Retinal thickness measurements in sickle cell patients with HbSS and HbSC genotype

[Evaluation of macular thickness by optical coherence tomography in homozygous SS sickle cell subjects in Yaoundé]

OBJECTIVE

To describe tomographic macular changes in homozygous SS sickle cell patients.

METHODS

In this cross-sectional study, the macular thickness of 42 patients (77 eyes) with sickle cell SS was compared quadrant by quadrant with that of 82 subjects (148 eyes) without sickle cell disease. The measurements were performed using the Topcon Maestro SD-OCT 3D and then mapped onto the 9 quadrants of the macular grid established by the Early Treatment Diabetic Retinopathy Study. The studied variables were: age, gender, number of annual vaso-occlusive events; prophylactic treatment, visual acuity corrected for distance and near, sickle cell retinopathy; mean macular thickness, mean central (foveolar), and mean temporal inner, nasal inner, superior inner, inferior inner, superior outer, inferior outer, nasal outer, and temporal outer retinal thicknesses. The differences were considered statistically significant for P values < 0.05.

RESULTS

Mean macular thickness was 271.3±20.9μm in homozygous SS sickle cell patients versus 272.4±20.9μm in non-sickle cell patients (P=0.891). This decreases with age; for each year, the macula thins by 0.72μm. The central macular thinning rate was 40.26%. There was significant thinning in sickle cell patients in the nasal outer (P=0.05), temporal outer (P=0.002) and inferior inner (P=0.02) quadrants and non-significant thickening in the inferior outer quadrant. The number of vaso-occlusive events was not significantly associated with thinning of these parameters.

CONCLUSION

Optical coherence tomography has made it possible to objectify subclinical macular involvement in homozygous SS sickle cell disease.

Automated Quantitative Assessment of Retinal Vascular Tortuosity in Patients with Sickle Cell Disease

Objective

To quantitatively assess the retinal vascular tortuosity of patients with sickle cell disease (SCD) and retinopathy (SCR) using an automated deep learning (DL)-based pipeline.

Design

Cross-sectional study.

Subjects

Patients diagnosed with SCD and screened for SCR at an academic eye center between January 2015 and November 2022 were identified using electronic health records. Eyes of unaffected matched patients (i.e., no history of SCD, hypertension, diabetes mellitus, or retinal occlusive disorder) served as controls.

Methods

For each patient, demographic data, sickle cell diagnosis, types and total number of sickle cell crises, SCD medications used, ocular and systemic comorbidities, and history of intraocular treatment were extracted. A previously published DL algorithm was used to calculate retinal microvascular tortuosity using ultrawidefield pseudocolor fundus imaging among patients with SCD vs. controls.

Main Outcome Measures

Cumulative tortuosity index (CTI).

Results

Overall, 64 patients (119 eyes) with SCD and 57 age- and race-matched controls (106 eyes) were included. The majority of the patients with SCD were females (65.6%) and of Black or African descent (78.1%), with an average age of 35.1 ± 20.1 years. The mean number of crises per patient was 3.4 ± 5.2, and the patients took 0.7 ± 0.9 medications. The mean CTI for eyes with SCD was higher than controls (1.06 ± vs. 1.03 ± 0.02, P < 0.001). On subgroup analysis, hemoglobin S, hemoglobin C, and HbS/beta-thalassemia variants had significantly higher CTIs compared with controls (1.07 vs. 1.03, P < 0.001), but not with sickle cell trait variant (1.04 vs. 1.03 control, P = .2). Univariable analysis showed a higher CTI in patients diagnosed with proliferative SCR, most significantly among those with sea-fan neovascularization (1.06 ± 0.02 vs. 1.04 ± 0.01, P < 0.001) and those with >3 sickle cell crises (1.07 ± 0.02 vs. 1.05 ± 0.02, P < 0.001).

Conclusions

A DL-based metric of cumulative vascular tortuosity associates with and may be a potential biomarker for SCD and SCR disease severity.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Correlations Between Visual Field Defects and Macular Thinning in Sickle Cell Disease

Purpose

The purpose of this study was to investigate the correlation between defects in automatic perimetry and macular temporal thinning in optical coherent tomography (OCT) on patients with sickle cell disease (SCD) to define the impact of its maculopathy on visual function.

