A hypomorphic variant of choroideremia is associated with a novel intronic mutation that leads to exon skipping.

INTRODUCTION: Molecular confirmation of pathogenic sequence variants in the CHM gene is required prior to enrolment in retinal gene therapy clinical trials for choroideremia. Individuals with mild choroideremia have been reported. The molecular basis of genotype-phenotype associations is of clinical relevance since it may impact on selection for retinal gene therapy. METHODS AND MATERIALS: Genetic testing and RNA analysis were undertaken in a patient with mild choroideremia to confirm the pathogenicity of a novel intronic variant in CHM and to explore the mechanism underlying the mild clinical phenotype. RESULTS: A 42-year-old male presented with visual field loss. Fundoscopy and autofluorescence imaging demonstrated mild choroideremia for his age. Genetic analysis revealed a variant at a splice acceptor site in the CHM gene (c.1350-3C > G). RNA analysis demonstrated two out-of-frame transcripts, suggesting pathogenicity, without any detectable wildtype transcripts. One of the two out-of-frame transcripts is present in very low levels in healthy controls. DISCUSSION: Mild choroideremia may result from +3 or -3 splice site variants in CHM. It is presumed that the resulting mRNA transcripts may be partly functional, thereby preventing the development of the null phenotype. Choroideremia patients with such variants may present challenges for gene therapy since there may be residual transcript activity which could result in long-lasting visual function which is atypical for this disease.

Loss of REP1 impacts choroidal melanogenesis and vasculogenesis in choroideremia.

Choroideremia (CHM) is a rare X-linked chorioretinal dystrophy affecting the photoreceptors, retinal pigment epithelium (RPE) and choroid, however, the involvement of the choroid in disease progression is not fully understood. CHM is caused by mutations in the CHM gene, encoding the ubiquitously expressed Rab escort protein 1 (REP1). REP1 plays an important role in intracellular trafficking of vesicles, including melanosomes. In this study, we examined the ultrastructure of the choroid in chmru848 fish and Chmnull/WT mouse models using transmission electron and confocal microscopy. Significant pigmentary disruptions were observed, with lack of melanosomes in the choroid of chmru848 fish from 4 days post fertilisation (4dpf), and a reduction in choroidal blood vessel diameter and interstitial pillars suggesting a defect in vasculogenesis. Total melanin and expression of melanogenesis genes tyr, tryp1a, mitf, dct and pmel were also reduced from 4dpf. In Chmnull/WT mice, choroidal melanosomes were significantly smaller at 1 month, with reduced eumelanin at 1 year. The choroid in CHM patients were also examined using spectral domain optical coherence tomography (SD-OCT) and OCT-angiography (OCT-A) and the area of preserved choriocapillaris (CC) was found to be smaller than that of overlying photoreceptors, suggesting that the choroid is degenerating at a faster rate. Histopathology of an enucleated eye from a 74-year-old CHM male patient revealed isolated areas of RPE but no associated underlying CC. Pigmentary disruptions in CHM animal models reveal an important role for REP1 in melanogenesis, and drugs that improve melanin production represent a potential novel therapeutic avenue.

Clinical and Genetic Findings in Korean Patients with Choroideremia.

PURPOSE: We share and analyze the clinical presentations and genotypes of Korean male patients and female carriers who visited our clinic. METHODS: Six male patients and three female carriers with comprehensive ophthalmic examinations and next-generation sequencing were included. Detailed clinical features were identified using visual field (VF) test and multimodal imaging including color fundus photography, fundus autofluorescence (FAF), and optical coherence tomography (OCT). RESULTS: Six male patients were diagnosed with choroideremia at the median age of 25 years. Before genetic testing, three patients (50.0%) were clinically diagnosed with choroideremia, while the other three patients (50.0%) with retinitis pigmentosa. Patients showed different types of hemizygous CHM variants, including two nonsense variants, c.715C>T:p.(Arg239*) and c.799C>T:p.(Arg267*); two frameshift variants, c.1584_1587del:p.(Val529Hisfs*7) and c.403_404del:p.(Asp135Phefs*9); one splicing variant c.1511-28_1511-2del; and one exon 2-8 duplication. The latter three variants were novel. Two female carriers had heterozygous exon 2-8 duplication and the other one female carrier had heterozygous nonsense variant c.715C>T:p. (Arg239*). Fundus showed diffuse yellow-whitish scleral reflex and granular pigmented lesions. FAF showed multiple patchy hypofluorescence lesions, sparing macula. OCT showed thinning of outer nuclear layer, ellipsoid zone, retinal pigment epithelium layer, choroid thickness, interlaminar bridges, outer retinal tubulations, and microcysts in the inner nuclear layer. VF showed ring scotoma pattern with small amount of remaining central field. Asymptomatic female carriers showed variable fundus findings and mild changes in OCT. CONCLUSIONS: A detailed description of the genotypes with three novel mutations and phenotypes of six choroideremia patients and three CHM mutation female carriers are presented.

