Ординатура / Офтальмология / Английские материалы / Optical Coherence Tomography in Age-Related Macular Degeneration_Coscas_2009

Clinical Signs

An 81-year-old woman, followed for AMD for 3 years, initially presented with sudden loss of visual acuity in her right eye. The fellow eye had several soft drusen and nonconfluent areas of atrophy.

VA RE: 20/800 - VA LE: 20/125.

Small fluorescent spots were observed in the inferior zone due to abnormal transmission through the altered RPE (Figure 10d).

SLO-ICG Angiography

Abnormal visibility of several large choroidal vessels in the area of the RPE tear.

In the inferior part, the retracted RPE was hyper-pig- mented, dense, and masked the choroid (Figure 10e).

Suggested Diagnosis:

Large, old tear in 2/3 of the circumference of a vascular-

ized PED. The inferior part of the lesion corresponded to

the prominence of the retracted RPE and the fibrovascu-

lar scar tissue.

Vertical section

The RPE was visualized from below upwards. It was initially normal and then formed a dome-shaped detachment from the choroid and was completely absent in the atrophic zone.

In the elevated zone, the RPE was irregular, partially retracted, and rolled onto itself.

The hyper-pigmentation caused intense back-shadowing, which completely masked the choroid.

Beyond this dome, the RPE was no longer visible and the choroid was directly in contact with the retina (which was thinned at this level). This thinning and absence of the RPE accounted for the intense posterior shadowing.

Oblique section

The section started at the superior part and showed retinal thinning and loss of the RPE in the area of the tear. The section then showed the rest of the retracted fibrovascular PED and finally the normal peripheral territory (Figures 11a and b).

a

FA

RPE retracted

ICG

The patient agreed to close follow-up for 3 years due to the severity of the lesions in the right eye, and the risk for the fellow eye. During the first year, this observation was performed by conventional imaging and TD-OCT (Stratus*) (Figure 12).

During the second year, observation was based on simultaneous angiography and SD-OCT (Spectralis*) imaging (Figure 13).

At the end of the first year

Central visual acuity remained low (20/800), but without metamorphopsias.

Stratus* TD-OCT, vertical section

The neurosensory retina was elevated with loss of the foveal depression due to the central lesion, but there was no SRF.

The RPE presented a persistent dome-shaped detachment from the choroid, but this was slightly less prominent 12 than before. Beyond this residual PED, the RPE was com-

pletely absent in the superior atrophic zone.

In the elevated zone, the RPE was irregular, retracted, and rolled up without signs of CNV proliferation. This thickening and hyper-pigmentation caused complete backshadowing as far as the choroid.

Beyond this dome, the RPE was no longer visible and the choroid was in direct contact with the retina, which was thinned at this level.

Thinning and loss of the RPE were responsible for intense back-shadowing (Figure 12).

At the end of the second year

Central visual acuity remained unchanged (20/800).

Spectralis* SD-OCT vertical section

In the elevated zone, the RPE was irregular and rolled up with marked hyper-reflectivity and thickening, which indicated reactive proliferation of the RPE that had invaded all of the outer retinal layers. Beyond this dome, the RPE was no longer visible, confirming the tear and retraction of the RPE with atrophy of the underlying layers.

Anterior to the RPE, in the residual PED, the IS/OS interface and external limiting membrane remained occasionally visible but were not clearly identified. The outer nuclear layer was invaded by a hyper-reflective extension of the RPE, sometimes extending as far as the inner limiting membrane.

In the atrophic zone, the IS/OS interface, external limiting membrane, and outer nuclear layer were absent, which brought the outer plexiform layer in contact with Bruch’s membrane and confirmed photoreceptor atrophy (Figure 13).

Fluorescein Angiography

Fluorescein angiography showed persistent zone of progressive hyper-fluorescence due to staining of all of the superior atrophic area. Numerous spots were visible in the inferior zone due to abnormal transmission through the RPE (Figures 12 and 13).

ICG Angiography

Abnormal visibility of several large choroidal vessels in the area of the tear. In the inferior part, the hyper-pig- mented and retracted RPE was dense and masked the choroid (Figures 12 and 13).

Clinical Signs

A 63-year-old woman, who had been followed for bilateral, asymmetrical macular lesions for more than two years, presented with progressive decline of visual acuity in her right eye for several months.

VA RE: 20/80 - VA LE: 20/40.

Biomicroscopic Examination

Biomicroscopic examination showed a central, oval lesion with a fairly well-delineated de-pigmented and atrophic superior portion and a darker, brownish inferior semicircle (Figure 14a).

Fluorescein Angiography

Almost all of the lesion was hypo-fluorescent, masking the hyper-fluorescent fundus. This hyper-fluorescence was especially visible in the periphery and superior part of the lesion and corresponded to abnormal transmission of fundus hyper-fluorescence due to alteration of the RPE without fluorescein leakage (Figures 14c and d).

