Surgical Pearls for Strabismus Surgery

By Aaron Miller, MD, MBA

Strabismus surgery on children and adults can be a very rewarding experience for the general ophthalmologist. As a practicing pediatric ophthalmologist who completed fellowship training only a few years ago, I am fortunate enough to take part in this type of eye care on a daily basis. The volume of strabismus that you encounter is highly dependent on your practice area and personal interest in the topic. The following are some valuable surgical pearls when considering and performing strabismus surgery.

1. Pre-operative Assessment. When deciding to perform strabismus surgery, it is important to have consistent and reliable pre-operative orthoptic measurements. If possible, obtain measurements in the horizontal and vertical gaze positions for a horizontal strabismus. In individuals with a vertical component to their eye misalignment, measurements of all nine directions of gaze in addition to head-tilt positions should be obtained. Pay attention to A and V-Patterns and if they appear to correlate to oblique extra-ocular dysfunction.
2. Medical Consent. It is very important to properly discuss with the patient and document the risks, benefits, alternates, and complications to the surgical procedure that you will be performing. Strabismus surgery is somewhat unique in that the surgical results can be highly variable. Published reports on “surgical success” typically range from 60% to 80% on the first surgery. This means that from 20% to 40% of all patients will need another procedure at some point in their lifetime. I make it a point to stress this with all patients and parents to ensure that realistic expectations are set prior to proceeding with surgery. I also discuss the likely presence of diplopia in the early post-operative period for most adult strabismus surgery. In most circumstances, this resolves in the first one to two weeks after surgery but rarely can extend beyond this period.
3. Surgical Incision Type. The decision to perform a fornix or limbal incision in strabismus surgery is purely up to the surgeon and can be affected by many conditions. Fornix based strabismus surgery is highly dependent on the quality and experience of your assistant. Limbal based strabismus surgery provides better extraocular muscle visualization without a heavy reliance on the assistant. In my experience, individuals with fornix based surgery have less post-operative discomfort and less scarring. In the end, choose the technique that you are most comfortable with.
4. Surgical Dose Tables. There are dozens of published surgical dose tables to guide you on the amount of recession or resection to perform for a case. I have had surgeons who measure to the 0.1 millimeter during their surgery and others who have “small, medium, and large” surgical doses. There are so many factors that go into the pre-operative assessment and surgery that I typically only measure to the 0.5 millimeter. The published surgical dose tables should only be used as a guideline for your surgery since every surgeon has slight variations in surgical technique. Over time, you will become more familiar with your surgical results and adapt your surgical dose accordingly.
5. Post-operative Assessment. All individuals who have undergone strabismus surgery should have a post-operative clinic evaluation less than one week after surgery. The focus of this visit should be gross eye alignment, attention to possible wound infections or dehiscence, and dramatic changes in visual acuity. Another good thing to document is the presence of a normal red reflex on retinoscopy. The final strabismus outcome can be very difficult to predict based on this visit – I encourage patients and other surgeons to be patient at this stage. Long-term results can sometimes be predicted at the one month follow-up visit.
6. Adult Strabismus. It continues to amaze me on the frequency that I meet an adult with strabismus who has been told by an ophthalmologist that their problem is cosmetic or uncorrectable. Adult strabismus surgery in the great majority of cases is a medically covered procedure. Most insurance carriers easily approve this procedure when proper documentation is provided on the medical necessity for surgical correction. This includes resolution of diplopia, improvement in peripheral field, enhancement in depth perception, and addressing the psycho-social stress that the condition imparts on the patient. If medical necessity is in question, I would encourage you to visit the AAPOS Adult Strabismus Policy Statement on the condition.