Methods

This single site retrospective cross-sectional study was conducted in a referral center for rare disease from January to July 2020. Fifty-eight patients with SCD were referred for an ophthalmological examination including automatic perimetry and OCT. The correlation between macular thickness and visual field defect in each Early Treatment Diabetic Retinopathy Study (ETDRS) quadrants was calculated.

Results

Visual acuity was normal in 104 eyes (94.5%). Thirty-three eyes (30.0%) had a defect of visual field in at least one ETDRS quadrant. There was a significant correlation between macular thinning on OCT and decrease of the mean defect in visual field in the temporal quadrant (P < 0.001). When comparing sickle cell genotype groups, macular thickness was significantly reduced in temporal outer quadrants in patients with the SS genotype, and in the inner and outer temporal quadrants in other genotypes.

Conclusions

Despite normal visual acuity, macular temporal thinning in patients with SCD is associated with visual field defects in SS genotypes. This points to a primitive vascular dysfunction rather than neurogenic mechanism in occurrence of SCD maculopathy.

Salmon patch maculopathy: An amblyogenic complication of pediatric sickle cell retinopathy

Purpose

To report a case of a large foveal sub-internal limiting membrane hemorrhage from sickle cell retinopathy in a pediatric patient.

Observations

A five-year-old boy with sickle cell disease (SCD) type SS (HbSS) and numerous complications was referred after a failed vision screening and was found to have a large yellow subacute sub-internal limiting membrane hemorrhage overlying the fovea in his right eye. There were several other peripheral salmon patches noted. Optical coherence tomography (OCT) revealed temporal inner retinal macular thinning in both eyes. Serial imaging showed rapid improvement over time of the hemorrhages, though amblyopia persisted.

Conclusions and importance

We describe an unusual amblyogenic presentation of non-proliferative sickle cell retinopathy in five-year-old patient with HbSS due to a foveal salmon patch. Numerous vision-threatening complications are possible in SCD, highlighting the need for early vision screening.

Longitudinal Assessment of Macular Thickness and Microvascular Changes in Children with Sickle Cell Disease

PURPOSE

To longitudinally assess macular thickness and microvascular changes in children with sickle cell disease (SCD).

DESIGN

A retrospective consecutive series.

SUBJECTS

Children with SCD aged ≤ 18 years who had an ophthalmic examination at Boston Children's Hospital between January 1998 and August 2022.

METHODS

Qualitative and quantitative analyses of both OCT and OCT angiography (OCTA) images were performed.

MAIN OUTCOME MEASURES

Total retinal thickness measured on macular OCT, superficial capillary plexus and deep capillary plexus (DCP) vessel density (VD), and foveal avascular zone (FAZ) area measured on 6- × 6-mm OCTA scans.

RESULTS

International Classification of Diseases, 10th Revision, code search identified 303 pediatric SCD patients who underwent ophthalmic examination during the study period. OCT and OCTA images were acquired on 104 (17.2%) and 60 (9.9%) eyes at presentation and on 159 (26.2%) and 100 (16.5%) eyes at final visit, respectively. Overall, temporal retinal thinning was noted qualitatively in 35.6% of SCD patients at presentation and 39.6% at final visit. Of those patients with macular thinning, 94.6% and 90.5% had peripheral sickle cell retinopathy (SCR) at presentation and final visit. On quantitative OCT analysis, HbSS eyes had a lower retinal thickness in the fovea and temporal parafovea compared with HbSC (P < 0.05). Eyes with peripheral SCR had a larger FAZ at presentation compared with eyes without peripheral SCR (P = 0.004), a lower DCP VD at final visit in the inferior temporal macula (P = 0.03), and a higher DCP VD at final visit in the superior nasal macula (P = 0.01). Eighty eyes of 40 patients had OCT, and 34 eyes of 20 patients had both OCT and OCTA images acquired at both initial and final visits. At final visit, retinal thickness decreased at the fovea, inferior perifovea, and temporal perifovea compared with presentation (P < 0.05). In parallel, VD DCP in the superonasal quadrant increased at final visit (P = 0.03).

