Ординатура / Офтальмология / Английские материалы / Applied Pathology for Ophthalmic Microsurgeons_Naumann, Holbach, Kruse_2008

5.4.1

Surgical Anatomy

The ciliary body extends between the scleral spur visible by gonioscopy to the ora serrata recognizable by funduscopy and indentation or by diaphanoscopy. The ciliary muscle extends between the scleral spur and the peripheral end of Bruch’s membrane as “tensor choroideae” which is responsible also for the “foveal tilt of the photoreceptors” during accommodation (Enoch et al. 1975). The circular portion of the ciliary muscle contains more mitochondria than that close to the sclera. Between the ciliary muscle and sclera there is the potential supraciliary space allowing almost free movement of the ciliary muscle – against the sclera. The nonpigmented ciliary epithelium frequently shows aging changes (Fig. 5.4.2). Also part of the ciliary muscle is progressively replaced by collagenous tissue distributed in between the muscle fibers (Fig. 5.4.3).

The vitreous base is attached to the posterior 1 – 2 mm of the pars plana and extends towards the peripheral sensory retina adjacent to the ora serrata. The zonula apparatus originates from the pars plicata and the pars plana, fusing with the vitreous base, extending towards the anterior and posterior lens capsule, and reaching up to the ring-shaped Wieger’s hyalocapsular ligament (see Chapters 5.5, 5.6).

The blood supply of the ciliary body originates from the long posterior ciliary arteries and anterior ciliary arteries forming a network of anastomosing vessels in connection with the major circle of the iris (Fig. 5.4.4). The ciliary processes contain many capillaries with a large diameter lined by fenestrated endothelium – even minor mechanical trauma may lead to marked hemorrhage. This was until recently one reason the ciliary body was considered a “taboo zone.” Venous outflow occurs posteriorly through the vortex vein and to a lesser degree via the anterior ciliary veins.

The ciliary body has a dense network of parasympathic sympathetic and sensory nerves. The sensory innervation originates from the nasociliary nerves of the first branch of the trigeminus.

Blood-Aqueous Barrier. In the pars plicata of the ciliary body this is formed by the zonulae occludentes of the non-pigmented ciliary epithelium. There is a physiologic defect in the transition between the face of the ciliary body and iris root which may contribute to spontaneous hemorrhages following opening of the anterior chamber in Fuchs’ complicated heterochromia and PEX iridopathy (see Chapter 2, Fig. 2.3; Chapter 6.3).

5.4.2

Surgical Pathology

5.4.2.1 Presbyopia

In children the ciliary muscle, on light microscopy, does not show obvious connective tissue between the muscle fibers. Beyond 60 years of age more than half of the cross-section of muscle fibers is replaced by collagenous fibrous tissue, suggesting a limited function of the muscle fibers in between the acquired connective tissue scaffold (Fig. 5.4.3).

5.4.2.2

Cataract Surgery

All intraand extracapsular cataract surgery cannot avoid traction on the lens capsule. This traction is transmitted via the zonular apparatus to the pars plicata and pars plana of the ciliary body and via the vitreous base also to the peripheral sensory retina. Most attempts at recovering accommodation after extracapsular cataract surgery and lens implantation rely on the residual action of the ciliary muscle. In view of the aging changes, skepticism regarding the function of the ciliary muscle in recovering pseudo-accommodation in the aged is justified and indicated.

b

5.4.2.3

Contusion Deformity

Blunt trauma to the eye may create a tear between the longitudinal and circular portion of the ciliary muscle combined with a retroplacement of the iris insertion and an abnormally wide open angle. These contusion effects are not limited to the ciliary muscle but also affect the trabecular meshwork, probably followed by disturbance of the contact inhibition between corneal and trabecular endothelial cells. The endothelial cells of the cornea proliferate and migrate posteriorly covering the surface of the trabecular meshwork and producing a basement membrane which may further increase outflow resistance and contribute to a secondary open angle glaucoma (see Chapter 5.2).

5.4.2.4

Traumatic Cyclodialysis

More intensive contusion may separate a sector of the insertion of the ciliary muscle completely from the scleral spur, producing a cyclodialysis opening the supraciliary space. The cyclodialysis increases the uveoscleral outflow and may induce persisting ocular hypotony (Fig. 5.4.5). If ocular hypotony persists longer than 6 weeks and the cyclodialysis extends for more than 60° (or 2 clock hours) of the circumference, spontaneous recovery of pressure is unlikely.

Surgically intended cyclodialysis today is rarely performed (Fig. 5.4.6). Direct cyclopexy is discussed below (Figs. 5.4.7, 5.4.8, Table 5.4.2).

