Devising an Algorithm for Resection Amount in Conjunctiva Sparing Ptosis Surgery

BACKGROUND: The conjunctiva sparing posterior ptosis technique (PCSP) has been shown previously to be very effective. The objective of this study was to devise a standardized algorithm for the procedure. Essentially, an ophthalmic surgeon would be able to formulate the amount of Müller's muscular tissue for resection and be able to correlate it to a predicted value of improvement in marginal reflex distance (MRD1) postoperatively at different time points. This would not only allow for more consistency with preoperative planning, but also allow for normalization of the procedure for more widespread use, improved patient outcomes, and less postoperative complications. METHODS: This is a retrospective chart review that looked at patients who suffered from moderate to severe ptosis and underwent a conjunctiva sparing posterior ptosis surgery alone or concurrently with another procedure. Patients who had either unilateral or bilateral ptosis were both included in the chart review. Both preoperative and postoperative photos were measured for the MRD1 based off of the average corneal reflex diameters for men and women at 11.77 mm and 11.64 mm respectively. The program ImageJ was used for measuring MRD1. All other information such as demographics and tissue resection amount was taken from the postoperative notes of patient charts. No patients were actively recruited. RESULTS: Patients who underwent the procedure from 2011-2017 with Dr. Ronald Mancini at UT Southwestern Medical Center were totaled at 32 patients. A significant increase in MRD1 was seen for both men and women with an average increase of at least 1.00 mm postoperatively from at least 3 months onwards. This increase was seen as statistically significant when compared to the amount of Müller's muscle resected at an average of 7.57 mm, however with increased variability. Multiple linear regressions were carried out with only one model showing a modest statistical relationship with a large amount of variability. This model presented the difference in postoperative MRD1 and amount of tissue resected, MRD1 (Y) = 0.192 + (0.260 * Tissue (mm)(X)). The results showed a r2 value of 0.0733. CONCLUSION: Ptosis improvement was noted to be as early as 1 week postoperatively going as far out as 3 years for a patient. The algorithm of the difference in MRD1 vs amount of tissue resected (both eyes) showed modest correlation however did not serve as a means to standardize the conjunctiva sparing posterior ptosis surgery procedure. It would be prudent for further studies to be conducted with a larger patient population set for better control of sampling error. Also, some patients had a concurrent procedure such as a blepharoplasty that may have been a confounding variable on increased improvement of postoperative MRD1 rather than those patients who underwent ptosis repair alone.