Sickle cell retinopathy in Jamaican children: further observations from a cohort study

Early diagnosis of sickle cell retinopathy by using ocular coherence tomography in pediatric population (7-18 years) in central India

BACKGROUND

Sickle cell disease (SCD) is the commonest inherited blood disorder leading to complications occurring due to vaso-occlusion including sight-threatening retinopathy. Retinopathy can be managed if diagnosed early and vision loss can be prevented. Since, very less data are available from India, hence, this study was conducted in children (7-18 years) with SCD to diagnose retinopathy by using ocular coherence tomography (OCT) in subclinical stages.

METHODS

This cross sectional single-center study was performed in 7-18 years age group children with SCD without any visual symptoms. Enrolled participants underwent complete ophthalmological examination including macula and optic disc thickness measurements using Cirrus HD-OCT and results were analyzed.

RESULTS

Among 55 participants, none had visual impairment. Significant fundoscopy finding (nonproliferative sickle cell retinopathy/NPSR) was found in three patients (5.4%), thinning of central macula in four patients (7.27%), inner macula thinning in eight patients (14.5%), outer macula thinning in one patient (1.81%), retinal nerve fiber layer thinning in five patients (9%), ganglion cell layer to inner plexiform layer thinning in eight patients (14.54%). Overall NPSR was found in 5.4% patients detected with fundoscopy, whereas retinal layer thinning was found in 14 patients (25.4%) using OCT.

CONCLUSION

Despite of the significant prevalence of SCR, it is still underdiagnosed complication, leading to thinning of the retina from early ages; thus, its early diagnosis by regular screening using newer diagnostic methods can prevent progression to sight-threatening complications and provide better quality of life for these patients.

Monitoring retinal pathology and cerebral injury in sickle cell disease using spectral-domain optical coherence tomography in pediatric patients

PURPOSE

This study aimed to confirm the correlation between sickle cell disease (SCD) genotype and retinal damage identified by spectral-domain optical coherence tomography (SD-OCT), and examine a potential link between hypoxic ischemic injury in the retina and brain.

METHODS

In this prospective, observational case series, 117 patients (56 males) aged 5-20 years with SCD (36 SC, 68 SS, eight Sβ+ thalassemia, five Sβ0 thalassemia) underwent ophthalmologic examination including funduscopy and SD-OCT imaging. Comparison of SCD genotypes and association between ocular findings and cerebrovascular disease (CVD) in subjects with SS/Sβ0 genotype were investigated.

RESULTS

Visual acuity ranged from 20/20 to 20/40. On funduscopic exam, 16 of 117 (13.7%) had retinopathy; 69 of 117 (59.0%) showed inner retina thinning on SD-OCT. Patients with SS/Sβ0 showed a higher frequency of sickle cell retinopathy (SCR) change (68.5% vs. 47.2%), bilateral SCR (49.9% vs. 25.0%), and foveal involvement (15.1% vs. 0) than the SC genotype. While funduscopic findings in our cohort with SS/Sβ0 genotype showed no correlation with CVD, 20 of 21 patients with CVD had abnormal SD-OCT. Elevated reticulocyte percentage and aspartate aminotransferase are associated with SD-OCT changes and CVD.

CONCLUSIONS

SD-OCT was better than funduscopy in detecting retinal changes, higher frequency, and more extensive retinal changes in the more severe SCD genotypes SS and Sβ0 as compared with SC. The correlation between abnormal SD-OCT and CVD strongly suggests that retinal exam using SD-OCT may aid in detection and monitoring SCD-related CVD. Retinopathy may be another component of the hemolytic subphenotype of SCD.

Varied Age of First Presentation of Sickle Cell Disease: Case Presentations and Review

Sickle cell disease is a multisystem condition characterized by hemolytic anemia and vasoocclusion. Not only are the symptoms of the first presentation but also the ages of presentation are very variable. Following three case reports, different causes of possible late presentation are discussed. Many factors are responsible for the age at which sickle cell disease is diagnosed: doctor's delay (unfamiliarity with the disease), patient's delay (education and financial position of the parents, cultural factors), high- versus low-resource country (availability of newborn screening), fetal hemoglobin, reticulocyte count, and genetic modulators, such as SCD genotype, alpha-thalassemia, fetal hemoglobin concentration, and G6PD deficiency. The individual course of sickle cell disease depends on (epi) genetic and environmental properties and the underlying interactions. In further studies, the role of each factor should be evaluated more deeply, and its use as a marker of disease severity or activity should be assessed.

Dark without pressure retinal changes in a paediatric age group

BACKGROUND/OBJECTIVES

We aim to describe the clinical and imaging characteristics of young children with dark without pressure- a well-defined area of dark retina in the mid periphery associated with attenuated hyperreflective outer segment bands on spectral domain OCT.

SUBJECTS/METHODS

Retrospective medical chart review. We reviewed the charts and retinal images of children with dark without pressure (DWP) seen in the paediatric eye clinic that had undergone retinal imaging.