Outer retinal and choriocapillaris modifications in choroideremia: three differentially impaired retinal regions and the potential diagnostic role of the external limiting membrane.

BACKGROUND: The external limiting membrane (ELM) is formed by the apical processes of Müller cells attached to the inner segments of the photoreceptor cells. Both cells are implicated in the pathogenesis of choroideremia (CHM). The purpose of this study was to explore the diagnostic role of ELM in CHM. METHODS: The study was designed as observational case series. Sixteen CHM eyes were examined by multimodal imaging and were compared to healthy controls. The main outcome was the measurement of ELM thickness and reflectivity over the follow-up, and its relationship with other multimodal imaging quantitative parameters. RESULTS: Baseline ELM was characterized by 11 ± 1 µm of thickness and 0.68 ± 0.13 of reflectivity, resulting 8 ± 1 µm (p < 0.01) and 0.65 ± 0.14 (p > 0.05) at the last follow-up. Choriocapillaris (CC) analysis revealed 3 regions. The first was characterized by normal vessel density (VD). The second surrounding the partially preserved islet, showing significantly lower baseline VD and undergoing minor changes over the follow-up. The third was localized in the partially preserved islet, showing significantly lower VD at baseline, and resulted atrophic at the last follow-up. ELM reflectivity and ELM thickness correlated both with outer retinal atrophy progression and the CC status. CONCLUSIONS: ELM may be considered a useful imaging biomarker in CHM. Its assessment confirmed a primary role of Müller cells impairment in the pathogenesis of CHM.

A generation of human-induced pluripotent stem cell line (MUi032-A) from a Choroideremia disease patient carrying a hemizygous mutation on the CHM gene.

Choroideremia (CHM) is a monogenic, X-linked inherited retinal disease caused by mutations in the CHM gene. CHM patients develop progressive loss of vision due to degeneration of cell layers in the retina. In this report, the human-induced pluripotent stem cell, MUi032-A, was generated from CD34+ hematopoietic stem/progenitor cells of a male CHM patient by co-electroporation of non-integration episomal vectors containing OCT4/shp53, Sox-2/KLF4, and L-MYC/LIN-28. The MUi032-A showed normal karyotype and a hemizygous c.715C > T mutation. They expressed pluripotency markers and differentiated into cells derived from three germ layers. This cell line may be useful for disease mechanisms and gene therapy studies.

Widespread subclinical cellular changes revealed across a neural-epithelial-vascular complex in choroideremia using adaptive optics.

Choroideremia is an X-linked, blinding retinal degeneration with progressive loss of photoreceptors, retinal pigment epithelial (RPE) cells, and choriocapillaris. To study the extent to which these layers are disrupted in affected males and female carriers, we performed multimodal adaptive optics imaging to better visualize the in vivo pathogenesis of choroideremia in the living human eye. We demonstrate the presence of subclinical, widespread enlarged RPE cells present in all subjects imaged. In the fovea, the last area to be affected in choroideremia, we found greater disruption to the RPE than to either the photoreceptor or choriocapillaris layers. The unexpected finding of patches of photoreceptors that were fluorescently-labeled, but structurally and functionally normal, suggests that the RPE blood barrier function may be altered in choroideremia. Finally, we introduce a strategy for detecting enlarged cells using conventional ophthalmic imaging instrumentation. These findings establish that there is subclinical polymegathism of RPE cells in choroideremia.

Choroideremia Carriers: Dark-Adapted Perimetry and Retinal Structures.

