Fig. 14.1 The fundus of a recent CRAO shows a cloudy, opaque and swollen infarcted retina particularly noticeable in the posterior pole where the retina is thickest. The fovea is the thinnest area of the posterior retina and there is little tissue here to infarct so that the underlying redness of the choroid is seen contrasting with the whiteness of the surrounding infarcted retina to give the classical ‘cherry red spot’ appearance. Within a few hours mild swelling of the optic disc often appears due to products of retrograde axoplasmic transport accumulating in the optic nerve head. In the acute stage blood in the retinal arteries is dark from stagnation and the arteries themselves are often attenuated. These acute appearances subside over a period of 2–4 weeks, usually leaving the eye with perception of light. Complete blindness should suggest more extensive vascular occlusion involving the choroidal or optic disc circulation or ophthalmic artery.

Fig. 14.2 Fluorescein angiography is not usually performed but if it is done in the acute stages there is a considerable delay in filling of the central retinal artery circulation following injection of dye; this is seen as black retinal arteries against the normal background choroidal fluorescence which, of course, is unaffected by the occlusion. The artery fills eventually either directly or by retrograde flow from the venous circulation. The central vessels in the posterior pole fill poorly, possibly due to the retinal oedema increasing external tissue pressure.

Fig. 14.3 Late changes following CRAO in the right eye. The optic disc is pale and the branches of the central retinal artery are attenuated in contrast to those of the normal left eye. Note the irregular whitish-yellowish deposition in the arterial walls which is probably a mixture of gliosis and lipid deposition from vascular endothelial damage.

Fig. 14.4 Histology shows atrophy of the inner two-thirds of the retina, (supplied by the retinal circulation), following CRAO. The outer retina is maintained by the choroid (see Ch. 13).

Fig. 14.5 Cilioretinal arteries of varying size are found in about 20 per cent of eyes. These are part of the posterior ciliary circulation and are therefore spared in a CRAO. The patch of retina supplied by the artery is left viable; if the patient is fortunate this will include the macula. A small cilioretinal vessel is seen clearly in this patient supplying an area of retina temporal to the optic disc. Minute cholesterol emboli can be seen in the inferior and superior temporal arteries and also in a small branch artery adjacent to the macula, indicating the aetiology of the occlusion. Fluorescein angiography demonstrates the slow rate of filling of the retinal circulation and the normal filling of the cilioretinal artery and choroid.

Fig. 14.6 This example of cilioretinal artery sparing in the presence of a CRAO in a pigmented eye demonstrates clumping of the blood column in the inferior temporal branch artery. This characteristic sign of a stagnant retinal circulation is known as ‘cattle trucking’.

Fig. 14.7 Cilioretinal infarction with central retinal artery sparing is the converse situation to that shown in Fig. 14.5. Here, a small cilioretinal branch is occluded, thus infarcting the retina temporal to the optic disc. A frill of axoplasmic material from the viable retina is seen surrounding the cilioretinal infarct. Cilioretinal infarcts have a similar aetiology to anterior ischaemic optic neuropathy, temporal arteritis, which although it usually presents with more extensive disc infarction, must be excluded as a potential cause.

Fig. 14.8 Cholesterol crystals are seen frequently as a coincidental finding in elderly patients and are a sign of atheromatous disease in the carotid circulation (usually at the bifurcation of the common carotid). They are flat crystals that glint and reflect light as the ophthalmoscope is tilted to examine the fundus and are most commonly found at bifurcations of the retinal arteries. Because of the planar shape of the crystal, blood flow may not be disturbed and the patient does not complain of any symptoms. Cholesterol emboli are also known as ‘Hollenhorst’ plaques after the Mayo Clinic ophthalmologist who made the first description.

Fig. 14.9 Cholesterol emboli usually arise at the bifurcation of the common carotid artery, less frequently at the origin of the great vessels. Calcific emboli usually arise from the aortic valve or ascending aorta.

Fig. 14.10 If the patient is likely to be a candidate for vascular surgery, imaging of the carotid bifurcation is indicated to define an atheromatous lesion. This can be done by Doppler ultrasonography or magnetic resonance angiography. These have now superseded formal arterial angiography which carries a significant risk of stroke in its own right. Clinical trials have established that if the patient is fit for surgery, symptomatic stenoses of greater than 70 per cent are best treated by surgical carotid endarterectomy. Milder degrees of stenosis and unfit patients are better treated medically with inhibitors of platelet aggregation.

Fig. 14.11 Lipid deposition may be seen in the retinal arterial wall following vascular endothelial cell damage after embolization. In this patient there is marked yellowish white sheathing at the origin of the superior temporal artery and, peripheral to this, the vessel is thin, attenuated and fibrosed. Collateral vessels can be seen on the retina and the optic disc has sectorial pallor; the patient had a dense inferior nasal arcuate scotoma. Sometimes the lipid deposition occurs at a bifurcation of a major retinal arteriole giving a ‘trouser leg’ pattern of sheathing to the vessel.