RESULTS

We identified 6 children (3 males, 3 females) ranging in age from 3 to 13 years with DWP lesions. These were an incidental finding in children referred for other disorders. The lesions spared the macula and were typically in the mid-peripheral retina. In those children who could cooperate with detailed imaging, the DWP lesions were hypoautofluorecent on fundus autofluorescence imaging and OCT imaging showed reduced reflectance of the outer segments and EZ line as has been described in older children and adults. In two of the six subjects a DWP lesion appeared in an area of previously normal fundus; in no subjects did the lesion resolve over the period of follow up.

CONCLUSIONS

The clinical and imaging characteristics of DWP lesions are similar in young children to those described in adults. The site of dysfunction appears to be at the level of the outer retina, but the precise cause is unknown. Recognition of this benign disorder will prevent patient anxiety and unnecessary further investigation.

Retinal Thickness and Microvascular Changes in Children With Sickle Cell Disease Evaluated by Optical Coherence Tomography (OCT) and OCT Angiography

PURPOSE

To compare the severity of macular vascular changes in children with sickle cell disease (SCD) vs age- and race-matched controls.

DESIGN

Cross-sectional study.

METHODS

Children (<18 years old) with HbSS and HbS variant (HbSC and HbS thalassemia) genotypes, and their age- and race-matched controls, were recruited between January 2017 and December 2018. All subjects underwent optical coherence tomography angiography (OCTA) scans centered on the fovea and temporal macula. Retinal thickness, superficial capillary plexus (SCP) and deep capillary plexus (DCP) vessel density (VD), and foveal avascular zone (FAZ) size were measured and compared between HbSS and HbS variant vs controls.

RESULTS

Thirty-four HbSS, 34 HbS variant (Goldberg staging 0-3 for SCD eyes), and 24 control eyes (total 48 children, aged 5-17 years) were included. Total VD (3-mm ETDRS circle) was lower in HbS variant eyes than in controls for both the SCP (42.9% vs 47.7%, P = .02) and DCP (47.4% vs 52.6%, P = .01). In HbSS eyes, VD was lower in the DCP (47.7%, P = .008) but not in the SCP (45.5%, P = .5), compared to controls. A higher proportion of HbSS (n = 18, 55%) than HbS variant eyes (n = 9, 26%) had pathologic areas of retinal thinning associated with SCP and DCP flow loss (P = .03). However, retinal thickness measurements and FAZ size did not differ between either HbSS or HbS variant group vs controls.

CONCLUSIONS

Children with SCD have similar retinal thickness but less dense vasculature on OCTA compared to age and race-matched controls, suggesting that microvascular insult may precede structural thinning.

Sickle cell retinopathy. A focused review

PURPOSE

To provide a focused review of sickle cell retinopathy in the light of recent advances in the pathogenesis, multimodal retinal imaging, management of the condition, and migration trends, which may lead to increased prevalence of the condition in the Western world.

METHODS

Non-systematic focused literature review.

RESULTS

Sickle retinopathy results from aggregation of abnormal hemoglobin in the red blood cells in the retinal microcirculation, leading to reduced deformability of the red blood cells, stagnant blood flow in the retinal precapillary arterioles, thrombosis, and ischemia. This may be precipitated by hypoxia, acidosis, and hyperosmolarity. Sickle retinopathy may result in sight threatening complications, such as paracentral middle maculopathy or sequelae of proliferative retinopathy, such as vitreous hemorrhage and retinal detachment. New imaging modalities, such as wide-field imaging and optical coherence tomography angiography, have revealed the microstructural features of sickle retinopathy, enabling earlier diagnosis. The vascular growth factor ANGPTL-4 has recently been identified as a potential mediator of progression to proliferative retinopathy and may represent a possible therapeutic target. Laser therapy should be considered for proliferative retinopathy in order to prevent visual loss; however, the evidence is not very strong. With recent development of wide-field imaging, targeted laser to ischemic retina may prove to be beneficial. Exact control of intraoperative intraocular pressure, including valved trocar vitrectomy systems, may improve the outcomes of vitreoretinal surgery for complications, such as vitreous hemorrhage and retinal detachment. Stem cell transplantation and gene therapy are potentially curative treatments, which may prevent retinopathy.

CONCLUSIONS

There is lack of evidence regarding the optimal management of sickle retinopathy. Further study is needed to determine if recent progress in the understanding of the pathophysiology and diagnosis of sickle retinopathy may translate into improved management and outcome.

Funduscopic examination and SD-OCT in detecting sickle cell retinopathy among pediatric patients

PURPOSE

To compare the results of fundus examination and spectral domain optic coherence tomography (SD-OCT) in detecting retinal changes in pediatric patients with sickle cell disease at a single center.

METHODS

In this prospective study, conducted over a period of 19 months, consecutive African American patients with sickle cell disease underwent complete ophthalmologic examination, and SD-OCT images of the maculas of both eyes were obtained.

