OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY OF CHOROIDAL NEOVASCULARIZATION IN FOUR INHERITED RETINAL DYSTROPHIES

Choroideremia presenting as vision loss secondary to choroidal neovascularization

BACKGROUND

Choroidal neovascularization (CNV) is a rare complication of choroideremia that occurs secondary to relative atrophy of the retinal pigment epithelium and eventual rupture of Bruch's membrane. The ideal management of CNV in choroideremia is unclear.

MATERIALS AND METHODS

Case report.

OBSERVATIONS

A 14-year-old male with no known ocular history presented to the eye emergency department complaining of a central scotoma in the right eye for 4 days. He had no past medical history and family history was unremarkable for known ocular disease. Visual acuity was 20/70 in the right eye and 20/30 in the left eye. Posterior segment exam revealed chorioretinal atrophy extending from the outer macula to the midperiphery in both eyes. There was CNV with associated subretinal hemorrhage in the right eye. Optical coherence tomography demonstrated the presence of CNV with subretinal fluid in the right eye and parafoveal outer retinal atrophy in both eyes. Genetic testing revealed a hemizygous exon 2 deletion on the CHM gene, pathogenic for choroideremia. The patient received a total of 3 injections 4 weeks apart followed by 1 injection 6 weeks later with resolution of the subretinal hemorrhage and reduction in CNV size with improvement in visual acuity to 20/20 at last follow-up exam.

CONCLUSIONS AND IMPORTANCE

Choroidal neovascularization is a rare cause of central vision loss in patients with choroideremia. In this report, we demonstrate a good functional and anatomic response to intravitreal bevacizumab in a 14-year-old patient with undiagnosed choroideremia who presented with CNV-induced central vision loss.

Macular neovascularization in inherited retinal diseases: A review

Inherited retinal diseases (IRDs) are the most common cause of blindness in working-age adults. Macular neovascularization (MNV) may be a presenting feature or occurs as a late-stage complication in several IRDs. We performed an extensive literature review on MNV associated with IRDs. MNV is a well-known complication of Sorsby fundus dystrophy and pseudoxanthoma elasticum. Those with late-onset Stargardt disease may masquerade as exudative age-related macular degeneration (AMD) when MNV is the presenting feature. Peripherinopathies may develop MNV that responds well to a short course of anti-vascular endothelial growth factor (anti-VEGF) therapy, while bestrophinopathies tend to develop MNV in the early stages of the disease without vision loss. Enhanced S-cone syndrome manifests type 3 MNV that typically regresses into a subfoveal fibrotic nodule. MNV is only a rare complication in choroideraemia and rod-cone dystrophies. Most IRD-related MNVs exhibit a favorable visual prognosis requiring less intensive regimens of anti-vascular endothelial growth factor therapy compared to age-related macular degeneration. We discuss the role of key imaging modalities in the diagnosis of MNV across a wide spectrum of IRDs and highlight the gaps in our knowledge with respect to the natural history and prognosis to pave the way for future directions of research.

Optical coherence tomography angiography of choroidal neovascularization in long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD)

Purpose

To report the clinical utility of optical coherence tomography angiography (OCTA) for demonstrating choroidal neovascularization (CNV) associated with Long-Chain 3-Hydroxyacyl-CoA Dehydrogenase Deficiency (LCHADD) retinopathy.

Methods

Thirty-three participants with LCHADD (age 7-36 years; median 17) were imaged with OCTA and the Center for Ophthalmic Optics & Lasers Angiography Reading Toolkit (COOL-ART) software was implemented to process OCTA scans.

Results

Seven participants (21 %; age 17-36 years; median 25) with LCHADD retinopathy demonstrated evidence of CNV by retinal examination or presence of CNV within outer retinal tissue on OCTA scans covering 3 × 3 and/or 6 × 6-mm. These sub-clinical CNVs are adjacent to hyperpigmented areas in the posterior pole. CNV presented at stage 2 or later of LCHADD retinopathy prior to the disappearance of RPE pigment in the macula.

Conclusion

OCTA can be applied as a non-invasive method to evaluate the retinal and choroidal microvasculature. OCTA can reveal CNV in LCHADD even when the clinical exam is inconclusive. These data suggest that the incidence of CNV is greater than expected and can occur even in the early stages of LCHADD retinopathy.

