Fig. 20.1
Normal posterior vitreous in the normal eye of a 30-year old woman. Horizontal 12-mm B-scan. (a) The vitreous cortex is completely attached to the retinal surface of the posterior pole but is only visible on the margin of the macula (yellow arrows). The bursa premacularis (asterisk) is an optically empty space over the macula. Its anterior wall is well visible (red arrow). The wall of Cloquet’s canal (large arrows) is in connection with the vitreous cortex. (b) Detail showing the progressive thinning of the vitreous cortex on the edge of the fovea
The initial stage of impending MH is usually visible when it occurs in a patient with an MH in the other eye. The symptoms are mild or absent, and the impending MH can only be detected by OCT of the fellow eye. When early signs of vitreomacular traction (VMT) are diagnosed in an eye without anomaly, there are no specific signs in the other eye indicating that the evolution will turn to an MH rather than to a more advanced VMT without hole. The vitreous cortex normally starts to detach from the surface of the macula in the fifth decade of life, and this process progressively progresses with age (Johnson 2010, 2012; Ma et al. 2014; Uchino et al. 2001) (Fig. 20.2).
Fig. 20.2
Uncomplicated natural history of a posterior vitreous detachment (PVD) in a fellow eye of a macular hole. (a) May 2010, partial detachment of the posterior vitreous cortex in temporal of the macula (arrow). The presence of the premacular bursa (asterisk) in front of the macula shows that the vitreous still adheres to the macular surface. (b) April 2011, the posterior vitreous cortex is now detached all around the foveal center and only adheres at the foveal pit. (c) June 2011, the posterior vitreous cortex is now completely detached from the posterior pole but not from the optic disc (OD) (blue arrow). There is a condensation in the plane of the detached vitreous cortex (large arrow) probably due to an avulsion of the foveal surface; the foveal pit is slightly irregular (red arrow)
Impending MHs have been described by Gass (1995) and classified into two stages (1A and B) based on biomicroscopy findings. The role of the perifoveal vitreous separation as well as the formation of intrafoveal cysts have subsequently been identified by time domain OCT (TD-OCT) (Gaudric et al. 1999; Haouchine et al. 2001).
SD-OCT has shown various degrees of foveal surface alterations more or less combined with microstructural intrafoveal changes, which constitute the spectrum of impending MHs, and the Gass classification is no longer useful. The earliest signs of vitreofoveal traction observed in a fellow eye of MH are minute changes in the curvature of the foveal pit. These anomalies could be only a part of the normal process of age-related vitreomacular detachment but have a special significance in the context of an MH in the other eye (Ma et al. 2014) (Fig. 20.3).
Fig. 20.3
Asymptomatic perifoveal posterior vitreous detachment in the fellow eye of a macular hole. (a) Horizontal B-scan showing the adherence of the posterior hyaloid to the foveal center without change in its curvature. Note an adherence between the posterior hyaloid and the retinal surface near the optic disc (arrow). (b) Vertical B-scan showing a discrete focal elevation of the foveal curvature (arrow) at the attachment point of the posterior hyaloid below the foveal center. The posterior hyaloid adheres more widely to the upper part of the macular surface (arrowheads)
More frequently, surface anomalies are associated with various degrees of foveal microstructural changes. They may be a simple discrete elevation of the ellipsoid zone (EZ), a change in the reflectivity of the foveal center, an inner foveal cyst, a central split in the fovea, an outer foveal cavitation, or a combination thereof (Takahashi et al. 2011a, b). Moreover, these anomalies may evolve overtime (Fig. 20.4). It is also of note that some anomalies are very small and may be present on only one B-scan even when tight rasters are used (Fig. 20.5).
Fig. 20.4
Various degrees of tractional anomalies in the fovea of fellow eyes of macular holes. (a) Discrete elevation and irregularity of the foveal floor (black arrow) at the junction with the partially detached posterior hyaloid (PH). Note the slight elevation of the ellipsoid and interdigitation zones at the foveal center (arrowhead). (b) More marked foveal floor elevation (arrows) due to the traction of the posterior hyaloid (PH). The elevation of the central photoreceptors, ellipsoid, and interdigitation zones is more marked (arrowhead). (c) In addition to the elevation of the foveal floor by traction of the posterior hyaloid (PH) and elevation of the central photoreceptors (arrowhead), there are also small cystic spaces in the inner part of the fovea
Fig. 20.5
Vitreomacular traction and spontaneous resolution (raster of 5 B-scans spaced by 75 μm). (a) Shallow posterior hyaloid (PH) detachment with discrete elevation of the foveal floor (arrow). (b) On the adjacent B-scan distant from 75 μm, there is a narrow full-thickness micro-hole (large arrow), visible only on this B-scan. (c) Three months later, the posterior hyaloid (PH) is detached from the macula and contains an operculum (arrow). The micro-hole is now closed
When the foveal floor is elevated due to the traction exerted by the posterior hyaloid on its center, a foveal cyst may occur (Gaudric et al. 1999; Haouchine et al. 2001). The retinal outer layers may be intact (Haouchine et al. 2001; Takahashi et al. 2011b). However, SD-OCT has shown that, more frequently than previously thought, the photoreceptor IS/OS layer may be elevated or even disrupted at the foveal center. The yellow spot visible on fundus examination, which may be associated with the inner foveal cyst, is probably due to the foveolar detachment of the cone outer segments (Takahashi et al. 2011a) (Figs. 20.6 and 20.7).