Fig. 14.12 Occlusion of a branch retinal artery is almost always the result of embolization. In this patient with a branch inferior temporal artery occlusion, a small embolus can be seen in the artery at a bifurcation. The embolus is white and globular, unlike a cholesterol embolus, and plugs the vessel. It originated from a stenotic aortic valve.

Fig. 14.13 Platelet and fibrin emboli originate from an ulcerating atheromatous plaque and look like soft porridgy material in the vessel. They produce retinal infarction or amaurosis fugax and can sometimes be observed moving slowly through the retinal arterial circulation as the attack evolves. Video fluorescein angiography shows that transient multiple platelet embolization is common during cardiac bypass procedures.

Fig. 14.14 Embolization from fragments of a calcific aortic valve are seen occasionally; their characteristic appearance is different from that of other types of emboli, so aiding their identification. They tend to be larger and globular with a pearly white appearance and lodge in the larger arteries at the optic disc. Echocardiography confirms the diagnosis.

Table 14.1 Investigation of patients with retinal vein occlusion

Fig. 14.15 There is a wide range of spectrum appearances which reflect the degree of severity. These eyes show mild venous dilatation and limited fundal haemorrhages. Fluorescein angiography shows venous and capillary leakage on the optic disc and in the retina. Retinal haemorrhages mask the choroidal fluorescence.

Fig. 14.16 Patients with CRVO and macular oedema (left and centre) present with blurring of vision which tends to improve over 3–4 months as the central retinal vein recanalizes or venous collateral vessels develop on the optic disc to the choroidal circulation. At this stage the visual acuity may improve and the retinal haemorrhages and macular oedema absorb. Six months later this patient shows a remarkable improvement with improvement of acuity from 20/60 to 20/30. (right). In more severe cases the macular oedema may persist with consequent visual loss.

Fig. 14.17 Signs suggestive of retinal ischaemia are dense, dark, blotchy haemorrhages and cotton-wool spots. Retinal haemorrhages make interpretation of the degree of ischaemia difficult in the acute stage as they mask the retinal capillary bed and angiography is more informative if postponed until these have been absorbed. The major vessels fill with dye but there are large areas of capillary nonperfusion. In the later stages there is gross leakage of dye from the major retinal vessels and the optic disc, especially in the ischaemic areas. Surprisingly, marked capillary closure in the posterior pole can sometimes be compatible with reasonable preservation of visual acuity, although the majority of such eyes have extremely poor vision.

Fig. 14.18 This eye shows gross retinal ischaemia and neovascularization on the optic disc.

Fig. 14.19 In the presence of gross capillary closure, 30–50 per cent of eyes develop rubeosis iridis and progress to thrombotic glaucoma. Rubeosis iridis classically appears about 3 months after the vein occlusion. In the earliest stages a fine neovascular network is seen around the pupil or the angle of the anterior chamber. This is followed by development of ectropion uveae from contraction of the neovascular membrane, further vascular proliferation, glaucoma and corneal oedema (see Ch. 8). This sequence of events can be forestalled by early panretinal photocoagulation as soon as the new vessels appear on the iris or angle; for this reason patients should be seen every month for 6 months after presentation. After treatment the rubeotic iris vessels will atrophy to leave the patient with an eye that has poor vision but is comfortable. Retinal or optic disc neovascularization is very uncommon after CRVO. Glaucomatous eyes with rubeosis and visual potential may be salvaged by a tube drainage procedure. Blind eyes can be made comfortable by topical steroid and mydriatic therapy but a proportion of these eyes will eventually have to be enucleated as blind painful eyes.

Fig. 14.20 CRVO may produce marked disc swelling that is distinguished from other causes of swollen optic discs by the presence of haemorrhages in the peripheral retina in all four quadrants. Some of these patients may develop concomitant cilioretinal artery occlusion. The perfusion pressure of the ciliary circulation is lower than that of the retinal circulation and the raised venous pressure increases the retinal perfusion pressure above that of the ciliary circulation causing infarction. This patient presented with mild blurring of vision that resolved, leaving a small centrocaecal scotoma.

Fig. 14.21 This eye shows collateral opticociliary shunt vessels on the optic disc as evidence of a previous resolved CRVO. These are derived from normal vessels and shunt blood from the obstructed retinal venous circulation to the unobstructed choroidal circulation with outflow through the vortex veins. The collateral vessels do not leak fluorescein, in contrast to neovascularization, because they are derived from normal vascular channels with tight endothelial cell junctions.