Clinical outcomes of treated macular neovascularisation secondary to inherited retinal diseases: a literature review

Many inherited retinal diseases (IRD) can be associated with, or be secondarily complicated by, macular neovascularisation (MNV), which has been variably treated with intravitreal antivascular endothelial growth factor, steroids, laser and surgery. In this article, we aim to present a consolidated literature review of management of IRD-related MNV.

Clinical Applications of Optical Coherence Tomography Angiography in Inherited Retinal Diseases: An Up-to-Date Review of the Literature

Optical coherence tomography angiography (OCT-A) is a valuable imaging technique, allowing non-invasive, depth-resolved, motion-contrast, high-resolution images of both retinal and choroidal vascular networks. The imaging capabilities of OCT-A have enhanced our understanding of the retinal and choroidal alterations that occur in inherited retinal diseases (IRDs), a group of clinically and genetically heterogeneous disorders that may be complicated by several vascular conditions requiring a prompt diagnosis. In this review, we aimed to comprehensively summarize all clinical applications of OCT-A in the diagnosis and management of IRDs, highlighting significant vascular findings on retinitis pigmentosa, Stargardt disease, choroideremia, Best disease and other less common forms of retinal dystrophies. All advantages and limitations of this novel imaging modality will be also discussed.

Towards a better understanding of non-exudative choroidal and macular neovascularization

Non-exudative macular and choroidal neovascularization (MNV and CNV) usually refers to the entity of treatment-naïve type 1 neovascularization in the absence of associated signs of exudation. Histopathological studies, dating back in the early 70s, identified the presence of non-exudative MNV, but the first clinical report of this finding was in the late 90s using indocyanine green angiography in eyes with age-related macular degeneration (AMD). With more advanced retinal imaging, there has been an ever increasing appreciation of non-exudative MNV associated with AMD and CNV with other macular disorders. However, consensus regarding the exact definition and the clinical management of this entity is lacking. Furthermore, there may be variation in the imaging features and clinical course suggesting that a spectrum of disease may exist. Herein, we review the large body of published work that has provided a better understanding of non-exudative MNV and CNV in the last decade. The prevalence, multimodal imaging features, clinical course, and response to treatment are discussed to elucidate further key insights about this entity. Based on these observations, this review also proposes a new theory about the origin and course of different sub-types of non-exudative MNV/CNV which can have different etiologies and pathways according to the clinical context of disease.

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.

Intravitreal bevacizumab treatment for exudative choroidal neovascularisation in best vitelliform macular dystrophy

PURPOSE

To describe results of intravitreal bevacizumab treatment of the secondary choroidal neovascularisation in Best vitelliform macular dystrophy in an adult and paediatric patient, and present the management of three asymptomatic patients with confirmed BEST1 gene mutation.

CASE SERIES DESCRIPTION

Five patients from the same family with the Best vitelliform macular dystrophy are presented. In two patients (aged 63 and 4 years) secondary choroidal neovascularisation caused a rapid decline in visual acuity. In the adult patient with advanced Best vitelliform macular dystrophy, visual acuity did not improve despite eight intravitreal bevacizumab injections to the right eye. The formation of a central scar and rapid reoccurrence of choroidal neovascularisation three months after completing the initial treatment affected the outcome. As for the paediatric patient with bilateral choroidal neovascularisation in the vitelliform stage of Best vitelliform macular dystrophy, a complete recovery of visual acuity was observed after two (left eye) and three (right eye) bevacizumab injections, with adjunctive amblyopia treatment. The other three patients with an abnormal electrooculogram reported no visual problems during more than 10 years of follow-up. Minimal changes were seen on optical coherence tomography in the youngest patient.

CONCLUSIONS

Intravitreal bevacizumab seems to be an effective treatment for exudative choroidal neovascularisation in the vitelliform stage of Best vitelliform macular dystrophy; however, it may not be beneficial in the advanced stages of Best vitelliform macular dystrophy. It is important to regularly screen all family members with an abnormal electrooculogram and confirmed mutation for vitelliform changes and choroidal neovascularisation from an early age. The decision for anti-vascular endothelial growth factor treatment should be made on a case-to-case basis as complications may arise.

