Dr. Jitendra Jethani, MS, Do, DNB, FNN
Director, Baroda Children Eye Care
And Squint Clinic, Vadodara
Dr. Siddharth Kesarwani
Chief consultant, Jnr Children Eye Care
Centre and Squint Clinic, Mumbai
Plication versus resection
Plication is a relatively new procedure as an alternate to resection with an advantage of being reversible and potentially vessel sparing. Concerns regarding its effectiveness has been reported previously. The series were very small. Houston and Hoover report their study on 222 patients with 88 patients with basic esotropia underwent MR recession with LR plication and 74 patients underwent MR recession with LR resection. For basic exotropia, 31 patients underwent MR plication with LR recession and 29 patients underwent LR recession and MR resection.
The mean change in ocular alignment (with standard deviation) for lateral rectus plication (27.7 +/- 5.8) and lateral rectus resection (27.0 +/-5.4) did not differ significantly. The mean change in ocular alignment for medial rectus plication (28.3 +/- 6.8) and medial rectus resection (26.2 +/-8.8) were not statistically different. This study is limited by the fact that patients were not randomized to the resection or plication procedures, with the latter procedure simply being adopted preferentially by the surgeon beginning in 2013. Study strengths include a large number of horizontal rectus muscle plication patients.
Though the authors state that the success was similar in both the groups. In Esotropia, Success rates at 4-16 weeks after surgery were 95.5% for lateral rectus plication and 89.2% for lateral rectus resection. However, in exotropia patients, success rates at 4-16 weeks after surgery were 96.6% for medial rectus resection and 77.4% for medial rectus plication. Though statistically the difference is not significant, it is can be seen that medial rectus resection was more effective in exotropia surgery. The followup for both the exotropia and esotropia was 4-16 weeks of surgery which in our view is short for assessing the effect of plication. This is especially few authors suggest that the effect of plication is reduced over a period of time.
Further Reading:
Huston PA, Hoover DL. Surgical outcomes following rectus muscle plication versus resection combined with antagonist muscle recession for basic horizontal strabismus. J AAPOS 2018;22:7-11
Unilateral or bilateral surgery for basic exotropia
The two commonly used options for exotropia surgery are bilateral lateral rectus recession versus unilateral recession and resection. This is especially debated for basic exotropia. While few authors believe that a unilateral recession and resection is more advantageous and more stable over long term, the other authors believe that bilateral recessions are more physiological.
Sun Y et al have done a meta analysis of the articles and initially identified 3175 studies, with 2263 remaining after removal of duplicates: 835 from Medline, 1245 from Embase, 1017 from Web of Science and 79 from Cochrane Register of Controlled Trials. Of these 2263 studies, 12 were comparative studies comparing BLR versus R&R procedure in X(T) according to abstracts. Six of them were randomized trials, and the others were retrospective cohort studies with comparative group. Ultimately, three randomized controlled trials and three retrospective cohort trials satisfied their criteria for inclusion in the metaanalysis. The success rate in R & R group was significantly higher than in the bilateral LR recession group. The recurrence rate was higher in bilateral LR recession group suggesting that patients subjected to bilateral LR recession had a higher chance of relapse. However, the overcorrection rates were not different in both the groups.
While several factors may contribute to differences in the outcomes of these procedures, a fairly consistent finding is the relative advantage of the R&R procedure. The limitation of this meta analysis were firstly, the follow-up periods of all the trials included were somewhat attenuated with surgery effects evaluated only for a limited followup period. Secondly, no assessment of publication bias was conducted. Third, though the authors evaluated the statistical heterogeneity using Chi-square-based Q statistic and the I2 confidence interval, they have poor power to detect true heterogeneity among studies when the meta analysis includes a small number of studies. As the BLR procedure resulted in higher rates of recurrence when assessed under conditions of conventional surgical amounts, further studies are warranted to determine if increasing surgical amount would improve the results of BLR.
Further Reading:
Sun Y, Zhang T, Chen J. Bilateral lateral rectus recession versus unilateral recession resection for basic intermittent exotropia: a meta-analysis. Graefes Arch Clin Exp Ophthalmol 2018 Mar;256(3):451-458.
