A Comparison between Fluorescein Angiography and

Optical Coherence Tomography Findings in Patients with

Clinically Significant Macular Edema

KoriAnne Elkins Galler, M.D.

Resident’s Day

May 30th, 2008

Introduction

• Macular edema is the most common cause of decreased visual acuity and quality of life in diabetic patients

• Slit lamp biomicroscopy is the gold standard for diagnosis based on the ETDRS criteria

• Laser photocoagulation is the mainstay of treatment for CSME

• Vascular leakage can be qualitatively measured with fluorescein angiography (FA)– Provides guidance for application of focal laser

– Leakage can be present without clinical evidence of edema

• Optical coherence tomography (OCT) is a non-invasive way to calculate macular thickening and demonstrate retinal swelling

Introduction

• Several authors have established a correlation between FA leakage and abnormal macular thickness or retinal swelling on OCT

• However, these studies have several limitations – Timing of FA and OCT data– Inclusion of only horizontal and vertical meridians for

comparison

Introduction

Otani T, Kishi S. Correlation between Optical Coherence Tomography and Fluorescein Angiography Findings in Diabetic Macular Edema. Ophthalmology 2007;114 Kang SW, Park CY, Ham DI: The correlation between fluorescein angiographic and optical coherence tomographic features in clinically significant diabetic macular edema. Am J Ophthalmol 2004;137:313–322. Özdek SC, Erdinç MA, Gürelik G, Aydın B, Bahçeci U, Hasanreisog B. Optical Coherence Tomographic Assessment of Diabetic Macular Edema: Comparison with Fluorescein Angiographic and Clinical Findings. Ophthalmologica 2005;219:86–92

• OCT has the potential to improve clinic efficiency

• In some places, OCT is being used in placed of FA

• In order for OCT to supplant FA, it must be able to reliably detect leakage and provide valuable information for treatment and follow-up

Introduction

Purpose• To evaluate the correlation between

fluorescein leakage and optical coherence tomography (OCT) abnormalities in diabetic patients with clinically significant macular edema (CSME)

Methods

• Retrospective review of 74 eyes of 48 patients with a diagnosis of CSME

• All patients that had fluorescein angiography (FA) and OCT testing on the same day were reviewed

Methods

• Treatment-naïve and treated patients (laser, intravitreal injection, or vitrectomy) were included in this study

Methods

• Fluorescein angiograms were graded by a single physician in a masked fashion

• OCTs were read independently of the FAs by a second masked physician

Methods: Fluorescein Angiography

• For each eye, digitized early-phase and late-phase FA images were reviewed– Early: 1-2 minutes post-injection– Late: 5-10 minutes post-injection

• Images were overlain with a modified ETDRS grid and type of leakage recorded

Methods: Fluorescein Angiography

Grades of FA leakage

FA Leakage Types

Grade 1 Normal

Grade 2 Focal

Grade 3 Mixed Focal & Diffuse

Grade 4 Diffuse

Grade 5 Cystoid Macular Edema

Methods: OCT Analysis

• OCT was performed on a Zeiss OCT3– 6.0-mm scans in 6 meridians (every 30

degrees) for each study eye

• A digitized grid was created for the radial OCT scans to correspond to the same areas as the ETDRS grid

Methods: OCT Analysis

Methods: OCT Types

OCT Abnormality Types

Type 1 Swelling without cysts

Type 2 Swelling with cysts

Type 3ANeurosensory detachment without VMT

Type 3BNeurosensory detachment with VMT

Methods: Comparison of FA’s to OCT’s

Methods: OCT Map Analysis

• The standard macular thickness map was used to record the thickness in 9 standard subfields

• Values of > 250 microns for central foveal thickness and > 300 microns for other subfields were considered abnormal

Results: Baseline Characteristics

Number Percentage

Men 23 47.9

Women 25 52.1

Age 58 (Range 39-75)

DM I 6 13.0

DM II 42 87.0

Treatment-naïve eyes

46 64.8

74 eyes of 48 patients the study

Results: Patterns of Leakage

Normal Focal Mixed Diffuse CME

FA/OCT Correlation

Only 42% of zone-by-zone comparisons had both an abnormal FA and OCT

74 Eyes x 9 zones per eye = 666 zones

Results: Abnormal OCT’s by FA Grade

Concordance of FA & OCT

• A total of 666 comparisons were made between FA and OCT zones– 386 (58%) showed consistent findings – 233 (35%) had an abnormal FA with a normal

OCT in all 3 subscans– 47 (7.1%) resulted in a normal FA with an

abnormal OCT in at least one scan

• Cohen’s kappa of 0.1673 (poorly concordant)

Macular Thickness Correlation & Distribution

FA Leakage PatternAbnormal OCT Thickness Measurements

Inner + outer zones (67 eyes) 46 eyes (64.8 %)

Inner zone only (2 eyes) 1 eye (50%)

Outer zone only (2 eyes) 0 eyes (0 %)

No leakage (0 eyes) 0 eyes (0 %)

Discussion• Of the 280 (42%) comparisons that resulted

in a mis-match between FA and OCT – 233 (35%) with abnormal FA and a normal OCT

– Only 47 (7.1%) instances with a normal FA but some abnormality detected on the OCT

• Additionally, in 35% of patients OCT thickness measurements were normal despite FA leakage

• This suggests that there is a large subset of patients that will have leakage detected on FA but no comparable OCT changes or increased macular thickness

Discussion

Discussion

• Two possibilities to account for this difference– First, these patients may still have a relatively

healthy retinal pigment epithelium • Able to pump out the additional fluid without

leading to retinal swelling or increased thickness

– Secondly, these patients may have preexisting retinal thinning that creates a falsely normal OCT

Limitations

• Small number of Type 1 diabetics, results may not generalize

• Treated vs. untreated patients not controlled for and comparison between groups was not made

In Conclusion

• Fluorescein is still a useful clinical tool for assessment of leakage and guiding treatment

• Although OCT is a less invasive testing modality for detection of DME, up to 1/3rd of patients with active leakage will be missed

• OCT not surrogate for clinical exam or FA and cannot be used as a guide for placement of laser photocoagulation

Acknowledgements

• Rohan J. Shah, M.D.

• Franco Recchia, M.D.