City, University of London Institutional Repository
Citation: Pelosini, L., Hull, C., Boyce, J. F., McHugh, D., Stanford, M. R. and Marshall, J.
(2011). Optical Coherence Tomography May Be Used to Predict Visual Acuity in Patients
with Macular Edema. Investigative Ophthalmology & Visual Science, 52(5), pp. 2741-2748.
doi: 10.1167/iovs.09-4493
This is the accepted version of the paper.
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version.
Permanent repository link: https://openaccess.city.ac.uk/id/eprint/5098/
Link to published version: http://dx.doi.org/10.1167/iovs.09-4493
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City Research Online
1
Optical Coherence Tomography maybe used to predict Visual Acuity in patients
with Macular Oedema
Lucia Pelosini
1
, Christopher C Hull
2
, James F Boyce
1
, Miles R Stanford
1
, John
Marshall
1
1
Department of Ophthalmology, Kings College London, Rayne Institute, St
Thomas’ Hospital, London, Lambeth Palace Road, London, SE1 7EH
2
Department of Optometry & Visual Science, City University, London
Grant information: The present study was funded by a grant of The Royal College
of Surgeons, London, United Kingdom
Disclosure:
JM is a paid consultant for OTI (Ophthalmic Technologies Inc., Toronto, Canada)
None of the other authors have a financial interest in the subject of the
presentation.
Word count:
Key words: cystoid macular oedema; optical coherence tomography (OCT);
spectral OCT; coronal (en-face) OCT; central macular thickness; ocular imaging.
2
Abstract
Purpose: To determine whether the volume of retinal tissue passing between the
inner and outer retina in macular oedema could be used to predict visual acuity.
Methods: Diabetic and uveitic patients with cystoid macular oedema (81 subjects,
129 eyes) were recruited. Best corrected LogMAR visual acuity and spectral optical
coherence tomography (OCT/SLO OTI, Toronto) were performed for all patients.
Coronal OCT scans obtained from a cross-section of the retina between the plexiform
layers were analyzed using a grid of 5 concentric radii (500µ, 1000µ, 1500µ, 2000µ,
2500µ centred on the fovea). The images were analyzed to determine the amount of
retinal tissue present within each ring. A linear regression model was developed to
determine the relationship between tissue integrity and LogMAR visual acuity.
Results: The volume of retinal tissue between the plexiform layers in ring 1 and 2 (up
to 1000 µ from the foveal centre) predicted 80% of the change in visual acuity using a
linear model. By contrast, central macular thickness within the central 1000 µ
predicted only 14% of the change in visual acuity.
Conclusions: This study showed that the cross-sectional area of retinal tissue between
the plexiform layers in cystoid macular oedema, as imaged by OCT, is a much better
predictor of visual acuity at baseline than central macular thickness. Further
prospective treatment trials are required to investigate this parameter as a predictor of
visual outcome after intervention.
3
Introduction
Macular oedema results from abnormal accumulation of fluid in the central retina and
indicates compromised function in one or both of the blood retinal barriers. It is a
common sequel of many ocular conditions and the main cause of visual loss in
diabetic retinopathy
1-5
.
Any abnormal pooling of extracellular fluid may result in displacement of the spatial
relationships between retinal neuronal components. Small amounts of fluid may lead
to an increase in overall retinal thickness, whilst larger amounts may give rise to cell
free spaces as seen in cystoid macular oedema
5
.
Observations from histology and optical coherence tomography (OCT) give a false
impression of multiple cysts delineated by tissue structures in the Z-plane of the retina
(Figure 1). However, scanning electron microscopy shows that more commonly a
single cystic space is present within which a number of structures extend from the
inner to the outer retina (Figure 2). Such structures consist of columns of Muller’s
fibres together with the axonal elements of bipolar cells passing between the two
plexiform layers
6
. Empirical studies have demonstrated that the two plexiform layers
together with the outer limiting membrane form a physical resistance barrier to fluid
movements
7
. Thus, extracellular fluid may be contained within layers defined by
these resistance barriers. In diabetic retinopathy, cystic spaces may occur either
between the inner and the outer plexiform layers or between the outer limiting
membrane and the outer plexiform layer. In the former location, there is a potential to
displace bipolar cells leading to cell loss or compromised function, whilst in the latter,
only photoreceptor cells are at risk
8, 9
.
Given the fundamental role of bipolar cells in being the sole communication pathway
between photoreceptors and ganglion cells, any loss of connectivity between these
