Foveal cavitation as an optical coherence tomography finding in central cone dysfunction

Analysis of Suspected Achromatopsia by Multimodal Diagnostic Testing

BACKGROUND

Achromatopsia (ACHM) as a hereditary cone disease might manifest in a stationary and progressive manner. The proper clinical and genetic diagnosis may allow an individual prognosis, accurate genetic counselling, and the optimal choice of low vision aids. The primary aim of the study was to determine the spectrum of clinical and genetic diagnostics required to characterize the ACHM.

METHODS

A retrospective analysis was performed in 8 patients from non-related families (5 ♀,3 ♂); age at diagnosis: 3 - 56 y, mean 18.13 (SD ± 18.22). Clinical phenotyping, supported by colour vision test, fundus photography-, autofluorescence- (FAF), infra-red- (IR), OCT imaging and electroretinography provided information on the current status and the course of the disease over the years. In addition, genetic examinations were performed with ACHM relevant testing (CNGA3, CNGB3, GNAT2, PDE6C, PDE6H and the transcription factor ATF6).

RESULTS

All patients suffered photophobia and reduced visual acuity (mean: 0.16 [SD ± 0.08]). Nystagmus was identified in 7 from 8 subjects and in one patient a head-turn right helped to reduce the nystagmus amplitude. Colour vision testing confirmed complete achromatopsia in 7 out of 8 patients. Electrophysiology found severely reduced photopic- but also scotopic responses. Thinning and interruption of the inner segment ellipsoid (ISe) line within the macula but also FAF- and IR abnormalities in the fovea and/or parafovea were characteristic in all ACHM patients. Identification of pathogenic mutations in 7 patients helped to confirm the diagnosis of ACHM (3 adults, 4 children; 3 ♀ and 4 ♂). Achromatopsia was linked to CNGA3 (2 ♀, 1 ♂) and CNGB3 variants (2 ♀, 3 ♂). The youngest patient (♀, 10 y) had 3 different CNGB3 variants on different alleles. In a patient (♂, 29 y) carrying 2 pathogenic digenic-triallelic CNGA3- and CNGB3-mutations, a severe progression of ISe discontinuity to coloboma-like macular atrophy was observed during the 12-year follow-up. The oldest female (67 y) showed a compound homozygous CNGA3- and heterozygous CNGB3-, as well as a heterozygous GUCY2D variants. The destruction of her ISe line was significantly enlarged and represented a progressive cone-rod phenotype in comparison to other ACHM patients. In a patient (♂, 45 y) carrying a pathogenic CNGB3 and USH2 mutation, a severe macular oedema and a rod-cone phenotype was observed. In addition, two variants in C2ORF71 considered as VOS were found. One patient showed the rare ATF6 mutation, where a severe coloboma-like macular atrophy was observed on the left eye as early as at the age of three years.

CONCLUSION

Combining multimodal ophthalmological diagnostics and molecular genetics when evaluating patients with ACHM helps in characterizing the disease and associated modifiers, and is therefore strongly recommended for such patients.

STELLATE MULTIFORM AMELANOTIC CHOROIDOPATHY: Clinical and Multimodal Imaging Features

PURPOSE

To describe the clinical and multimodal imaging features of stellate multiform amelanotic choroidopathy (SMACH; also known as serous maculopathy due to aspecific choroidopathy).

METHODS

Retrospective observational case series of eyes presenting with SMACH. Multimodal imaging including fundus photography, optical coherence tomography (OCT), OCT angiography (OCTA), and indocyanine green angiography (ICGA) was analyzed.

RESULTS

Eighteen eyes from 18 patients (mean age: 28 ± 19 years) were included. The mean follow-up duration was 9 years. Ophthalmoscopy showed a yellowish orange, dendriform choroidal lesion. At presentation, subretinal fluid (SRF) was seen in 10 of 18 cases (56%). Eight patients (44%) showed no evidence of SRF during a mean follow-up of 6 years. Cross-sectional OCT showed hyperreflective fibrous-like changes within the inner choroid with choriocapillaris flow preservation on OCTA. En face OCT showed a hyperreflective choroidal lesion with finger-like projections oriented in a stellate configuration. On ICGA, SMACH showed early and late hypofluorescence. None of the cases showed lesion growth.

