RAMB - DEZEMBRO

ickle

cell

retinopathy

: A

literature

review

ssoc

ras

2017; 63(12):1100-1103

1101

observed at the periphery of the retina, resulting in unper-

fused and presumably ischemic areas. Retinal neovessels,

in turn, tend to develop in these areas, but not necessarily.

Individuals with SCD as well as sickle cell trait (AS) are at

increased risk of developing increased intraocular pressure

when they present with hyphema (bleeding in the anterior

chamber of the eye).

Low fetal hemoglobin (HbF) is gen-

erally associated with increased intravascular sickling and

is responsible for several vaso-occlusive complications in

homozygous SS.

In addition, Roy et al. associated prolif-

erative retinopathy with low levels of HbF.

Another possible change cited by Ballas et al.

is glau-

coma, due to high ocular pressure caused by clogging of

the trabecular meshwork and the inflow of aqueous humor.

Vaso-occlusion leads to optic nerve damage, causing visual

impairment even before the occurrence of retinal changes.

Non-proliferative retinopathy can occur with small

intra-retinal hemorrhages, possibly due to ischemic vessel

wall necrosis, called salmon patches; the bleeding then

becomes yellow and then white, disappearing without a

trace. There may also be hyperpigmented lesions in deep-

er or sub-retinal hemorrhages, called black sunbursts

(Figure 2).

Maculopathy occurs as a result of chronic

changes in the perifoveal capillary network.

According to David et al.,

there was macular change

in 14.4% of the patients. However, Clarkson found 4.6%

of this same type of lesion. Both found higher prevalence

in the SS type.

Although proliferative retinopathy has the same

genesis as nonproliferative retinopathy, their progression

differs. It was divided by Goldberg in five stages,

12,18

cor-

relating them with their order of appearance: Stage I is

characterized by definitive arteriolar occlusion, with

consequent retinal hypoxia and rearrangement of adja-

cent capillaries. In the next stage (stage II), the budding

of new vessels begins, with possible dilatation, aiming

to join the vascular and avascular retina. In stage III,

under the action of angiogenic events, pre-retinal neo-

vascularization occurs, forming the so-called retinal sea

fans.

These new vessels develop from arteriovenous

loops or crossings, and often undergo self-infarctions

probably caused by the unusual characteristics of the

flow. The new vessels are fragile, immature and adherent

to the vitreous. This facilitates the occurrence of vitreous

hemorrhage and characterizes stage IV of proliferative

retinopathy in sickle cell disease. When bleeding reach-

es the visual axis, it causes scotomas and amaurosis. The

repetition of these hemorrhagic phenomena leads to

rupture, retinal detachment and vision loss (stage V), the

final stage of sickle cell proliferative retinopathy.

Sickle cell retinopathy develops in up to 42% of sick-

le cell individuals in the second decade of life.

Vascular

tortuosity is the most common finding (Figure 1), re-

ported by the authors in about 30-50% of cases.

5,19,20

Cury

et al.

found a prevalence of 19.6%, a result that may be

justified by the fact that the study was conducted in chil-

dren only. In addition, about 10-20% of patients will de-

velop proliferative retinopathy,

mainly in the fourth and

fifth decades of life.

iagnosis

In the early stages, the disease is asymptomatic, and me-

ticulous ophthalmologic monitoring should be performed.

Diagnosis is made by retinography and fluorescein angi-

ography in cases with fundoscopic alterations, as well as

measurement of visual acuity and intraocular pressure.

5,7,8,13

reatment

Treatment is performed in different ways, including dia-

thermy, cryotherapy and argon or xenon photocoagulation.

FIGURE 1

Increased vascular tortuosity.

FIGURE 2

“Black sunburst.”