Fig. 20.6
Three different cases of vitreomacular traction with inner foveal cysts, in fellow eyes of macular holes. (a) Vitreomacular traction on the foveal center resulting in the formation of an inner foveal cyst. The outer retina is intact. (b) The inner foveal cyst is larger than in (a), but the outer retina is also intact. (c) Voluminous tractional cystoid spaces in the inner part of the fovea. There is a defect in the ellipsoid line (black arrow) which seems in continuity with the posterior hyaloid (PH) and the septa separating cystoid spaces (large arrow)
Fig. 20.7
Vitreomacular traction with inner foveal cystic spaces and central alteration of the interdigitation zone. (a) Horizontal 9-mm B-scan showing the traction of the posterior hyaloid (PH) on the roof of the foveal cystic spaces. (b) Three dimensional reconstructions showing the focal adhesion of the posterior hyaloid to the cystic foveal center. (c) En-face OCT showing the radial distribution of the foveal cystoid spaces. (d) Detail of the B-scan showing a small interruption of the continuity of the interdigitation zone; the ellipsoid zone is intact. (e) One year later, normalization of the macular profile after spontaneous release of the vitreomacular traction
Inner foveolar cysts may also communicate with an outer retinal cavitation forming an “occult” MH (Gass 1995). The retinal layers are disrupted in the whole thickness of the fovea except at a very superficial layer containing the inner limiting membrane (ILM) on which the posterior hyaloid is still attached (Gaudric et al. 1999; Haouchine et al. 2001; Michalewski et al. 2011; Takahashi et al. 2011a, b). In this regard, some impending MHs (former stage 1B) are true occult MHs. At any stage of impending MH, a complete resolution is possible if the VMT decreases or spontaneously releases (Figs. 20.8 and 20.9).
Fig. 20.8
Vitreomacular traction with outer retinal break in a fellow eye of a macular hole. (a) Fundus color photo showing a yellow spot in the foveal center. (b) Red-free photograph on which green lines 1 and 2 refer to the two B-scans displayed in c and d and separated by 75 μm. (c) B-scan 1 mainly shows a voluminous inner foveal cyst and an outer retina which seem intact. (d) B-scan 2 shows that in fact there is a central break in the outer retina
Fig. 20.9
Worsening and spontaneous resolution of an impending macular hole. (a) Vitreomacular traction with small elevation of the foveal floor (black arrow). The interdigitation and ellipsoid zones are slightly elevated or focally disrupted (large arrow). (b) Six months later, formation of an inner foveal cyst whose roof is disrupted (black arrow) by the posterior hyaloid traction. Elevation of the foveal photoreceptors with disruption of the ellipsoid zone (large arrow). (c) Six months later, spontaneous release of the vitreous traction with avulsion of an operculum (black arrow). Reattachment of the central photoreceptors but the continuity of the ellipsoid zone is not yet complete (large arrow)
However, there is a significant risk of evolution toward a full-thickness macular hole (FTMH). There are few data on the risk of MH in a fellow eye when a VMT is associated or not with structural intrafoveal anomalies. According to recent publications, the risk could range between 30 and 50 % (Kumagai et al. 2011; Takahashi et al. 2011b) (Fig. 20.10).
Fig. 20.10
Evolution of a vitreomacular traction toward a full-thickness macular hole. (a) Vitreomacular traction with focal elevation of the foveal floor and microcystic space (black arrow), elevation of the central photoreceptors (large arrow) and vertical hyperreflective line (arrow head). (b) Four months later, worsening of the vitreomacular traction with elevation of the foveal floor (black arrow) which forms the roof of a large foveal cyst. Breakdown of the photoreceptor layer (large arrow). This case can be considered as an “occult” macular hole. (c) Three months later, the vitreous has detached, but a full-thickness macular hole is present
20.3 Full-Thickness Macular Holes
The recent international classification (Duker et al. 2013) proposes to differentiate MHs according to the presence of a vitreomacular adhesion and the hole diameter (Table 20.1).
