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Ocular growth in newborn rabbit eyes implanted with a poly(methyl methacrylate) or silicone intraocular lens
U Kugelberg1, C Zetterström, B Lundgren
1Department of Ophthalmology, S:t Eriks Eye Hospital/Karolinska Institute, Stockholm, Sweden.
Insights
In young rabbits, poly(methyl methacrylate) intraocular lenses (IOLs) significantly reduced eye growth and damaged ocular tissues. Silicone IOLs improved ocular growth compared to PMMA IOLs in infant rabbit eyes.
Area of Science:
- Ophthalmology
- Developmental Biology
- Biomaterials Science
Background:
- Infant eye growth is crucial for visual development.
- Intraocular lenses (IOLs) are used to correct vision after cataract surgery.
- The impact of different IOL materials on growing eyes requires investigation.
Purpose of the Study:
- To compare eye growth in infant rabbits after lensectomy and implantation of poly(methyl methacrylate) (PMMA) or silicone intraocular lenses (IOLs).
- To assess the histological effects of PMMA and silicone IOLs on ocular tissues.
Main Methods:
- Lensectomy was performed on 3-week-old rabbits.
- Group 1: One eye received a heparin-surface-modified (HSM) PMMA IOL, the other remained aphakic.
- Group 2: One eye received an HSM PMMA IOL, the fellow eye received a silicone IOL. Axial length, corneal dimensions, and intraocular pressure were measured. Histological examination of ocular tissues was conducted.
Main Results:
- Eyes with HSM PMMA IOLs showed significantly reduced axial length compared to aphakic eyes and eyes with silicone IOLs.
- Histological analysis revealed retinal degeneration, ciliary body neovascularization, and inflammation in eyes with PMMA IOLs.
- Silicone IOLs resulted in fewer and less severe histological changes compared to PMMA IOLs.
Conclusions:
- Standard-sized HSM PMMA IOLs in young rabbits can impair eye growth and damage intraocular tissues.
- Silicone IOLs appear to be better tolerated, promoting improved ocular growth compared to PMMA IOLs in this model.
- Material properties of IOLs significantly influence ocular development and tissue response in infant eyes.
Purpose:
To examine eye growth in lensectomized infant rabbits implanted with a poly(methyl methacrylate) (PMMA) or a silicone intraocular lens (IOL).
Setting:
S:t Eriks Eye Hospital, Karolinska Institute, Stockholm, Sweden.
Methods:
Two groups of 3-week-old rabbits were used. In Group 1 (n = 13), lensectomy was performed in both eyes. In one randomly selected eye, a +30 diopter (D) heparin-surface-modified (HSM) PMMA IOL was implanted in the capsular bag; the other eye was left aphakic. In Group 2 (n = 10), a +21 D HSM PMMA IOL was implanted in one randomly selected eye and a +21 D silicone IOL was implanted in the other. Axial length, corneal diameter, corneal thickness, and intraocular pressure (IOP) were measured in all eye preoperatively and 1, 2, and 3 months after surgery. The wet mass of the after-cataract was measured 3 months after surgery. The ciliary body with the ciliary processes and the peripheral retina were examined histologically after formalin fixation. The two IOL types were compressed to 7.0 MM, corresponding to the diameter of the 3-week-old rabbit lens.
Results:
In Group 1, the axial length was significantly decreased in the eye with an HSM PMMA IOL compared with the fellow aphakic eye (P < .01, two-way analysis of variance [ANOVA]). No significant difference in corneal diameter, corneal thickness, or IOP was found between the eyes. The wet mass of the dissected after-cataract was significantly less in the eye implanted with an IOL. Two animals had an elevated IOP with secondary glaucoma in their aphakic eye and were excluded from the study. In Group 2, axial length in eyes with the HSM PMMA IOL was less than in the eyes with the silicone IOL (P < .25, two-way ANOVA). No difference in corneal diameter, corneal thickness, or IOP was found. The amount of after-cataract was not altered. Histologically, the eyes with the HSM PMMA IOL showed retinal degeneration, neovascularization of the ciliary body accompanied by a large number of inflammatory cells, and tumid ciliary processes. The eyes with the silicone IOL showed only minor changes. The aphakic eyes presented even less histological change. The compression test demonstrated that three time the compression force was needed to squeeze the HSM PMMA lens than the silicone IOL.
Conclusion:
The results suggest that in the young rabbit eye, implanting a regular size HSM PMMA IOL destroys intraocular tissues and reduces eye growth significantly. Replacing the PMMA IOL with a silicone IOL improves the ocular growth.