Imaging of Dome shaped macula in high myopia with swept source optical coherence tomography

1. Abdallah A Ellabban
2015年1月7日
京都大学大学院医学研究科眼科学

2. Am J Ophthalmol. 2014;158(5):1062-1070
Am J Ophthalmol. 2013;155(2):320-328.

3. Dome Shaped Macula
Study II: Dome Shaped Macular configuration: Longitudinal
Changes in The Sclera and Choroid by Swept-Source
Optical Coherence Tomography Over 2 Years
Study I: Three Dimensional Tomographic Features of Dome
Shaped Macula by Swept Source Optical Coherence
Tomography
Sclera
Choroid
Retina

5. High myopia is often defined as a refractive error of - 6 Diopters or
more (Refractive definition) or an axial length of 26.5 mm or more
(Biometric definition). (Normal Axial length = 22-24 mm)
High myopia is associated with axial elongation of the globe with
concomitant thinning of the retina, choroid, and sclera and subsequent
development of macular pathologic features.

6. The progressive elongation of the globe can lead to scleral ectasia
“Staphyloma” which usually occur in the posterior pole, and may take
different patterns and shapes.
Posterior Staphyloma types (Curtin BJ 1977)
Staphyloma

7. 1 mm 1 cm 10 cm
Penetrat
ion
depth
(log)
1 mm
10 mm
100 mm
1 mm
Resolution
OCT
microscopy
Clinical Imaging
(CT, MRI, US)
Depth
The OCT fills the gap between clinical
imaging methods and microscopy with a
micrometer-scale resolution.
Over the past 2 decades, the introduction of optical
coherence tomography (OCT) has revolutionized the field of
ophthalmology; diagnosis and guided therapy.

8. The OCT can acquire an “Optical biopsy” of retinal layers.
OCT scan of the normal retina

9. EndoscopyVessel plaqueskin cancers Teeth

10. Spectral Domain
Swept Source
30,000
1996 2006 2012
Speed
(A-scans per sec)
50,000
70,000
100,000
90,000
80,000
60,000
40,000
20,000
10,000
Time Domain
Year

11. Reference
Beam
splitter
SLD
Detector
Time domain
Sample arm
Referencearm
OCT is analogous to ultrasound but uses light instead of sound.
Sample
It utilizes partial coherence interferometry to construct retinal images.
A-scan
Interference/
Signal
Processing
OCT image
Long wavelength 1050 nm
sweeping laser
Swept source
Fourier transform

12. Swept Source OCT => potential advantages for imaging highly myopic eyes:
1. High speed (>100,000 A scan / second)=>
allows for 3D imaging in less than 1 second with
minimal motion artifact.
2. Wide scan range up to 12 mm =>
covers wide area of the staphyloma.
3. Deeper penetration owing to its long
wavelength (1050 nm)=>
Imaging of choroid, even sclera in high myopia

14. Dome-shaped macula (DSM) was first described by Gaucher et al. as an
unexpected inward bulge of the macula in highly myopic eyes within the
posterior staphyloma.
Dome Shaped macula Normal eye curvature
Steep curvature in High Myopia
Gaucher et al. (AJO 2008)
Dome Shaped macula

15. By using 3D MRI, Moriyama et al. ,
reported that 63 % of highly myopic eyes
had more than one ocular protrusion and
the presence of ocular protrusion may be
related the Dome shaped macula
tomographic appearance in OCT.
(Ophthalmology 2011)
3D MRI showing 3 protrusions at
the posterior pole.
Later, Imamura et al. reported that DSM
may be due to relative localized thickness
variation of the sclera at the fovea in
highly myopic eyes. (AJO 2010)

16. So far, it is still unknown:
•The actual 3D appearance of dome-shaped macula.
•Prevalence of vision threatening complications.
•The mechanisms underlying dome-shaped macula.
It is now recognized that dome shaped macular configuration is not rare,
with estimated prevalence between 9.3 - 10.7 % in highly myopic eyes.
Gaucher et al, AJO 2008
Ohsugi et al. AJO 2014
Our initial pilot study showed that dome shaped macula is associated with
multiple vision threatening complications in at least half of the patients.

17. To study the tomographic features and path-omorphology of dome-
shaped macula with Swept-Source Optical coherence Tomography

18. Prospective Cross-sectional study.
• 51 eyes .
• High myopia (> -6 Diopters or Axial Length > 26.5 mm).
• Dome shaped macula:
>50 µm
Dome shaped maculaRetinal Pigment Epith (RPE)
We defined dome shaped macula as “An inward bulge of the retinal pigment
epithelium (RPE) of more than 50 µm on the vertical sections of OCT above a
presumed line tangent to the outer surface of RPE at the bottom of the posterior
staphyloma”.

