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Thomas Stahnke, Thomas Noack, Robert Patejdl, Steffen Hartleib, Andreas Wree, Oliver Stachs, Niels Grabow, Rudolf Guthoff; Determination of porcine ciliary muscle contractility to adapt innovative lens replacement materials. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3953.
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© ARVO (1962-2015); The Authors (2016-present)
New approaches like Lens Refilling address the problem of accommodation loss in presbyopia and following IOL implantation. It is known that in early stages of presbyopia loss of accommodation is predominantly caused by an increase of lens stiffness with little or no involvement of the ciliary muscle. In order to take advantage of ciliary muscle contractility in the aging eye as a driving force for refilled lenses it is necessary to know as much as possible of its biomechanics.
Immediately after slaughtering of pigs enucleations were carried out. Circular explants of the ciliary muscles (2 cm length, 2 mm width) were dissected. The specimens were mounted in an organ bath (37°C Krebs solution, gassed with carbogen) to prevent degenerative processes, and fixed to a force transducer (sensibility: > 10 µN). After acclimatization (1h), acetylcholine (ACh) and/or the Ca2+ channel opening substance Bay-K 8644 were added in increasing concentrations. Alterations in contractile responses were recorded and tension (mN/mm2) for each specimen was calculated. Histological sections of paraffin embedded porcine ciliary bodies were stained (AZAN) to analyse individual ciliary muscle micromorphology of the specimens.
The average contractility of ciliary muscle was 0.025 mN at 10-5 mol/l and 0.05 mN at 10-4 mol/l ACh concentrations. This is equivalent to tensions of 0.0125 mN/mm2 and 0.025 mN/mm2, respectively. Incubation of ciliary muscles with Bay-K 8644 could not provoke measurable contractions. In contrast, preincubation with Bay-K 8644 showed an increase in ACh induced contractility to 0.15 mN at 10-4 mol/l ACh, with a tension of 0.075 mN/mm2. Histological analysis of individual ciliary muscles revealed loose packed smooth muscle cells embedded within the connective tissue. Interfering dissection artefacts could not be observed.
Determination of ACh induced contractility of the porcine ciliary muscle was carried out successfully. The loose packed muscle cells within the ciliary body with its high amount of connective tissue are responsible for low contractility values. For an effective transfer into finite element analysis of the pseudophakic process, further physiological investigations of human ciliary muscle contractility forces are necessary to define innovative lens replacement materials.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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