Fundus: Other Retinal Vascular Disorders

Question 0

The retinal vascular changes in hypertension comprise which two general responses?

Answer 0

1. The vasospastic reaction to an acute pressure rise (the true hypertensive response)
2. The arteriolosclerotic response to chronic elevation.

Question 1

Name three “other” retinal vascular disorders (ie. excluding occlusions and diabetic retinopathy).

Answer 1

1. Hypertensive retinopathy
2. Retinopathy of prematurity
3. Sickle-cell retinopathy

Question 2

What is malignant hypertension? And in the retina, what category of hypertensive changes is it characterised by?

Answer 2

Malignant hypertension is the clinical syndrome of an accelerated rise in blood pressure.
In the retina, it is characterised by Grade 4 hypertensive changes (generalised and focal narrowing plus cotton wool spots, retinal haemorrhages, hard exudates, AND swelling of the optic disc).
Untreated, mortality at 1 year is 90%.

Question 3

What are the four grades of retinal changes in hypertension?

Hypertensive retinopathy

Answer 3

G1. Generalised arteriolar narrowing.
G2. More marked generalised narrowing with irregular points of focal constriction (vasospastic effect).
G3. Generalised and focal narrowing, plus cotton wool spots, retinal haemorrhages, hard exudates (a “star” at the macula).
G4. As grade 3, but with swelling of the optic disc (thought to be caused by local ischaemia. Rarely, there is raised ICP - “true” papilloedema).

Question 4

What are the four grades of retinal change in arteriolosclerosis?
(Hypertensive retinopathy)

Answer 4

1. Decreased venular visibility at arteriovenous crossing points, slight broadening of arteriolar light reflex
2. Deflection of the venule at arteriovenous crossing points
3. ‘Copper wire’ arterioles, marked venule narrowing and deflection at crossing points
4. ‘Silver wire’ arterioles, extreme crossing changes

Question 5

What are the 8 clinical features to find in hypertensive retinopathy?
(As summarised in grading system questions)

Answer 5

1. Generalised arteriolar narrowing
2. Focal arteriolar narrowing
3. Flame haemorrhages
4. Cotton wool spots
5. Exudates
6. Optic disc swelling
7. Arteriolar macroaneurysms
8. Microaneurysms

Question 6

What is retinopathy of prematurity (ROP)?

Answer 6

A fibrovascular retinal proliferative disorder which occurs in premature and low birth weight babies.

Its development is associated with a high inhaled oxygen concentration during the neonatal period. Other less-well defined risk factors include maternal smoking, neonatal sepsis and blood transfusion.

Question 7

When is normal development of retinal vascularisation complete?

Answer 7

Full-term gestation.

It is thought that in the premature baby, normal retinal vascularisation ceases, perhaps because of adequate oxygenation from the inspired air, then either continues normally (resolved ROP) or proceeds in an abnormal manner, vessels growing forwards into the vitreous cavity. These vessels may bleed. The associated fibrous component can contract, detaching the retina.

Question 8

What are the clinical features of active ROP?

Answer 8

Active ROP may progress through 5 stages of increasing severity, culminating in total retinal detachment.
S1: demarcation line between vascular and avascular retina.
S2: an elevated ridge at the demarcation line.
S3: fibrovascular proliferation from the ridge into the vitreous cavity.
S4: subtotal retinal detachment
S5: total retinal detachment. Fibrous tissue contracts and detaches the retina, like tightening purse string. Surgery not successful.

Question 9

What is a positive prognostic factor for ROP?

Answer 9

The more anterior the limit of vascularised retina at the time of development of active ROP (the ‘zone’ of ROP), the better the prognosis.

Spontaneous regression of earlier stages occurs without intervention in a majority, but sequelae may still cause sight loss.

Question 10

Which three ‘plus’ disease changes in ROP have poor prognostic significance?

Answer 10

1. Dilated veins and tortuous arteries at the posterior pole
2. Vitreous haemorrhage
3. Iris vascularisation (rubeosis)

Question 11

Which three ocular issues are premature babies also susceptible to, in addition to ROP?

Answer 11

1. Strabismus
2. Myopia
3. Intracranial haemorrhage causing cortical blindness

Question 12

When is screening recommended for ROP?

Answer 12

Babies born at or less than 31 weeks gestational age, or less than 1500g at birth.

Dilated fundal examination is carried out regularly from 6 or 7 weeks after birth until the nasal retina is fully vascularised.
A very premature subgroup are screened more intensely.

Question 13

When is treatment indicated for ROP?

Answer 13

When there is ‘threshold disease’: defined as extensive stage 3 changes. This is the severity of disease that is likely to progress to visual loss, and at which the benefits of Rx outweigh the risks.

The avascular area is ablated using either cryotherapy or the indirect laser to induce regression of abnormally growing new vessels.

Question 14

What is sickle-cell retinopathy?

Answer 14

It is caused by the impaction of deformed red cells (due to mutant haemoglobin) in the retinal vasculature, leading to occlusion and ischaemia.

Question 15

What is the most common and the least severe combination of abnormal haemoglobin?

Answer 15

Haemoglobin S combined with haemoglobin A (sickle trait).
Hb S is common in blacks but extremely rare in whites.

Paradoxically, sickle cell disease (pure haemoglobin S) does not cause the most severe retinopathy.

Question 16

Name two systemic manifestations and two ocular manifestations of sickle-cell disease.

Answer 16

1. Anaemia
2. Sickle crisis
   Ocular:
3. Proliferative retinopathy: develop after vascular occlusikn and arteriovenous anastomosis. The new vessels resemble a fan (‘sea-fan’ neovascularisation. Vitreous haemorrhage, tractional retinal detachment or formation of retinal tears may occur.
4. Non-proliferative retinopathy: black ‘sunburst’ scars and ‘salmon-patch’ retinal haemorrhages are probably a result of infarction. Venous tortuosity is common. Retinal artery or vein occlusion may occur.

Question 17

Management of sickle-cell retinopathy?

Answer 17

Patients with sickle disease should be screened for retinopathy at regular intervals, and observed more frequently if signs develop.
Laser photocoagulation is performed for neovascularisation (ie. ‘sea-fan’ neovascularisation).