Fig. 9.1 The iris consists of loose, pigmented vascularized tissue anteriorly and a double layer of pigment epithelium posteriorly. The sphincter muscle lies towards the pupillary margin and the dilator muscle in close relation to the pigment epithelium. About 1–2 mm from the pupillary margin on the anterior surface there is a frill known as the collarette. This is the site of the embryological pupillary membrane which atrophies in the eighth month of gestation, and of the minor arterial circle of the iris.

Fig. 9.2 A posterior view of the lens and anterior segment shows the insertion of the retina into the pars plana at the ora serrata and the ciliary processes of the pars plicata. A few remaining zonular fibres can be seen supporting the cataractous lens.

Fig. 9.3 The ciliary body extends from the scleral spur to the ora serrata. Under higher magnification the details of the pars plicata are seen more clearly. Note the two layers of ciliary epithelium, the zonular fibres and the major arterial circle of the iris. At the ora serrata, the neurosensory retina becomes attenuated and cystic, and terminates as the inner non-pigmented epithelium of the ciliary body. The retinal pigment epithelium is continued as the outer pigmented epithelial layer of the pars plana.

Fig. 9.4 The normal choroid is a highly vascular tissue. Its macroscopic appearance is black owing to pigmentation from stromal melanocytes. In this histological section the retina is artefactually detached.

Fig. 9.5 Diagram showing the vascular supply of the choroid by the anterior and posterior ciliary circulations. (Further details of the anterior ciliary and conjunctival circulations are described in Chapter 5 and the optioc disc in Chapter 17.)

Fig. 9.6 The choroidal arteries divide rapidly to form the choriocapillaris lying beneath Bruch’s membrane. These capillaries have fenestrations between the endothelial cells allowing plasma to leak into the extracellular space. Although there are anatomical anastomoses between the choroidal vessels, physiologically the choriocapillaris functions on a lobular basis.

Fig. 9.7 Clinically this is demonstrated in the earliest phases of a fluorescein angiogram as patchy delayed filling of the choroidal bed, and is seen as choroidal infarcts such as Elschnig’s spots or Siegrist streaks (see Ch. 14).

Fig. 9.8 A digest preparation of a cast viewed from the choroidal side in the vicinity of the optic disc shows choroidal arteries supplying the choriocapillaris and drained by the choroidal veins.

By courtesy of Miss J Olver.

Fig. 9.9 These digest casts of the human choroid show the choriocapillaris from the retinal aspect. At the posterior pole the pattern is uniform (left), in the equatorial fundus a lobular pattern is more apparent (middle), and in the periphery large fan-shaped lobules can be seen (right).

By courtesy of Miss J Olver.

Fig. 9.10 Iris colobomas are sometimes associated with segmental absence of the lens zonules causing a localized indentation of the lens and usually with defects in the choroid and retina. This child with bilateral iris colobomata also has a poorly sighted divergent left eye due to a large chorioretinal coloboma involving the macula.

Fig. 9.11 Retroillumination of the eyes of a child with aniridia shows the lens and zonular gap. The iris remnant remains as a frill that forms peripheral anterior synechiae to obstruct the angle causing glaucoma usually in early adulthood.

By courtesy of Mr David Taylor.

Fig. 9.12 An oculocutaneous tyrosinase-negative patient with congenital nystagmus and a right convergent squint. Note the white eyelashes.

Fig. 9.13 Retroillumination of the iris through the pupil demonstrates the gross lack of iris pigmentation. Fundus photography in the same patient shows the lack of retinal and choroidal pigmentation. Large choroidal vessels are clearly seen.

Fig. 9.24 Choroidal naevi occur in about 10–30 per cent of the Caucasian population and are usually detected after puberty. Most naevi are small and flat with a slate-grey colour and the overlying retinal pigment epithelium shows minimal secondary change.

Fig. 9.25 A small proportion of choroidal naevi are relatively bulky and therefore induce degenerative changes in the overlying retinal pigment epithelium, similar to those caused by melanomas. Clinical features indicative of a benign nature are a tumour thickness of less than 2 mm, the presence of hard drusen on the surface, the absence of clumps of ‘orange pigment’, and the absence of a serous retinal detachment over the tumour. Such signs are not reliable indicators, however, and suspicious naevi should be monitored for growth comparing the ophthalmoscopic appearances with a baseline colour photograph. The patient should be seen after 3–4 months and then 6 monthly and eventually once a year. Such monitoring should be lifelong because malignant growth can occur after many years of apparent inactivity.