CONCLUSION

SMACH seems to be a unilateral choroidopathy characterized by distinctive multimodal imaging features. As SRF was absent in some cases, while a dendriform pattern was a consistent finding in all eyes, the authors propose renaming this entity "stellate multiform amelanotic choroidopathy," a name that retains its previous abbreviation "SMACH."

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.

Stargardt disease and progress in therapeutic strategies

Background: Stargardt disease (STGD1) is an autosomal recessive retinal dystrophy due to mutations in ABCA4, characterized by subretinal deposition of lipofuscin-like substances and bilateral centrifugal vision loss. Despite the tremendous progress made in the understanding of STGD1, there are no approved treatments to date. This review examines the challenges in the development of an effective STGD1 therapy.Materials and Methods: A literature review was performed through to June 2021 summarizing the spectrum of retinal phenotypes in STGD1, the molecular biology of ABCA4 protein, the in vivo and in vitro models used to investigate the mechanisms of ABCA4 mutations and current clinical trials.Results: STGD1 phenotypic variability remains an challenge for clinical trial design and patient selection. Pre-clinical development of therapeutic options has been limited by the lack of animal models reflecting the diverse phenotypic spectrum of STDG1. Patient-derived cell lines have facilitated the characterization of splice mutations but the clinical presentation is not always predicted by the effect of specific mutations on retinoid metabolism in cellular models. Current therapies primarily aim to delay vision loss whilst strategies to restore vision are less well developed.Conclusions: STGD1 therapy development can be accelerated by a deeper understanding of genotype-phenotype correlations.

Stargardt disease: Multimodal imaging: A review

Stargardt disease (STGD1) is an autosomal recessive retinal dystrophy, characterised by bilateral progressive central vision loss and subretinal deposition of lipofuscin-like substances. Recent advances in molecular diagnosis and therapeutic options are complemented by the increasing recognition of new multimodal imaging biomarkers that may predict genotype and disease progression. Unique non-invasive imaging features of STDG1 are useful for gene variant interpretation and may even provide insight into the underlying molecular pathophysiology. In addition, pathognomonic imaging features of STGD1 have been used to train neural networks to improve time efficiency in lesion segmentation and disease progression measurements. This review will discuss the role of key imaging modalities, correlate imaging signs across varied STGD1 presentations and illustrate the use of multimodal imaging as an outcome measure in determining the efficacy of emerging STGD1 specific therapies.

Serous business: Delineating the broad spectrum of diseases with subretinal fluid in the macula

A wide range of ocular diseases can present with serous subretinal fluid in the macula and therefore clinically mimic central serous chorioretinopathy (CSC). In this manuscript, we categorise the diseases and conditions that are part of the differential diagnosis into 12 main pathogenic subgroups: neovascular diseases, vitelliform lesions, inflammatory diseases, ocular tumours, haematological malignancies, paraneoplastic syndromes, genetic diseases, ocular developmental anomalies, medication-related conditions and toxicity-related diseases, rhegmatogenous retinal detachment and tractional retinal detachment, retinal vascular diseases, and miscellaneous diseases. In addition, we describe 2 new clinical pictures associated with macular subretinal fluid accumulation, namely serous maculopathy with absence of retinal pigment epithelium (SMARPE) and serous maculopathy due to aspecific choroidopathy (SMACH). Differentiating between these various diseases and CSC can be challenging, and obtaining the correct diagnosis can have immediate therapeutic and prognostic consequences. Here, we describe the key differential diagnostic features of each disease within this clinical spectrum, including representative case examples. Moreover, we discuss the pathogenesis of each disease in order to facilitate the differentiation from typical CSC.