Pediatric choroidal neovascularization: Etiology and treatment outcomes with anti-vascular endothelial growth factors

PURPOSE

To describe the etiology and treatment outcomes of choroidal neovascularization (CNV) in a pediatric population with intravitreal anti-vascular endothelial growth factors (VEGF).

METHODS

Retrospective single center interventional case series. A total of 26 eyes of 23 consecutive pediatric patients with CNV of various etiologies were treated with intravitreal injection of anti-VEGF agents.

RESULTS

There were 15 males (65.2%) and eight females (34.8%), diagnosed with CNV during the study period. The mean age at presentation with CNV was 11.7 ± 3.3 years, (range 4-16 years) and the mean follow was 28.1 ± 18 months, (range 8-72 months). Inflammatory CNV was the most common etiology. The mean best corrected visual acuity (BCVA) and mean central macular thickness (CMT) at presentation, were logMAR 0.8 ± 0.3 and 367.6 ± 134.8 µm respectively. At the final visit, CNV in all eyes remained regressed with significant improvement in mean BCVA to logMAR 0.4 ± 0.4 (p < 0.0001) and mean CMT to 242.5 ± 82.4 µm (p < 0.0001). A mean of two intravitreal injections per eye was required for CNV regression.

CONCLUSION

Intravitreal anti-VEGF therapy for pediatric CNV is an effective treatment in majority of affected eyes.

Choriocapillaris: Fundamentals and advancements

The choriocapillaris is the innermost structure of the choroid that directly nourishes the retinal pigment epithelium and photoreceptors. This article provides an overview of its hemovasculogenesis development to achieve its final architecture as a lobular vasculature, and also summarizes the current histological and molecular knowledge about choriocapillaris and its dysfunction. After describing the existing state-of-the-art tools to image the choriocapillaris, we report the findings in the choriocapillaris encountered in the most frequent retinochoroidal diseases including vascular diseases, inflammatory diseases, myopia, pachychoroid disease spectrum disorders, and glaucoma. The final section focuses on the development of imaging technology to optimize visualization of the choriocapillaris as well as current treatments of retinochoroidal disorders that specifically target the choriocapillaris. We conclude the article with pertinent unanswered questions and future directions in research for the choriocapillaris.

Multimodal Imaging Characteristics of Quiescent Type 1 Neovascularization in Best Vitelliform Macular Dystrophy

This case report of a 38-year-old man with bilateral Best vitelliform macular dystrophy (BVMD) presents bilateral quiescent type 1 neovascularizations (NV) detected by optical coherence angiography (OCTA) and their multimodal imaging characteristics. It was emphasized that this kind of quiescent and asymptomatic NV may be present in nearly every stage of BVMD and it was concluded that OCTA is a noninvasive, easy, and rapid method that is superior to other imaging methods in detecting them.

OCT angiography for the diagnosis and management of choroidal neovascularization secondary to choroideremia

Purpose

To describe the multimodal imaging findings and treatment outcomes in choroidal neovascularization secondary to Choroideremia.

Observations

A 13-year-old male presented with reduced visual acuity in the left eye. He gave a history of nyctalopia. His best-corrected visual acuity (BCVA) was 20/20 in the right eye and 20/40 in the left eye. Based on multimodal imaging, the diagnosis of choroideremia in both eyes with a subfoveal choroidal neovascularization in the left eye was made. He underwent five intravitreal anti-vascular endothelial growth factor (VEGF) injections of Ranibizumab over a period of 3 years, with the final injection given due to recurrence of neovascularization. Post-treatment, his BCVA improved to 20/20 in the left eye with regression of the neovascular network.

Conclusions and importance

This case highlights the role of OCTA in diagnosis of choroidal neovascularization in choroideremia as well as its successful management with anti-VEGF injections with long term follow up.

En-face OCT and OCT angiography analysis of macular choroidal macrovessel

Purpose

To analyze en-face optical coherence tomography (OCT) and decorrelation signals on OCT angiography (OCTA) in two cases of macular choroidal macrovessel (MCM).

