As someone who underwent the Kastenbaum-Anderson procedure in the late 90’s, I can attest to its effectiveness. My null point was moved more or less to the center of my vision, and instead of appearing like I was peering off into a corner, I was able to focus directly on the subject. Being 12 at the time, recovery was very quick. However, I can’t say how someone older would react to the procedure in terms of recovery.
Currently, Kestenbaum-Anderson is the go-to procedure for those affected by congenital nystagmus, because it simply works. The procedure was originally proposed in 1953 by two doctors, JR. Anderson and A. Kestenbaum. While it may be considered a cosmetic procedure by some, in my particular case, moving the null point actually improved my vision and decreased focus time.
When carrying out the Kestenbaum-Anderson procedure, the surgeon detaches the muscles and rotates the eye in the direction of the patients head turn, and in the opposite direction of the null point. The null point is basically the head position and posture where the person with nystagmus achieves their clearest vision. Each of the eyes undergoes what is known as a recession-resection procedure, so they move in the same direction. In none-medical speak, this procedure basically means that one set of muscles is weakened by removing and reattaching to the eye at a point further back so it has less pull. The other muscle is repositioned so it basically has better leverage. This makes it more difficult for the patient to look toward the previous null point, thereby damping the nystagmus more toward center gaze.
The degree to which recession-resection procedures are carried out has been altered over the years as more patient feedback data has been acquired. For example, from the first surgery to the third, the adjustments were increased from 40% to 60% of the original. Of course the total adjustment in each eye is equal to ensure the rotation of both eyes is equal. For example, a face turn of 30° would benefit from a 40% augmented procedure. In the case of a rather severe 45°, up to 60% augmentation procedure is recommended. The heavily modified procedures may cause mobility restrictions of the eye in some cases. However, this is mostly necessary to ensure the procedure has a satisfactory outcome.
In some nystagmus cases, the patient will also have vertical torticollis, which basically means the head and/or neck are tilted, twisted, etc to help achieve the ideal null point. Personally, when I’m not watching myself, I have a slight head tilt even though I think I’m looking straight ahead. As with left or right gazing, the muscles controlling the vertical movement of the eye are realigned so the patient is forced to looked more or less straight ahead, thus reducing the tilt. The amount of surgery is usually 5–7 mm of recession and resection of the vertical rectus muscles of each eye.
For someone who has nystagmus with strabismus (misalignment of the eyes), the surgery should be carried out on the dominant fixating eye; surgery on the non-dominant eye is adjusted to account for the strabismus. For example, a patient who is right-eye dominant and has a right head turn and left gaze null zone would undergo a right medial rectus recession and right lateral rectus resection. This procedure could lessen or eliminate a coexisting esotropia and would increase an exotropia. Surgery on the nonpreferred eye is tailored to these possibilities. Here’s a translation of the last paragraph. The patient is right eye is dominant, has a right head turn, and the null point is to the left. The muscles would be snipped and reattached, so the eye is forced to look right, forcing the patient to keep their head more or less straight, while alignment is also adjusted so as to allow it work together with the left eye more.
These are always a work in progress. Feel free to submit clarifications and corrections.