hole operculum. To find the maximum measurement, the OCT slice with the widest macular hole width should be used—this can be facilitated by using a dense horizontal line scanning protocol or using multiple radial scans.