The role of multimodal imaging and vision function testing in ABCA4-related retinopathies and their relevance to future therapeutic interventions

The aim of this review article is to describe the specific features of Stargardt disease and ABCA4 retinopathies (ABCA4R) using multimodal imaging and functional testing and to highlight their relevance to potential therapeutic interventions. Standardised measures of tissue loss, tissue function and rate of change over time using formal structured deep phenotyping in Stargardt disease and ABCA4R are key in diagnosis, and prognosis as well as when selecting cohorts for therapeutic intervention. In addition, a meticulous documentation of natural history will be invaluable in the future to compare treated with untreated retinas. Despite the familiarity with the term Stargardt disease, this eponymous classification alone is unhelpful when evaluating ABCA4R, as the ABCA4 gene is associated with a number of phenotypes, and a range of severity. Multimodal imaging, psychophysical and electrophysiologic measurements are necessary in diagnosing and characterising these differing retinopathies. A wide range of retinal dystrophy phenotypes are seen in association with ABCA4 mutations. In this article, these will be referred to as ABCA4R. These different phenotypes and the existence of phenocopies present a significant challenge to the clinician. Careful phenotypic characterisation coupled with the genotype enables the clinician to provide an accurate diagnosis, associated inheritance pattern and information regarding prognosis and management. This is particularly relevant now for recruiting to therapeutic trials, and in the future when therapies become available. The importance of accurate genotype-phenotype correlation studies cannot be overemphasised. This approach together with segregation studies can be vital in the identification of causal mutations when variants in more than one gene are being considered as possible. In this article, we give an overview of the current imaging, psychophysical and electrophysiological investigations, as well as current therapeutic research trials for retinopathies associated with the ABCA4 gene.

Optical Gap Biomarker in Cone-Dominant Retinal Dystrophy

PURPOSE

To characterize the progression of optical gaps and expand the known etiologies of this phenotype.

DESIGN

Retrospective cohort study.

METHODS

Thirty-six patients were selected based on the identification of an optical gap on spectral-domain optical coherence tomography (OCT) from a large cohort of patients (N = 746) with confirmed diagnoses of inherited retinal dystrophy. The width and height of the gaps in 70 eyes of 36 patients were measured by 2 independent graders using the caliper tool on Heidelberg Explorer. Measurements of outer and central retinal thickness were also evaluated and correlated with gap dimensions.

RESULTS

Longitudinal analysis confirmed the progressive nature of optical gaps in patients with Stargardt disease, achromatopsia, occult macular dystrophy, and cone dystrophies (P < .003). Larger changes in gap width were noted in patients with Stargardt disease (78.1 μm/year) and cone dystrophies (31.9 μm/year) compared with patients with achromatopsia (16.2 μm/year) and occult macular dystrophy (15.4 μm/year). Gap height decreased in patients with Stargardt disease (6.5 μm/year; P = .02) but increased in patients with achromatopsia (3.3 μm/year) and occult macular dystrophy (1.2 μm/year). Gap height correlated with measurements of central retinal thickness at the fovea (r = 0.782, P = .00012). Interocular discordance of the gap was observed in 7 patients. Finally, a review of all currently described etiologies of optical gap was summarized.

CONCLUSION

The optical gap is a progressive phenotype seen in an increasing number of etiologies. This progressive nature suggests a use as a biomarker in the understanding of disease progression. Interocular discordance of the phenotype may be a feature of Stargardt disease and cone dystrophies.

Choroidal Cavitary Disorders

The structure and functions of the choroid have been long acknowledged but the pathophysiology behind various anomalies has been difficult to understand until the advent of optical coherence tomography (OCT). With OCT imaging, choroidal cavitations appear as optically empty spaces between the outer retinal and choroidal layers with attenuation or loss of outer retinal layers. Choroidal cavitations are found in the posterior pole and seen in conditions such as pathologic myopia, north carolina macular dystrophy (NCMD), focal choroidal excavation (FCE), and torpedo maculopathy (TM). To date, these disorders have not been linked. A commonality they all share is malformation of the RPE-photoreceptor-choroid complex. The following report describes the differences and similarities of choroidal cavitation amongst the different retinal disorders and emphasizes the importance of multimodal imaging in the detection and management of potential complications.

