This article is more than 5 years old. Information may no longer be current.
Study: Acrylic IOLs better choice for pediatric cataracts
Long-term biocompatibility of IOLs should be considered because the lenses could remain in children’s eyes for decades.
Hydrophilic acrylic IOLs have superior uveal biocompatibility compared with lenses made from other materials, according to a study involving pediatric cataract patients.
Marek Prost, MD, an ophthalmologist at the Polish Air Force Institute of Aviation Medicine and the Center for Pediatric Ophthalmology, Warsaw, evaluated four types of IOLs to compare uveal and capsular biocompatibility in children with congenital cataracts. He presented the results at last year’s European Society of Cataract and Refractive Surgeons annual meeting.
Because such lenses are intended to remain in the eyes for decades, biocompatibility is of greater importance in children than in adults, he noted.
“One can say that hydrophilic acrylic lenses have superior uveal biocompatibility in children. In my opinion, [these] lenses are most suitable for long-term implantation in children, especially small children,” he said. He noted that good biocompatibility was also observed with hydrophobic acrylic lenses.
Four lenses
Study details | |
Source: Prost M |
The study included 85 children between the ages of 1.5 and 8 years. Twenty-eight patients were implanted with a PMMA lens (235 U, Rayner), 17 with a heparin surface-modified PMMA lens (PMMA HSM 811, Pfizer), 15 with an acrylic hydrophobic lens (AcrySof SA30AL, Alcon) and 25 with an acrylic hydrophilic lens (Centerflex, Rayner).
Dr. Prost told Ocular Surgery News in an e-mail interview that the designs of the lenses are somewhat different. The 235 U and the PMMA HSM 811 have modified C-loop haptics, while the AcrySof SA30AL and Centerflex have specially designed loops.
The AcrySof SA30AL and Centerflex lenses also have sharp-edge lens designs, which help prevent lens epithelial cell (LEC) proliferation. However, he said this should not affect biocompatibility measures.
“It is impossible to find lenses of the same design produced from different materials because the manufacturers often adapt the designs [of the lenses] to the materials used,” he said. “However, I think that for biocompatibility studies, the design has little effect on end results. Accumulation of IOL precipitates, pigment deposits and synechia is not influenced, or should not [be influenced], by the design of the IOL.”
The same surgical technique was used in all cases, except a scleral tunnel incision was used on patients implanted with rigid lenses and a limbal incision was used for foldable IOLs, Dr. Prost said.
In all patients, the anterior capsulorrhexis was created using a radiofrequency device, and the lens cortex was removed using bimanual aspiration. After lens removal, Dr. Prost performed a posterior capsulectomy and shallow anterior vitrectomy.
Foldable IOLs were implanted using injector systems. The incisions were sutured.
Lens biocompatibility was evaluated at 1-year postop.
Biocompatibility indicators
To compare biocompatibility among the four lenses, Dr. Prost evaluated four main indicators: IOL precipitates, pigment deposits, LEC proliferation and occurrence of iris synechia.
IOL precipitates were compared by evaluating the presence of each type of precipitate present on each type of IOL. The number of each precipitate was counted and graded on a scale of 0 to 3 that was developed specifically for the study, Dr. Prost said.
A similar system was used to evaluate occurrence of IOL pigment deposits, he said.
Iris synechia at the pupillary margin was also evaluated on a scale of 0 to 3. According to the study, no iris synechia equaled 0, single synechia equaled 1, cumulative iris synechia less than 180° equaled 2 and cumulative iris synechia between 180° and 360° equaled 3.
LEC proliferation was evaluated on a scale similar to this system, he said.
PMMA scores poorly
According to Dr. Prost, IOL precipitates and pigment deposits developed most frequently on PMMA lenses, followed by heparin surface-modified (HSM) lenses and hydrophobic acrylic lenses.
Hydrophilic acrylic lenses developed the fewest deposits and lens precipitates, he said.
According to the study, 66% of the PMMA lenses, 47% of the HSM lenses, 26% of the hydrophobic acrylic lenses and 8% of the hydrophilic acrylic lenses developed IOL precipitates.
Pigment deposits developed on 78% of PMMA lenses, 47% of HSM lenses, 27% of hydrophobic acrylic lenses and 20% of hydrophilic acrylic lenses.
Iris synechiae at the pupillary margin were most frequent in patients implanted with PMMA lenses (0.8) followed by HSM lenses (0.4) and hydrophobic acrylic lenses (0.2). Dr. Prost said no iris synechia was seen in children implanted with hydrophilic acrylic lenses.
Proliferation of LECs was also most frequently observed in PMMA lens patients (2.8) followed by HSM lens patients (1.8).
Dr. Prost said there was no significant difference in LEC proliferation between the two types of acrylic lenses, 0.5 for hydrophobic acrylic and 0.9 for hydrophilic acrylic.
For Your Information:
- Marek Prost, MD, can be reached at Warszawa-Anin, ul.Hertza 9/2, Warsaw, Poland; +48-22-815-20-09; e-mail: mprost@wiml.waw.pl. Dr. Prost has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.