Kestenbaum surgery is a procedure done to improve visual acuity or reduce a bothersome head posture in nystagmus. Nystagmus is characterized by to and from involuntary eye movements that can either be congenital or acquired. These eye movements can be horizontal, vertical, or torsional.
Nystagmus affects visual acuity since it destabilizes fixation and lessens foveation time (the brief period when the eye remains still and pointed at the object of regard). Acquired nystagmus can lead to oscillopsia (the perception that the world is ever on the move).
Kestenbaum and Anderson first proposed that nystagmus with abnormal head posture could be corrected by surgery in 1953. Various surgeons consequently proposed multiple techniques, but it's the modified Kestenbaum strategy that is widely performed today.
There are different types of head postures, with the most common being turning the face to one side or the other, some with minor degrees of depression, the elevation of the chin, or tilting of the head.
Congenital nystagmus is present at birth, but surgery should not be performed until the child gets to seven to 8 years. There is a risk of these children developing strabismus in binocular cases, primarily if the procedure was performed on the vertical recti.
Patients with infantile nystagmus (IN) may consider having Kestenbaum surgery. IN is caused by a defect of the motor in the efferent pathways, in children born normal. It is usually not noted at birth but becomes apparent in the first few months after birth. It may occur together with acquired or congenital visual sensory system deficit. Research indicates that when Kestenbaum surgery is combined with posterior fixation suture, it has better surgical outcomes than using Kestenbaum surgery alone to correct IN.
Before the Procedure
Patients with congenital nystagmus require extensive medical and ophthalmic examination before the surgery to exclude sensory causes of nystagmus. The eye doctor carries out a comprehensive clinical evaluation which includes:
- Neuroimaging if there is need
- Optic nerve and macula defects
- Orthoptic assessment and slit-lamp examination
- Visual acuity, color vision, and a dilated fundoscopic exam
- Electroretinogram in case of photophobia, myopia, and paradoxical pupillary reactions
- Measuring eye position, speed, and target position in attempted fixation at different angles of gaze
- Pupil examination, pupillary dilation with light, and iris examination for transillumination defects
- History which includes family history of nystagmus, refractive history treatment, medical or surgical intervention history, presence of neurological disorders, and whether the child tilts or turns the head
- Motility tests which include covering one eye, recording ductions (eye movement involving only one eye), and observing the direction of gaze (torsional, vertical, horizontal, or mixed). The eye doctor estimates and assesses head turns by requesting patients to fixate on a small, distant object. Patients who qualify for surgical intervention should have an unacceptable head position that cannot be corrected by eyeglasses (300 or higher).
Prisms may be used to assess the level and type of nystagmus but do not carry much value for long-term therapy.
The patient is put under general anesthesia. The procedure involves bilateral recession and resection of all four horizontal recti (extraocular muscles). An equal amount of 5 mm resection is applied to all four recti. The procedure increases the foveation period resulting in improved visual acuity. It includes moving the extraocular muscles to place the null zone (field of gaze with minimal nystagmus) in the primary position.
The surgeon rotates the eyes in the direction of the head-turn, which is an underlying principle behind this procedure. In some cases, the abnormal head posture can recur, necessitating the re-resection of muscles that had previously been resected by 5 mm. The re-resection is done together with a posterior fixation procedure on the previously resected muscles.
Vertical anomalous head postures are corrected by recessions and resections of various vertical muscles.
Risks & Complications
Risks and complications may include:
- Head turn may be under corrected
- Restriction of motility postoperatively
- Visual acuity not registering any improvement
- A chance of developing heterotopia after surgery
- Recurrence of a head turn immediately after surgery
- Horizontal movements in the direction of muscle recession with limited posterior fixation
- Increased risk of anterior segment ischemia because nystagmus patients may eventually need surgery on all the rectus muscles
Aftercare & Recovery
The patient needs a long follow-up period, which can range from six months to more than 100 months. The first appointment is scheduled at one day, then a week later, one month, and every three months as per the need.
The most significant benefit of Kestenbaum surgery is often cosmetic as the best-corrected visual acuity usually does not change.