Bruch's membrane and Brücke's muscle in the pars plana region

Abstract

PurposeTo examine Bruch's membrane (BM) in association with the longitudinal part of the ciliary muscle (LPCM) in the pars plana region.MethodsUsing light microscopy, we histomorphometrically assessed BM and the LPCM in the pars plana region.ResultsThe histomorphometric study included 51 eyes (51 patients; mean age: 60.8 ± 15.0 years; axial length: 26.0 ± 3.3 mm; range: 21.0–36.0 mm). The LPCM (total length: 4.60 ± 1.10 mm) ended 1.15 ± 0.56 mm anterior to the ora serrata. Within the pars plana region, the LPCM (length: 2.58 ± 0.98 mm) had direct contact with BM for 1.95 ± 0.99 mm (71.1 ± 18.4% of the BM undersurface), while a capillary layer was interposed between the BM and the LPCM for 0.70 ± 0.40 mm (29.0 ± 18.4%). In the pars plana region free of LPCM close to the ora serrata, the percentage of BM covered by the capillary layer was higher than in the pars plana region containing the LPCM (63.0 ± 42.1% vs. 29.0 ± 18.4%; p < 0.001). At the LPCM end, BM was in direct contact with a collagenous tissue from the LPCM and was focally thickened as compared to BM with an underlying capillary layer (9.5 ± 5.3 μm vs. 4.3 ± 1.2 μm; p < 0.001).ConclusionsThe direct contact of BM with the LPCM in the pars plana in association with focal BM thickening at the LPCM end suggests an insertion of LPCM on the BM. Taking into account the biomechanical strength of BM, it may imply a functional unit of the LPCM with BM in the process of accommodation with a secondary movement of the posterior BM and tertiary thickening of the subfoveal choroidal space.

Ciliary body size in chronic angle-closure glaucoma

“…As also described in detail previously, we also determined the length of the longitudinal part of the ciliary muscle, the distance between the end of the longitudinal part of the ciliary muscle and the ora serrata, the length of the pars plana region and pars plicata region of the ciliary body, and Bruch’s membrane thickness in the pars plana region. We noted the presence of cobble stones in the fundus periphery, macular Bruch’s membrane defects or and of scleral staphyloma 9 .

Figure 1 Histo-photograph showing the ciliary body of an enucleated human eye with open anterior chamber angle.

…”

“…Although numerous studies have examined the light microscopical and ultrastructural anatomy of the ciliary body including the ciliary muscle and the ciliary processes, the size of the CBS in general, and in dependence of the morphology of the anterior chamber angle in particular, has not extensively been explored yet, except for a study conducted by Ueno and Naumann in 1989 1 – 9 , 11 – 15 . Examining eyes with secondary glaucoma, mostly with an anterior chamber closure, Ueno and Naumann reported that the mean thickness of the ciliary muscle was smaller (P < 0.001) in the glaucomatous group than in a group of eyes with malignant uveal melanoma 15 .…”

“…As also described in greater detail in previous reports, the eyes had been fixed at once after surgical enucleation 9 , 10 . They were kept in the fixation solution consisting of 4% formaldehyde and 1% glutaraldehyde for one week at room temperature.…”