Observations

Case report. Both the 64-year-old and 71-year-old females presented for a routine evaluation, and multimodal imaging analysis, including color fundus photography, indocyanine green angiography (ICG), spectral-domain optical coherence tomography (SD-OCT) and OCTA, was performed to diagnose a MCM. En-face OCT, en-face OCTA and decorrelation signals were analyzed through the MCM. In both reported cases, color fundus photograph revealed a serpiginoid lesion in the temporal macula. Red-free imaging enhanced the appearance of this lesion resembling a dilated choroidal vessel. Cross-sectional OCT showed an enlarged choroidal vessel causing elevation of the retinal pigment epithelium (RPE) within the fovea. En-face OCTA with segmentation below the choriocapillaris enhanced the MCM delineation. En-face OCT with segmentation below the choriocapillaris showed MCM with a greater distinctness than the en-face OCTA imaging. Decorrelation signals were not observed within MCM on cross-sectional OCTA.

Conclusion and importance

En-face OCT and decorrelation signals on OCTA may have diagnostic value in distinguishing macular choroidal macrovessel from other choroidal vascular diseases.

Optical Coherence Tomography Angiography Quantitative Assessment of Macular Neovascularization in Best Vitelliform Macular Dystrophy

Purpose

To describe quantitative characteristics of macular neovascularization (MNV) in vitelliform macular dystrophy (VMD) patients by means of optical coherence tomography angiography (OCTA).

Methods

The study design was a prospective case series. All patients underwent complete ophthalmologic assessment, optical coherence tomography, and OCTA. The quantitative OCTA parameters examined included vessel tortuosity and vessel dispersion of the MNV. The primary outcome was OCTA characterization of MNV in VMD. Secondary outcomes included the evolution of MNV over the follow-up.

Results

A total of 78 eyes were recruited for the study. MNV was identified in 50 eyes (64%) at baseline and in 51 eyes (65%) at the end of the follow-up (mean follow-up, 24.7 ± 9.7 months). MNV was detected in four out of the 30 eyes classified as stages 2 and 3 (13%), showing exudative manifestations and undergoing ranibizumab treatment, leading to clinical stabilization. OCTA detected MNV in 46 out of 48 eyes (96%) classified as stages 4 and 5, showing no evidence of exudative manifestation. All of the non-exudative MNVs were merely observed over the follow-up and received no treatment. At the end of the follow-up, 47 out of 48 eyes displayed MNV (98%). Non-exudative MNVs remained stable over the follow-up. Statistically significant differences were found when comparing vessel tortuosity and vessel dispersion in the two MNV subforms.

Conclusions

VMD is characterized by two MNV subforms. Exudative MNV is rare and may develop in the early stages of the disease, in association with bleeding and fluid formation. Non-exudative MNV develops very commonly in the advanced stage of VMD, without any exudative manifestation.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY FOR THE DETECTION OF SECONDARY CHOROIDAL NEOVASCULARIZATION IN VITELLIFORM MACULAR DYSTROPHY

PURPOSE

Optical coherence tomography angiography (OCTA) is used to assess vascular abnormality in advanced stage vitelliform macular dystrophy (VMD2).

METHODS

Multimodal imaging including spectral domain (SD) OCT, autofluorescence (AF), fluorescein (FA) and indocyanine green angiography (ICGA) as well as optical coherence tomography angiography were performed.

PATIENTS

Two eyes in one young patient with diagnosed vitelliform macular dystrophy were investigated for progressive visual dysfunction.

RESULTS

Optical coherence tomography angiography identified neovascular formation within the outer retina and the choriocapillaris respectively while all other imaging methods were inconclusive.

CONCLUSION

Optical coherence tomography angiography was superior to conventional angiography in the detection of choroidal neovascularization (CNV) in advanced retinal disorders like vitelliform macular dystrophy.

