Chapter 13

■Spectral optical coherence tomography (SOCT) offers a 3D mode and has faster scanning times, when compared with time domain OCT. SOCT therefore gives us the opportunity to study retinal pathologies in a more detailed way.

■SOCT enables differentiation between full-thick- ness macular holes, lamellar macular holes and macular pseudoholes.

■The diameter of the macular hole is the most important factor determining the functional outcome after surgery.

■Spontaneous resolution of full-thickness macular holes is rare.

■Pars plana vitrectomy with internal limiting membrane peeling and air/gas exchange is the treatment of choice for full-thickness macular holes.

■After macular hole repair, different retinal pathological features are present.

■In cases of lamellar macular hole with deteriorated vision or metamorphopsia, surgical treatment should be considered.

13.1  Stages of Full-Thickness Macular Hole in

Spectral OCT

Macular hole stages were originally described by Gass [1] and modified by Gaudric et al., who presented a study of macular hole formation documented by optical coherence tomography (OCT) in the 1990s [2].

Stage I macular hole, or impending macular hole, was originally described by Gass as progressive loss of foveal depression with a yellow ring or spot, which Gass explained as detachment of the fovea [47]. In OCT/ SOCT, one can see that it is in fact an intraretinal split or cyst, localised in the inner retinal layers and prefoveal vitreous cortex with a centripetally directed tangential force [2, 3]. On SOCT, elevation of the photoreceptor layer can additionally be observed. Visual acuity is often good at this stage, although patients may complain of blurring and metamorphopsia (Fig. 13.1a).

Stage II macular hole, according to Gass, is a full-thick- ness macular hole with a diameter smaller than 400 µm, with posterior hyaloid still attached to the retinal surface. Gaudric et al. described its OCT appearance as a large

opening of the photoreceptor layer and an incomplete opening of the operculum, with posterior hyaloids still attached to the operculum [2]. In SOCT, intraretinal cystoid spaces at the edges of the hole can be noted. Visual acuity deteriorates to a level of 20/40 to 20/100, and metamorphopsia increases. Progression to stage III macular hole can last for several weeks to months (Fig. 13.1b).

Stage III macular hole has a diameter of more than 400 µm. Elevated and slightly thickened retina with cystoid spaces can be observed around the hole. Localised separation of the vitreous cortex is usually noted because of the presence of an operculum, hyperreflective in OCT/ SOCT. In addition, as the hole enlarges, discrete white deposits appear on the surface of the retinal pigment epithelium (RPE) at the base of the macular hole that represent nodular proliferations of the RPE cells. Visual acuity ranges from 20/60 to 20/200 (Fig. 13.1c).

Stage IV macular hole, according to Gass, has a diameter of up to approximately one third of the optic disc diameter and is surrounded by elevated retina [1]. Posterior hyaloid detachment can be seen as the Weiss ring. In OCT/SOCT, there is no difference, except in size, between stage III and IV macular holes (Fig. 13.1d).

13 

Fig. 13.1  (a) Stage I, (b) stage II, (c) stage III, (d) stage IV macular hole (Copernicus HR; Optopol, Zawiercie, Poland). TR asymmetric traction, CS cystoid space; E IS/OS elevation of the hyperreflective line between the inner and outer segments of the photoreceptors, RPE retinal pigment epithelium, IS/OS hyperreflective line between inner and outer segments of photoreceptors, ELM external limiting membrane, IS/OSD photoreceptor layer defect

13.2  Clinical Features

The condition is most common in women over 55 years of age and bilateral in 1.2–28.6% of the cases. This wide range, taken from the literature, is probably due to differences in the examination methods used. SOCT data show bilateral appearance of the disease in about 15% of the cases [3].

Macular holes can be asymptomatic in their early stages; the diagnosis can also be delayed in patients with good visual acuity of the fellow eye. Metamorphopsia, central scotoma and decreased visual acuity can also occur.