Purpose: In choroideremia (CHM) carriers, scotopic sensitivity was assessed by dark adapted chromatic perimetry (DACP) and outer retinal structure was evaluated by multimodal imaging. Methods: Nine carriers (18 eyes) and 13 healthy controls (13 eyes) underwent DACP testing with cyan and red stimuli. Analysis addressed peripapillary (4 test locations closest to the optic disc), macular (52 locations), and peripheral (60 locations outside the macula) regions. Responses were considered to be rod-mediated when cyan relative to red sensitivity was >5 dB. Fundus imaging included spectral domain optical coherence tomography (SD-OCT), short-wavelength (SW-AF), near-infrared (NIR-AF), ultrawide-field (200 degrees) pseudocolor fundus imaging, and quantitative (qAF) fundus autofluorescence. Results: Detection of the cyan stimulus was rod mediated in essentially all test locations (99.7%). In the macular and peripheral areas, DACP sensitivity values were not significantly different from healthy eyes. In the peripapillary area, sensitivities were significantly decreased (P < 0.05). SD-OCT imaging ranged from hyper-reflective lesions and discontinuities of the outer retinal bands to hypertransmission of signal. SW-AF and NIR-AF images presented with peripapillary atrophy in seven patients (14 eyes). Mosaicism was detectable in SW-AF images in seven patients and in NIR-AF images in five patients. Frank hypo-autofluorescence was visible in eight patients with distinct chorioretinopathy in seven patients. The qAF values were below the 95% confidence interval (CI) of healthy age-matched individuals in 12 eyes. Conclusions: Rod mediated scotopic sensitivity was comparable to that in control eyes in macular and peripheral areas but was decreased in the peripapillary area where changes in retinal structure were also most severe.

Automated Assessment of Photoreceptor Visibility in Adaptive Optics Split-Detection Images Using Edge Detection.

Purpose: Adaptive optics scanning laser ophthalmoscopy (AOSLO) is a high-resolution imaging modality that allows measurements of cellular-level retinal changes in living patients. In retinal diseases, the visibility of photoreceptors in AOSLO images is affected by pathology, patient motion, and optics, which can lead to variability in analyses of the photoreceptor mosaic. Current best practice for AOSLO mosaic quantification requires manual assessment of photoreceptor visibility across overlapping images, a laborious and time-consuming task. Methods: We propose an automated measure for quantification of photoreceptor visibility in AOSLO. Our method detects salient edge features, which can represent visible photoreceptor boundaries in each image. We evaluate our measure against two human graders and two standard automated image quality assessment algorithms. Results: We evaluate the accuracy of pairwise ordering (PO) and the correlation of ordinal rankings (ORs) of photoreceptor visibility in 29 retinal regions, taken from five subjects with choroideremia. The proposed measure had high association with manual assessments (Grader 1: PO = 0.71, OR = 0.61; Grader 2: PO = 0.67, OR = 0.62), which is comparable with intergrader reliability (PO = 0.76, OR = 0.75) and outperforms the top standard approach (PO = 0.57; OR = 0.46). Conclusions: Our edge-based measure can automatically assess photoreceptor visibility and order overlapping images within AOSLO montages. This can significantly reduce the manual labor required to generate high-quality AOSLO montages and enables higher throughput for quantitative studies of photoreceptors. Translational Relevance: Automated assessment of photoreceptor visibility allows us to more rapidly quantify photoreceptor morphology in the living eye. This has applications to ophthalmic medicine by allowing detailed characterization of retinal degenerations, thus yielding potential biomarkers of treatment safety and efficacy.

A UNILATERAL FOVEAL VITELLIFORM LESION IN A CHOROIDEREMIA CARRIER.

PURPOSE: To describe a unilateral foveal vitelliform lesion associated with subnormal visual acuity in a choroideremia carrier. METHODS: A retrospective case report, assessment of the best-corrected visual acuity, fundus photography, wide-angle scanning laser ophthalmoscopy, optical coherence tomography, and microperimetry. RESULTS: A 37-year-old woman with a pathogenic 907C>T mutation in the choroideremia gene encoding Rab escort protein-1 presented with blurred vision in her left eye.The Snellen best-corrected visual acuity was 20/20 in the right eye and 20/32 in the left eye, a unilateral decrease because it was 20/20 in both eyes at the most recent examination nine years earlier. In the left eye, a large vitelliform lesion with a diameter of 1,300 µ m had developed in the fovea, whereas in the right eye, a smaller similar lesion was seen close to the fovea. Both eyes showed classical radial patterns of multiple bright fundus patches with associated autofluorescence defects and focal drusenoid lesions of the outer retina. CONCLUSION: With its large size and foveal location the vitelliform lesion in this patient's left eye is an unusual manifestation in an otherwise common Rab escort protein-1 mutation carrier state, and its unilaterality fits the assumption of random X-chromosome inactivation.

