Purpose. To analyse the posterior capsular opacification (PCO) development pattern in the long term in eyes implanted with a monofocal intraocular lens (IOL) with a square edge all around the optic. Methods. Longitudinal retrospective study is data analyzed from a total of 7059 eyes from 4764 patients (mean age: 75.8 years) undergoing cataract surgery with implantation of an aspheric monofocal IOL (Bi-Flex HL 677AB/677P, Medicontur, Budapest, Hungary). These data were retrospectively collected using the electronic medical record of the hospitals involved. Nd : YAG capsulotomy rates were calculated per year during a follow-up of more than 10 years. The Kaplan–Meier analysis was used to establish the transparent capsule survival rate. Results. The Nd : YAG capsulotomy rate increased from 1.1% at 1 year postoperatively to 17.2% at 5 years after surgery. No significant differences were found between eyes with and without capsulotomy in terms of age
p
=
0.202
, gender
p
=
0.061
, type of anaesthesia used
p
=
0.128
, and presence of conditions such as hard cataract
p
=
0.111
or pseudoexfoliation
p
=
0.137
. IOL power was significantly lower in those eyes of patients requiring Nd : YAG capsulotomy during the follow-up
p
<
0.001
. Significantly more eyes implanted with the preloaded model of the IOL required capsulotomy
p
<
0.001
. Mean survival time and rate were 9.38 years and 85.9%, respectively. Conclusions. Most eyes undergoing cataract with implantation of the Bi-Flex IOL do not develop a clinically significant PCO requiring Nd : YAG capsulotomy in the long term. IOL material and design may be the main factors accounting for this finding.