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Ribeiro MVMR et al.
1100 Rev Assoc Med Bras 2017; 63(12):1100-1103
REVIEW ARTICLE
Sickle cell retinopathy: A literature review
Marina Viegas Moura Rezende Ribeiro1, João Vitor de Omena Jucá2*, Anna Luyza Correia dos Santos A lves2,
Caio V ictor Oliveira Ferreira2, Fabiano Timbó Barbosa3, Êurica Adélia Nogueira Ribeiro4
1Ophthalmologist, MSc in Health Science, Professor at Universidade Tiradentes, Maceió, AL, Brazil
2Medical Student, Universidade Tiradentes, Maceió, AL, Brazil
3PhD in Health Science, Professor at Universidade Tiradentes, Maceió, AL, Brazil
4PhD in Pharmacology, Professor at Universidade Federal de Alagoas, Health Science Graduate Program, Maceió, AL, Brazil
Summary
Study conducted at Universidade
Tiradentes, Maceió, AL, Brazil
Article received: 5/3/2017
Accepted for publication: 5/22/2017
*Correspondence:
Address: Rua Adolfo Gustavo, 304
Maceió, AL – Brazil
Postal code: 57046-341
Hemoglobinopathies are a group of hereditary diseases that cause quantitative
or qualitative changes in the shape, function or synthesis of hemoglobin. One
of the most common is sickle cell anemia, which, due to sickling of erythrocytes,
causes vaso-occlusive phenomena. Among the possible ocular manifestations,
the most representative is retinopathy, which can lead to blindness if left untreated.
Therefore, periodic ophthalmologic monitoring of these patients is important
for early diagnosis and adequate therapeutic management, which can be done
localy by treating the lesions in the eyes, or systemically.
Keywords: retinal diseases, anemia, sickle cell, review, hemoglobinopathies.
Introduction
Sickle cell disease is the most frequent and disabling
chronic hemolytic anemia in our country. Sickle cell ane-
mia is characterized by the production of abnormal he-
moglobins that deform and stiffen red blood cells, caus-
ing increased blood viscosity and microcirculation
occlusion to varying degrees.1 These hemoglobins are
insoluble at low oxygen concentrations, and tend to crys-
tallize.2 Sickle hemoglobin (HbS) is characterized by a
mutation in the β -globin gene involving a single nucleo-
tide (GAG à GTG) which replaces glutamine with valine
in sixth amino acid position.3,4 The most common geno-
types are homozygous (SS), heterozygous or sickle cell
trait (SA), hemoglobin C trait (SC), hemoglobin D trait
(SD), and thalassemia genotype (S-Thal).1,5-8
The World Health Organization (WHO) estimates
that more than 5% of the world population has some type
of hemoglobinopathy. The estimate of new cases in Bra-
zil is 700 to 1,000 per year, with a prevalence of over 2
million carriers of the HbS gene.9 Sickle cell retinopathy,
the subject of this study, develops in up to 42% of sickle
cell individuals in the second decade of life.10
The systemic manifestations of sickle cell disease may
be neurological, ophthalmologic, cardiac, pulmonary,
gastrointestinal/hepatobiliary, renal/genitourinary, splen-
ic, muscular/skeletal, and growth and developmental
disorders.11 They are more severe in homozygotes for cell
disease (SS) than in heterozygotes with sickle hemoglobin
C (SC), and yet visual loss due to proliferative retinopathy
is more common in the latter. 6
Sickle cell retinopathy is not frequently reported in
the literature, and studies in this regard are very old. This
was one of the motivations for our study, which seeks to
gather the information known and thereby clarify the
progression of the disease, its diagnosis and treatment.
Method
We searched the PubMed (US National Library of Medicine
– National Institutes of Health) database using the fol-
lowing keywords: “retinopathy,” “sickle cell,” “sickle cell
disease” and “sickle cell anaemia.”
Ocular manifestations
Ocular manifestations of sickle cell anemia include or-
bital, conjunctival, uveal, papillary, and especially retinal
changes. 5,7,12 Retinal changes characterize sickle cell reti-
nopathy, which may be non-proliferative or proliferative
and is divided into five stages.1,10,12,13
Among the forms of sickle cell anemia, SS patients
present a more severe systemic clinical picture than those
with type SC. On the other hand, occlusive ocular effects
are more predominant in SC patients, who present only
moderate anemia and higher blood viscosity.5 These vaso-
occlusions occur primarily in younger people, and are first