Magnetic Implants for treatment of Nystagmus
Nystagmus has been an intriguing problem for ophthalmologists for a very long time. It can affect visual function in many different ways that include, but are not limited to, impaired visual acuity and reduced field of binocular vision. Acquired nystagmus is more disabling because of oscillopsia associated with it. Several different approaches have been tried in the past in order to dampen the oscillatory movement of the eye. Pharmacological interventions have their own side effects and response varies from case to case. Surgery succeeds in dampening nystagmus to a certain degree and helps in correcting abnormal head posture by shifting null point. An article published recently in Ophthalmology and authored by Parashkev Nachev and co workers1 ,describes a novel approach to dampen nystagmus using a set of magnetic prosthesis. One of the magnets is attached to the orbital wall using cyanoacrylate glue while the other is sewn to the adjacent muscle. The location of implant depends on the direction of the nystagmus. The floor is chosen for vertical nystagmus while the lateral wall is preferred if the nystagmus is predominantly horizontal. In the experimental case described in the article, the patient had oscillopsia secondary to a paraneoplastic condition which was refractory to pharmacological treatment and so disabling for the patient that he could not indulge in any productive occupation. Using eye movement recording, a procedure was planned. Pre-operatively, the strength of the magnets was chosen using contact lenses and an external magnet. The idea was to have the strength of the magnet such that its just enough to dampen nystagmus but not enough to dampen saccadic movements of the eye. The operative procedure described is simple and comprises of implanting a set of 2 rare earth magnetic implants using non magnetic surgical instruments. The magnets were made bio-compatible by encasing them in titanium cases. This patient had upbeat nystagmus. One magnet was implanted under the sheath of inferior rectus muscle while the other was implanted on the adjacent orbital floor. Postoperative eye movement recordings show significant reduction in nystagmus. The visual acuity improved and patient reported a reduction in oscillopsia. The patient could get back dampen the oscillatory movement of the eye. Pharmacological interventions have their own side effects and response varies from case to case. Surgery succeeds in dampening nystagmus to a certain degree and helps in correcting abnormal head posture by shifting null point. An article published recently in Ophthalmology and authored by Parashkev Nachev and co workers1 ,describes a novel approach to dampen nystagmus using a set of magnetic prosthesis. One of the magnets is attached to the orbital wall using cyanoacrylate glue while the other is sewn to the adjacent muscle.
The location of implant depends on the direction of the nystagmus. The floor is chosen for vertical nystagmus while the lateral wall is preferred if the nystagmus is predominantly horizontal. In the experimental case described in the article, the patient had oscillopsia secondary to a paraneoplastic condition which was refractory to pharmacological treatment and so disabling for the patient that he could not indulge in any productive occupation. Using eye movement recording, a procedure was planned. Pre-operatively, the strength of the magnets was chosen using contact lenses and an external magnet. The idea was to have the strength of the magnet such that its just enough to dampen nystagmus but not enough to dampen saccadic movements of the eye. The operative procedure described is simple and comprises of implanting a set of 2 rare earth magnetic implants using non magnetic surgical instruments. The magnets were made bio-compatible by encasing them in titanium cases. This patient had upbeat nystagmus. One magnet was implanted under the sheath of inferior rectus muscle while the other was implanted on the adjacent orbital floor. Postoperative eye movement recordings show significant reduction in nystagmus. The visual acuity improved and patient reported a reduction in oscillopsia. The patient could get back to a productive occupation. Complete range of extraocular movement was preserved while only the nystagmus was dampened. This breakthrough provides a new vertical for research into all types of nystagmus of different origins.
Further Reading
Nachev P, Rose GE, Verity DH, Manohar SG, et al. Magnetic Oculomotor Prosthetics for Acquired Nystagmus. Ophthalmology. 2017 Oct;124(10):1556-1564.
“Pivothead” glasses for remote evaluation of Strabismus
Limited number of trained personal concentrated in cities makes it difficult for patients in remote locations to access quality medical services by super-specialists. Rapid strides in the field of tele-medicine have the potential of solving this problem. Case in point is the use of fundus camera with an uplink for helping people with diabetes and infants with ROP. Recently in a report published in JAAPOS online, authors Tiffany Ho and co-workers describe the use of commercially available “Pivothead” glasses for remotely examining strabismus patients2. These glasses have a camera mounted on the bridge of the frame and hence the remote examiner seeing the live feed sees exactly what the
actual examiner wearing the glasses is seeing. There was a very good correlation between the findings of the doctor performing the actual examination and the doctor watching the live feed.
This breakthrough may help strabismus patients use the telemedicine platform.
Further Reading Tiffany Ho, Talia Kolin, Mark Borchert,Carly Stewert, et al. Evaluation of high definition video glasses for telemedicine strabismus consultations. JAAPOS online. Aug 2017;21(4):e8-e9