Top 9 Mistaken Diagnoses

2. Herpetic Keratitis

Image: Dendritiform epithelial keratitis, suspicious for herpetic keratitis.

Epithelial keratitis classically presents as dendritiform lesions (see image above), but can also have a more geographic appearance, making it more difficult to differentiate from corneal abrasions or healing epithelial defects. Herpes can also present as stromal keratitis with or without ulceration and as endotheliitis. Keep herpes on the differential, especially if there is decreased corneal sensation, elevated intraocular pressure or corneal findings not responsive to other therapy.

Note that herpes can affect any part of the eye, so it’s therefore important to dilate every patient that presents with suspected viral infection to rule out posterior segment pathology, such as acute retinal necrosis.

3. Giant Cell Arteritis (GCA)

Image: Optic nerve pallor with a broad differential, including giant cell arteritis.

Keep GCA on your differential in patients over the age of 50 with new onset headache, loss of vision, diplopia, jaw claudication or other systemic findings. If there is a high index of suspicion or if lab work (erythrocyte sedimentation rate or ESR, C-reactive protein or CRP) is positive, start urgent treatment with steroids to prevent progression and involvement of the other eye. Plan for a temporal artery biopsy for pathologic confirmation.

4. Ocular Ischemic Syndrome (OIS)

Image: Attenuated vessels and midperipheral dot and blot hemorrhages, suspicious for ocular ischemic syndrome. (© 2021 American Society of Retina Specialists. Image by Andreas Ebneter, MD, PhD. All rights reserved.)

OIS is often confused with diabetic retinopathy or central retinal vein occlusion. Classic presentation includes subacute vision loss and orbital pain. The exam is often consistent with midperipheral dot and blot hemorrhages, including dilated veins and narrowed arteries; there may also be anterior segment inflammation and neovascularization with elevated intraocular pressure. Because carotid atherosclerosis is the main cause, patients need to be referred to their internists for carotid imaging.

5. Papilledema/
Pseudopapilledema

Images: (Top) Blurred disc margins without obscuration of vessels, suggesting pseudopapilledema, and a “lumpy, bumpy appearance,” suggestive of disc drusen. (Bottom) Blurred disc margins with obscuration of vessels as they cross the border of the disc, consistent with disc edema.

Watch out for subtle differences between these two. The nerve in the top image above initially appears to be elevated, but there are no obscurations of the vessels, and it is more consistent with disc drusen (pseudopapilledema). The bottom image, on the other hand, shows dilated blood vessels and multiple vessels that are obscured as they cross the border. (In this case, disc edema was bilateral and associated with elevated intracranial pressure, which equals papilledema.) Patients with true papilledema require urgent evaluation.

6. Syphilis

Image: Optic neuropathy, one of the various presentations of syphilis.

Syphilis typically presents as uveitis but can mimic a variety of ocular diseases (including optic neuropathy and interstitial keratitis). Other masqueraders that are important to include in the broad differential for ocular inflammation include tuberculosis, sarcoidosis and malignancy such as intraocular lymphoma. The infectious masqueraders must be ruled out before initiation of systemic steroid therapy for uveitis.

7. Carotid-Cavernous (C-C) Fistula

Images: Dilated corkscrew-like tortuous conjunctival vessels (top) warrant further imaging for carotid-caverous fistula (bottom).

C-C fistulas may be misdiagnosed as conjunctivitis or thyroid eye disease, as they have a broad spectrum of presentation, including mild conjunctival injection with or without proptosis, diplopia, elevated intraocular pressure, retinal venous congestion and/or variable discomfort. Look closely for small, tortuous corkscrew-type conjunctival blood vessels. Supportive findings can include blood in Schlemm’s canal on gonioscopy and presence of an orbital bruit. Urgent imaging is warranted.

8. Central Retinal Artery Occlusion (CRAO)

Image: Cherry red spot that may be present in central retinal artery occlusion.

CRAO is a time-sensitive diagnosis, as some patients may benefit from intra-arterial fibrinolysis or other maneuvers within a short time interval; additionally, patients have increased risk of stroke and cardiac events requiring urgent same-day referral for bloodwork and imaging. Look out for a new afferent pupillary defect in a patient with sudden vision loss. The classic cherry-red spot may not be visible initially. Always order lab tests to rule out giant cell arteritis in cases of suspected CRAO.

9. Retinoblastoma

Image: Pseudohypopyon is one of the many diverse presentations of retinoblastoma.

Retinoblastoma is the most common intraocular childhood tumor. Although it most frequently presents as leukocoria (white pupillary reflex), it can also present as strabismus, pseudohypopyon (see image above), inflammation, cellulitis or retinal detachment, to name a few.