Dimensions of the ciliary muscles of Brücke, Müller and Iwanoff and their associations with axial length and glaucoma.

BACKGROUND: To assess the dimensions of Brücke's muscle, as the longitudinal portion, and of Müller's muscle and Iwanoff's muscle combined as circular and radial/reticular portions of the ciliary muscle. METHODS: The histomorphometric study included human globes that had been enucleated due to an ocular tumor or end-stage glaucoma. After immunohistochemical staining of the ciliary muscles, the histology slides were examined under a light microscope applying a digitized image analysis system. RESULTS: The study included 55 globes [axial length 25.6 ± 3.0 mm (range 21.0 mm-36.0 mm)] from 55 patients [mean age, 33.7 ± 18.3 years (range:1-66 years)]. Length of Brücke's muscle (mean 3.40 ± 0.76 mm) increased with longer axial length (P < 0.001; regression coefficient beta: 0.52) and was not significantly associated with age (P = 0.12), presence of glaucoma (P = 0.11) or Brücke's muscle thickness at the scleral spur (P = 0.32), at the site of the maximum thickness of the ciliary body (P = 0.84) or at the posterior end of Müller's/Iwanoff's muscle (P = 0.66), or with thickness (P = 0.29) and cross-sectional area (P = 0.85) of Müller's/Iwanoff's muscle. Mean distance between Brücke's muscle end and the ora serrata measured 1.73 ± 1.13 mm and increased with longer axial length (P < 0.001; beta: 0.46). Distance from the scleral spur to the ora serrata (mean: 4.94 ± 1.42 mm; range: 3.08-9.09 mm) increased with longer axial length (P < 0.001; beta: 0.61). Maximal thickness (mean: 245 ± 125 µm) and cross-section area (mean: 0.19 ± 0.11 mm2) of Müller's/Iwanoff's muscle decreased significantly with the diagnosis of glaucoma (P = 0.02;beta:-0.38) and longer axial length (P = 0.03; beta: -0.35). CONCLUSIONS: Length of Brücke's muscle increased with axial length of the globe, while its cross-sectional area was independent of axial length. Müller's/Iwanoff's muscle decreased in cross-sectional area with longer axis, and in particular with the presence of glaucoma, while the dimensions of Brücke's muscle were not related to glaucoma.

Bruch´s membrane thickness in relationship to axial length.

PURPOSE: To assess a potential role of Bruch´s membrane (BM) in the biomechanics of the eye, we measured its thickness and the density of retinal pigment epithelium (RPE) cells in various ocular regions in eyes of varying axial length. METHODS: Human globes, enucleated because of an ocular tumor or end-stage glaucoma were prepared for histological examination. Using light microscopy, the histological slides were histomorphometrically examined applying a digitized image analysis system. RESULTS: The study included 104 eyes with a mean axial length of 27.9±3.2 mm (range:22.6mm-36.5mm). In eyes without congenital glaucoma, BM was significantly thickest (P<0.001) at the ora serrata, followed by the posterior pole, the midpoint between equator and posterior pole (MBEPP), and finally the equator. BM thickness was not significantly correlated with axial length (ora serrata: P = 0.93; equator:P = 0.31; MBEPP:P = 0.15; posterior pole:P = 0.35). RPE cell density in the pre-equatorial region (P = 0.02; regression coefficient r = -0.24) and in the retro-equatorial region (P = 0.03; r = -0.22) decreased with longer axial length, while RPE cell density at the ora serrata (P = 0.35), the MBEPP (P = 0.06; r = -0.19) and the posterior pole (P = 0.38) was not significantly correlated with axial length. Highly myopic eyes with congenital glaucoma showed a tendency towards lower BM thickness and lower RPE cell density at all locations. CONCLUSIONS: BM thickness, in contrast to scleral and choroidal thickness, was independent of axial length in eyes without congenital glaucoma. In association with an axial elongation associated decrease in the RPE cell density in the midperiphery, the findings support the notion of a biomechanical role BM may play in the process of emmetropization/myopization.

[Study of collagen mimetic peptide's triple-helix structure and its thermostability by circular dichroism].

In the present study, the authors explore the triple-helix conformation and thermal stability of collagen mimetic peptides (CMPs) as a function of peptide sequence and/or chain length by circular dichroism(CD). Five CMPs were designed and synthetized varying the number of POG triplets or incorporating an integrin alpha2beta1 binding motif Gly-Phe-Hyp-Gly-Glu-Arg (GFOGER). CD spectroscopy from 260 to 190 nm was recorded to confirm the existence of triple-helix conformation at room temperature, while thermal melting and thermal annealing of triple-helix (thermal unfolding and refolding of triple-helix, respectively) was characterized by monitoring ellipticity at 225 nm as a function of temperature. The results demonstrated that all the CMPs adopted triple-helix conformation, and the thermal stability of the CMPs was enhanced with increasing the number of POG triplets. In contrast to natural collagen, the thermal denaturation processes of CMPs were reversible, i. e. the triple-helix unfolded upon heating while refolded upon cooling. Meanwhile, the phenomenon of "hysteresis" was observed by comparing melting and thermal curves. These findings add new insights to the mechanisms of collagen and CMPs assembly, as well as provide an alternative approach to the fabrication of artificial collagen-likes biomaterials.