Multimodal imaging of foveal cavitation in retinal dystrophies

Clinical profile and demographic distribution of Stargardt disease phenotypes: An Electronic medical record-driven big data analytics from a multitier eye care network

Purpose

To describe the demographics and clinical profile of Stargardt disease in patients presenting a multitier ophthalmology hospital network in India.

Methods

This cross-sectional hospital-based study was performed among 2,834,616 new patients presenting between August 2010 and June 2021 in our network. Patients with a clinical diagnosis of Stargardt disease in at least one eye were included as cases. The data were collected using an electronic medical record system.

Results

Overall, 1,934 (0.069%) patients were diagnosed with Stargardt disease. Most of the patients were male (63.14%). The most common age group at presentation was during the second decade of life, with 626 (31.87%) patients. The overall prevalence was higher in patients from a higher socioeconomic status (0.077%), in those presenting from the urban geography (0.079%), and in students (0.197%). Systemic history of hypertension was seen in 56 (2.85%) patients, while diabetes mellitus was seen in (2.49%) patients. Of the 3,917 eyes, 1,910 (48.76%) eyes had moderate visual impairment (>20/70-20/200) followed by severe visual impairment (>20/200 to 20/400) in 646 (16.49%) eyes. The most commonly associated retinal signs were retinal flecks in 1,260 (32.17%) eyes, followed by RPE changes in 945 (24.13%) eyes. The most documented investigations were autofluorescence (39.85%), followed by optical coherence tomography (23.90). Cataract surgery was the commonest performed surgical intervention in (0.66%) eyes, followed by intravitreal injection in 4 (0.10%) eyes. The family history of parent consanguinity marriage was reported by 212 (10.79%) patients.

Conclusion

Stargardt disease was seen more commonly in males presenting during the second decade of life. It is predominantly a bilateral disease, with the majority of the eyes having moderate visual impairment.

Volume-accumulated reflectivity of the outer retina (integral) on spectral domain optical coherence tomography as a predictor of cone cell density: a pilot study

BACKGROUND

The study aims to investigate the relationship between the volume-accumulated reflectivity (termed "integral") on spectral domain optical coherence tomography (SD-OCT) and cone density on adaptive optics (AO) imaging.

METHODS

In this cross-sectional study, both eyes of 32 healthy subjects and 5 patients with inherited retinal diseases (IRD) were studied. The parameter, integral, was defined as the volume-accumulated reflectivity values in a selected region on OCT images; integrals of the ellipsoid zone (EZ) and interdigitation zone (IZ) were measured at 2°, 3°, 4°, 5°and 6° eccentricity along the four meridians on fovea-centered OCT B-scans. Cone density in the same region was measured using a flood illumination adaptive optics camera RTX1.

RESULTS

Integrals of EZ, IZ and cone density shared similar distribution patterns. Integral of the IZ was better correlated with cone density in both healthy people (r = 0.968, p < 0.001) and those with IRD (r = 0.823, p < 0.001) than direct measurements of reflectivity on OCT images. A strong correlation was found between best corrected visual acuity (BCVA) and cone density at 2° eccentricity (r = -0.857, p = 0.002). BCVA was also correlated with the integral of the IZ at the foveola (r = -0.746, p = 0.013) and fovea (r = -0.822, p = 0.004).

CONCLUSIONS

The new parameter "integral" of the photoreceptor outer segment measured from SD-OCT was noted to correlate with cone density and visual function in this pilot study.

Widefield Optical Coherence Tomography in Pediatric Retina: A Case Series of Intraoperative Applications Using a Prototype Handheld Device

Optical coherence tomography (OCT) has changed the standard of care for diagnosis and management of macular diseases in adults. Current commercially available OCT systems, including handheld OCT for pediatric use, have a relatively narrow field of view (FOV), which has limited the potential application of OCT to retinal diseases with primarily peripheral pathology, including many of the most common pediatric retinal conditions. More broadly, diagnosis of all types of retinal detachment (exudative, tractional, and rhegmatogenous) may be improved with OCT-based assessment of retinal breaks, identification of proliferative vitreoretinopathy (PVR) membranes, and the pattern of subretinal fluid. Intraocular tumors both benign and malignant often occur outside of the central macula and may be associated with exudation, subretinal and intraretinal fluid, and vitreoretinal traction. The development of wider field OCT systems thus has the potential to improve the diagnosis and management of myriad diseases in both adult and pediatric retina. In this paper, we present a case series of pediatric patients with complex vitreoretinal pathology undergoing examinations under anesthesia (EUA) using a portable widefield (WF) swept-source (SS)-OCT device.