Table 20.1
Comparison of the classification commonly used for macular holes, adapted from Gass classification, with the international VMT study classification
Classification commonly used for full-thickness MH | International VMT study |
|---|---|
Stage 2: small hole | Small or medium FTMH with VMT |
Stage 3: large hole | Medium or large FTMH with VMT |
Stage 4: FTMH with PVD | Small, medium, or large FTMH without VMT |
20.3.1 Macular Hole with Persistent Vitreous Traction
MH with persistent vitreous traction includes what has been called stage 2 MH. Stage 2 MH has been described as an eccentric oval, crescent, or horseshoe-shaped retinal defect inside the edge of the yellow ring and a diameter of less than 400 μm (Johnson and Gass 1988; Gass 1995). OCT has subsequently shown that the incompletely detached operculum is pulled in an oblique direction by the traction of the posterior hyaloid (Gaudric et al. 1999; Hee et al. 1995) (Fig. 20.11).
Fig. 20.11
Large full-thickness macular hole with vitreomacular traction. (a) Montage of horizontal B-scans showing the traction of the posterior hyaloid (PH) on the operculum (arrow) of the macular hole. The vitreous is still attached to the optic disc (OD). The bursa premacularis (asterisk) is elevated with partial detachment of the vitreous. (b) Three-dimensional OCT showing the adherence of the vitreous on the operculum. (c) Horizontal B-scan showing the operculum still attached to the edge of the hole (arrow). The diameter of the hole on this B-scan is 495 μm. (d) Horizontal B-scan, distant of 75 μm from the scan in c. The posterior hyaloid (PH) seems detached from the retina. However, the shape of double arc converging toward the fovea does not fit with a PH completely detached from the macular surface. The diameter of the hole on this B-scan is 488 μm
Moreover, recent observations by Takahashi et al. (2010, 2011a, b) have shown that the neuronal elements formed a constitutive part of the operculum at least in some cases (Fig. 20.12). This observation corroborates the histological findings of Ezra, who has shown the presence of cone components in two-thirds of the opercula he examined (Ezra et al. 2001) (Fig. 20.13).
Fig. 20.12
Full-thickness macular hole with vitreomacular traction. (a) Horizontal B-scan showing the vitreomacular traction on the operculum attached to the hole edge. (b) The vertical B-scan does not pass through the marginal opening of the operculum, and the case may be misinterpreted as an impending macular hole. (c) Detail of the scan above: the external limiting membrane (ELM) and the ellipsoid zone (EZ) are detached in the area of the hole. The photoreceptor outer segments are also detached (black arrow) and elongated. Note also debris of photoreceptors at the posterior face of the operculum (blue arrow). Proliferation of the retinal pigment epithelium in the area of the hole (large arrow)
Fig. 20.13
Spontaneous closure of a small macular hole with vitreomacular traction. (a) Small macular hole (diameter of 133 μm) with vitreomacular traction on a small operculum. (b) Three months later, increase in the vitreous traction on the operculum. At the same time, a diaphragm closes the hole in its middle (arrow). (c) After 5 months, the posterior hyaloid has detached from the macula with the operculum (black arrow), and the healing process has closed the hole, leaving only a small interruption in the ellipsoid zone (large arrow). (d) Two years later, remodeling of the fovea: there is no more defect in the ellipsoid zone. A discrete cleavage is present in the nasal edge of the fovea
Small MHs may close spontaneously when the VMT spontaneously releases, but this event is rare (Privat et al. 2007). OCT shows that MH with persistent vitreous traction may present various profiles and a large range of diameters from the extra small break to a large foveal opening greater than 400 μm, although small holes are the majority.
20.3.2 Macular Hole with Released Vitreous Traction
According to international classification (Duker et al. 2013), this category includes all the cases in which the posterior hyaloid is detached from the hole edge regardless of whether the vitreous is also detached or not from the optic disc. In the Gass definition, stage 3 MH was a central round retinal defect with a diameter greater than 400 μm, a rim of elevated retina, with or without prefoveolar pseudo-operculum, and without a Weiss ring. The presence of a Weiss ring defined the stage 4. Subsequently, OCT has shown that even when the vitreous was not detached from the optic disc, it could be completely detached from the retinal surface over the posterior pole and not connected to the hole edge.