A Case of Best Disease Accompanied by Pachychoroid Neovasculopathy

The aim of this case presentation is to describe ocular findings of a 22-year-old patient with Best vitelliform macular dystrophy accompanied by pachychoroid neovasculopathy. Color fundus photography, fundus autofluorescence (FAF), optical coherence tomography (OCT), and optical coherence tomography angiography (OCTA) images were reviewed. Fundoscopic examination showed bilateral yellowish vitelliform-like submacular deposits. FAF revealed these deposits as hyperautofluorescent spots. OCT showed flat irregular pigment epithelial detachments corresponding to these submacular deposits. OCT showed choroidal thickening and dilatation of the large outer oval choroidal vessels. Fundus fluorescein angiography could not be performed because the patient was pregnant. En face OCTA images of the choriocapillaris illustrated the choroidal neovascular network. In this case report, we describe for the first time the coexistence of Best vitelliform macular dystrophy and pachychoroid neovasculopathy with OCTA images enabling visualization of the neovascular network in a patient with contraindication for fluorescein angiography.

Optical Coherence Tomography Angiography Imaging in Inherited Retinal Diseases

Optical coherence tomography angiography (OCTA) is a novel, noninvasive imaging modality that allows depth-resolved imaging of the microvasculature in the retina and the choroid. It is a powerful research tool to study the pathobiology of retinal diseases, including inherited retinal dystrophies. In this review, we provide an overview of the evolution of OCTA technology, compare the specifications of various OCTA devices, and summarize key findings from published OCTA studies in inherited retinal dystrophies including retinitis pigmentosa, Stargardt disease, Best vitelliform macular dystrophy, and choroideremia. OCTA imaging has provided new data on characteristics of these conditions and has contributed to a deeper understanding of inherited retinal disease.

Choroideremia: Update On Clinical Features And Emerging Treatments

Choroideremia (CHM) is an X-linked chorioretinal dystrophy characterized by progressive degeneration of the choroid, retinal pigment epithelium and retina. This disease is caused by mutations in the X-linked CHM gene encoding a Ras-related GTPase Rab escort protein (REP)-1, which is extremely important for the retinal function. Clinically, male-affected patients have a progressive reduction in visual acuity. This disease is formally considered incurable, although new promising treatments have been recently introduced. In this article, a review of the salient pathogenetic features of choroideremia, essential for the proper interpretation of therapeutic approaches, is followed by a discussion of the fundamental clinical features of this hereditary disease. Finally, relevant new therapeutic approaches in this disease will be discussed, including gene therapy, stem cells, small molecules, and retinal prosthesis.

Choroidal neovascularization in an adolescent with RDH12-associated retinal degeneration

Background: Leber congenital amaurosis (LCA) due to RDH12 mutations typically manifests with severe vision loss and panretinal dystrophy. We sought to describe a case of LCA with choroidal neovascularization (CNV) in a 17-year-old patient. Materials and Methods: Case report of a 17-year old with LCA who presented with acute central vision loss of the right eye in the context of a chronic retinal dystrophy. Multimodal retinal imaging including spectral-domain optical coherence tomography and indocyanine green angiography revealed CNV. Results: A 17-year-old boy with previously diagnosed LCA/early-onset retinal dystrophy (EOSRD), with subsequently identified biallelic mutations in RDH12 was found to have type 2 CNV. Patient was treated with intravitreal ranibizumab and exhibited improvement on follow-up exam. Conclusions: Choroidal neovascularization may be a unique occurrence in RDH12-associated retinal dystrophy. Successful treatment of the neovascularization could be accomplished with intravitreal antivasogenic therapy.

Morphometry of the normal retinal periarteral capillary-free zone and changes during severe nonproliferative diabetic retinopathy

PURPOSE

To explore the normal morphological features of the retinal periarteral capillary free zone (paCFZ) and the changes associated with severe non-proliferative diabetic retinopathy (NPDR) by optical coherence tomography angiography (OCTA).

METHODS

A total of 148 normal subjects and 115 patients with severe NPDR were enrolled. Spectral-domain OCTA was used to acquire the image with a Cirrus prototype. Diameter and area of each paCFZ quadrant and adjacent large artery diameter was estimated.

RESULTS

In healthy subjects, the maximum width of paCFZ in the temporal quadrant (169.38 ± 19.26 μm) was smaller than the other three quadrants (all P <0.001). The ratio of maximum paCFZ width to artery caliber was much larger in the nasal quadrants than the rest quadrants (Ps <0.05). In patients with severe NPDR, both maximum width and area of paCFZ were significant larger, and the retinal artery inner diameters significant smaller in each quadrant compared to normal subjects (Ps <0.05). The ratio of paCFZ maximum width to artery caliber maximum width was significant greater, and the ratio of paCFZ area to artery caliber was significantly higher in all quadrants compared to normal eyes (Ps <0.05).