Phenotype Analysis of Retinal Dystrophies in Light of the Underlying Genetic Defects: Application to Cone and Cone-Rod Dystrophies

Phenotypes observed in a large cohort of patients with cone and cone-rod dystrophies (COD/CORDs) are described based on multimodal retinal imaging features in order to help in analyzing massive next-generation sequencing data. Structural abnormalities of 58 subjects with molecular diagnosis of COD/CORDs were analyzed through specific retinal imaging including spectral-domain optical coherence tomography (SD-OCT) and fundus autofluorescence (BAF/IRAF). Findings were analyzed with the underlying genetic defects. A ring of increased autofluorescence was mainly observed in patients with CRX and GUCY2D mutations (33% and 22% of cases respectively). “Speckled” autofluorescence was observed with mutations in three different genes (ABCA4 64%; C2Orf71 and PRPH2, 18% each). Peripapillary sparing was only found in association with mutations in ABCA4, although only present in 40% of such genotypes. Regarding SD-OCT, specific outer retinal abnormalities were more commonly observed in particular genotypes: focal retrofoveal interruption and GUCY2D mutations (50%), foveal sparing and CRX mutations (50%), and outer retinal atrophy associated with hyperreflective dots and ABCA4 mutations (69%). This study outlines the phenotypic heterogeneity of COD/CORDs hampering statistical correlations. A larger study correlating retinal imaging with genetic results is necessary to identify specific clinical features that may help in selecting pathogenic variants generated by high-throughput sequencing.

Long term follow-up of a family with GUCY2D dominant cone dystrophy

AIM

To describe long term follow-up in a family with GUCY2D dominant cone dystrophy.

METHODS

Optical coherence tomography scans and fundus autofluorescence images were obtained. Flash and pattern electroretinograms (ERGs) and occipital pattern reversal visual evoked potentials were recorded.

RESULTS

Two members of the same family (father and son) were identified to have the heterozygous R838C mutation in the GUCY2D gene. The father presented at the age of 45 with bilateral bull's eye maculopathy and temporal disc pallor. Over 13y of serial follow up visits, the bull's eye maculopathy progressed gradually into macular atrophy. Electrophysiological tests were significantly degraded suggesting poor macular function. Spectral-domain optical coherence tomography (SD-OCT) scans showed progressive loss and disruption of the ellipsoid layer at the foveal level. His son presented at the age of 16 with bilateral granular retinal pigment epithelial changes in both maculae. Electrophysiological testing was initially borderline normal but has gradually deteriorated to show reduced cone ERGs and macula function. SD-OCT demonstrated gradual macular thinning and atrophy bilaterally. Unlike his father, there was no disruption of the ellipsoid layer.

CONCLUSION

Both family members exhibited gradual changes in their fundi, electrophysiological testing and multimodal imaging. Changes were milder than those observed in other mutations of the same gene.

RETINAL MANIFESTATIONS OF SPINOCEREBELLAR ATAXIA TYPE 7 IN TWO CONSECUTIVE GENERATIONS

PURPOSE

To report a diagnosis of spinocerebellar ataxia Type 7 (SCA-7) first diagnosed in the daughter followed by the father, with proven genetic testing and display of progressive anticipation of disease penetrance.

METHODS

A 5-year-old African American female admitted for failure to thrive underwent full ocular examination and fundus photography, with genetic confirmation of SCA-7. The father carried a previous diagnosis of possible solar retinopathy; however, with further genetic testing, he was also found to have SCA-7.

