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 firstname.lastname@example.org!
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).
*The AAO reading schedule is based off the 2015-2016 BCSC series, available starting June 15, 2015.
**My reading schedule is based off the 2012-2013 BCSC series, as I do not own the new editions.
Week 27 Overview
In this week, you’ll be continuing through Neuro-ophthalmology if you’re following the AAO’s plan, and continuing Last Minute Optics and Refractive Surgery if you’re following ours.
The AAO Plan:
There are several small sections in this reading that are important to know – nystagmus, pupils, and diplopia being the notable ones. Transient vision loss is also clinically important. Higher cortical visual dysfunctions are tough to understand conceptually, partially because the anatomy is a bit complicated, and also because we just don’t really understand them all that well. Thankfully, it’s not as important to know.
Ophthalmology Review’s Plan:
Keep working through the optics and refractive surgery sections! Just a few short weeks left!
Week 27 Tips and Helpful Resources
For tips and resources on reading these sections, please check out the following pages (I will be working on developing more content for this section):