Nahinfrarot-Autofluoreszenz: klinische Anwendung und diagnostische Relevanz

Die Nahinfrarot-Autofluoreszenz (NIA) ist ein nicht-invasives Verfahren zur Untersuchung des retinalen Pigmentepithels (RPE) basierend auf der Darstellung des antioxidativen Schutzfaktors Melanin in den RPE-Zellen. Die NIA verbessert die Früherkennung chorioretinaler Erkrankungen, da bei vielen dieser Erkrankungen mit der NIA Strukturveränderungen des RPE nachweisbar sind, bevor sich in anderen Untersuchungen Krankheitszeichen erkennen lassen.

[Near-infrared Fundus Autofluorescence: Clinical Application and Diagnostic Relevance]

Near-infrared autofluorescence (NIA) is a non-invasive retinal imaging technique for examination of the retinal pigment epithelium (RPE) based on the autofluorescence of melanin. Melanin has several functions within the RPE cells, in one of them it serves as a protective antioxidative factor within the RPE cells and is involved in the phagocytosis of photoreceptor outer segments. Disorders that affect the photoreceptor-RPE complex result in alterations of RPE cells which are detectable by alterations of NIA. Therefore, NIA allows to detect early alterations in inherited and acquired chorioretinal disorders, frequently prior to ophthalmoscopical visualisation and often prior to alterations in lipofuscin associated fundus autofluorescence (FAF) or optical coherence tomography (OCT). Although NIA and FAF relate to disorders affecting the RPE, findings between both imaging methods differ and the area involved has been demonstrated to be larger in NIA compared to FAF in several disorders (e.g., age-related macular degeneration, retinitis pigmentosa, ABCA4-gene associated Stargardt disease and cone-rod dystrophy, light damage), indicating that NIA detects earlier alterations compared to FAF. In addition, due to the absence of blue-light filtering which limits foveal visualisation in FAF, foveal alterations can be much better detected using NIA. A reduced subfoveal NIA intensity is the earliest sign of autosomal dominant BEST1-associated disease, when FAF and OCT are still normal. In other disorders, a normal subfoveal NIA intensity is associated with good visual acuity. This review summarizes the present knowledge on NIA and demonstrates biomarkers for various chorioretinal disorders.

Case Report: Multimodal Imaging Features of an ABCA4 Cone Dystrophy

SIGNIFICANCE

Cone dystrophies and cone-rod dystrophies are a group of rare inherited pathologies characterized by degeneration of cone photoreceptors and subsequent rod involvement. The identification of causative genes is essential for diagnosis, and advanced imaging is acquiring great value in the characterization of the different phenotypic expressions.

PURPOSE

We describe genotype-phenotype associations of an autosomal recessive ABCA4-associated cone dystrophy using multimodal imaging.

CASE REPORT

A 34-year-old woman presented with progressive visual acuity decay. Visual acuity was 20/32 for her right eye and 20/25 for her left eye. A central scotoma was detected on a 10-2 Humphrey visual field in both eyes. Funduscopy revealed perifoveal retinal pigment epithelial changes, and fundus autofluorescence using blue excitation light showed decreased autofluorescence in the central fovea of both eyes with surrounding annular ring of increased autofluorescence in the perifoveal zone; green excitation light fundus autofluorescence was more accurate in the characterization of the size, perimeter, and circularity of central hypofluorescent lesions. Optical coherence tomography revealed an incomplete focal cavitation in both foveas, and optical coherence tomography angiography images showed a reduction in the superficial and deep capillary plexus density, an increased foveal avascular area, and subtle voids in choriocapillaris blood flow. Electroretinography was consistent with cone dystrophy, and molecular testing revealed the alteration of the ABCA4 gene.

CONCLUSIONS

The identification of an incomplete focal cavitation could alert the clinician to consider early ABCA4 central cone dystrophy. The patient in this case also exhibited reduced vessel density in the foveal area. Both of these characteristics could be important features related to the underlying genetic mutation.