RESULTS

A total of 69 (37 males) patients aged 5-20 years (mean 12.89 ± 4.09; range, 2-20) with sickle cell disease (SC, 26; SS, 36; Sβ+, 5; Sβ0 thalassemia, 2) were examined. Patients' visual acuity range was 20/20 to 20/40. On funduscopic examination, 11 of 69 showed signs of retinopathy, whereas 47 of 68 showed inner retina thinning in the watershed zone temporal to the fovea on SD-OCT. On average, SD-OCT diagnosed disease 1.78 years earlier than fundus examination. Of patients <10 years of age, 1 was diagnosed with retinopathy by funduscopy, whereas retinal changes were evident on SD-OCT in 12 of 22. Fundus examination showed no significant difference in retinal findings between SS/Sβ0 and SC genotypes. On SD-OCT, SS/Sβ0 showed worse disease process than SC in frequency of diagnosis (82% vs 56%), bilateral involvement (87% vs 43%), and foveal involvement (18% vs 0).

CONCLUSIONS

The peripheral retina could be visualized on fundus examination but not easily imaged on SD-OCT, which, however, had a higher detection rate and offered earlier diagnosis. In our patient cohort SD-OCT showed that the severity of retinal change was associated with more severe sickle cell disease genotypes (SS and Sβ0).

Genetic modifiers of severity in sickle cell disease

Sickle cell disease (SCD) is one of the most common single disease disorders world-wide. It is remarkable for its clinical heterogeneity, even among individuals with identical genotypes. Some individuals experience morbidity and mortality in early childhood, while others have a relatively mild course, and normal or near normal life expectancy. Many clinical complications are associated with SCD; most notably frequent pain episodes, stroke, acute chest syndrome, avascular necrosis, nephropathy, retinopathy and pulmonary hypertension. While the effects of higher fetal hemoglobin (HbF) levels, UGTA1A polymorphisms, alpha-thalassemia and G6PD deficiency on SCD has been extensively studied, these variables do not explain all of the clinical heterogeneity of SCD. It is not known why some patients develop certain complications, and it is difficult to predict which complications a particular patient will experience. Much work has been done to identify genetic variants associated with these disease complications; many associations remain unvalidated. As the field continues to move beyond small sample collections and candidate gene approaches into whole genome sequencing and merging of samples from all over the world, we will identify more genetic variants associated with development of specific SCD related complications, and hopefully leverage this knowledge into targeted therapies.

Sickle cell retinopathy: A literature review

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.

Sickle cell retinopathy and other chronic complications of sickle cell anemia: A clinical study of 84 Sub-Saharan African cases (Cameroon)

OBJECTIVE

Sickle retinopathy is a severe complication of sickle cell disease than can lead to blindness. We aim to describe the epidemiology of sickle retinopathy in homozygous sickle cell (SS) African patients and to analyze its association with non-ophthalmologic disease complications of sickle cell anemia.

METHODS

We conducted a nested study within the CADRE cohort in Cameroon. Eighty-four consecutive SS outpatients, aged 10 years and older, with no visual symptoms, underwent an ophthalmologic examination. Mean age was 23±10 years. Clinical and biological features were compared between patients with and without sickle retinopathy. We compared the prevalence of the clinical complications and main biological characteristics in patients with and without sickle retinopathy using a univariate logistic regression. The same analysis was used to compare the patients with non-proliferative sickle retinopathy to those with proliferative sickle retinopathy. Statistical analyses were done using the R software (version 3.1.2).

RESULTS

Fifty-two patients (62%) displayed sickle retinopathy, among them 23 (27%) had a non-proliferative sickle retinopathy, and 29 (35%) had proliferative sickle retinopathy. Patients with proliferative sickle cell retinopathy had a mean age of 28±11 years. Sickle retinopathy was associated with higher hemoglobin level (P=0.047) and fewer leg ulcers (P=0.018). Proliferative SR was associated with increasing age (P=0.008) and male sex (P=0.025) independently of the hemoglobin level.

CONCLUSIONS

Sickle retinopathy is particularly frequent in sub-Saharan sickle cell SS patients, which advocates for early systematic screening.

New Ways to Detect Pediatric Sickle Cell Retinopathy: A Comprehensive Review

Sickle retinopathy reflects disease-related vascular injury of the eye, which can potentially result in visual loss from vitreous hemorrhage or retinal detachment. Here we review sickle retinopathy among children with sickle cell disease, describe the epidemiology, pediatric risk factors, pathophysiology, ocular findings, and treatment. Newer, more sensitive ophthalmological imaging modalities are available for retinal imaging, including ultra-widefield fluorescein angiography, spectral-domain optical coherence tomography, and optical coherence tomography angiography. Optical coherence tomography angiography provides a noninvasive view of retinal vascular layers that could previously not be imaged and can be quantified for comparative or prospective analyses. Ultra-widefield fluorescein angiography provides a more comprehensive view of the peripheral retina than traditional imaging techniques. Screening for retinopathy by standard fundoscopic imaging modalities detects a prevalence of approximately 10%. In contrast, these more sensitive methods allow for more sensitive examination that includes the retina perimeter where sickle retinopathy is often first detectable. Use of these new imaging modalities may detect a higher prevalence of early sickle pathology among children than has previously been reported. Earlier detection may help in better understanding the pathogenesis of sickle retinopathy and guide future screening and treatment paradigms.

