Diagnosis of an idiopathic full-thickness MH

Most MHs occur in eyes with no previous pathology (‘idiopathic’). The patient generally complains of acute or subacute decrease in both far and near visual acuity (VA), ± metamorphopsia and/or micropsia, ± positive or negative scotoma. Five percent of patients are asymptomatic⁷. The visual loss caused by MH is variable. VA decreases gradually with time, and after several months of evolution it is usually around 0.1. In a series of unoperated MHs, more than 80% of eyes had a VA between 0.1 and 0.05 after 5 years of follow-up⁸. In practice, the VA of an eye with a full-thickness MH is usually less than 0.5 (typically 0.2). Patients rarely identify a central scotoma, but fairly frequently report what is indicative of a negative microscotoma (i.e. the disappearance of a letter from a word). The distortion or constriction of images and words is also reported.

At fundus biomicroscopy, the MH appears as a round full-thickness defect with sharp edges located at the center of the fovea. The size of the hole varies and tends to increase with time^8–10. The surrounding retina is usually thickened by edema and microcysts, and is slightly detached from the retinal pigment epithelium (RPE). In half the cases, 1–15 yellow deposits are present on the exposed RPE. An operculum may also be found in front of the hole. It is generally smaller than the hole, usually round but sometimes irregular in shape, translucent, discreetly yellow, and slightly mobile with eye movements. An epiretinal membrane may also be present around the hole. It appears as a discreet reflection, usually with no wrinkling of the internal limiting membrane (ILM). The prevalence of epiretinal membranes is higher in long-standing MHs^11–13. Posterior vitreous detachment may vary, from incomplete separation of the vitreous from the macula to a vitreous completely detached from the macula and even from the disc^3,4.

OCT allows a reliable diagnosis of MHs by confirming the existence of a full-thickness opening in the center of the fovea with no interposition of tissue between the vitreous cavity and the RPE. OCT also clearly differentiates full-thickness MHs from lamellar or pseudo-holes, shows the stage of MH, measures its diameter, and provides information regarding the risk of developing a MH in the fellow eye. No other ancillary testing is mandatory. Fundus photographs can be used as archive. Fundus autofluorescence images and fluorescein angiography are not of great interest for MHs. The defect is usually hyperautofluorescent and after fluorescein injection shows a discrete early hyperfluorescence. The surface area of fluorescence does not increase during angiography and its intensity decreases at later phases with no dye diffusion (Fig. 66.1)^14,15.

Fig. 66.1 Full thickness macular holes as they are seen (from top to bottom) by color, red-free and blue filter fundus photographs (note an epiretinal membrane appearing as a clearer area on the blue filter photograph); fundus auto-fluorescence (hyper-autofluorescence of the hole) and fluorescein angiography (central hyperfluorescence).

Differential diagnosis

Without OCT, MHs might be misdiagnosed. With OCT, the differential diagnosis is very reliable. Unlike a full-thickness MH, in a macular lamellar or pseudohole there is an interposition of retinal tissue between the vitreous cavity and RPE on OCT scans. Lamellar holes, usually due to an aborted process of MH formation, are characterized by thinning of the base of the foveal center, and normal thickness of the foveal edge that presents a cleft between its inner and outer retina¹⁶. Pseudoholes are due to tangential retraction of an epiretinal membrane that thickens the foveal edge with a normal or thin foveal center¹⁶.

Impending MHs

In most cases, early stage MHs are foveal cysts^3,4. VA in these cases is usually normal or above 0.5. The macula may look normal on fundus biomicroscopy, or else an outer central yellow spot may be present, combined with a flattened foveal pit and foveolar radial striae¹⁷. In more advanced cases, outer MHs, the foveola has a cystic appearance, with radial striae. An outer yellow ring is present¹⁷.

Secondary MHs

Post-traumatic MHs mostly occur in young males. Traumatic MH is due to a violent deformation of the eyeball, which results in rupture of the fovea^18,19. The vitreous remains completely attached to the retinal surface. The profile of the traumatic hole is not different from that of the idiopathic hole, except in cases in which the retina is thinner than normal at the hole edge due to post-traumatic atrophy of the pigment epithelium. Indeed, in some cases, these MH may be associated with a break in Bruch’s membrane or an area of pigment epithelium atrophy at the posterior pole, which on OCT scans corresponds to retinal thinning and to a deep scotoma in the visual field. If the lesion involves the foveal center, there is a risk that vision will not improve, even if the MH is closed.

In about 10% of highly myopic eyes, OCT reveals the presence of a MH in the staphyloma, which causes moderate loss of vision and is not seen on biomicroscopy. In eyes with high myopia, an MH may also occur after a long evolution of a myopic foveoschisis, especially when it is complicated by foveal detachment²⁰.

Vitreomacular traction syndrome, as described in the previous chapter, may worsen and lead to an MH. The frontier between these cases and an impending MH is not clearly delimited.

Very occasionally, other conditions may also give rise to an MH by causing atrophy of the foveal center. For example, in group 2 macular telangiectasis the foveal center tends to become more atrophic with time. In some cases the process may result in an MH. Adult-onset pseudovitelliform dystrophy may also sometimes result in significant thinning of the foveal center in front of the subretinal deposit. In rare cases this thinning evolves into an atrophic MH, an evolution that coincides with the disappearance of the deposit. MHs may also occur in Best’s disease.