Comparing Retinal Structure in Patients with Achromatopsia and Blue Cone Monochromacy Using OCT

Purpose

To compare foveal hypoplasia and the appearance of the ellipsoid zone (EZ) at the fovea in patients with genetically confirmed achromatopsia (ACHM) and blue cone monochromacy (BCM).

Design

Retrospective, multi-center observational study.

Subjects

Molecularly confirmed patients with ACHM (n = 89) and BCM (n = 33).

Methods

We analyzed high-resolution spectral domain optical coherence tomography (SD-OCT) images of the macula from aforementioned patients with BCM. Three observers independently graded SD-OCT images for foveal hypoplasia (i.e. retention of one or more inner retinal layers at the fovea) and four observers judged the integrity of the EZ at the fovea, based on an established grading scheme. These measures were compared with previously published data from the ACHM patients.

Main Outcome Measures

Presence of foveal hypoplasia and EZ grade.

Results

Foveal hypoplasia was significantly more prevalent in ACHM than in BCM (p<0.001). In addition, we observed a significant difference in the distribution of EZ grades between ACHM and BCM, with grade II EZ being by far the most common phenotype in BCM (61% of patients). In contrast, ACHM patients had a relatively equal prevalence of EZ grades I, II, and IV. Interestingly, grade IV EZ was 2.6 times more prevalent in ACHM compared to BCM, while grade V EZ (macular atrophy) was present in 3% of both the ACHM and BCM cohorts.

Conclusions

The higher incidence of foveal hypoplasia in ACHM than BCM supports a role for cone activity in foveal development. Although there are differences in EZ grades between these conditions, the degree of overlap suggests EZ grade is not sufficient for definitive diagnosis, in contrast to previous reports. Analysis of additional OCT features in similar cohorts may reveal differences with greater diagnostic value. Finally, the extent to which foveal hypoplasia or EZ grade is prognostic for therapeutic potential in either group remains to be seen, but motivates further study.

Novel clinical presentation of a CRX rod-cone dystrophy

We describe a novel clinical presentation of a CRX rod-cone dystrophy in a single family. Two boys ages 6 and 12 years presented with clinical and optical coherence tomography features suggestive of X-linked retinoschisis, but with optic nerve swelling without increased intracranial pressure. One patient had an electronegative electroretinogram (ERG) and the other had rod-cone dysfunction. Neither had retinoschisin (RS1) gene mutations. Biological mother and sister presented with retinal pigment epithelium (RPE) changes and abnormal cone-rod ERG responses. On further testing, next generation sequencing with array comparative genomic hybridisation showed a deletion in exon 4 of the CRX gene. Cystoid maculopathy in young male children can be difficult to distinguish from RS1-associated schisis. Phenotypic variants within a family must prompt a thorough retinal dystrophy evaluation even with electronegative ERG in the presenting child. This novel phenotype for CRX presents with optic nerve swelling and cystoid maculopathy in men, and RPE changes in women.

Phenotypic Differences in a PRPH2 Mutation in Members of the Same Family Assessed with OCT and OCTA

Choroidal dystrophies comprise a group of chorioretinal degenerations. However, the different findings observed among these patients make it difficult to establish a correct clinical diagnosis. The objective of this study was to characterize new clinical findings by optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) in these patients. Four family members with a PRPH2 gene mutation (p.Arg195Leu) were included. OCT was performed at the macula, and the thickness of the outer and inner retina, total retina, and choroid was measured. The features of the vascular network were analyzed by OCTA. Patients showed a decreased outer nuclear layer in the avascular area compared with the controls. Two patients presented greater foveal and parafoveal degeneration of the outer retina, whereas the most degenerated area in the rest was the perifovea. Disruption of the third outer band at the foveola is one of the first-altered outer bands. Slow blood flow areas or capillary dropout were main signs in the deep capillary plexus. Microaneurysms were frequently observed in less degenerated retinas. Vascular loops and intraretinal microvascular abnormalities (IRMAs) were present in the superficial plexus. Extensive degeneration of the choriocapillaris was detected. Phenotypic differences were found between patients: two showed central areolar choroidal dystrophy and the rest had extensive chorioretinal atrophy. These signs observed in OCT and OCTA can help to more appropriately define the clinical disease in patients with choroidal dystrophies.