CONCLUSIONS

OCTA provides noninvasive and quantitative measurement of paCFZ dimensions. The maximum width and area of paCFZ quadrants and the ratios of these parameters to adjacent inner artery width and area are elevated in severe NPDR, suggesting that changes in paCFZ dimension can be used as clinical indices for diseases associated with changes in retinal microcirculation and oxygen pressure.PRÉCIS:Optical coherence tomography angiography revealed differences in retinal periarteral capillary free zone (paCFZ) morphometry between health retina and severe non-proliferative diabetic retinopathy. Morphometric indices of paCFZ may be useful for monitoring disease occurrence and progression.

Choroideremia: from genetic and clinical phenotyping to gene therapy and future treatments

Choroideremia is an X-linked inherited chorioretinal dystrophy leading to blindness by late adulthood. Choroideremia is caused by mutations in the CHM gene which encodes Rab escort protein 1 (REP1), an ubiquitously expressed protein involved in intracellular trafficking and prenylation activity. The exact site of pathogenesis remains unclear but results in degeneration of the photoreceptors, retinal pigment epithelium and choroid. Animal and stem cell models have been used to study the molecular defects in choroideremia and test effectiveness of treatment interventions. Natural history studies of choroideremia have provided additional insight into the clinical phenotype of the condition and prepared the way for clinical trials aiming to investigate the safety and efficacy of suitable therapies. In this review, we provide a summary of the current knowledge on the genetics, pathophysiology, clinical features and therapeutic strategies that might become available for choroideremia in the future, including gene therapy, stem cell treatment and small-molecule drugs with nonsense suppression action.

A 5-Year-Old Case of Choroidal Neovascularization in Enhanced S-Cone Syndrome Treated with Ranibizumab

Introduction

We describe the youngest case of enhanced S-cone syndrome (ESCS) associated with choroidal neovascularization (CNV) successfully treated with intravitreal ranibizumab injections.

Case Report

A 5-year-old boy presented with round-shaped fibrotic subretinal lesions in both eyes with surrounding subretinal fluid and progressive visual deterioration in the right eye. Fine foci of increased autofluorescence were observed along the arcades in both eyes. Fluorescein angiography revealed the presence of CNV in his right eye, and treatment with ranibizumab was initiated, with significant improvement in vision. Subsequent electroretinogram examination and genetic studies of the patient and his two younger siblings confirmed the diagnosis of ESCS.

Conclusion

CNV has been reported to occur in different inherited retinal degenerations, including ESCS. Our experience confirms that treatment with ranibizumab in patients with CNV-complicated ESCS can be potentially vision-saving.

Choroidal imaging biomarkers

The choroid is the vascular coat of the eye, and its role has been studied in multiple chorioretinal disorders. Recent advancements in choroidal imaging techniques, including enhanced depth imaging optical coherence tomography, swept source optical coherence tomography, en face optical coherence tomography, and optical coherence tomography angiography have facilitated an in-depth analysis of the choroid. The gradual shift from manual to automated segmentation and binarization methods have led to precise and reproducible measurements of choroidal parameters. These qualitative and quantitative parameters, called choroidal imaging biomarkers, have evolved over the past decade from a simple linear subfoveal choroidal thickness to more complex 3D choroidal reconstruction, thus widening the spectrum encompassing multiple parameters. These biomarkers have provided a better understanding of the pathogenesis, are helpful in diagnostic dilemmas, and, in the future may also help to devise treatment options. The lack of normative data, absence of standardized parameters, and limitations of the imaging techniques, however, have led to ambiguity and difficulty in the interpretation of these variables. We attempt to address these lacunae in the literature and provide a basic understanding of the choroid in both health and disease using these choroidal biomarkers.

Ocular gene therapy for choroideremia: clinical trials and future perspectives

Introduction

Gene therapy offers the potential for targeted replacement of single gene defects in inherited retinal degenerations.