13.3  Examination

With fundoscopy, stages I–IV, as classified by Gass, can be differentiated (Fig. 13.2a).

With autofluorescence, a round or oval, well-circum- scribed, hyperfluorescent area is seen in the foveal region (Fig. 13.2b). The hyperfluorescence is due to the lack of macular pigment in the hole. This allows the excitation light to reach the RPE unimpeded.

With fluorescein angiography, hyperfluorescence is visible in the area of the macular hole (Fig. 13.2c).

With scanning laser ophthalmoscopy, a round or oval hyporeflective area can be observed in the fovea. It can be distinguished from non-full-thickness macular defects when height deviation from the retinal surface is detected on the topography scale (Fig. 13.2d).

OCT and SOCT are the gold standard in the diagnostics of macular holes. They present as full-thickness retinal defects in the fovea (Fig. 13.2e).

Microperimetry and electrophysiology may confirm the diagnosis, but their importance is usually limited to scientific publications.

13.4  Natural History

Spontaneous resolution of stage I macular holes occurs in 40–90% of the cases [4].

Spontaneous closure of idiopathic stage II–IV macular holes is rare. Epidemiological data from before the OCT era described a spontaneous macular hole closure rate of about 33% for stage II and about 14% for stage III macular holes [4]. It is possible that some findings may have been misinterpreted in those times, because, in some cases, diagnosis of the disease (without OCT) may have been incorrect. In our clinic, only four cases of spontaneous resolution of stage II–IV macular holes were noted from approximately 200 cases that were evaluated with SOCT in the last 3 years.

In cases of ocular trauma, it should be considered that the macular hole may close spontaneously during the first few weeks following ocular trauma. Therefore, it is

Fig. 13.2  Macular hole. (a) Fundus photography. (b) Auto­ fluorescence. A hyperfluorescent round region, representing a lack of macular pigment in the hole can be seen (Spectralis; Heidelberg Engineering, Heidelberg, Germany). (c) Late phase of fluorescein angiography. A round, well-circumscribed hyperfluorescent region can be noted (Spectralis). (d) Scanning laser ophthalmoscopy of the

advisable to qualify patients for surgery after a few weeks subsequent to the onset of the macular hole.

Summary for the Clinician

■Macular holes can be asymptomatic in the early stages.

■SOCT should be performed if a macular hole is suspected on fundoscopy.

■Because the disease is often bilateral, careful examination of the follow-up of the fellow eye should be a rule.

■Spontaneous resolution is rare; thus, surgery should be proposed for patients with a full-thick- ness macular hole.

■Post-traumatic macular holes can spontaneously close during the first few weeks after ocular trauma.

13.5  Ultra-High Resolution OCT and Spectral

OCT Findings in Macular Holes

Improvements in the quality of OCT may be achieved in two different ways. First, it is possible to use an alternative light source in time domain OCT, e.g. femtosecond laser, which improves the resolution of OCT images up to 3 µm

macular hole. The white circle and white arrow represent the minimal diameter of the macular hole. The yellow circle and yellow arrow represent the area of edema around the hole. The red arrows present the height difference on the topography scale (HRT II; Heidelberg Engineering, Heidelberg, Germany). (e) Spectral optical coherence ophthalmoscopy of the macular hole (Spectralis)

of axial resolution, but does not influence the speed of image acquisition. This method has been presented in the literature as ultra-high resolution OCT. Devices for ultrahigh resolution OCT are experimental and have been presented in different papers [5–8].

Another method is the use of Fourier domain or spectral domain OCT (SD-OCT), a new technique in macula examination, which first became available in 2006. SD-OCT changes the method of signal detection and increases the speed of the examination, and improves the image resolution (5–7 µm axial resolution). This method additionally allows serial B- and C-scans of the macular area to be achieved. Various commercially available instruments using this technology have been produced.

