Pars plana capsulotomy effectively manages posterior capsule in pediatric cataract: study

Younger eyes more prone to secondary opacification, study shows.

ByBob Kronemyer

CHARLESTON, U.S.A. — Pars plana posterior capsulotomy with anterior vitrectomy is a safe and effective surgical method for managing the posterior capsule in pediatric cataract surgery with IOL implantation, according to a recent study. However, the investigators found a significantly higher risk of opacification postoperatively in patients younger than 6 months of age.

“The management of the posterior capsule in pediatric cataract surgery remains controversial,” said lead investigator George Alexandrakis, MD, a pediatric ophthalmologist at the Storm Eye Institute here. “A clear visual axis is especially important in pediatric patients, given the risk for the development of amblyopia. Yet there is a high incidence of secondary membrane formation after cataract removal, with or without IOL implantation.”

The retrospective study consisted of 76 eyes of 61 consecutive patients who underwent pars plana capsulotomy and anterior vitrectomy, with at least 1 year of follow-up (mean 29 months). The median age at the time of surgery was 21 months, with 18 of the 76 procedures performed in 13 patients younger than 6 months of age. All surgeries were performed over a 6-year period by the same surgeon, using the same technique. An equal number of patients received a PMMA or AcrySof lens in the bag.

“The lens was placed in the bag in 72 of the 76 eyes. The posterior capsular opening was also approximately the same size as the anterior capsular opening,” Dr. Alexandrakis said.

VA outcomes

Final best-corrected visual acuity was 20/40 or better in 42% of eyes and 20/50 to 20/200 in 28% of eyes.

“Poor visual acuity was associated with young age, lack of cooperation for visual acuity testing, as well as optic nerve dysplasia or hyperplasia. There were no intraoperative or postoperative complications such as IOL dislocation or postop retinal events,” Dr. Alexandrakis said.

Seven eyes of five patients developed a reopacified visual axis postop.

“These patients were very young, with a median age of 2 months, and developed postoperative reopacification of the visual axis at a mean of 4 months postop. This reopacification was secondary to posterior membrane formation in five of the seven eyes, and secondary to cortical reproliferation around the optic in the remaining two eyes of two patients,” he said.

Overall, 30% of patients younger than 6 months developed a secondary membrane postop versus only 2% of patients older than 6 months.

“This finding is highly statistically significant,” said Dr. Alexandrakis, who presented study results at the annual meeting of the American Association for Pediatric Ophthalmology and Strabismus in Orlando, Fla.

The visual axis was surgically restored in four of these five patients by pars plana membranectomy and anterior vitrectomy. The remaining patient underwent YAG capsulotomy.

First study results

---Postoperative photograph shows a clear, open anterior and posterior capsulotomy.

In 1993, Edward Buckley, MD, a pediatric ophthalmologist from Duke University, reported the first series of 20 consecutive patients who underwent a pars plana capsulotomy and anterior vitrectomy during cataract removal with IOL implantation. All patients in his series enjoyed excellent visual acuity postop. No patients developed a secondary membrane formation, although the mean age was significantly higher at 5 years. One patient developed IOL dislocation postop.

In addition to including younger patients in the current study, Dr. Alexandrakis said the study used modern microsurgical techniques. Two drawbacks of the procedure are potential postop IOL dislocation and retinal hole formation (which may occur if the retina is penetrated instead of the pars plana).

“However, the risk of vitreous ‘wick’ to the wound is significantly reduced compared to a limbal approach. There were no cases of dislocation or retinal events in our series,” Dr. Alexandrakis said.

Mechanisms at work

Several mechanisms may cause secondary reopacification.

“We think that in patients with formation of a secondary membrane, the reopacification could be secondary to an inadequate posterior capsulotomy, inadequate anterior vitrectomy or both. Patients with cortical regrowth may have a lack of apposition of the anterior and the posterior capsular leaflets, leaving a space between the optic and the capsule for the cortex to reproliferate around the optic,” Dr. Alexandrakis said.

In any event, the Venturi pump is recommended when performing a pars plana capsulotomy.

“This pump cuts the capsule better; also, knowledge of the pediatric anatomy is important in order to avoid entry into the retina,” he said. “This approach allows the surgeon to create a large capsulotomy in a controlled fashion with low risk because the lens has already been implanted in the capsular bag.”

Dr. Alexandrakis and colleagues will continue to investigate secondary membrane formation after cataract surgery in children until a drug is found that can be injected in the capsular bag after cataract removal. Meanwhile, continued follow-up of these patients is important in order to assess long-term outcomes, he said.

For Your Information:

George Alexandrakis, MD, can be reached at Storm Eye Institute, 167 Ashley Ave., Charleston, SC 29425 U.S.A.; +(1) 843-792-7622; fax: +(1) 843-792-1166; e-mail: eyemuscledoc@yahoo.com.