ICG Angiography

The lesion was composed of hypo-fluorescent material, dense in the inferior half and in the superior periphery, with several fine extensions. This material was more rare and almost absent in the superior part, revealing the hyperfluorescent fundus crossed by several large choroidal vessels but with no fluorescein leakage (Figures 14e and f).

Suggested Diagnosis:

Vitelliform macular dystrophy with regression and atrophy

of the material in more than half of the superior lesion.

Horizontal section

The RPE was almost completely absent in the central subfoveal zone with persistence of several scattered hyperreflective islands anterior to Bruch’s membrane.

The IS/OS interface was completely absent in the same zone, while the external limiting membrane was still visible. The hypo-reflective outer nuclear layer presented normal thickness.

Vertical section

The RPE in the inferior zone of the lesion was preserved with accumulation of fairly dense hyper-reflective material.

This material appeared to proliferate anteriorly in a localized zone of the outer nuclear layer at the center of the section. The other retinal layers were normal (Figures 15a and b).

Clinical Signs

An 82-year-old woman had been followed with bilateral, asymmetrical macular lesions for several years. She presented with progressive decline of visual acuity in the left eye over several months.

VA RE: 20/63 - VA LE: 20/200.

Biomicroscopic Examination

Slightly prominent, rounded, irregular, de-pigmented lesion with jagged and slightly pigmented edges without hemorrhage.

On red-free images, the lesion had poorly-defined margins and appeared to be de-pigmented, as on the red light image (Figures 16a, b, and c).

Fluorescein Angiography

The lesion became rapidly hypo-fluorescent with progressive staining, particularly intense in the inferior and nasal sectors. Its surface area did not increase and no fluorescein leakage was observed (Figure 16d).

Suggested Diagnosis:

Vitelliform macular dystrophy with accumulation of ma-

terial, which induced slight elevation in the inferior and

nasal macula.

3D Examinations

The 3D image clearly visualized the regular, dome-shaped elevation of the macular surface.

The corresponding section revealed the main findings visible on the high-definition section:

▬RPE atrophy,

▬Hypo-reflective space,

▬Elevation of outer retinal layers,

▬Thinning of the outer nuclear layer, which was displaced by denser material (Figure 17b).

The 3D image with segmentation allowed even clearer distinction of the structures situated anterior and posterior to the RPE.

The anteroposterior section can also be located in relation to the fundus image (Figure 17c).

Various imaging modalities can achieve this objective.

▬ Red light monochromatic images often demonstrate areas of atrophy, even at an early stage when these areas are not clearly visible on biomicroscopy or redfree monochromatic images.

▬ Areas of atrophy are easily detected on fluorescein and ICG angiography, creating a window defect through which choroidal vessels of variable atrophy are clearly visible.

▬ Autofluorescence examinations, easy to perform and without the need for an IV injection, rapidly demonstrate the presence of lipofuscin-rich material. Progressive regression of this material (accompanying RPE atrophy) results in a zone of marked hypofluorescence.

Time-Domain OCT

TD-OCT provides even more precise information that is as easy to obtain as autofluorescence.

▬Partial or complete atrophy of the RPE with persistence of Bruch’s membrane is a very characteristic sign.

▬The presence of islands of material or material accumulated in the junctional zone is also easy to recognize and can be used to follow the patient’s course.

Spectral-Domain OCT

SD-OCT, especially with the Spectralis* machine, allows much more precise analysis of alterations of the outer retinal layers and constitutes a remarkable progress in ophthalmology.

▬Various degrees of severity of the lesion can be identified by studying visibility of the IS/OS interface and the external limiting membrane.

At a later stage, loss of the outer nuclear layer reflects not only RPE atrophy but also complete and irreversible damage to photoreceptors

▬The diagnosis is confirmed by thinning of the neurosensory retina, which is easily quantifiable. Separate measurement of the various retinal layers and RPE, which will be possible in the near future, will facilitate follow-up and assessment of the response to treatment.

▬3D SD-OCT studies can also demonstrate zones of atrophy of the RPE and outer retinal layers and measure the surface area involved.

Progression of atrophy must be evaluated not only by measuring the surface and peripheral extension, but more importantly, its relation to the fixation point. The presence of a zone of central sparing is very important for the patient’s quality of life.

Automatic eye-tracking systems allow accurate follow-up comparisons.

OCT therefore provides a major contribution, even in dry AMD, which is poorly amenable to treatment.

However, in the case of deterioration and when there is a doubt about its cause, comparison of the various imaging modalities can specify the diagnosis, confirm the various prognostic factors, and guide treatment.