Optical Coherence Tomography Angiography and Ultra-widefield Fluorescein Angiography for Early Detection of Adolescent Sickle Retinopathy

PURPOSE

Based on standard screening techniques, sickle retinopathy reportedly occurs in 10% of adolescents with sickle cell disease (SCD). We performed a prospective, observational clinical study to determine if ultra-widefield fluorescein angiography (UWFA), spectral-domain optical coherence tomography (SD-OCT), and optical coherence tomography angiography (OCT-A) detect more-frequent retinopathy in adolescents with SCD.

DESIGN

Cross-sectional study.

METHODS

Setting: Institutional.

SUBJECTS

Sixteen adolescents with SCD, aged 10-19 years (mean age 14.9 years), and 5 age-equivalent controls (mean age 17.4 years).

OBSERVATION PROCEDURES

Examinations including acuity, standard slit-lamp biomicroscopy, UWFA, SD-OCT, and OCT-A were performed.

MAIN OUTCOME MEASURES

Sickle retinopathy defined by biomicroscopic changes, Goldberg stages I-V, Penman scale, flow void on OCT-A, or macular thinning on SD-OCT.

RESULTS

While 22 of 32 SCD eyes (68.8%) had retinopathy on biomicroscopy, by UWFA 4 of 24 (16.7%) SCD eyes had peripheral arterial occlusion (Goldberg I), and 20 of 24 eyes (83.3%) had peripheral arteriovenous anastomoses (Goldberg II) in addition. No patients had Goldberg stages III-V. By SD-OCT and OCT-A, thinning of the macula and flow voids in both the superficial and deep retinal capillary plexus were found in 6 of 30 (20%) eyes.

CONCLUSIONS

All 24 eyes with adequate UWFA studies demonstrated sickle retinopathy. SD-OCT and OCT-A, which have not been previously reported in the adolescent population, detected abnormal macular thinning and flow abnormalities undetected by biomicroscopy. These findings suggest that pediatric sickle retinopathy may be more prevalent than previously suspected. If these findings are confirmed with larger cross-sectional and prospective analyses, these approaches may enhance early screening for sickle retinopathy.

Ocular manifestations in egyptian children and young adults with sickle cell disease

In sickle cell disease (SCD), ocular lesions result from stasis and occlusion of small eye vessels by sickled erythrocytes. Vaso-occlusive disease of the retina can be responsible for nonproliferative (NPR) and proliferative retinopathy (PR). Patients are often asymptomatic until serious complications arise as, vitreous hemorrhage and retinal detachment. This work aimed to study the frequency and pattern of ocular manifestations in Egyptian children and young adults with SCD. In this cross-sectional study, 40 steady state patients (80 eyes) aged 2-28 years (30 children and 10 young adults) with established diagnosis of SCD (26 with homozygous SS and 14 with S/β thalassemia underwent complete ophthalmic examination with dilated fundoscopy. Fluorescein angiography was performed for patients ≥12 years old. The overall frequency of retinal lesions was 47.5 % (46.2 and 50 % of SS and S/β patients respectively). PR and NPR were evident in 32.5 and 27.5 % of all enrolled patients respectively (five patients having both). Peripheral retinal occlusion was a frequent ocular finding in both groups; the youngest patient showing PR was 15 years old. Older age, longer disease duration and splenectomy were significantly more prevalent among patients with PR. Despite lack of visual symptoms, children and young adults are at risk of PR. Frequency of retinal lesions was comparable in SS and S/β patients. Periodic ophthalmologic examination starting at the age of 12 years is recommended for timely-identification of retinal lesions thus minimizing the risk of sight threatening retinopathy.

Clinical and laboratory factors associated with the severity of proliferative sickle cell retinopathy in patients with sickle cell hemoglobin C (SC) and homozygous sickle cell (SS) disease

Proliferative sickle cell retinopathy (PSCR) is the most frequent vision-threatening complication of sickle cell disease (SCD). We investigated the relationship between the severity of sickle cell retinopathy in heterozygous (SC) or homozygous (SS) adult SCD patients and the clinical and laboratory data obtained during visits to a national SCD referral center. This retrospective longitudinal analysis included 942 SCD patients (313 patients with SC and 629 with SS disease) with ophthalmologic evaluations who were followed over a 19-year period by a multidisciplinary team in a referral center. PSCR was graded using the Goldberg classification. We identified patient and SCD characteristics associated with sickle cell retinopathy severity using multinomial logistic-regression models. Multivariate analysis associated severe PSCR forms (stages III-V) with older age (p=0.032), pulmonary involvement (documented pulmonary hypertension with pulmonary arterial pressure≥40 mm Hg, restrictive syndrome>20%, or previous history of pulmonary embolism diagnosed by vascular imaging) (p=0.029), deafness or tinnitus (p=0.026), and no history of osteomyelitis (p=0.013) for SC patients; and with older age (p<0.001), male sex (p=0.003), and acute pyelonephritis (p=0.04) for SS patients. The model of severe PSCR versus no PSCR showed good calibration and discrimination for SC and SS patients. Awareness of the clinical and laboratory factors significantly associated with severe PSCR in patients with SC or SS SCD may contribute to improved preventive strategies.