19.  3D Swept Source OCT.
 Simultaneous Fluorescein and Indocyanine angiogram for eyes
with macular complications.
 Axial length measurement using ocular biometry.
 The type of staphyloma was classified by indirect ophthalmoscopy
according to Curtain BJ.
Curtin BJ. Trans Am Ophthalmol Soc 1977;75:67-86.
 Visual acuity, Autorefractometry, and Color photography.

20. By Swept source OCT at 1050 nm
III- Segmentation of the RPE:
To create 3-D images of the topography of the
posterior pole.
I- Multi-averaged scan (12 mm)
Vertical and Horizontal scans → to confirm Diagnosis
Vertical scan
Horizontal scan
II- 3D imaging of the macula:
Raster scan protocol covering 12 x 8 mm2
3D scan

21. Fig 1
1- Retinal, choroidal, and scleral thicknesses at the fovea.
2- The height of the macular bulge above a presumed line tangent to the Retinal
pigment epithelium surface at the bottom of the posterior staphyloma.
2000 µm 2000 µm
3- Choroidal and scleral thicknesses at surrounding parafoveal regions at 2000µm
superiorly and inferiorly (vertical scan); temporally and nasally (horizontal scan).
Retroocular
tissue
Retina
Choroid
Sclera
Macular
bulge

22. Characteristics of Eyes with a Dome-Shaped Macula
Number of eyes(patients) 51 (35)
Sex (male/female) 8/27
Visual acuity (logMAR) 0.36 ± 2.16
Age (yrs) 65.6 ± 11.3 (40 to 87)
Axial length (mm) 29.53 ± 2.16 (26.16 to 34.89)
Refractive error (diopters) −13.69 ± 5.86 (−6.75 to −31.0)
Type of posterior staphyloma
I 18
II 26
III 3
IX 4

23. 23
The reconstructed 3D images revealed the curvature of the posterior pole.
In all eyes, two outward concavities were seen within the posterior staphyloma
and a horizontal ridge was seen traversing the macula.
42 eyes (82.4 %): showed a
band-shaped configuration.
9 eyes (17.6 %): showed a
typical dome-like bulge.
2 concavities
2 concavities
Horizontal
ridge
Horizontal
ridge
OCT scans showed marked scleral thinning
consistent with the two outward concavities.

24. The vertical scan showed a convex configuration, but the horizontal scan
showed an almost flat RPE line.
Vertical scan Horizontal scan
Both vertical and horizontal OCT scans showed a convex configuration.

25. 25
Inferior
concavity
Superior
concavity

27. Vertical scan
Horizontal scan

28. Comparison between the Two Types of Dome- Shaped Macula
Band-shaped
configuration
Typical dome-
shaped convexity
P value
Number of eyes 42 (82.4%) 9 (17.6%)
Sex (male/female) 11/31 0/9 0.09a
Age (years) 66.6 ± 10.6 61.1 ± 14.1 0.192b
Axial length (mm) 29.75 ± 2.26 28.52 ± 1.28 .121b
Refractive error (diopters) −14.19 ± 6.19 −11.54 ± 3.10 .277b
Visual acuity (logMAR) 0.32 ± 0.36 0.29 ± 0.28 .818b
Foveal retinal thickness (μm) 193.5 ± 90.6 178.6 ± 52.8 .638b
Foveal choroidal thickness (μm) 32.8 ± 26.9 42.7 ± 37.9 .358b
Foveal scleral thickness (μm) 501.5 ± 93.6 598.3 ± 76.8 .006b
Height of the inward bulge (μm) 151.9 ± 63.8 154.2 ± 27.3 .864b
aFischer’s exact test, bUnpaired t-test

29. Complications in the Eyes with a Dome-Shaped
Macula
Choroidal neovascularization 21 (41.2%)
Serous retinal detachment 3 (5.9%)
Patchy chorioretinal atrophy 4 (7.8%)
Lamellar macular hole 3 (5.9%)
Full-thickness macular hole 1 (1.9%)
Foveal schisis 1 (1.9%)
Extrafoveal retinal schisis 9 (17.6%)
About 58.8 % of eyes had vision
threatening complications.
Choroidal neovascularization
(growth of new blood vessels from the choroid to invade the retina.)
Serous macular detachment Lamellar macular hole
(partial defect at the center of the fovea)
Extrafoveal schisis
(splitting of the retinal layers)
Incidence of choroidal neovascularization
in High myopia is about 5.2% in USA and
11.3% in Japan. Grossenkalus HE et al Retina (1992)
Hayashi K et al. Ophthalmology (2010)

