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Fig. 9.2 Vitreous separation may start temporally but attachments at the fovea are stronger commencing the process of macular hole formation
9.2Idiopathic Macular Hole
9.2.1Clinical Features
9.2.1.1 Introduction
Age-related macular hole is a dehiscence of the neuroretina at the fovea, which occurs in middle-aged or elderly patients, and more often in females (3.321 females:1 male, with 7.8/100,000 population) (McCannel et al. 2009). They are bilateral in 12–13 % in 2 years after presentation in one eye (Lewis et al. 1996). Patients present with blurred vision or distortion. In the early stages (grade 1), the patient notices a small central grey patch without distortion of the image. Distortion becomes a
feature as the fovea dehisces and the photoreceptors are moved outwards onto the rim of the hole (grades 2 and 3). Typically, the features at the centre of an image (e.g. the nose and mouth of a face) are seen as smaller, giving the appearance that the centre of someone’s face is ‘scrunched up’. The receptors are on the perimeter of the hole and spread out by the dehiscence. The brain therefore receives fewer signals than it should in the central of the macula and interprets this as a falsely small image centrally. Eventually, the receptors at the edge of the hole will stop functioning (grades 3 and 4) and the patient will only perceive a central scotoma.
Fig. 9.3 A patients’ representation of the distortion of their faces created by their own macular hole because the central receptors are spread around the edge of the hole; the cental image is minified
Fig. 9.4 An early macular hole may show traction (arrows) on OCT indicating tearing towards the disc
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Fig. 9.6 A grade 1 hole is a very subtle sign often as a small yellow spot in the fovea
Fig. 9.5 A patient’s description of symptoms before and after macular hole surgery
9.2.1.2 Watzke–Allen Test
The phenomena of distortion and loss of vision are exploited in the Watzke–Allen test (Watzke and Allen 1969). This involves shining a thin line of light (usually vertically) via the slit lamp biomicroscope over the macular hole, whilst asking the patient to describe whether the line of light is straight or has a narrowing (waist) or gap (break) centrally (Watzke and Allen 1969). A straight line indicates an intact fovea whilst a narrowing or a gap is seen in macular holes (Tanner and Williamson 2000). A narrowing indicates separated but functioning foveal receptors and a break loss of function of those receptors. If you place the beam on the edge of the hole, a kink is perceived with the apex pointing towards the hole.
Vitreous detachment stimulates the dehiscence of the fovea. Indeed, a subclinical separation of the vitreous is visible on optical coherence tomography (OCT) of the macula and can sometimes be seen clinically, evidenced by the pres-
ence of a prefoveal operculum in the early stages. The oper- Fig. 9.7 A grade 1A macular hole culum does not consist of full thickness retina but is made up
of glial tissue and a few neural tissue remnants or receptors (Ezra et al. 1997, 2001).
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Fig. 9.8 Grade 1B, a ring of yellow spots
Fig. 9.9 A grade 1B hole with an incomplete ring of spots
Fig. 9.10 A grade 2 vitreous attached and hole diameter less than 400 mm
Fig. 9.11 A grade 3 vitreous attached with hole diameter 400 m or more. This hole has some surrounding retinal thickening and subretinal fluid
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9.2.1.3 Grading
It is useful to use the grading system devised by Gass to describe macular holes because these have been shown to relate to surgical success rates and visual outcome.
Grade 1 The hole commences as a foveal intraretinal cyst (Haouchine et al. 2001) (1A) or ring of cysts (1B), seen as a central yellow spot or ring of spots (Gass 1988, 1995; Johnson and Gass 1988) at which point the patient may be asymptomatic or have mild blur or distortion
Grade 2 A small crescentic or round hole less than 400 mm.
Grade 3 A large round hole of more than 400 mm diameter
Grade 4 A hole with an associated posterior vitreous detachment.
Note: The grading system Gass devised relates to ophthalmoscopy and not to OCT findings; therefore, a microseparation of the vitreous, with or without an operculum, in an eye with a full thickness break would be graded as 3 not a grade 4.
Fig. 9.12 A long-standing macular hole with yellow flecks in its base OCT can be used to measure the width of the hole at its narrowest separation to discriminate grades 2 and 3.
9.2.1.4 Natural History
Grade 1 holes progress to full thickness holes in approximately 40 % of cases (de Bustros 1994).
Grade 1 holes with poorer vision have a higher chance of progressing (Kokame and de Bustros 1995)
Grade 2 holes have 74 % chance of proceeding to stage 3 or 4 in 6–12 months (Kim et al. 1995).
At 5 years without treatment, there is a 75 % chance of 20/200 vision or worse (Casuso et al. 2001; Lewis et al. 1996).
Spontaneous closure can occur especially with grade 2 holes, 11.5 % (Ezra and Gregor 2004), reducing in grade 3 and 4 holes to 4 % (Freeman et al. 1997).
Fig. 9.13 Different patterns of abnormality are seen in Watzke–Allen Test including a break, central narrowing and bowing of this slit lamp beam. The first two are associated with macular hole. The second two are associated with epiretinal membrane, but this abnormality can also be demonstrated on the edge of macular holes
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Fig. 9.14 When examining the risk to the fellow eye of a patient with macular hole, any sign of traction from the posterior hyaloid on the fovea as in this patient (which has been named as grade 0 macular hole) increases the risk of progression to full thickness macular hole to 40 %. In absence of this sign, risk of progression is low
Fig. 9.15 Mild foveal disruption is present from vitreofoveal traction. The vitreous separated without progression to macular hole
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Fig. 9.16 The vitreous has separated taking a small operculum of tissue (usually glial tissue) with it
Fig. 9.17 A grade 1A macular hole may stay stable for months but usually with mild visual loss (20/40 in this patient)
Fig. 9.19 The vitreal traction can be clearly seen on this OCT of a grade 1 macular hole
Fig. 9.20 This sequence of OCTs show the progression of a stage 1 hole with 20/60 vision deteriorating to 20/120 and then to a grade 2 hole with counting fingers vision (see Figs. 9.21 and 9.22)
Fig. 9.21 See previous figure
Fig. 9.18 High-definition OCT of a grade 1 macular hole
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Fig. 9.23 A grade 1 hole which regressed without progression to a full thickness hole. Note the separation of the posterior hyaloid membrane. Vision remained 20/60 (see Fig. 9.24)
Fig. 9.25 A grade 2 hole with traction of vitreous and its closure after PPV and gas (see Fig. 9.26)
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Fig. 9.26 See previous figure
Fig. 9.27 Spontaneous closure of a grade 2 hole can occur in the first Fig. 9.28 See previous figure 2 months as in this case. It may be prudent to wait for 1 or 2 months for
spontaneous closure before proceeding to surgery
Fig. 9.29 A very early grade 2 macular hole seen on HD OCT
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Fig. 9.30 A grade 2 macular hole on HD OCT showing cystoid spaces beginning to appear at the edge of the hole
Fig. 9.31 A grade 2 hole progresses from outer retina dehiscence to full thickness hole
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Fig. 9.32 A large grade 4 macular hole
Fig. 9.35 See previous figure
Fig. 9.33 A postoperative HD OCT of a grade 2 macular hole with 20/30 vision
Fig. 9.34 Macular holes may appear to close postoperatively as in this patient only to reopen later (see Fig. 9.35)