**5.1 Classification**

Idiopathic full-thickness macular holes are produced by traction exerted by the posterior vitreous cortex on the neurosensory retina in the central macular area. Disinsertion of the overlying glial plug may result in the formation of a foveal "cyst." Further traction with removal of the cyst roof produces a free-floating operculum on the posterior vitreous cortex. The neurosensory retina then displaces centrifugally as a full-thickness retinal hole.

Gass described MHs according to clinical evolution:


A new classification introduced by the International Vitreomacular Traction Study Group was facilitated by high-resolution OCT imaging and was defined as: vitreomacular adhesion (VMA), vitreomacular traction (VMT) and macular hole (**Table 1**) [2].

Evidence from a large surgical series of 1483 primary MH repairs reported by Steel et al. [6] treated with vitrectomy, ILM peel, and gas or air tamponade noted that a linear diameter of 500 μm or less was the threshold for successful hole closure. Other studies demonstrated a similar correlation between MH size and successful hole closure, and it was suggested that the definition of large MH's should be changed to


**Table 1.**

*International Vitreomacular traction study group classification.*

≥500 μm [7–9]. The evolution of holes is variable, with a tendency to progress with time in 74% of cases within 2 years [10]. Small holes may close spontaneously in about 5% of cases and it may be reasonable to closely observe small holes with good vision in case of spontaneous resolution [11].

High myopia is a well-recognised risk factor for unsuccessful MH repair, with an axial length (AL) > 26 mm or refraction higher than 6 Diopters making successful hole closure less likely [12]. Anatomical success is reduced as the degree of myopia increases and ranges from 91.7% (AL: 26–29.9 mm) to 0% in eyes with AL > 30 mm [13].

### **6. Pharmacologic treatment**

The only pharmacologic treatment available to date as an alternative to surgical treatment is Ocriplasmin (OCP). This treatment is approved in cases of symptomatic VMA including VMA with MH less than 400 microns. While Ocriplasmin releases VMT in the majority of eyes, the success rate for macular hole closure remains limited and is in the range of 40–50% in eyes with a small-diameter macular hole but decreases to 15–20% in the medium-sized macular hole [14, 15]. Floaters can still be troublesome after OCP and there is a side effect profile that has resulted in most vitreoretinal surgeons still favouring a formal surgical procedure over pharmacological vitreolysis with OCP.
