Variations in anterior segment vasculature of the eye and their implication in strabismus surgery and other surgical procedures

Abstract

Objective: Anterior segment ischemia (ASI) is a serious complication of strabismus surgery and other
ocular procedures. The purpose of this study is to evaluate variation of the long posterior artery (LPCA).
These variations may predispose patients to anterior segment ischemia following strabismus surgery,
and proper mapping may provide surgical “danger zones” for other invasive ocular procedures.

Subjects: A total of 100 preserved cadaveric eyeballs from University of Nebraska Medical Center
(UNMC), Creighton University, and Kansas City University (KCU) were utilized for this study.
Methods: LPCAs were identified, isolated, and counted prior to removal of the choroid. Two distances
were measured from within the orbit: (1) the penetration point of the LPCA through the sclera to the
center of the optic nerve and (2) the penetration point of the LPCA through the sclera to the superior
border of the corresponding rectus muscle. The data was analyzed to determine the number and location
of LPCAs that contribute to the major arterial circle of iris. Independent sample t-tests were used to
determine significant differences comparing the number of arteries and penetration points between right
and left eyes, medially and laterally located arteries, and sex.

Results: Significant differences were found between subjects with one vs two LPCAs, males vs females,
and medially vs laterally located arteries in at least one of the two measurements. Thirty-three of 100
eyeballs had only one LPCA (33%).

Conclusions: This study demonstrates that a larger percentage of patients may be predisposed to
anterior segment ischemia than previously reported. It also provides a surgical “danger zone” that
will enable surgeons to avoid damaging the long posterior ciliary artery during invasive choroidal and
orbital procedures. This knowledge will facilitate more appropriate management of patients including
preoperative screenings, intraoperative isolation of the long posterior ciliary artery, more frequent
postoperative monitoring, and accelerated initiation of treatment plans.