Differential Diagnosis

Conditions Associated With Congenital Nystagmus: The 4 A's

There are many different eye conditions that are associated with congenital nystagmus; theoretically, any bilateral visually-significant pathology present at birth or in infancy during the critical period of visual development may interfere with the development of stable fixation (1)  Eventually I'll get around to discussing the finer points of nystagmus; but for now, I'm sticking to some basic study stuff.

Conditions With Increased Risk Of Glaucoma

This review is somewhat multi-disciplinary in nature. As you wrap up your reviews, one of the things I found useful was to create tons of different lists. Regardless of which test you're studying for, there are many questions that are organized differently than how one might go about learning a particular disease. As such, I started making lists of different ways to group otherwise disparate diseases that might show up as a test question, or at least help me remember a specific feature of the disease.

Follicular Conjunctivitis

Follicular conjunctivitis is one of those topics that always seems to pop up on exams.  Because questions can be asked about the pathology and differential diagnosis, this is a topic that probably should be very familiar to you.

Causes of Symblepharon

Symblepharon is an external eye finding in which an adhesion forms between the palpebral conjunctiva and bulbar conjunctiva (1).  There are many causes of symblepharon, which is typically a response to trauma or inflammation.

Collagen Types

A considerable amount of the eye is composed of collagen.  Because many eye diseases are related to dysfunction of collagen, it may be useful to categorize these diseases based on the type of collagen and the structures affected.  While this list is not comprehensive, it hopefully is a helpful review.

Congenital Optic Disc Anomalies

Funny-looking optic discs are a "fun" diversion in an ophthalmology clinic (sarcasm implied here).  What was initially a routine exam immediately turns into an agonizing "is this normal or not" exercise.  Part of the angst that comes from seeing anomalous optic discs is that some of the congenital disc anomalies are associated with systemic diseases.  If there is concurrent visual field loss or decreased visual acuity, the challenge becomes deciding if those defects in the visual system are due to the anomalous nerve, or if there is some other ophthalmic cause that we don't want to miss.

Optociliary Shunt Vessels

Optociliary shunt vessels (retinochoroidal shunts), are normal congenital collaterals between the retinal and choroidal venous circulation.  In conditions that cause chronic central retinal vein obstruction, venous outflow becomes redirected to the choroidal venous circulation, resulting in dilation of these collateral vessels.

The 8 Causes of Tunnel Visual Fields

There are relatively few causes for tunnel visual fields (or “gun barrel” visual fields), which is a relatively common finding in neuro-ophthalmology.  There are 8 major categories of tunnel visual fields, which can be determined systematically through careful history and examination.  This differential diagnosis is adopted from Duane’s Clinical Ophthalmology.