30. Table . Characteristics of Eyes with CNV vs. without CNV
Eyes without
CNV
Eyes with
CNV P value
Number of eyes (%) 30 (58.8%) 21 (41.2%)
Age (years) 65.5 ± 12.4 65.8 ± 10.0 .936b
Axial length (mm) 29.60 ± 2.13 29.45 ± 2.24 .816b
Refractive error (diopters) −13.61 ± 6.26 −14.06 ± 5.35 .806b
Visual acuity (logMAR) 0.24 ± 0.32 0.53 ± 0.42 .007b
Foveal retinal thickness (μm) 190.1 ± 62.0 191.9 ± 111.6 .943b
Foveal choroidal thickness (μm) 38.5 ± 32.8 28.8 ± 21.8 .212b
Foveal scleral thickness (μm) 518.0 ± 109.7 519.4 ± 79.6 .958b
Height of the inward bulge (μm) 167.3 ± 59.5 131.0 ± 51.7 .028b
The mean height of the macular bulge was significantly more in eyes without CNV (P = .028).
aFischer exact test, bUnpaired t-test
Choroidal neovascular membrane
RPE atrophy

31. We speculated that = > The bulge in eyes with DSM may act as a macular
buckle or ”indent” mechanism, indenting the fovea similar to a macular
exoplant, and thus change the tractional forces over the fovea.
Macular Buckle
(used previously for treatment for myopic foveoschisis and
myopic macular hole)
The incidence of extrafoveal schisis “splitting of the retina” was similar to reports on
high myopia while foveo-schisis “splitting of retinal layers at the fovea” was quite
low as compared to highly myopic eyes without dome shaped configuration.
High myopia with foveo-schisisSuperior schisis in DSM Inferior schisis in DSM

32. ◆ In highly myopic eyes with DSM , a horizontal ridge is formed within
the posterior staphyloma between two outward concavities of RPE.
◆ 3D reconstructed images showed that DSM may involve 2
configurations; more common Band shaped ridge and Less frequent
Dome shaped convexity.
◆ 3D reconstruction of the shape of the posterior pole using OCT is a
useful method to study the topography of the globe.

34. Since the sclera is the primary determinant of eyeball shape and the
main changes in ocular elongation in high myopia take place at the
scleral coat, tracking changes in the sclera may help to elucidate the
mechanism underlying the formation of a dome-shaped macula.
Based on our previous 3D data, DSM has shown to be more complex
and the mechanisms that underlie DSM are still speculative.
Sclera

35. To study longitudinal changes in the posterior pole in eyes
with dome-shaped macular configuration.
2 years

36. 36
-Tracked the changes in sclera and choroid at the fovea and at 4 parafoveal
locations 2000 µm from the foveal center => Scleral thickness maps.
-Tracked changes in Macular bulge and dynamic changes in the posterior pole.
• 35 eyes with High myopia and Dome-shaped macula.
• Mean follow up 24.8 ± 2.5 months.
• Using Swept Source OCT
Prospective Cross-sectional study.
1 2
Macular bulge
*
A
Sclera
B

37. 1st scan (January 2011)
2nd Scan (July 2013)
A
B
A
B
Scleral thickness map
Scleral thickness map

38. Longitudinal changes in The Sclera Over 2 Years
At initial visit At the end of follow up P valuea
Visual acuity (logMAR) 0.37 ± 0.49 0.36 ± 0.45 .804
Foveal scleral thickness (μm) 496.1 ± 95.7 484.7 ± 96.2 < .001
Macular bulge height (μm)b 136.5 ± 60.9 157.6 ± 67.0 < .001
Parafoveal Scleral thicknesses
At 2000 µm superiorly (μm) 280.9 ± 87.1 258.2 ± 87.2 < .001
At 2000 µm inferiorly (μm) 263.1 ± 68.7 239.0 ± 66.7 < .001
At 2000 µm temporally (μm) 307.6 ± 97.3 286.3 ± 95.5 < .001
At 2000 µm nasally (μm) 372.7 ± 88.2 360.9 ± 90.1 < .001
aPaired t-test

39. July 2011
Jan 2013
Jan 2014
A
B
A
B
A
B

40. Scleral thickness map (µm)
Sep 2013
A
B
151µm
November 2011
}}}}
A
B
Superior Inferior
Scleral thickness map (µm)
Nov 2011

41. Decline In Scleral Thickness Per Year at Various Macular Points
Scleral Thick.
decline over 2
years (μm)
Estimated Scleral
thickness decline/year
(μm)
P Valuea
Foveal center 11.2 5.62 -
At 2000 µm superiorly 22.7 11.14 .002
At 2000 µm inferiorly 24.1 12.11 <.001
At 2000 µm temporally 21.3 10.39 .009
At 2000 µm nasally 11.6 5.83 .907
aComparisons with the foveal center (using one-way analysis of variance with least significant difference post-hoc analysis).

42. 42
22.7
11.2
24.1
21.3 11.6
Decline of scleral thickness over 2 years
11.2 11.6
The relatively preserved sclera at the fovea and nasal side may
act as a macular pillar to support the expanding globe.

43. The sclera becomes entirely thinner over time in eyes with dome-
shaped macular configuration.
The scleral thinning is asymmetric and the progression of such
asymmetric scleral thinning leads to the dome-shaped tomographic
appearance.
Dome Shaped macular configuration is an independent scleral change
related to regional difference in the structural integrity of the sclera.