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.
Here’s a little mnemonic that I used to help me remember some of the conditions associated with congenital nystagmus, the 4 A’s:
Leber’s congenital Amaurosis
References and Additional Reading
Dell’Osso LF, Daroff RB. Chapter 11: Nystagmus and Saccadic Intrusions and Oscillations. In: Duane’s Ophthalmology on CD-ROM, 2006 Ed. Lippincott Williams and Wilkins, 2006. Available online.
Do you have other suggestions for how to remember conditions associated with congenital nystagmus? Leave a comment, visit our forum, or e-mail me at email@example.com!
Best of luck to all those taking the ABO’s Written Qualifying Exam this weekend! I’m on vacation this week for Spring Break, so I haven’t been able to post as many reviews as I was hoping to before the exam.
In any case, I’m going to try to post a few more generalized reviews, as I have a little bit of time before my family and I go do some more vacationy stuff.
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.
Because glaucoma is a potentially sight-threatening/blinding disease, it is important to know if a particular condition is associated with glaucoma in any way, so that appropriate screening can be initiated. While the following list is by no means comprehensive, it is a list that I started putting together while I was studying for the OKAP.
Another caveat is that each individual condition will likely be featured as many individual articles in the future. For the sake of brevity (which I have a hard time doing), I am purposefully not including significant details about each disease. I am still going to try to include images of each condition, since repetition and visual pattern recognition are vital to review, and I will try to include details about the pathophysiology of glaucoma and some basic information about each condition. Hopefully this list can serve as yet another scaffold for you to remember the copious amounts of information needed for testing and clinical practice.
As you can probably tell, I’m starting to skip around a little bit while I put together these OKAP review articles. I have a fairly large list of topics to cover, but hopefully these will all be helpful pieces of information. I decided to skip to aniridia, because it is one of those conditions that seems to be very popular in practice questions.
As the figure states, aniridia refers to the absence of the iris. In most cases, there can be a residual stump or only partial aniridia; complete absence of the iris is actually less common.
Inheritance and Genetics
PAX6: PAX6 is a transcription factor for eye development. It is inherited in an autosomal dominant pattern, and its disruption is the most common cause of aniridia.
PAX6 gene mutations are an example of haploinsufficiency – for some proteins, both genes need to be functioning normally to produce a normal result.
In rare cases, aniridia can also be inherited in a sporadic or autosomal recessive fashion. De novo mutations are associated with Wilms tumor (see below).