Pediatric sickle cell retinopathy: correlation with clinical factors

BACKGROUND

Sickle cell disease (SCD) occurs in 1 of every 500 African American births and 1 of every 36,000 Hispanic American births. Of children with SCD, 16.7% to 96.3% develop sickle retinopathy (SR). This study was designed to determine whether certain factors are associated with SR and whether SR is correlated with a greater incidence of other SCD manifestations.

METHODS

A retrospective analysis was performed of 258 children with SCD seen in the ophthalmology clinic at a large urban children's hospital. Of these, 54 children with SR were matched for age and sickle variant with 54 children with normal examinations. Data extracted included demographics, type of retinopathy, presence of glucose-6-phosphate dehydrogenase (G6PD) deficiency, and history of acute chest syndrome, transfusions, pulmonary hypertension, renal disease, cerebrovascular accident, aplastic crisis, splenic sequestration, priapism, osteonecrosis, gallstones, pneumonia, leg ulcers, vaso-occlusive pain crises, and death.

RESULTS

Of the children with SR, 11 (20.3%) had active proliferative disease, 32 (56.1%) had hemoglobin SS, 18 (31.6%) had hemoglobin SC, and 4 (7.0%) had hemoglobin S-beta thalassemia. Several factors were correlated with retinopathy: pain crisis (odds ratio [OR], 5.00; p=0.011), male sex (OR, 4.20, p=0.004), and splenic sequestration (OR, 4.00; p=0.013). G6PD deficiency was more common in patients with retinopathy, although this was not statistically significant (OR, 4.20; p=0.054). No other factors, including frequency of pain crisis, were statistically significant.

CONCLUSIONS

Patients with pain crisis and splenic sequestration should be considered for early ophthalmic evaluation. Those with G6PD deficiency may also deserve early screening. By identifying patients at high risk for SR, we can refine screening protocols to safeguard patients from vision loss.

Health status and healthcare use in a national sample of children with sickle cell disease

BACKGROUND

There is a paucity of population-based data describing health status and use of health services among children with sickle cell disease (SCD).

PURPOSE

This study provides estimates of co-occurring conditions, health impact and utilization, and barriers to care for a national sample of children with SCD.

METHODS

Data were derived from the 1997-2005 National Health Interview Survey Child Sample Core. The study included 192 children aged 0-17 years with SCD whose race was reported as black or African-American, and 19,335 children without SCD of the same age and race. Parents or other knowledgeable adults reported on medical and developmental conditions, health status, and healthcare use and access.

RESULTS

After adjusting for demographic characteristics, black children with SCD had higher odds of frequent severe headaches or migraines, intellectual disabilities, regular use of prescription medication, and fair or poor health status compared with black children without SCD. While healthcare and special education services use were generally higher for black children with SCD than for black children in the general population, those with SCD also had higher odds of reporting delays in accessing health care.

CONCLUSIONS

The health burden for children with SCD and their families is profound and may be exacerbated by barriers to accessing comprehensive medical care. Additional study of the extent of unmet needs for U.S. children with SCD is warranted.

[Epidemiology and prognostic factors for sickle cell retinopathy in Ouagadougou (Burkina Faso)]

INTRODUCTION

The frequency of sickle cell disease varies from 5% to 20% in Africa.

PATIENTS AND METHOD

This retrospective study investigated 173 patients in an ambulatory setting from August 2000 to July 2006. The study included 98 women and 75 men, aged 15-62 years, with a mean age of 26.7 years.

RESULTS

Only 89 patients (71 SC and 18 SS) were seen in ophthalmology, 44 (49%) had sickle cell retinopathy with 26 (29%) cases nonproliferative and 18 cases proliferative (20%). Among the 71 SC patients, 35 (50%) had sickle cell retinopathy, with 40% the proliferative form. Of the 18 SS patients, nine had a retinopathy (50%), with four cases proliferative.

DISCUSSION

Retinopathy is a frequent complication of sickle cell disease, which can lead to blindness, and its management better accessibility to the ophthalmologic examination and preventive treatment by laser photo coagulation.

Retinal hemorrhage and pediatric brain injury: etiology and review of the literature

Retinal hemorrhages have long been linked with child abuse and, in particular, the "shaken baby/shaking-impact" syndrome. However, the presence of retinal hemorrhages is neither necessary nor sufficient for the diagnosis of child abuse. Additionally, retinal hemorrhages are also associated with an ever-expanding list of conditions, each of which carries important implications for patients and their families. To correctly interpret a patient's retinal hemorrhages, the physician requires a broad knowledge base, including of child abuse, the "shaken baby/shaking-impact" syndrome, the differential diagnosis of retinal hemorrhages and the types of retinal hemorrhage and their diagnostic implications. We review the literature regarding types of retinal hemorrhage and their associated etiologies.