Both alternative light source and Fourier domain OCT are combined in the Copernicus HR SOCT (SOCT HR; Optopol, Zawiercie, Poland), which gives us the opportunity both to achieve up to 3 µm of axial resolution and to create serial B- and C-scans of the examined area.

As the resolution of the retinal tissue with ultra-high resolution is similar to that of the commercially available SOCT, this chapter will also present the data published regarding this technology.

Ko et al. presented a multi-case report with images of macularholesexaminedusingultra-highresolutionOCTin 2004. They reported that posterior hyaloid may be attached

to the fovea, and on their images, small portions of sensory retina that detached from RPE were visible. Furthermore, small cystic changes were visible in the ganglion cell layer and in the nuclear layer. Enhanced visualisation of fine

13  intraretinal features of the external limiting membrane (ELM) and Henle’s fibres from the outer plexiform layer were presented in stage I macular holes. After surgery, Ko et al. also demonstrated resolution of cystic intraretinal spaces and intact photoreceptor inner segments/outer segments (IS/OS) connected to the RPE, as well as some elevation of the outer retina in stage IV macular holes after vitrectomy. These data were confirmed in a case study by Scholda et al. with ultra-high resolution OCT [5–7].

Optical coherence tomography images and ultra-high resolution OCT show an increase in signal from the RPE

near the hole, most likely due to the absence of scattering and absorption from the inner retina.

Srinivasan et al. additionally demonstrated the presence of epiretinal membrane formation combined with full-thickness macular hole on ultra-high resolution OCT [8].

SOCT with resolution up to 3 µm allows visualisation of all those findings with commercially available devices. The additional advantage of SOCT over high-resolution OCT is the opportunity to achieve up to 200 B-scans on the surface up to 10 × 10 mm, which allows 3D reconstruction of the macular hole. Additionally, currently available SOCT devices have software that allows the ophthalmologist to present minute details of the vitreous and retinal structures (Fig. 13.3).

Fig. 13.3  (a) Pathological features of particular retinal layers in a spectral optical coherence tomography (SOCT) image of a macular hole (Spectralis). ELM external limiting membrane, IS/ OS hyperreflective line representing the junction between the inner and outer segments of the photoreceptors. (b) A picture

with enhanced visualisation of a macular hole with vitreoretinal traction with 3D OCT (Topcon Company, Tokyo, Japan). (c) Spectral domain OCT (Copernicus HR; Optopol, Zawiercie, Poland) with an axial resolution of 3 µm and maps of particular retinal layers

Quite recently, the possibility of using a hand-held non-contact SD-OCT system that combines a viewing screen with a movable hand-held scanner connected via a flexible fibre-optic cable to a movable cart holding the SD-OCT system was presented. This device allows good quality SD-OCT B-scans of macular holes in patients who cannot be examined in a sitting position, e.g. children [9].

The size of the macular hole may be an important factor in determining the anatomical and functional outcome after surgery. It may be easily measured with SOCT.

The hole form factor (HFF) may be counted with SOCT, as presented in Fig. 13.4 (HFF = c + d/a). According to Ullrich et al., in all patients with HFF > 0.9, the macular hole was closed following surgical procedure, whereas in eyes with HFF < 0.5, the anatomical success rate was

67%. A better postoperative visual outcome correlated with higher HFF (p = 0.050) [10, 11].

The minimum diameter of the macular hole is an important factor determining the visual outcome. Our results showed that all macular holes with a diameter less than 500 µm were closed after surgery, and eyes with a preoperative macular hole area of less than 0.2 mm2 achieved final visual acuity of more than or equal to 0.3 (Fig. 13.4) [12].

Measurements of macular hole size performed with OCT and HRT showed a difference in size between the two imaging techniques in about 10% of cases. This could be explained by the fact that in some cases, the macular hole is not round but oval. In these cases, measurements performed with time domain OCT may not be adequate, because they are measured in specifically determined planes. Therefore, spectral domain OCT seems to be