20.3.2.1 Diameter of the Macular Hole and Vitreomacular Status
Moreover, the precise measurement of the hole diameter on OCT scans has shown that the size of MH with and without VMT varies greatly. Although the diameter of stage 2 MHs generally tends to be smaller than that of stage 3 MHs; large stage 2 and small stage 3 MHs are in fact not uncommon (Privat et al. 2007; Takahashi et al. 2011b).
In a recent study conducted on 100 consecutive idiopathic full-thickness macular holes (FTMH), we have found that the mean preoperative hole diameter was not significantly different according to the presence or absence of a VMT: 339 ± 134 μm in eyes with VMT and 423 ± 191 μm in eyes without VMT (p = 0.057). Only 13 % of cases had a diameter of 400 μm or less, and 6 % had a diameter of 250 μm or less (Philippakis 2015) (Fig. 20.14).
Fig. 20.14
Variations in diameter of macular holes without vitreomacular traction. (a) Horizontal scan of a large macular hole (880 μm). (b) Horizontal scan of a small macular hole (75 μm)
20.3.2.2 Method for Measuring Macular Hole Diameter
The aperture size is measured using the caliper function on SD-OCT devices. The minimum hole width is measured at the narrowest hole point in the mid-retina, using the OCT caliper function, as a line parallel to the retinal pigment epithelium (RPE) (Duker et al. 2013). Empirically, it corresponds to a line drawn between the terminations of the detached photoreceptor outer segments. Other methods have also been studied (Wakely et al. 2012; Xu et al. 2013), but the minimum hole width tends to be a standard. The accurate measurement of the MH size has several practical consequences. MHs of 250 μm or less have a likelihood of about 50 % to be closed by intravitreal ocriplasmin injection (Stalmans et al. 2012). MHs of 400 μm or less have an increased likelihood to be closed surgically than larger ones (Ip et al. 2002; Tadayoni et al. 2006). ILM peeling could be only needed in MH larger than 400 μm (Chang 2012; Tadayoni et al. 2006, 2009) (Fig. 20.15).
Fig. 20.15
Accurate measurement of the macular hole diameter (aperture size). (a) Horizontal 9-mm B-scan showing a full-thickness macular hole without vitreomacular traction. (b–d) Horizontal 6-mm B-scan raster (b) and (c) are spaced by 50 μm and (c) and (d) by 100 μm. The diameter of the hole aperture is measured at the narrowest hole point in the mid-retina using the OCT caliper as a line parallel to the retinal pigment epithelium. It corresponds to the end of the photoreceptor outer segments (blue bar). In this example, the size may vary from 308 to 392 μm depending on the location of the scan. Due to the instable fixation of these eyes, a raster of several tight B-scans should be obtained. The largest value corresponds to the exact diameter of the hole aperture (macular hole size)
20.4 Macular Hole and Epiretinal Membrane
A noncontractile epiretinal membrane (ERM) may cover the macular surface around the hole. It is especially well visualized on blue reflectance photographs (Blain et al. 1998). The frequency of the formation of an ERM increases with the stage, duration, and size of the hole (Blain et al. 1998; Cheng et al. 2000, 2002). However, this does not affect the surgical prognosis once the membrane has been peeled off during surgery (Fig. 20.16).
Fig. 20.16
Epiretinal membrane associated with macular holes. (a) The epiretinal membrane is not visible on the fundus image (left) but is present on the OCT B-scan on the right (arrow). (b) The epiretinal membrane induces some stellar superficial folds on the en-face OCT image on the left (arrow) but is not visible on the horizontal OCT B-scan (right)
20.5 Differential Diagnosis
Differentiating a full-thickness MH from other roundish anomalies of the fovea is no longer a problem since the advent of OCT, which clearly shows the characteristic profiles of lamellar MHs and macular pseudoholes. However, foveal cysts of various origins as well as micro-holes may be more difficult to differentiate from idiopathic FTMH.
20.5.1 Lamellar Macular Hole
The term of lamellar macular hole (LMH) has been coined by Gass in 1975 to characterize a macular lesion resulting from the opening of the central cyst of a cystoid macular edema. The term lamellar hole has been used to describe both the end stage of a cystoid macular edema (Frangieh et al. 1981) and the aborted process of formation of a MH (Haouchine et al. 2001, 2004).
Lamellar MHs, i.e., defects in the inner fovea due to the avulsion of the roof of a foveal cyst (either tractional or due to a cystoid macular edema), are characterized on OCT by an irregular thinning of the foveal floor, a cleavage between the inner and outer retina at the lamellar hole edge and the absence of a contractile ERM (Haouchine et al. 2004) (Figs. 20.17 and 20.18).