Angiogenic factors in human proliferative sickle cell retinopathy

BACKGROUND/AIMS

Preretinal neovascular formations called sea fans develop at the border of non-perfused peripheral retina in sickle cell retinopathy. Angiogenic factors which could contribute to their development, however, have not been examined previously. The objective of this study was to determine immunohistochemically if vascular endothelial growth factor (VEGF) or basic fibroblast growth factor (bFGF) were associated with sea fan formations.

METHODS

Immunohistochemistry on cryosections was used to localise bFGF, VEGF, heparan sulphate proteoglycan, human serum albumin, collagens IV and II, and von Willebrand factor in tissue from five sickle cell and one control subject.

RESULTS

The greatest immunoreactivity for VEGF and bFGF was in the feeder and preretinal vessels of sea fans (p<0.01). The most prominent reaction product was localised to vascular endothelial cells. In retinal vessels, VEGF and bFGF immunoreactivities were greater in sickle cell subjects (both proliferative and non-proliferative) than in the control subject (p<0.01 and p<0.02 respectively). In the sickle cell retina, no angiogenic factor immunoreactivity was detected in non-perfused periphery and there was no significant difference in bFGF or VEGF immunoreactivity between perfused retina and the border of perfused and non-perfused areas.

CONCLUSION

Our results demonstrate for the first time that VEGF and bFGF are associated with sea fan formations in sickle cell retinopathy. Both factors may function in an autocrine manner because immunoreactivity for these factors was greater within the neovascularisation than in adjacent retina.

Nonperfusion of retina and choroid in transgenic mouse models of sickle cell disease

PURPOSE

To determine if vascular occlusion and nonperfusion is associated with the outer retinal atrophy, retinopathy, and choroidopathy (chorioretinopathy) that occurs in the alpha H beta S[beta MDD] and alpha H beta S [alpha MD beta MDD] transgenic mouse models of sickle cell disease.

METHODS

Mice from the alpha H beta S[beta MDD] and alpha H beta S[alpha MD beta MDD] transgenic mouse lines that express high levels of human beta S globin were anesthetized and administered horseradish peroxidase (HRP) intracardially. After 1 min, the animals were sacrificed, and the retina from one eye was excised, fixed, and developed in diaminobenzidine (DAB). The contralateral eye was fixed, embedded whole in glycol methacrylate, and HRP developed in 2.5 microns sections.

RESULTS

HRP reaction product (HRP-RP) and stained erythrocytes (RBCs) (due to endogenous peroxidase) were diffusely distributed within all vascular lumens in flatmount retinas from control animals (littermates homozygous for the mouse Beta Major deletion not expressing the beta S transgene). In 42.5% of the transgenic mice expressing beta S without any proliferative retinopathy, many blood vessels contained RBC plugs and lacked lumenal HRP-RP. In addition to packed RBCs, fibrin was sometimes present at sites of occlusion. In sections from whole eyes of the same animals, foci of photoreceptor degeneration were associated with areas of choriocapillaris nonperfusion (lumen that lacked HRP-PR). In areas with normal photoreceptors, the choriocapillaris appeared perfused (HRP-RP was present). In animals with proliferative chorioretinopathy, some neovascular formations lacked luminal HRP-RP, suggesting autoinfarction.

CONCLUSIONS

Nonperfused retinal and choroidal vessels were observed in mice from the alpha H beta S[beta MDD] and alpha H beta S[alpha MD beta MDD] lines without retinal and choroidal neovascularization, whereas, all mice with neovascularization had nonperfused areas. Furthermore, small foci of PR loss were associated with areas of nonperfused choriocapillaris. These results suggest that sickle cell-mediated vaso-occlusions are an initial event in the chorioretinopathy and outer retinal atrophy that occurs in these models.

Pathophysiology of vaso-occlusion

Sickle cell anemia is a very complex disease. Vascular occlusion, the major event that accompanies SS, is itself a complex and multifactional process. Microvascular occlusion results in acute painful crises, whereas macrovascular occlusion seems to be the cause of organ failure. Understanding the basic pathophysiologic events of vascular occlusion may elucidate the clinical manifestations of SS, its natural history, and complications, and it may give new insights into preventive and curative therapy.

Eye disease in sickling disorders

When treating patients with sickling disorders, hematologists and oncologists should know those eye lesions that require referral to an ophthalmologist, those that should lead to referral, and those that rarely are associated with decreased vision. Hyphema in any patient whose red cells contain hemoglobin S falls into the first category. Retinal neovascularization (proliferative retinopathy) and its consequence vitreous hemorrhage fall into the second. The comma sign, angioid streaks, and abnormal color vision fall into the third category. The roles of preoperative transfusion and experimental antisickling therapy in treatment and prevention of eye lesions are incompletely defined at present.

Ocular findings in Saudi Arabian patients with sickle cell disease

AIM

This study was set up to determine whether or not retinal changes occur in sickle cell disease in Saudi Arabian subjects with either the Benin, which exists in the south western part of the kingdom, or Asian haplotypes in the east, and to compare the findings with those in sickle cell disease in Jamaica.

