Table 1.

Gass classification	OTC findings	Classification IVTS
Stage 0	Minimal changes in the foveal contour with perifoveal detachment of the perifoveal vitreous cortex without traction	VMA
Stage 1A: imminent MH	Foveal cysts and sensory foveolar detachment associated with perifoveal detachment with traction of the posterior vitreous on the foveal internal limiting membrane	VMT
Stage IB	Cyst in the outer retina causing rupture of the cones layer. Perifoveal detachment of posterior vitreous	VMT
Stage 2: small MH	Full-thickness MH of small diameter, with partial rupture of the internal wall of the cyst. Partial detachment of the posterior vitreous, which still remains adhered to the operculum	FTMH small/medium with VMT
Stage 3: large MH	MH of a larger size. Total detachment of the posterior vitreous at the level of the macular area, which persists adhered to the papilla. Occasionally, a free operculum adhered to the posterior vitreous can be seen	FTMH medium/large with VMT
Stage 4: full-thickness MH with PVD	Total detachment of the posterior vitreous. In some cases, the vitreous is not observed on OCT scans. Larger diameter of the hole with halo of outer retinal detachment in many occasions	FTMH small/medium/large without TVM

FTMH: full-thickness macular hole, MH: macular hole, OCT: optical coherence tomography, PVD: posterior vitreous detachment, VMA: vitreomacular adhesion, and VMT: vitreomacular traction.