Areas covered

Choroideremia is an X-linked blinding retinal disease resulting from deficiency of the CHM gene product, REP1. The disease represents an ideal target for retinal gene therapy, as it is readily diagnosed in the clinic, relatively homogenous in phenotype and slow progressing, thereby providing a wide therapeutic window for intervention. Ongoing clinical trials of retinal gene therapy for choroideremia using an adeno-associated viral vector have demonstrated safety and early efficacy. We review the clinical characteristics of the disease with a view to interpreting the findings of gene therapy clinical trials and discuss future directions.

Expert commentary

Choroideremia gene therapy has so far demonstrated good safety profile and early functional visual acuity gains in a proportion of trial participants, which appear to be sustained.

Clinical applications of optical coherence tomography angiography: What we have learnt in the first 3 years

A review of the literature from 2014 to 2016 was conducted, focusing on the results of optical coherence tomography angiography in different chorioretinal diseases. In only 3 years, optical coherence tomography angiography has been shown to be an effective tool for diagnosing choroidal neovascularization complicating age-related macular degeneration, pathologic myopia, and inflammatory conditions. The technique has sometimes been considered superior to conventional multimodal imaging, for example, in choroidal neovascularization associated with chronic central serous chorioretinopathy or multifocal choroiditis. In retinal vascular diseases, optical coherence tomography angiography has helped to understand the condition described as paracentral acute middle maculopathy and has been considered highly effective for the analysis of retinal vascular macular changes secondary to retinal vein occlusion or macular telangiectasia. Changes in the foveal avascular zone, also reported in diabetic maculopathy, have been shown to occur before any angiographic signs. A reduction in capillary vascular density has been reported in the fovea of eyes with malignant melanoma, but not in eyes with choroidal nevus. However, optical coherence tomography angiography is a recent technique that probably needs refinements and further studies. Nevertheless, the first 3 years of optical coherence tomography angiography use suggest its clinical relevance and useful applications in daily clinical practice.

Retinal Vascular Impairment in Best Vitelliform Macular Dystrophy Assessed by Means of Optical Coherence Tomography Angiography

PURPOSE

To evaluate vascular abnormalities at superficial (SCP) and deep (DCP) capillary plexuses and choriocapillaris (CC) in patients with Best vitelliform macular dystrophy (BVMD) by means of optical coherence tomography angiography (OCT-A).

DESIGN

Cross-sectional case series.

METHODS

Sixty-six eyes of 33 patients with BVMD (16 male) and 33 controls were consecutively enrolled. Patients were subdivided into classic stages and underwent best-corrected visual acuity (BCVA), fundus autofluorescence and spectral domain-optical coherence tomography, and 4.5 × 4.5-mm swept-source OCT-A. Choroidal neovascularization (CNV) and capillary dilations were qualitatively assessed by 2 masked ophthalmologists. Each OCT-A slab was imported into ImageJ 1.50 and digitally binarized for quantitative analyses. Foveal avascular zone (FAZ) area was measured manually; vessel density was then quantified after the exclusion of the FAZ pixels. Eyes classified as stages 3 and 4 were evaluated together.

RESULTS

Nineteen eyes (28.8%) revealed capillary dilations at DCP, 15 of which were in stages 1 and 2. Interestingly, CNV was detected in 24 eyes (36.4%). Quantitative analysis disclosed that stages 3-4 and 5 carry significant impairment at both SCP (P < .0001 and P = .02, respectively) and DCP (P < .0001 and P = .0004, respectively) compared to controls. FAZ area was enlarged at the DCP (P = .001). Only DCP vessel density significantly correlated with the stage and BCVA.

CONCLUSIONS

Patients with BVMD show significant vascular impairment at both superficial and deep retinal plexuses, correlating with functional outcomes. These findings, especially at DCP, may improve our understanding about the pathogenesis, and may help in predicting BVMD treatment efficacy.

Optical coherence tomography angiography: Technical principles and clinical applications in ophthalmology

Optical coherence tomography angiography (OCTA) is a functional extension of OCT that provides information on retinal and choroidal circulations without the need for dye injections. With the recent development of high-speed OCT systems and efficient algorithms, OCTA has become clinically feasible. In this review article, we discuss the technical principles of OCTA, including image processing and artifacts, and its clinical applications in ophthalmology. We summarize recent studies which qualitatively or quantitatively assess disease presentation, progression, and/or response to treatment.