METHODS

Retinal examination and fluorescein angiography were performed in 61 patients with SS disease (40 eastern, 20 south western, 1 central region) and 10 with sickle cell beta(0) thalassaemia.

RESULTS

Peripheral retinal vascular changes were common, and a qualitatively abnormal vascular border believed to imply risk of proliferative sickle retinography (PSR) was significantly more common in south western SS patients and PSR was shown in one of these. There were no differences in visual acuity, the presence of peripheral retinal patches, or the circumferential or posterior extent of peripheral retinal vessel closure between SS disease and sickle cell beta(0) thalassaemia or between SS disease in the two regions. Compared with the Jamaican Cohort Study, > 180 degrees of the peripheral retinal vasculature was seen significantly less frequent, suggesting factors inhibiting vascular remodeling in Saudi patients in early life.

CONCLUSION

Sickle cell disease in Saudi Arabia affects the retina and represents a potential threat to vision. Changes occur whatever the haplotype, and is similar to that observed in Jamaica.

Screening for ophthalmic manifestations of sickle cell disease in the United Kingdom

There are marked variations in the manifestations of sickle disease in different populations. The ocular complications of this condition amongst the Afro-Caribbeans living in the United Kingdom have not previously been reported. We present the preliminary results of an ophthalmic screening programme at King's College Hospital, London. One hundred eyes of 50 patients with sickle cell disease were assessed. Full ocular examination was performed including fundus fluorescein angiography. We have looked at the haematological and clinical profile of the patients involved as well as the number of days spent in hospital during the year preceding the eye examination. The incidence of grade II retinopathy was found to be significantly higher than grade I in SC disease. This concurs with the results of the Jamaican screening and confirms that these patients are at higher risk of visual impairment than those with SS disease. Our results also agree with the Jamaican experience which suggest that visual morbidity is mostly due to complications of proliferative sickle retinopathy (PSR). However, the findings in patients without proliferative changes are different; in particular, angioid streaks leading to disciforms are an important cause of visual loss in Jamaica, but were not seen in any of the 98 eyes examined in this study. No correlation was found between the grade of retinopathy and age, sex, systemic complications and various haematological parameters except for the percentage of haemoglobin F, which was significantly higher in patients with grade I (7.6) compared with grade II (4.2) retinopathy (p = 0.0127).

New classification of peripheral retinal vascular changes in sickle cell disease

The systemic complications of homozygous sickle cell disease (SS) are more severe than in sickle cell haemoglobin C (SC) disease, and yet visual loss due to proliferative retinopathy is more common in the latter. This anomaly is unexplained. It is believed that proliferative disease occurs in response to closure of the peripheral retinal vasculature, yet a systematic longitudinal survey of the peripheral retinal vascular bed has not been undertaken. In the Jamaica Sickle Cohort study all subjects are scheduled to receive annual ocular examination and fluorescein angiography. The results have now been analysed in subjects with SS and SC disease using a new classification system based on a comparison of the peripheral retinal vascular bed with that recorded in the cohort with normal haemoglobin (AA) genotype. The vascular patterns could be classified as qualitatively normal (type I) or abnormal (type II). An abnormal vascular pattern was identified more commonly with age, in a significantly larger proportion of subjects with SC than SS disease, and was associated with the development of proliferative disease. In order to establish the dynamics of change, the angiograms were analysed in the 18 subjects (24 eyes) who developed proliferative disease. It is shown that a qualitatively normal vascular pattern may be retained despite loss of capillary bed and posterior displacement of the vascular border. A border which is qualitatively abnormal does not revert to normal, and once abnormal, continuous evolution may occur before development of proliferative lesions. The peripheral border of the retinal vasculature was too peripheral to photographed in 13 of the 24 eyes before it becoming qualitatively abnormal. It is concluded that a normal border, if posterior, results from gradual modification of the capillary bed and indicates low risk of proliferative disease. A qualitatively abnormal vascular border occurs as a radical alteration of retinal perfusion in subjects in whom little modification of the vascular bed occurred before the event, and signals risk of proliferative disease. This classification system is useful in identifying the likelihood of threat to vision in young Jamaicans with sickle cell disease, and the higher frequency of proliferative retinopathy in SC can be explained by the higher prevalence of a qualitatively abnormal peripheral retinal vasculature.

Peripheral retinal vasculature in normal Jamaican children

A prospective study of the peripheral retinal vasculature in a Jamaican cohort of subjects with sickle cell disease has been in progress over a period of 12 years using fluorescein angiography. Various vascular patterns were identified but their significance was unclear since no comparable records were available in subjects of a similar age with normal (AA) haemoglobin genotype. Fluorescein retinal angioscopy and angiography have been performed in 76 haemoglobin AA controls participating in the cohort study. The peripheral retinal capillary bed could be seen and photographed in a limited portion of the temporal peripheral fundus in a majority of this group, and there was considerable variation in the vascular pattern which could be characterised. These observations allow deviations from normal to be identified in the retinal vasculature in subjects with sickle cell disease.