RESULTS

The patient was admitted for failure to thrive with suspicion of ataxia neurodegenerative disorder. Visual acuity was hand motion. Fundus examination showed retinal pigment epithelium pigmentary changes in the macula and peripheral retina. Further genetic workup revealed 96 CAG repeat expansion compared with a normal of <20 repeats. Ocular examination of patient's father displayed a milder form of retinopathy with genetic testing showing 47 CAG repeat expansion. Diagnosis of SCA-7 was made displaying genetic anticipation.

CONCLUSION

Spinocerebellar ataxia Type 7 is a disease of expanded CAG repeats showing genetic anticipation. Patients display progressive cerebellar ataxia, dysarthria dysphagia, slow saccadic eye movements, and cone photoreceptor loss leading to progressive vision loss. CAG repeat length tends to expand with transmission resulting in dramatic symptoms in offspring sometimes resulting in diagnosis before parents' diagnosis. Awareness of this condition may help in earlier diagnosis and unnecessary testing resulting in more effective counseling for the patient and their family.

The use of handheld spectral domain optical coherence tomography in pediatric ophthalmology practice: Our experience of 975 infants and children

Purpose:

Optical coherence tomography (OCT) is an important imaging tool assessing retinal architecture. In this article, we report a single centers experience of using handheld spectral domain (SD)-OCT in a pediatric population using the Envisu 2300 (Bioptigen Inc., Research Triangle Park, NC, USA).

Methods:

We studied SD-OCT images from 975 patients imaged from January 2011 to December 2014. The variety of cases that underwent an SD-OCT was analyzed. Cases examples from different case scenarios were selected to showcase unique examples of many diseases.

Results:

Three hundred and sixty-eight infants (37.7%) were imaged for retinopathy of prematurity, 362 children (37.1%) underwent the test for evaluation of suboptimal vision or an unexplained vision loss, 126 children (12.9%) for evaluation of nystagmus or night blindness, 54 children (5.5%) for an intraocular tumor or a mass lesion such as retinoblastoma, and 65 children (6.7%) for other diseases of the pediatric retina. The unique findings in the retinal morphology seen with some of these diseases are discussed.

Conclusion:

The handheld SD-OCT is useful in the evaluation of the pediatric retinal diseases. The test is useful in the assessment of vision development in premature children, evaluation of unexplained vision loss and amblyopia, nystagmus and night blindness, and intraocular tumors (including retinoblastoma).

Multimodal imaging of foveal cavitation in retinal dystrophies

PURPOSE

Inherited retinal dystrophies and cone dysfunction syndromes may show a sharp hyporeflective interruption in the outermost retinal layers on optical coherence tomography (OCT), known as foveal cavitation (FC). The aim of the study was to describe the morpho-functional features of FC in patients affected by retinal dystrophies by means of multimodal imaging.

METHODS

A consecutive series of patients affected by FC were prospectively recruited for the study. Patients underwent short-wavelength (SW) and near-infraRed (NIR) fundus autofluorescence (FAF), spectral domain OCT (SD-OCT), microperimetry (MP), and multifocal electroretinogram (mfERG). Mean size of FC on OCT was correlated with best-corrected visual acuity (BCVA).

RESULTS

Overall, 15 patients (30 eyes) were enrolled. Mean age was 38.2 ± 14.5 years (range: 10-60), with nine females (60 %). Mean BCVA was 0.5 ± 0.4 LogMAR. SD-OCT revealed focal loss of outer retinal layers and disruption of inner segment ellipsoid zone. Vertical height of FC (mean 27.77 ± 18.77 μm) was indirectly related to BCVA; complete forms of FC, with total loss of outer OCT bands, showed a poorer visual outcome. The FC size on NIR-FAF turned out to be larger with respect to SD-OCT and SW-FAF.

CONCLUSION

Our data indicate that the presence of FC worsens functional outcome in patients affected by retinal disorders; complete and higher lesions are associated with a worse morpho-functional prognosis in these eyes.

