Macular hole surgery

Published on 08/03/2015 by admin

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Last modified 08/03/2015

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CHAPTER 66 Macular hole surgery

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Introduction

Macular hole (MH) was an incurable condition until the late 1980s, when its first successful surgical treatment was reported1. Since then it has aroused ophthalmologists’ interest, which has led to improved understanding of its pathogenesis, surgical treatment, and postoperative results.

Clinical features, diagnosis, and differential diagnosis

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 time810. 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 MHs1113. 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 disc3,4.

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.

Impending MHs

In most cases, early stage MHs are foveal cysts3,4. 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 fovea18,19. 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.

Anatomical considerations

Before OCT became available, Gass classified MHs into several stages on the basis of fundus biomicrospy. Later he revised his classification. This revised classification is still in use and is summarized in Box 66.1. Mainly on the basis of OCT examination of MHs and their relationship with posterior vitreous detachment, Gaudric et al. and Haouchine et al. gave the description of the different steps in MH formation and evolution (Fig. 66.2)3,4. Gaudric’s description of MHs is also used as a system of classification mainly based on OCT. In this classification the size of the MH is indicated separately. The information provided by Gaudric’s classification is more accurate.