5.4.2.5

Pseudoadenomatous Hyperplasia (“Fuchs’ Adenoma”)

This is present in 25 % of autopsy eyes (Hillemann and Naumann 1972; Fig. 5.4.2). The process is rarely larger than 1 mm in diameter. As an exception large processes may cause a focal narrowing of the chamber angle by pushing the iris root forward. Clinically they can be detected by ultrasound biomicroscopy and OCT. Usually this process requires no microsurgical intervention.

5.4.2.6

Tumors of the Ciliary Body

Malignant melanomas of the anterior uvea are most frequently observed (Table 5.4.3). Ninety percent of them show histopathologically invasion of the inner layers of the sclera and chamber angle in serial section

– most pronounced between the scleral spur and Schwalbe’s line into Schlemm’s canal and its collector channels (Fig. 5.4.7). The extent of the scleral invasion cannot be judged clinically if the tumor is not pigmented. Shedding of tumor cells into the aqueous and the adjacent structures occurs frequently and must be ruled out by biocytology (see Chapter 5.3). Only then can a curative local excision be achieved.

Local removal and preservation of the eye can be achieved by block excision involving the adjacent anterior uvea together with the adjacent full-thickness sclera and cornea (Tables 5.4.4 – 5.4.8). The ensuing defect in the eye wall needs to be closed by corneal or corneoscleral graft (see below).

Table 5.4.3. Tumors of the ciliary body: differential diagnosis

A.Neuroepithelial

I. Glioneuroma

II.Embryonal forms Medulloepithelioma (diktyoma)

Benign

Malignant

Teratoid medulloepithelioma

Benign

Malignant

III.Adult forms Adenoma Adenocarcinoma

IV. Pseudoadenomatous hyperplasia (Fuchs’ adenoma)

B.Pigmented ciliary epithelium

I. Adenomas

II.“Ringschwiele,” subretinal and reactive hyperplasia in cyclitic membrane

C.Stroma of ciliary body: Leiomyoma Neurofibroma Schwannoma Rhabdomyosarcoma

Benign Tumors. Progressive tumors of the ciliary body with a benign histology account for more than approximately 25 % of our 135 patients with progressive tumors of the anterior uvea treated by block excision (Tables 5.4.5 – 5.4.7).

Table 5.4.4. Block excision of processes of the anterior uvea in 210 patients (Universities of Hamburg, Tübingen, Erlangen)

Table 5.4.5. Block excisions of tumors of the anterior uvea (including iris, ciliary body, peripheral cornea and sclera): rationale

1. Tumors of chamber angle and iris root always involve ciliary body

2. Tumors must be localized: no seeding of tumor cells in aqueous and vitreous (biocytology)

3. Angle of not more than 150° involved

4. Full thickness removal of adjacent sclera, cornea and other tissues. Invasion of inner sclera and outflow system cannot be detected clinically if not pigmented

5. > 25 % of expanding tumors of ciliary body and iris root are benign and radioresistant

Table 5.4.6. Block excisions of epithelial ingrowth: reasons

1. Cysts of angle and iris root always involve face of ciliary body

2. Location of non-pigmented epithelial strands in cornea, limbus and sclera cannot be recognized clinically (unless fistula)

3. Variable thickness of epithelial lining (1 – 20 layers) prevents indirect total destruction by laser or toxic solutions

4. Direct manipulation of one to two cell layers would disrupt cyst and convert to diffuse epithelial ingrowth

5. Iridectomy alone converts from cystic to diffuse ingrowth

6. Diameter of epithelial cyst can be reduced by aspiration (through parts of limbus later removed)

7. Adjacent iris, pars plicata of ciliary body – full thickness cornea and sclera forming a “shell” for block excision allowing complete curative removal

Table 5.4.7. Block excision of expanding ciliary body tumors involving chamber angle: histopathologic diagnosis: 26 “benign”! (Erlangen 1980 – 2003, n = 104) (evaluated by Arne Viestenz, MD, 2004)

a

b

Fig. 5.4.9. Malignant melanomas of the ciliary body and iris root: invasion of sclera, Schlemm’s canal and outflow channels. a Episcleral extension from malignant melanoma of ciliary body and iris root. b Histology showing invasion of Schlemm’s canal, outflow channels up to the episcleral conjunctival tissue

Table 5.4.8. Block excision of epithelial ingrowth (Erlangen 1980 – 2003; n = 59) (evaluated by Arne Viestenz, MD, 2004, personal communication)