Peripheral proliferative retinopathies: an update on angiogenesis, etiologies and management

Many clinical entities may be associated with the development of peripheral retinal neovascularization. In this paper, we review the mechanisms of normal and abnormal angiogenesis in the retina. Specific disease entities associated with peripheral proliferative retinopathies are discussed. These include vascular disease with ischemia, inflammatory diseases with possible ischemia and a variety of miscellaneous causes, including hereditary diseases and tumors. Basic principles for the clinical evaluation of patients with retinal neovascularization are described. Finally, the treatments for retinal neovascularization, including cryopexy and local and panretinal photocoagulation are reviewed, and techniques and possible mechanisms of the beneficial results of treatment are described.

Influence of alpha thalassaemia on the retinopathy of homozygous sickle cell disease

Homozygous alpha+ thalassaemia (alpha-/alpha-) ameliorates some of the clinical manifestations of homozygous sickle cell (SS) disease but its effect on retinal complications remains unknown. This has been assessed by visual examination and fluorescein angiography in 39 subjects with SS disease and homozygous alpha+ thalassaemia and in 39 age/sex matched controls with SS disease but with a normal alpha globin genotype (alpha alpha/alpha alpha). The results indicate that homozygous alpha+ thalassaemia reduces the extent of peripheral retinal vessel closure but has no apparent effect on the frequency of proliferative sickle retinopathy.

Fundus hemorrhages in infancy

The anatomical location and appearance of retinal hemorrhages in the infant provide important clues in the diagnosis of underlying disorders. While neonatal retinal hemorrhages related to birth trauma are common, benign, and self-limited, other retinal hemorrhages in infancy may signify intracranial aneurysms, accidental or non-accidental injury, and a variety of ocular (e.g., Coats' disease, PHPV, ROP, retinal dysplasia, hypertension, myopia) or systemic disease (e.g., hematologic or cardiovascular disorders, infection, protein C deficiency). In this review, retinal hemorrhages are illustrated and classified according to location, appearance, and etiology. Prompt diagnosis of retinal hemorrhages in infants is crucial, because treatment may be required to prevent early deprivation amblyopia and blindness. Ophthalmological findings may also be a valuable contribution to the overall medical evaluation of the infant.

Relationship between peripheral vascular closure and proliferative retinopathy in sickle cell disease

In a study involving 97 patients with hemoglobin SC sickle cell disease (Hb SC) and 87 subjects with hemoglobin SS sickle cell disease (Hb SS) on the island of Curaçao, we found a higher incidence of peripheral retinal vascular closure and proliferative retinopathy in the former as compared with the latter. Examination of composite fluorescein angiograms obtained from 15 Hb SS and 36 Hb SC patients, whose mean and median age were the same and in whom more advanced stages of sickle retinopathy were equally represented, revealed statistically significantly smaller measurements of perfused retina (indicative of larger areas of non-perfusion) in Hb SC patients as compared with Hb SS patients (P = 0.002, P = 0.014) as well as in subjects exhibiting neovascularization as compared with those who did not (P = 0.022, P = 0.004). This suggests that a vaso-occlusive tendency in the retina is greater in individuals with Hb SC than in those with Hb SS; the more extensive ischemic areas provide a stimulus for neovascularization, explaining the higher prevalence of proliferative retinopathy in the former patients as compared with the latter.

Ocular findings in sickle cell patients on Curaçao

We examined about half the estimated number (based on gene frequency) of sickle cell patients on the island of Curaçao. This study may represent one of the most comprehensive and a selective cross-sectional surveys available. Studying 81 Hb SS and 97 Hb SC patients, we were able to confirm the correlation between iris atrophy and proliferative sickle retinopathy (PSR), the correlation between Hb SC and proliferative sickle retinopathy (PSR) and the major role of PSR in blindness in sickle cell patients. In Hb SC patients over the age of 18 PSR occurred in 50%, leading to vitreous hemorrhage in 18% and to retinal detachment in 8%. We found a frequency of blindness in one eye (fingers counting or less) of 4% in the entire sickle population, and 6% among Hb SC patients. Bilateral blindness was rare: one Hb SS patient, due to cortical blindness. The relatively frequent occurrence of severe complications in a narrowly defined population should stimulate our efforts to prevent these from occurring.

Risk factors for proliferative sickle retinopathy

The prevalence, incidence, and risk factors associated with proliferative sickle retinopathy (PSR) were investigated in 786 patients with homozygous sickle cell (SS) disease and 533 patients with sickle cell haemoglobin C (SC) disease. PSR was more common in SC disease, in which there was a significant predominance of males, and it increased with age in both genotypes. In SC disease the risk of developing PSR was highest between 15 and 24 years in males, between 20 and 39 years in females, and in SS disease between 25 and 39 years in both sexes. PSR tended to be bilateral, especially in SC disease. There was no evidence of familial clustering of PSR in SC siblings, and insufficient numbers of SS siblings were available to test for clustering. Haematological risk factors associated with PSR in SS disease were a high haemoglobin in males and a low fetal haemoglobin in both sexes and in SC disease, a high mean cell volume, and a low fetal haemoglobin in females.