Study Investigates Link Between Strabismus and Retinal Detachment Surgery

In the medical field, there are a number of conditions and entities that have a scientific name that is less commonly known amongst the lay community. For example, the web between your thumb and forefinger is called the purlicue (and is pronounced just like “curlicue”). The small, triangular pink bump on the inside corner of each eye is called the caruncula. Paresthesia is that tingling sensation when your foot falls asleep.

So too is strabismus known by another term, one that has been the bane of kids in the schoolyard subjected to bullying, for a long time: strabismos. It is a common condition and the term comes from the ancient Greek strabismus, meaning “to squint.” Many of us will remember that kid in junior school, or maybe we were that kid, with the eye patch, but that was actually used to treat amblyopia or “lazy eye,” and in fact, strabismus is a different kettle of fish.

Getting the Eyes to Align

Strabismus occurs when your eyes are not lined up properly and they point in different directions. One eye may look straight ahead while the other eye turns in, out, up or down, and the misalignment can shift from one eye to the other. The most obvious symptom of the condition is where one of the patient’s eyes looks in a different direction to the other one.

It is more common among children and can be caused by a number of conditions including cerebral palsy, Down syndrome and hydrocephalus, and while it can affect vision it is often treatable by either wearing special glasses or via surgery in more severe cases. Patient outcomes in childhood strabismus are usually good especially if treatment is performed quickly on the presentation of symptoms.¹

In adults, however, it can be more severe, especially if their childhood strabismus was untreated as this can lead to permanent double vision. When it occurs later in life, it is usually caused by ocular trauma including accidents or damage during surgery; it can also be caused by a number of other conditions including diabetes, thyroid disease, Myasthenia gravis, brain tumors or stroke. Surgery is the most common treatment and often involves more than one surgery to treat the condition.²

Now while the aforementioned causes of strabismus in adulthood are among the most common, there are of course rarer reasons — ones which make for an interesting article to sink your proverbial teeth into. Retinal detachment, which involves the separation of retinal cells from the layer of blood vessels that provides oxygen and nourishment to the eye, does not in itself usually cause strabismus. However, in rare cases it can also occur following retinal detachment surgery, leading to a group of researchers from Atlanta, Georgia (USA) and Bucheon, South Korea, to investigate the issue.

Can strabismus surgery re-detach your retina?

The published paper, Effect of Scleral Buckle Removal on Strabismus Surgery Outcomes After Retinal Detachment Repair,³ investigated the effect of scleral buckle removal on outcomes of strabismus surgery in patients with a prior history of retinal detachment surgery. Scleral buckling has been considered to be an effective means to reattach the retina for over 50 years, but it has also been associated with the development of strabismus. Removing the scleral buckle can resolve the strabismus issue, but may, of course, result in the retina becoming detached again.

The researchers, therefore, reviewed the medical records of 18 patients who underwent strabismus surgery following a scleral buckling procedure at one institution. The effect of multiple variables on outcomes like gender, age, surgeon, number of strabismus surgeries, adjustable suture use, previous pars plana vitrectomy, preoperative best-corrected visual acuity, and time of surgery were considered to eliminate any anomalies in data recording. The Fisher’s exact test and Mann-Whitney test were used and outcomes were considered successful if there was ≤10 prism diopter (PD) residual horizontal and/or ≤4 PD residual vertical deviation.

The researchers found that strabismus surgery coupled with scleral buckle removal was associated with a higher rate of success at 62.5%, with success without buckle removal at 10.0% (p=0.04). In fact, despite concerns about detachment, none occurred after scleral buckle removal in any of the 18 patients. Noting that recent studies have uncovered post-scleral buckling retinal detachment rates of a maximum of 8%, they also found that removing the scleral buckling element either before or during strabismus surgery was associated with improved ocular alignment.³

References:

1. Strabismus in Children. The American Academy of Ophthalmology. Available at https://www.aao.org/eye-health/diseases/strabismus-in-children. Accessed on Wednesday, August 4, 2021.
2. Strabismus in Adults. The American Academy of Ophthalmology. Available at https://www.aao.org/eye-health/diseases/what-is-strabismus. Accessed on Wednesday, August 4, 2021.
3. Chang JH, Hutchinson A, Zhang M, Lambert SR. Effect of Scleral Buckle Removal on Strabismus Surgery Outcomes After Retinal Detachment Repair. Strabismus. 2013;21(4):235-241.