Reviewing the Role of Ultra-Widefield Imaging in Inherited Retinal Dystrophies

Inherited retinal dystrophies (IRD) are a heterogeneous group of rare chronic disorders caused by genetically determined degeneration of photoreceptors and retinal pigment epithelium cells. Ultra-widefield (UWF) imaging is a useful diagnostic tool for evaluating retinal integrity in IRD, including Stargardt disease, retinitis pigmentosa, cone dystrophies, and Best vitelliform dystrophy. Color or pseudocolor and fundus autofluorescence images obtained with UWF provide previously unavailable information on the retinal periphery, which correlates well with visual field measurement or electroretinogram. Despite unavoidable artifacts of the UWF device, the feasibility of investigations in infants and in patients with poor fixation makes UWF imaging a precious resource in the diagnostic armamentarium for IRD.

Near-infrared fundus autofluorescence in early age-related macular degeneration

PURPOSE

To describe the patterns on near-infrared fundus autofluorescence in eyes affected by early age-related macular degeneration.

DESIGN

Cross-sectional observational case series.

PARTICIPANTS

A total of 84 eyes of 84 patients suffering from early age-related macular degeneration (>63 μm but <125 μm drusen and no-to-mild retinal pigment epithelium abnormalities) were enrolled.

METHODS

Patients underwent best-corrected visual acuity, biomicroscopy, infrared reflectance, short-wavelength fundus autofluorescence, and near-infrared fundus autofluorescence. Eyes were classified according to different patterns of near-infrared fundus autofluorescence. Main outcome was definition of relative prevalence and features of each near-infrared fundus autofluorescence pattern; secondary outcomes were correlation between near-infrared fundus autofluorescence and short-wavelength fundus autofluorescence and between near-infrared fundus autofluorescence patterns and best-corrected visual acuity.

RESULTS

Four different patterns of near-infrared fundus autofluorescence identified: normal foveal signal (Pattern A, 7%); normal foveal signal with hyperautofluorescent/hypoautofluorescent spots not involving the fovea (Pattern B, 65.5%); hyperautofluorescent/hypoautofluorescent spots involving the fovea (Pattern C, 15.5%); patchy pattern (Pattern D, 12%). best-corrected visual acuity was lower in eyes with foveal signal alteration (Patterns C and D).

CONCLUSION

Near-infrared fundus autofluorescence pattern in early age-related macular degeneration might be suggestive of visual function deterioration when the fovea is involved. Longitudinal studies are warranted to confirm our preliminary results.

Monitoring and Management of the Patient with Stargardt Disease

Stargardt disease (STGD1) represents one of the major common causes of inherited irreversible visual loss. Due to its high phenotypic and genotypic heterogeneity, STGD1 is a complex disease to understand. Non-invasive imaging, biochemical, and genetic advances have led to substantial improvements in unveiling the disease processes and novel promising therapeutic landscapes have been proposed. This review recapitulates the modalities for monitoring patients with STGD1 and the therapeutic options currently under investigation for the different stages of the disease.

Quantitative and Qualitative Features of Spectral-Domain Optical Coherence Tomography Provide Prognostic Indicators for Visual Acuity in Patients With Choroideremia

BACKGROUND AND OBJECTIVE

To identify qualitative and quantitative features of spectral-domain optical coherence tomography (SD-OCT) as prognostic indicators of visual acuity (VA) loss in patients with choroideremia (CHM).

PATIENTS AND METHODS

Retrospective study of 57 male patients with CHM. Central foveal thickness (CFT), subfoveal choroidal thickness (SCT), fundus autofluorescence area, and evidence of outer retinal and choroidal degeneration were analyzed by SD-OCT.

RESULTS

Best-corrected VA logMAR at baseline was associated with CFT at baseline (r = -0.47; P < .01), CFT at most recent follow-up (r = -0.27; P < .01), and SCT at baseline (r = -0.31; P < .01). Ellipsoid zone (EZ) rupture was associated with a higher CFT loss (r = 0.33; P < .01) and macular cystic spaces (MCS) with a reduction in VA over time (hazard risk = 0.48; P = .05).

CONCLUSION

Reduced CFT at baseline, EZ rupture, and MCS are poor prognostic indicators for VA outcome. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:711-716.].