In crowded eyes, removal of vitreous through a one-port pars plana vitrectomy is the only viable strategy to deepen the anterior chamber and allow safe phacoemulsification, according to R.J. Mackool Jr., MD.
Take-home message: In crowded eyes, removal of vitreous through a one-port pars plana vitrectomy is the only viable strategy to deepen the anterior chamber and allow safe phacoemulsification, according to R.J. Mackool Jr., MD.
By Cheryl Guttman Krader; Reviewed by R.J. Mackool Jr., MD
Astoria, NY-One-port pars plana vitrectomy (PPV) is the only effective technique to deepen the anterior chamber when performing phacoemulsification in crowded eyes, according to R.J. Mackool Jr., MD.
Dr. Mackool Jr. reported the experience of two surgeons (Richard Mackool Sr., MD, and Dr. RJ Mackool Jr.) with single-port pars plana vitrectomy in a series of 54 eyes of 41 patients. Cases from the series were performed between 2010 and 2012 with a follow-up ranging from 4 months to 4 years.
The rate of zonular laxity in the series proved extremely high at 54%, and 5% of the eyes had no zonular support, requiring implantation of an anterior chamber IOL (ACLs were chosen given advanced patient age). The only complication in the series was one case of cystoid macular edema which resolved with topical steroid.
“Surgeons must assess chamber depth on the operating room table to determine if phaco can be performed without damaging the endothelium,” said Dr. Mackool Jr., assistant director of the Mackool Eye Institute and Laser Center in Astoria, NY. “The space needed will vary, depending on the density of the lens and the surgeon’s phaco technique.
“If there is any doubt about adequate chamber depth, the surgeon should err on the side of safety by performing a one-port PPV,” Dr. Mackool Jr. said.
Dr. Mackool Sr. has been performing and teaching the one-port PPV technique since the early 1980s and David Chang, MD, published his experience with pars plana vitrectomy to deepen the anterior chamber in 2001.
A one-port PPV is performed by creating a pars plana wound 3.5 mm posterior to the limbus with the gauge of choice (Drs. Mackool tend to use a 23-gauge vitrector). The vitrector is advanced into the posterior segment in the direction of the optic nerve until the tip is visible. Vitreous is removed until the eye is soft by digital palpation and the anterior chamber is filled with viscoelastic.
“Vitrectomy should not be performed with infusion since aqueous misdirection can occur with no increase in chamber depth, leaving the surgeon wondering whether the chamber is still shallow due to a choroidal hemorrhage or infusion misdirection,” Dr. Mackool Jr. said.
He noted that visibility may be limited due to cataract density. In these cases the surgeon should score the vitrector 10 to 12 mm from the tip as a guide to proper insertion depth.
“The vitrector is then advanced toward the optic nerve until the mark is at the pars plana incision and the vitrectomy is then performed,” he said.
Dr. Mackool Jr. noted that intravenous administration of mannitol has been described as a strategy for deepening the anterior chamber. However, he said that mannitol can have untoward systemic effects and does not sufficiently deepen the anterior chamber.
R.J. Mackool Jr., MD
This article was adapted from a presentation by Dr. Mackool Jr. at the 2014 meeting of the American Academy of Ophthalmology. Dr. Mackool Jr. is a speaker for Alcon Laboratories.