Fig. 9.26 The choroid is slightly thickened by a proliferation of heavily pigmented melanocytes. The choriocapillaris is spared and the histological features are those of a choroidal naevus.

Fig. 9.27 Ophthalmoscopically, abnormal deposits of lipofuscin accumulate over the surface of the tumour (‘orange pigment’).

Fig. 9.28 This patient has a large malignant choroidal melanoma that has not broken through Bruch’s membrane.

Fig. 9.29 The degree of pigmentation in uveal melanomas varies greatly even within the same tumour, but this cannot always be properly appreciated clinically unless the overlying retinal pigment epithelium is atrophic or absent. Melanomas may have tapering margins where the overlying retinal pigment epithelium is still relatively healthy; therefore, unless the tumour is deeply pigmented, such lateral extentions may be clinically invisible.

Fig. 9.30 This is an amelanotic collar-stud melanoma with engorged tumour blood vessels. These are usually visible ophthalmoscopically only if the tumour has ruptured the retinal pigment epithelium and is nonpigmented. The pigmented base of this collar stud tumour is due to multilayering of the retinal pigment epithelium and not to melanin in the tumour.

Fig. 9.31 Choroidal melanomas are moulded into a smooth dome by the overlying Bruch’s membrane and retinal pigment epithelium. When the tumour ruptures these layers it herniates into the subretinal space. The edge of the break in Bruch’s membrane strangulates the blood vessels in the prolapsed part of the tumour so that they become engorged, also leaking fluid. The herniated part of the tumour becomes globular so that the melanoma develops a mushroom shape (also described as ‘collar-stud’ or ‘dumb-bell’).

Fig. 9.32 A small proportion of choroidal melanomas infiltrate the uvea without forming a bulky tumour. Such ‘diffuse’ melanomas tend to be highly aggressive and have often extended extraocularly by the time they are diagnosed.

Fig. 9.33 The episcleral blood vessels overlying a large ciliary body tumour tend to become dilated and tortuous and may be mistaken for episcleritis. Such ‘sentinel vessels’ can occur with benign tumours and are not necessarily a sign of malignancy.

Fig. 9.34 Choroidal melanomas, and indeed other tumours, tend to cause secondary degenerative changes in the overlying tissues that influence their ophthalmoscopic features. The choriocapillaris is eventually totally destroyed. The retinal pigment epithelium becomes multilayered in some areas and atrophic in others, and multiple small pigment epithelial detachments may develop over the tumour.

Fig. 9.35 If the retinal pigment epithelium is still present over a melanoma, drusen and small pigment epithelial detachments will appear as hyperfluorescent spots. When fluorescein diffuses from the residual choriocapillaris and tumour vessels through defects in the retinal pigment epithelium, there is diffuse late hyper-fluorescence as the dye accumulates in the subretinal space. In comparison to fluorescein angiography, indocyanine green angiography provides more information about tumour extent and vascularity deep to the retinal pigment epithelium.

Fig. 9.36 If the melanoma is exposed to view because Bruch’s membrane is ruptured or the retinal pigment epithelium is absent or atrophic, the angiographic appearances depend on the degree of pigmentation. An amelanotic collar-stud tumour is hyperfluorescent and large choroidal vessels are visible near its surface.

Fig. 9.37 This deeply pigmented collar-stud melanoma has broken through retina as well as Bruch’s membrane and retinal pigment epithelium. The angiogram shows how the tumour itself is totally nonfluorescent. The surrounding hyperfluorescence arises from drusen and subretinal fluid over abnormal retinal pigment epithelium anterior to the tumour and from the sclera where the retinal pigment epithelium and choroid are atrophic.

Reproduced with permission of Eye.

Fig. 9.38 Transpupillary transillumination will help to distinguish pigmented from nonpigmented tumours. Not all pigmented tumours are melanomas, however, and conversely not all melanomas are pigmented. Transpupillary transillumination gives an approximate indication of the extent of a pigmented tumour. Care must be taken not to be misled by oblique illumination of the tumour or by an adjacent subretinal haematoma.

Fig. 9.39 When making a diagnosis or planning therapy, A and B scan ultrasonography (see Ch. 1) are essential for measuring the dimensions and defining the extent of the tumour. Ultrasonography can help to identify extraocular extension before surgery and to confirm or exclude the presence of a tumour when the ocular media are opaque. Melanomas tend to have a highly reflective surface with a low internal acoustic reflectivity; this helps to distinguish them from haemangiomas and secondary neoplasms which have high reflectivity. Rare nonmelanomatous uveal tumours such as leiomyoma can be indistinguishable from melanoma. A collar-stud configuration is almost pathognomonic of melanoma.