CONCLUSIONS

Macular retinal thinning was progressive and observed in eyes with and without peripheral SCR. Over time, there was a compensatory increase in DCP VD in the nasal macula on OCTA.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Chronic Effects of e-Cigarette Aerosol Inhalation on Macular Perfusion Assessed Using OCT Angiography

Purpose: To determine whether there are significant differences in the microvasculature and central retinal thickness (CRT) between e-cigarette users (user group) and age-matched nonusers (control group) using optical coherence tomography angiography (OCTA). Methods: In this prospective cross-sectional observational study, OCTA images were acquired of 52 eyes of 26 users and 25 eyes of 25 age-matched nonusers. Daily e-cigarette users with no ocular history were identified from provider information in the electronic medical record. A custom algorithm was used to calculate the foveal avascular zone (FAZ), vessel area density (VAD), and vessel length density (VLD). OCT software was used to calculate the foveal, superior, inferior, nasal, and temporal CRT. Generalized estimating equations using the Z-statistic were used to determine how the FAZ, VAD, VLD, and CRT parameters varied between groups and to assess the differential contribution of descriptive data in the user group. Results: No statistically significant difference was found between the user group and control group in the FAZ, superficial vascular complex (SVC) VAD, SVC VLD, or deep vascular complex (DVC) VAD. A statistically significant difference was found for DVC VLD (P = .002), with the user group having a slightly higher VLD on average. Superior, temporal, and inferior inner macular thicknesses were significantly thinner in the user group (P = .038, P = .012, and P = .035, respectively). Conclusions: Significant negative differences were found in CRT measures but not in retinal microvasculature parameters between e-cigarette users and nonusers. Decreased inferior, temporal, and superior inner macular thickness in e-cigarette users may show an early chronic structural effect that warrants further assessment of retinal effects as this population ages and continues to use e-cigarettes.

Retinal atrophy and markers of systemic and cerebrovascular severity in homozygous sickle cell disease

Introduction

While paramacular retinal atrophy (PRA) is known to be found in 48% of eyes of adults and 42% of eyes of children with homozygous SCD (SS-SCD), the aim of this study is to assess the association between PRA and red blood cell (RBC) deformability, hematological markers and brain imaging abnormalities in SS-SCD.

Methods

This study is a subset of DREAM2, a prospective observational study performed between August 2015 and August 2016. Children (5–17 years) with SS-SCD and no history of large vessel vasculopathy, were included. Ophthalmological characteristics including visual acuity, fundus examination, OCT of central and temporal retina (with several retinal thickness measurements) were explored in relation with RBC deformability (ektacytometry), hematological and biochemical (hemolysis parameters), and neurological (cerebral oxygenation estimated by Near Infrared Spectroscopy, brain magnetic resonance imaging) investigations.

Results

17 children (5 boys; mean age: 13 years) with complete ophthalmological investigations were included in the analysis; 8 exhibited PRA. RBC deformability was found to be significantly lower in children with PRA for measurements made at 1.69 Pa (0.16 a.u ± 0.02 vs 0.21 a.u ± 0.03, p = 0.02) and above, as well as cerebral oxygenation (59.25% ± 9.9 vs 71.53% ± 4.9, p = 0.02). A significant positive correlation was found between temporal retinal thickness and hemoglobin level (ρ = 0.65, p = 0.007), hematocrit (ρ = 0.53, p = 0.04) and RBC deformability at 3 Pa (ρ = 0.75, p = 0.005) and above.

Conclusions

These results suggest that PRA could be an early marker of systemic severity and cerebral oxygenation in SCD. Whether it could help predicting cerebral vasculopathy requires further investigations.

EVALUATION OF MACULAR FLOW VOIDS ON OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY AS POTENTIAL BIOMARKERS FOR SILENT CEREBRAL INFARCTION IN SICKLE CELL DISEASE

PURPOSE

To determine the relationship between macular microvascular abnormalities on optical coherence tomography angiography and silent cerebral infarctions (SCIs) on cerebral magnetic resonance imaging in sickle cell disease.

METHODS

Patients (age <18 years old) from our previous pediatric sickle cell disease study cohort who had prior optical coherence tomography angiography and brain magnetic resonance imaging were identified. Brain magnetic resonance imaging images were compared with macular optical coherence tomography angiography scans to identify macular vascular density differences between patients with SCI and without SCI.

