Abstract and Introduction
Abstract
Aims To compare the ability to detect cystoid macular edema (CME) and its late complications between spectral-domain optical coherence tomography (SD-OCT) and fluorescein angiography (FA).
Methods Retrospective, observational, case series. 85 Eyes who had FA and SD-OCT performed on the same day at first visit and/or at follow-up visits were included. FA and SD-OCT images were evaluated for the evidences associated with CME and other structural changes of macula. FA and SD-OCT images were then superimposed to determine the relationships of diagnostic features between the two images. Main outcome measure was the correlation between FA and SD-OCT findings of macula in patients with CME.
Results The common causes of CME in our study were retinal vein occlusion (RVO, 63%), diabetic retinopathy (DR, 21.18%) and posterior uveitis (3.53%). CME associated with RVO, age-related macular degeneration and DR were missed by FA in 18.52%, 33.33% and 33.33% of cases, respectively. Subretinal fluid was undetectable by FA in 54.55%, which mainly were in the RVO group. SD-OCT gave earlier CME diagnosis than FA in three (3.53%) eyes. Residual CME at follow-up visits were missed by FA in one (1.18%) eye. Late complications of long-standing CME (secondary macular hole (two eyes), secondary subretinal fluid (five eyes), retinal pigment epithelium detachment (one eye) and photoreceptor atrophy (one eye)) were detectable only by SD-OCT.
Conclusions SD-OCT demonstrated greater sensitivity than FA in detecting CME, particularly those associated with RVO, DR and age-related macular degeneration. SD-OCT was also more sensitive than FA for detecting subretinal fluid and late complications of long-standing CME.
Introduction
Cystoid macular edema (CME) is a common pathological condition of the macula that is the result of cystic accumulation of extracellular intraretinal fluid in the outer plexiform and inner nuclear layers of the retina, as a result of breakdown of the blood-retinal barrier. Common causes of CME are postsurgical (cataract, glaucoma and laser surgeries), intraocular inflammatory diseases, medications, diabetic retinopathy and retinal vein occlusions. Treatments of CME vary from observation, medical and surgical. The visual outcomes are basically related to retinal structural changes of the macula especially in the long-standing cases. The ability to characterise the existence of CME is important in providing early treatment and knowing when to stop the treatment. This is critical in prevention of structural damages in long-standing CME that takes effect on the patient final visual outcomes.
The conventional standard tool for the diagnosis of CME is fluorescein angiography (FA), which is an invasive contrast-assisted modality. Doctors recognise CME as a classic “flower petal” leakage pattern in FA. However, the FA finding is dynamic and sometimes difficult to be interpreted, especially with the presence of retinal hemorrhages and exudates.
Optical coherence tomography (OCT) is a non-invasive and non-contact method that allows quantitative measurements of retinal thickness and volume. It provides cross-sectional images of the retina and useful information on vitreoretinal morphological changes associated with a variety of posterior segment diseases. Spectral-domain OCT (SD-OCT) is the latest generation of the technique and can provide images with high axial resolution and fewer motion artefacts. It allows identification of individual retinal layers approaching histological details with significant clinicopathological information in several retinal conditions. CME appears as cavitations of the outer plexiform and inner nuclear layers in the OCT scan. The present study correlates the SD-OCT and FA findings of CME at exact locations within the lesions.