Circumscribed outer foveolar defects in spinocerebellar ataxia type 7

PURPOSE

To report circumscribed outer foveolar defects in a 40-year-old man with a history of spinocerebellar ataxia type 7.

METHODS

A 40-year-old man with genetically confirmed spinocerebellar ataxia type 7 presented with progressive vision loss and decreased color perception for 3 years. He underwent a full ocular examination, fundus photography, autofluorescence, spectral-domain optical coherence tomography imaging, and a full-field electroretinogram.

RESULTS

The patient's ocular examination and fundus autofluorescence were both normal except for mild temporal pallor of both optic discs. Spectral-domain optical coherence tomographic imaging showed foveal thinning with an outer foveolar defect because of focal loss of photoreceptors, disruption of the inner segment-outer segment junction but preservation of the external limiting membrane, and thinning of the outer plexiform layer in both eyes. Electroretinography showed severely reduced cone function with mildly reduced rod function.

CONCLUSION

Spinocerebellar ataxia type 7 should be included in the differential diagnosis for "outer retinal holes" or "foveal cavitation," which also includes solar retinopathy, juxtafoveal telangiectasia, Welder maculopathy, tamoxifen retinopathy, Stargardt disease, amyl nitrate abuse, and cone or cone-rod degeneration syndromes.

Multimodal imaging and multifocal electroretinography demonstrate autosomal recessive Stargardt disease may present like occult macular dystrophy

PURPOSE

To describe multimodal imaging and electrophysiologic characteristics of an unusual subset of patients with genetically confirmed autosomal recessive Stargardt disease (STGD1) who exhibited a central form of cone dysfunction resembling occult macular dystrophy that preceded the development of lipofuscin flecks, atrophy of retinal pigment epithelium (RPE), or full-field electroretinography abnormalities.

METHODS

Retrospective, observational descriptive case series.

RESULTS

Five patients with compound heterozygous ABCA4 mutations presented with bilateral visual acuity reduction, normal-appearing fundi, and blocked choroidal fluorescence on fluorescein angiography. One sibling each of two probands with identical genotypes was also included for analysis. Full-field electroretinography testing was normal in all patients, but multifocal electroretinography demonstrated centripetally depressed amplitudes exceeding areas of fundus autofluorescence, infrared imaging, and spectral domain optical coherence tomography abnormalities. Spectral domain optical coherence tomography initially revealed disruption of the inner segment ellipsoid band accompanying an ovoid hypofluorescent foveolar lesion. Progression to later stages was accompanied by the loss of the foveal photoreceptor outer segments, creating foveal cavitation with preservation of the RPE. Fundus autofluorescence and infrared imaging demonstrated corresponding bull's eye lesions. Over time, the foveal potential space on spectral domain optical coherence tomography collapsed, and three patients developed RPE atrophy and visible lipofuscin flecks. The flecks were detectable by fundus autofluorescence and infrared imaging earlier than by biomicroscopy. From these findings, a staging system for this subset of Stargardt disease presenting with central cone dysfunction was developed and presented herein.

CONCLUSION

Autosomal recessive Stargardt disease may present as a central cone dysfunction syndrome before the development of lipofuscin flecks, atrophy of RPE, or full-field electroretinography abnormalities. If emerging therapies for Stargardt disease succeed, early recognition and treatment of patients with preserved foveal photoreceptor and RPE cell bodies may yield a more favorable visual prognosis.

Structural and genetic assessment of the ABCA4-associated optical gap phenotype

PURPOSE

To investigate the developmental stages and genetic etiology of the optical gap phenotype in recessive Stargardt disease (STGD1).

METHODS

Single and longitudinal data points from 15 patients, including four sibling pairs, exhibiting an optical gap phenotype on spectral-domain optical coherence tomography (SD-OCT) with confirmed disease-causing ABCA4 alleles were retrospectively analyzed. Fundus images with corresponding SD-OCT scans were collected with a confocal scanning laser ophthalmoscope. Structural phenotypes were assigned to three developmental stages according to SD-OCT. The ABCA4 gene was screened in all patients.