Fig. 14.22 CRVO is common with glaucoma. The IOP and optic disc of the fellow eye must be checked carefully in any patient with CRVO as this may become the patient’s only functioning eye. In many patients with glaucoma the CRVO is subclinical, indicated only by the presence of shunt vessels as a coincidental finding (see Ch. 7).

Fig. 14.23 The optic nerve of a patient whose eye was enucleated for thrombotic glaucoma shows gliosis and atrophy of the nerve (compare with the normal nerve see Ch. 17). The common fascial sheath of the central retinal artery and vein is demonstrated; the artery is identified by its muscular wall. A thrombus containing cholesterol crystals is lodged in the arterial lumen, the vein is pushed to one side, and there is recanalization with multiple channels.

Fig. 14.24 A small macula branch vein occlusion is seen in a hypertensive patient who presented with blurred vision. Fluorescein angiography shows the site of occlusion at an arteriovenous crossing with retinal vascular leakage, haemorrhage and oedema in the affected area. Some weeks later the haemorrhage can be seen to be resolving with corresponding improvement in vision.

Fig. 14.25 In some patients the central retinal vein divides within the disc and a major branch can be occluded within the disc, producing a hemisphere venous occlusion analogous to a central vein occlusion.

Fig. 14.51 Diagram of ROP zones.

Fig. 14.52 In this baby with stage I ROP there is a thin white demarcation line between vascularized and nonvascularized nasal retina, signifying the onset of disease. This occurs at a gestational age of approximately 32 weeks in the majority of cases.

By courtesy of Mr P Watts.

Fig. 14.53 In stage II the retinal lesion acquires volume and projects out of the retinal plane.

By courtesy of Mr P Watts.

Fig. 14.54 Stage III occurs at about 36 weeks of gestational age. There is extraretinal fibrovascular proliferation from the posterior edge of the ridge or posterior to it which projects into the vitreous, which may be either segmental or continuous.

By courtesy of Mr P Watts.

Fig. 14.55 ‘Plus’ disease indicates activity. There is engorgement and increased tortuosity of the retinal vessels in the posterior pole, iris vessel engorgement, pupil rigidity and vitreous haze. This stage is of great clinical importance as it precedes the onset of vitreoretinal disease, which may be prevented by timely intervention. Severe ROP tends to progress rapidly and the window for therapeutic intervention is short—about 2 weeks.

By courtesy of Mr P Watts.

Fig. 14.56 Regression after laser photocoagulation is characterized by decreased congestion and tortuosity of the retinal vasculature; formation of a brush border at the demarcation line; and a change in colour of the stage III retinal lesion from salmon pink to red as the retinal lesion becomes more differentiated into a fibrovascular component and finally into white scar tissue.

By courtesy of Mr P Watts.

Fig. 14.57 The onset of vitreoretinal disease (stages IV and V) is signified by the sudden onset of a secondary vitreous haze in the presence of stage III disease. With the onset of stage IVa (subtotal extrafoveal detachment) and IVb (with foveal detachment), retinal ablation becomes ineffective and traction retinal detachment usually follows within 1 week. Progression to total retinal detachment (stage V) usually occurs approximately at term, producing a vascularized white retrolental mass that must be differentiated from other causes of leucocoria in an infant (e.g. retinoblastoma, congenital cataract, persistent hyperplastic primary vitreous, retinal colobomas or folds and endophthalmitis).

By courtesy of Dr B Fantl.

Table 14.2 Sequelae of retinopathy of prematurity

Fig. 14.58 Late cicatricial changes in eyes with vitreoretinopathy produce dragging of the macula and temporal vessels towards the temporal periphery. Such eyes usually have poor vision and nystagmus and may develop cataracts or retinal detachment from peripheral lattice degeneration and hole formation in early adult life.

By courtesy of Mrs R Zakir.

Fig. 14.63 These photographs were taken 3 weeks after a severe road traffic accident in which the patient suffered fractures to the left femur and humerus and a crush injury to the chest from the seat belt. The patient complained of dimness of vision in this eye and patchy visual loss that made reading difficult although he could still read J3. Some months later there was disc pallor, arterial attenuation and extensive nerve fibre loss. The symptoms remained unchanged and the fellow eye was normal.

Fig. 14.64 These photographs show an acute Purtscher’s retinopathy associated with acute pancreatitis. Cotton-wool spots are present as well as a cloudy whitish intraretinal infiltrate in each eye.

Fig. 14.65 This patient received radiotherapy for an ethmoidal sinus tumour and presented 18 months later with an acuity of counting fingers. Colour images show a localized area of ischaemia in the posterior pole that was inadvertently covered in the radiation field. Fluorescein angiography demonstrates the area of ischaemia and leakage which does not correspond to an anatomical vascular distribution. The eye eventually developed rubeotic glaucoma and became totally bind.