RESULTS

Sixty-eight eyes from 34 patients who underwent optical coherence tomography angiography were evaluated, of whom 28 eyes from 14 patients met the inclusion criteria for this study. Eight patients (57%) with SCI and 6 patients (43%) without SCI were identified. The mean age (17 years in SCI and 16.3 years in non-SCI) was comparable between groups. There was no statistically significant difference in systemic complications. Deep capillary plexus vessel density was lower in the temporal quadrant in patients with SCI (49.3% vs. 53.7%, P = 0.014).

CONCLUSION

Patients with SCI were found to have lower vessel density in the deep capillary plexus compared with those without SCI. This finding suggests that deep capillary plexus vessel density may have utility as an imaging biomarker to predict the presence of SCI.

Artificial intelligence for improving sickle cell retinopathy diagnosis and management

Sickle cell retinopathy is often initially asymptomatic even in proliferative stages, but can progress to cause vision loss due to vitreous haemorrhages or tractional retinal detachments. Challenges with access and adherence to screening dilated fundus examinations, particularly in medically underserved areas where the burden of sickle cell disease is highest, highlight the need for novel approaches to screening for patients with vision-threatening sickle cell retinopathy. This article reviews the existing literature on and suggests future research directions for coupling artificial intelligence with multimodal retinal imaging to expand access to automated, accurate, imaging-based screening for sickle cell retinopathy. Given the variability in retinal specialist practice patterns with regards to monitoring and treatment of sickle cell retinopathy, we also discuss recent progress toward development of machine learning models that can quantitatively track disease progression over time. These artificial intelligence-based applications have great potential for informing evidence-based and resource-efficient clinical diagnosis and management of sickle cell retinopathy.

Central macular thickness in patients with sickle cell disease and no signs of retinopathy: a cross-sectional study of Jordanian patients

OBJECTIVES

To measure central macular thickness in Jordanian patients with sickle cell disease who did not have retinopathy and compare the findings with age- and sex-matched controls using spectral domain optical coherence tomography (SDOCT).

METHODS

In this cross-sectional study, participants underwent visual acuity testing, slit-lamp bio-microscopy, dilated ophthalmoscopy, and SDOCT imaging to measure central macular thickness. Macular quadrant measurements and thickness difference indexes (TDIs) were compared between groups.

RESULTS

Twenty eyes with sickle cell disease and 20 control eyes were enrolled. The median visual acuity in both groups was 20/20. The mean macular thickness was significantly lower in eyes with sickle cell disease than in matched controls (mean difference, 22.15 ± 6.44 µm). Peripheral quadrants were all significantly thinner in eyes with sickle cell disease, especially in superior and temporal quadrants. TDIs were lower in eyes with sickle cell disease than in control eyes.

CONCLUSIONS

Eyes with sickle cell disease that had no clinical evidence of retinopathy exhibited significantly lower central macular thickness in all quadrants, compared with eyes in age- and sex-matched controls. SDOCT is a non-invasive imaging modality that can detect preclinical changes in eyes with sickle cell disease and can be used to screen and monitor the disease process.

Sickle Cell Maculopathy: Prevalence, Associations and Impact on Visual Acuity

AIMS

To investigate the prevalence of sickle cell maculopathy (SCM), and associations with age, sex, genotype, proliferative sickle cell retinopathy (PSR) stage, and the impact on visual acuity.

METHODS

Age, sex, and visual acuity were recorded and spectral domain OCT and ultra-wide-field images of the macula and retina were reviewed in a consecutive series of 74 adults with sickle cell disease.

RESULTS

The median age was 37 years (range 19-73 years) and 36 cases (48.6%) were male. SCM was present in at least 1 eye of 40 cases (54.1%) or in 67 of all eyes (42.3%). SCM prevalence was 54.8%, 62.5%, and 25% for the HbSS, HbSC, and HbS/BThal or other genotypes, respectively. SCM was observed in 41 (39.4%) of the eyes with PSR stages 0, 1, and 2, and in 21 (51.2%) of the eyes with PSR stages 3, 4, and 5, respectively. Mild visual impairment or worse was present in 3 eyes (4.8%) with SCM but this was secondary to other pathology.

CONCLUSION

SCM is a frequent finding in the eyes of adults with sickle cell disease. The prevalence is similar for the HbSS and HbSC genotypes and is not related to the PSR stage. High-contrast distance visual acuity is typically preserved.

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.