Fig. 9.40 Melanin has short T1 and T2 relaxation times so that T1-weighted images are relatively hyperintense and T2-weighted images are hypointense compared with vitreous on MRI. These characteristic paramagnetic features may be helpful in distinguishing melanoma from other conditions (e.g. metastasis, haemangioma and haematoma). It must be remembered, however, that other tumours (e.g. melanocytomas, adenocarcinomas and leiomyomas) can contain melanin which may confuse the result.

By courtesy of Dr Nigel McMillan.

Fig. 9.41 CT is less useful than ultrasonography and MRI for intraocular tumours. Ultrasonography and CT are extremely helpful though in the diagnosis of hepatic metastases. Although melanomas enhance with contrast this sign is nonspecific.

Fig. 9.42 Spindle cells (left) are fusiform with indistinct cell membranes and are arranged in tight bundles. The nuclei vary from slender to plump; nucleoli may or may not be distinct. Epithelioid cells (right) are larger, polyhedral and more pleomorphic with abundant cytoplasm. The cell membranes are distinct and extracellular space often separates cells. Nuclei are large with prominent nucleoli. Mitotic figures are seen more frequently than in spindle cells.

Fig. 9.43 In some tumours spindle cells have a fascicular arrangement. This has no pathological significance.

Fig. 9.44 Uveal melanomas spread usually trans-sclerally along the channels of the vortex veins and ciliary vessels; extension along the optic nerve is rare.

Fig. 9.45 This malignant melanoma of the ciliary body has invaded the iris anteriorly and penetrated the sclera with hyperaemia of the conjunctival vessels. Scleral spread occurs usually either through the emissary vein or by direct sceral invasion.

Fig. 9.46 In most specialist centres, brachytherapy using a ¹⁰⁶Ru or ¹²⁵I plaque is the first choice of treatment. Another method of directing radiation at the tumour is by means of a highly collimated beam of heavily charged particles, such as protons, delivered with a cyclotron. The scope of stereotactic radiotherapy is being investigated. Transpupillary thermotherapy, which has superseded photocoagulation, gently raises the tumour temperature to between 45°C and 60°C for about 1 min, by means of a 3-mm diode laser beam. It is usually used in conjunction with radiotherapy (sandwich technique), but in some centres it is administered alone to small tumours located close to the disc or fovea.

Fig. 9.47 After plaque radiotherapy the tumour gradually flattens over 2–3 years, usually leaving a residual pigmented mass surrounded by choroidal atrophy. As long as there is no tumour regrowth, further treatment is not needed.

Fig. 9.48 In a few centres tumours considered to be unsuitable for radiotherapy because of their large size or juxtapapillary location can be treated by local resection, performed either trans-sclerally or trans-retinally (i.e. endoresection). With pseudophakic correction, this dressmaker retained visual acuity of 20/15 and her occupation 7 years after endoresection of a juxtapapillary choroidal melanoma in the right eye.

Fig. 9.49 Choroidal metastases are amelanotic and tend to grow rapidly so that the retinal pigment epithelium has little time to develop marked proliferative changes. Such tumours are therefore white or yellow with scattered clumps of residual retinal pigment epithelial cells giving rise to a leopard-spot pattern. They may be bilateral and in a minority of patients multiple lesions occur in one or both eyes.

Fig. 9.50 This patient with an intraocular metastasis had widespread secondaries. Biopsy showed the tumour to be an adenocarcinoma, probably arising from the bronchus.

Fig. 9.51 This patient with skeletal metastases from carcinoma of the breast presented with bilateral visual loss from pale plaque-like metastatic lesions at the posterior pole of each eye. She died from carcinomatosis 2 months later.

Fig. 9.52 Histological findings from another patient show plump pleomorphic cells from a bronchial carcinoma invading the choroid. Bruch’s membrane and the retinal pigment epithelium are still intact.

Fig. 9.53 Uveal effusions (see also Ch. 8) may resemble melanoma but are lobulated because of tethering of the choroid to the sclera by vortex veins (left). They tend to occur in the horizontal meridian. Acute effusions can be associated with ocular hypotony. Effusions occur spontaneously as the uveal effusion syndrome in nanophthalmic eyes (axial length <20 mm), in normal-sized eyes with thickened sclera, with posterior scleritis and most commonly as a response to hypotony after intraocular surgery. In the absence of hypotony after recent intraocular surgery the aetiology is thought to be disruption of trans-scleral fluid outflow; if the effusion does not resolve spontaneously these patients respond to a surgical scleral decompression procedure. Leopard-spot pigmentation can be seen over chronic effusions and there may be associated serous retinal detachment. Ultrasonography confirms the absence of solid tumour as shown in this patient with posterior scleritis (right).

