Nonpseudophakic Cystoid Macular Edema Workup

Updated: Nov 03, 2023
  • Author: Hamoon Eshraghi, MD; Chief Editor: Hampton Roy, Sr, MD  more...
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Laboratory Studies

Laboratory studies for cystoid macular edema (CME) vary depending on the presumed etiology of the edema.

If findings suggestive of diabetes are present, the patient should have blood glucose testing or a glucose tolerance test.

In the presence of uveitis, an appropriate evaluation for chronic uveitis should be initiated. See Uveitis, Evaluation and Treatment for details.


Imaging Studies

Optical coherence tomography (OCT) is the gold standard in the identification of CME. OCT is a noninvasive imaging modality that can determine the presence of CME by visualizing the fluid-filled spaces in the retina. The amount of CME can be monitored over time by quantifying the area of cystoid spaces on a cross-sectional image through the macula.

Studies have reported OCT to be comparable to FA in the evaluation of CME, especially with newer, high-resolution OCT scanners. OCT is beneficial by quantifying the thickness of the retina and by allowing quantitative measurements of macular edema over time. This noninvasive method is especially useful in monitoring the response to treatment.

Newer software for OCT has increased the resolution of this imaging modality and has led to the identification of specific patterns of CME.

Spectral domain OCT has increased the resolution of OCT imaging to as low as 2-3 microns and is more sensitive in detecting intraretinal fluid associated with CME.

OCT images are shown below.

Ocular coherence tomographic image of cystoid macu Ocular coherence tomographic image of cystoid macular edema in a patient with uveitis.
Ocular coherence tomographic image of cystoid macu Ocular coherence tomographic image of cystoid macular edema in an eye with nonproliferative diabetic retinopathy.

FA is an alternative imaging study to evaluate CME. Fluid accumulation may be delayed in certain conditions; thus, late phase fluorescein photos, sometimes as long as 20 minutes or more, may be required to properly evaluate the CME. Associated findings on FA may help determine the etiology of CME.

If leaking microaneurysms are present in the setting of diabetic retinopathy, then diabetes likely is the cause. This is shown in the images below.

Fundus photograph of nonproliferative diabetic ret Fundus photograph of nonproliferative diabetic retinopathy with clinically significant macular edema and cystoid macular edema.
Fluorescein angiogram of same eye as in the image Fluorescein angiogram of same eye as in the image above, revealing both cystoid macular edema and leakage from microaneurysms associated with diabetic retinopathy.

Vascular collaterals crossing the horizontal raphe on FA can help determine that the etiology of the edema (and retinal hemorrhages if present) is likely due to a vascular occlusion.

The absence of leakage from CME on FA suggests a diagnosis of nicotinic acid retinopathy, Goldmann-Favre disease, or X-linked juvenile retinoschisis.

FA also is helpful to verify the presence of CME when it is difficult to establish clinically.


Other Tests

In the appropriate clinical setting, an electroretinogram may be indicated to confirm a diagnosis of RP with associated CME.



Occasionally, in cases of uveitis with associated CME, a diagnostic vitreous biopsy or vitrectomy can aid in determining the correct diagnosis. The vitreous fluid can be sent for the appropriate laboratory tests based upon the clinical picture. It is beyond the scope of this article to discuss the full laboratory workup for uveitis.

In cases of orbital pseudotumor, an incisional biopsy for the purpose of confirming a diagnosis is indicated; however, CME rarely is associated with this condition.