Author(s): Thomas Chang
Mentor(s): Qi Wei, Department of Bioengineering
AbstractStrabismus (crossed eyes) is a prevalent vision disorder that involves binocular misalignment. It is usually treated surgically but with suboptimal outcomes. Evaluating the quantitative surgical effects of different operations on treating strabismus is valuable to guide future surgical treatment. Inferior rectus (IR) recession, inferior oblique (IO) recession, and their combination are common operations for treating the most common type of strabismus, Superior Oblique (SO) Palsy. To characterize these surgeries we used Hess Screening Tests (HST) results measured at 21 unique gaze positions from before and after treatment. HST charts were automatically translated through a MatLab program to determine the horizontal and vertical positions of each corresponding gaze. Of the reviewed clinical summaries, 19 patients met the inclusion criteria and underwent either ipsilateral IO recession (N=5), contralateral IR recession (N=4), or both (N=10). Early correction was calculated as the difference between the pre- and post-operation HST changes and late correction was calculated similarly between the follow-up and post-operation changes. Of the early correction caused by each surgical technique, IO recession produced the most incomitant correction. IR recession produced nearly comitant correction with less magnitude than IO recession. Combined IO & IR recession created incomitant correction greatest in IO‘s field of action & double that of IO recession alone. Analysis of the contralateral eye showed the expected, inverted results. This suggests that there is significant correction caused by surgical intervention and a difference between each surgical technique which behaves according to the field of action affected.
Audio TranscriptHi, my name is Thomas Chang I’m in the bioengineering department and I will be presenting on the quantitative analysis on superior oblique palsy surgical outcomes using Hess screening tests. My mentor for this project is Dr. Wei.
Some background on the issue; strabismus, also known as crossed eyes, is misalignment of the eyes due to defects in neural control or extraocular muscle balance. On the right is an image of the 6 extraocular muscles. Superior oblique palsy, or trochlear nerve palsy, is when the superior oblique muscle atrophies, hindering the eye‘s ability to move in certain ways causing strabismus. The goal for this project is to quantify some commonly used surgical interventions to better understand how changing the eye will impact its movement and hopefully advise future surgeries.
To do this we used hess screening test results. Here are two examples of Hess tests, where 21 different gaze positions were plotted on a grid where each box represents 5 degrees and the center of the box is the primary gaze. The top image is of a pre-surgery test, and as you can see a lot of the gaze positions are further from the ideal positions marked by the orange dots as compared to the bottom image which is of a post-surgery test. We automatically translated these graphs and subtracted them to find vector fields characteristic of each surgery.
Here are the group and results mentioned. The first group is of patients who underwent recession of the antagonist muscle, the inferior oblique; the second group is of patients who underwent surgery on their unaffected eye‘s inferior rectus which controls downward movement; and the third group is of patients who underwent both of the previous surgeries. Two main things to note are the incomitant correction, which is saying that each gaze position changes a different amount and the general trend towards the ideal gaze positions marked by a blue dot.
Here is the same data but focusing on the vertical displacements scaled onto a heatmap. These show a much clearer correlation between each surgery and the field of action of the inferior oblique groups
Finally, we looked at post-surgery results for patients who came back 3-7 months from the date of their surgery. These all were scaled up by 3 times, so progression especially on the IO & IR group are a little misleading, but the main thing observed was the tendency for IO recession patients to see further correction towards the ideal position.
Some acknowledgments for this project include Dr. Lee and the OSCAR office. Dr. Demer and Dr Lai from the Jules Stein Eye Institute in UCLA, Andrew Ryan who made the program to translate the charts, and Dr. Wei for helping with ideas, figures, code, and being a great mentor. Thank you.
Some background on the issue; strabismus, also known as crossed eyes, is misalignment of the eyes due to defects in neural control or extraocular muscle balance. On the right is an image of the 6 extraocular muscles. Superior oblique palsy, or trochlear nerve palsy, is when the superior oblique muscle atrophies, hindering the eye‘s ability to move in certain ways causing strabismus. The goal for this project is to quantify some commonly used surgical interventions to better understand how changing the eye will impact its movement and hopefully advise future surgeries.
To do this we used hess screening test results. Here are two examples of Hess tests, where 21 different gaze positions were plotted on a grid where each box represents 5 degrees and the center of the box is the primary gaze. The top image is of a pre-surgery test, and as you can see a lot of the gaze positions are further from the ideal positions marked by the orange dots as compared to the bottom image which is of a post-surgery test. We automatically translated these graphs and subtracted them to find vector fields characteristic of each surgery.
Here are the group and results mentioned. The first group is of patients who underwent recession of the antagonist muscle, the inferior oblique; the second group is of patients who underwent surgery on their unaffected eye‘s inferior rectus which controls downward movement; and the third group is of patients who underwent both of the previous surgeries. Two main things to note are the incomitant correction, which is saying that each gaze position changes a different amount and the general trend towards the ideal gaze positions marked by a blue dot.
Here is the same data but focusing on the vertical displacements scaled onto a heatmap. These show a much clearer correlation between each surgery and the field of action of the inferior oblique groups
Finally, we looked at post-surgery results for patients who came back 3-7 months from the date of their surgery. These all were scaled up by 3 times, so progression especially on the IO & IR group are a little misleading, but the main thing observed was the tendency for IO recession patients to see further correction towards the ideal position.
Some acknowledgments for this project include Dr. Lee and the OSCAR office. Dr. Demer and Dr Lai from the Jules Stein Eye Institute in UCLA, Andrew Ryan who made the program to translate the charts, and Dr. Wei for helping with ideas, figures, code, and being a great mentor. Thank you.
3 replies on “Quantitative Analysis of Surgical Intervention on Strabismus Using Hess Charts”
Great work, team! I am not much of a science person and this looks impressive!
Hi Thomas. This project is super interesting! The comparison of pre- and post-surgery graphs, along with the analysis of different surgical approaches, provides valuable insights into optimizing eye movement corrections. Looking forward to seeing further advancements in this field.
Well done. You did a great job explaining a fairly technical topic and included interesting and helpful visuals. Cool stuff.