RESULTS

At least two disease-causing ABCA4 variants where identified in each patient; all except one (91%) were compound heterozygous for the p.G1961E mutation. All patients exhibited structural findings on SD-OCT that grouped into three progressive developmental stages over several years. Stage 1 was characterized by mild disruptions of the ellipsoid zone (EZ) band over the fovea. Stage 2 was a progressive expansion of the EZ band loss resulting in an empty lesion devoid of photoreceptors. Stage 3 observed a structural collapse of the inner retinal layers into the optical gap space leading to involvement and atrophy of the RPE thereafter.

CONCLUSIONS

The optical gap phenotype in STGD1 can be structurally divided into three progressive stages spanning several years. This particular phenotype also appears to be highly associated with the p.G1961E mutation of ABCA4. Taken together, it appears that a focal loss of photoreceptors sequentially precedes RPE dysfunction in the early development of ABCA4-associated optical gap lesions.

Diagnostic fundus autofluorescence patterns in achromatopsia

PURPOSE

To describe the unique diagnostic fundus autofluorescence (FAF) patterns in patients with achromatopsia and the associated findings on optical coherence tomography (OCT).

DESIGN

Observational case series.

METHODS

We evaluated 10 patients with achromatopsia by means of best-corrected visual acuity (BCVA), ophthalmoscopy, Goldmann visual field, full-field electroretinography (ffERG), OCT, and FAF photography. FAF patterns were compared with patient age and foveal changes on OCT.

RESULTS

Patients fell into two dichotomous age groups at the time of evaluation: six patients ranged from 11 to 23 years of age, and 3 patients ranged from 52 to 63 years of age. All patients had severely reduced photopic ffERG responses, including those exhibiting preserved foveal structure on OCT. The younger patients had absent to mild foveal atrophy on OCT, and four of the six demonstrated foveal and parafoveal hyperfluorescence on FAF. In addition, a 7-month-old child with compound heterozygous mutations in CNGA3 demonstrated similar foveal hyperfluorescence. The older patients demonstrated advanced foveal atrophy and punched-out foveal hypofluorescence with discrete borders on FAF imaging corresponding to the area of outer retinal cavitation on OCT.

CONCLUSIONS

Foveal hyperfluorescence is an early sign of achromatopsia that can aid in clinical diagnosis. In our cohort, patients with achromatopsia demonstrated age-dependent changes in FAF, which are likely to be progressive and to correlate with foveal atrophy and cavitation on OCT. This finding may be useful in charting the natural course of the disease and in defining a therapeutic window for treatment.

Human cone visual pigment deletions spare sufficient photoreceptors to warrant gene therapy

Human X-linked blue-cone monochromacy (BCM), a disabling congenital visual disorder of cone photoreceptors, is a candidate disease for gene augmentation therapy. BCM is caused by either mutations in the red (OPN1LW) and green (OPN1MW) cone photoreceptor opsin gene array or large deletions encompassing portions of the gene array and upstream regulatory sequences that would predict a lack of red or green opsin expression. The fate of opsin-deficient cone cells is unknown. We know that rod opsin null mutant mice show rapid postnatal death of rod photoreceptors. Using in vivo histology with high-resolution retinal imaging, we studied a cohort of 20 BCM patients (age range 5-58) with large deletions in the red/green opsin gene array. Already in the first years of life, retinal structure was not normal: there was partial loss of photoreceptors across the central retina. Remaining cone cells had detectable outer segments that were abnormally shortened. Adaptive optics imaging confirmed the existence of inner segments at a spatial density greater than that expected for the residual blue cones. The evidence indicates that human cones in patients with deletions in the red/green opsin gene array can survive in reduced numbers with limited outer segment material, suggesting potential value of gene therapy for BCM.