To determine the causes of postoperative myopia associated with capsular bag distention
syndrome (CBDS) and characterize the associated findings.
Prospective, multicenter, nonrandomized, comparative (self-controlled) trial.
Six eyes from six patients had CBDS develop after phacoemulsification and posterior
chamber intraocular lens implantation.
Keratometric values, axial length, visual acuity, and manifest refraction were assessed
in each eye. Using 20-MHz (I3SYSTEM-ABD, Innovative Imaging Inc, Sacramento, CA) and
50-MHz (Ultrasound Biomicroscope, Zeiss Humphrey Systems, Dublin, CA) ultrasonographic
probes, images and measurements of the anterior segment were obtained. After neodymium:yttrium-aluminum-garnet
(Nd:YAG) capsulotomy, these measures were repeated and correlated with predicted and
actual refractive changes.
Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), manifest refraction,
and anterior chamber depth before and after treatment of CBDS.
Although intended postoperative refraction averaged -0.58 diopters (D) (range, -0.12
to -1.63 D), eyes with CBDS had an average spherical equivalent refraction of -2.35
D (range, +0.13 to -4.50 D), P < 0.05 (one-tailed, paired t test). BCVA averaged 20/24
(range, 20/15-20/40-1), but UCVA averaged 20/133 (range, 20/60 to 20/400). Average
distance from the corneal surface to the anterior intraocular lens (IOL) optic surface
was 3.55 mm in eyes with CBDS, and 4.30 mm after Nd:YAG capsulotomy. Posterior movement
of the IOL optic after capsulotomy accounted for 1.23 D of hyperopic shift or 82%
of the CBDS-induced myopia. Treatment of CBDS resulted in both improved UCVA and BCVA.
Nd:YAG capsulotomy also released the colloidal suspension within the capsular bag
posterior to the IOL optic. The incidence of CBDS was 0.3% in one of the practices
reviewed.
Capsular bag distention syndrome includes unexpected myopia and poor UCVA after cataract
surgery with lens implantation in cases involving a continuous capsulorhexis. A dramatic
posterior distention of the posterior capsule is observed, as well as anterior chamber
shallowing, tight apposition of the iris to the IOL, and anterior bowing of the iris.
A slightly turbid colloidal suspension behind the IOL implant and late posterior capsular
fibrosis are also observed. Timely treatment of CBDS can correct unwanted myopia,
improve UCVA and BCVA, and restore normal anatomic relationships in the eye.