Reproduced from Ocular Tumours: Diagnosis and Treatment. Damato: Butterworth Heinemann, 2000.

Fig. 9.54 This child has the typical facial naevus of the Sturge–Weber syndrome. Ocular involvement is said to be more common when the upper lid is involved by the naevus. Facial hemihypertrophy is a common feature, as in this patient.

With permission from the patient and his family.

Fig. 9.55 These rare tumours usually arise near the posterior pole of the eye as a slightly elevated lesion. They may be discrete and up to several disc diameters in size or diffuse. Both types of haemangioma have indistinct margins and can cause cystic degeneration and serous detachment of the overlying retina. Characteristically, they have the same colour as the adjacent choroid. Haemangiomas usually regress after external-beam or plaque radiotherapy but this approach is being replaced by photodynamic therapy.

Fig. 9.56 On fluorescein angiography, haemangiomas rapidly develop diffuse hyperfluorescence and do not tend to show the same retinal pigment epithelium changes as melanomas.

Fig. 9.57 On ultrasonography haemangiomas have a characteristic high internal acoustic reflectivity from the multiple changes in tissue density throughout their structure which is diagnostic.

Fig. 9.58 Melanocytomas may increase in size slowly and protrude into the vitreous or spread out on to the retina or into the choroid in which case differentiation from a malignant melanoma may be exceptionally difficult. Field defects can occur although visual acuity is not normally affected.

Fig. 9.59 Melanocytomas are well circumscribed tumours within the optic disc. They are composed of plump, heavily pigmented melanocytes.

Fig. 9.60 This photograph shows a typical peripheral area of retinal pigment epithelial hyperplasia with lacunae. The lesion is flat and sharply circumscribed with a depigmented margin.

Fig. 9.61 This eye shows a juxtapapillary osseous choristoma adjacent with overlying retinal vascular abnormalities.

Fig. 9.62 On ultrasonography, osseous choristomas have a highly reflective anterior surface and a prominent linear shadow extending posteriorly into the orbit. Calcification can also be seen on an orbital CT scan.

Fig. 9.63 The choroid is replaced by mature bone containing vascular spaces.

Reproduced with permission from Yanoff and Fine. Ocular Pathology. Gower Medical Publishing, 1988.

Fig. 9.64 These eyes show a combined hamartoma of the retina and retinal pigment epithelium centred on the optic disc with macular traction and retinal vascular abnormalities.

Fig. 9.65 Histological appearance from another patient shows proliferation of the retinal pigment epithelium through the optic disc margin into the retina, with proliferating cells and abnormal vessels.

Reproduced with permission from Yanoff and Fine. Ocular Pathology. Gower Medical Publishing, 1988.

Fig. 9.66 A vascular, pinkish white, ciliary body tumour can be visualized in these children.

Reproduced from Damato B. Ocular Tumours: Diagnosis and Treatment. Butterworth Heinemann, 2000.

Fig. 9.67 Histologically medulloepitheliomas are of two types: nonteratoid and teratoid. The nonteratoid tumour (left) has a myxoid or fibrous stroma in which proliferating epithelial cells form tubules and acini. In the teratoid type (right) the presence of heterologous elements such as cartilage (as in this case), skeletal muscle or neural tissue can also be found, reflecting the pluripotential nature of the optic cup. Malignancy depends on the degree of differentiation but metastic deaths are rare.

Fig. 9.68 Macular disciform lesions can resemble melanoma if they are bulky. Active lesions tend to have subretinal haemorrhage and exudation, signs that are rare with melanoma. Mature disciform lesions have discrete irregular margins, unlike the smooth diffuse margins of melanoma and white subretinal fibrosis. In an elderly patient a macular mass with vitreous hemorrhage is more likely to be a disciform lesion than melanoma. The diagnosis should be established by waiting for the haemorrhage to clear spontaneously or by vitrectomy and observing shrinkage of the lesion. Sequential ultrasonographic scans are likely to show shrinkage with a disciform lesion and growth with a melanoma.

Fig. 9.69 Eccentric disciform lesions differ from melanoma in that they are usually associated with haemorrhages and exudates (left) and because they eventually regress, leaving an irregular scar (right). They are usually temporal and circumferential.