PERIPHERAL OPTICAL COHERENCE TOMOGRAPHY FINDINGS IN A CHOROIDEREMIA CARRIER.

PURPOSE: To describe the peripheral optical coherence tomography findings in a female choroideremia carrier. METHODS: A 56-year-old woman was referred for visual disturbance complaining of some occasional photopsias and increasing difficulty with her vision at night in both eyes. Best-corrected visual acuity was 20/20 in the right eye and 20/150 in the left eye. Fundus examination revealed mildly tilted disks and peripapillary atrophy with subtle retinal pigment epithelial changes in the periphery. RESULTS: Macular optical coherence tomography in the right eye appeared unremarkable, but the in the left eye, there was diffuse ellipsoid zone band disruption. Green-light fundus autofluorescence revealed mottled areas of decreased autofluorescence in the mid and far periphery creating an irregular mosaic pattern. Peripheral optical coherence tomography scans revealed more diffuse ellipsoid zone alterations than were apparent on the fundus autofluorescence imaging. Genetic testing revealed a heterozygous pathogenic variant in the CHM gene (c.715C>T, p.Arg239). An additional heterozygous mutation was noted in the CNGB1 gene (c.290+2T>C, splice donor). CONCLUSION: Choroideremia carriers may manifest widespread photoreceptor alterations, which may be more extensive than apparent on fundus autofluorescence imaging.

An In Silica Model for RPE Loss Patterns in Choroideremia.

Purpose: To use empirical data to develop a model of cell loss in choroideremia that predicts the known exponential rate of RPE loss and central, scalloped preservation pattern seen in this disease. Methods: A computational model of RPE loss was created in Python 3.7, which constructed an array of RPE cells clusters, binarized as either live or atrophic. Two rules were applied to this model: the background effect gave each cell a chance of dying defined by a background function, and the neighbor effect increased the chance of RPE cell death if a neighbor were dead. The known anatomic distribution of rods, RPE, choriocapillaris density, amacrine, ganglion, and cone cells were derived from the literature and applied to this model. Atrophy growth rates were measured over arbitrary time units and fit to the known exponential decay model. The main outcome measures: included topography of atrophy over time and fit of simulated residual RPE area to exponential decay. Results: A background effect alone can simulate exponential decay, but does not simulate the central island preservation seen in choroideremia. An additive neighbor effect alone does not simulate exponential decay. When the neighbor effect multiplies the background effect using the rod density function, our model follows an exponential decay, similar to previous observations. Also, our model predicts a residual island of RPE that resembles the topographic distribution of residual RPE seen in choroideremia. Conclusions: The pattern of RPE loss in choroideremia can be predicted by applying simple rules. The RPE preservation pattern typically seen in choroideremia may be related to the underlying pattern of rod density. Further studies are needed to validate these findings.

Whole-exome sequencing identified a novel mutation in CHM of a Chinese family.

Choroideraemia (CHM) is a rare X-linked progressive-inherited retinal disease. In this study, we diagnosed and explored the genetic cause in a Chinese pedigree exhibiting nyctalopia and decreased visual acuity in early life. Clinical data and peripheral blood samples were collected from available family members. Sanger sequencing of RPGR and RP2 genes, and subsequently whole-exome sequencing was carried out to investigate the molecular cause. The proband was initially diagnosed as retinitis pigmentosa and experienced night blindness at an early age and decreased visual acuity in teens. The other affected males in this family suffered from the same problem. Direct sequencing failed to reveal the genetic cause and hence a novel hemizygous mutation c.861_862insGCTT was detected by WES in CHM gene resulting in a premature stop codon and a truncated protein. Subsequently, it was confirmed by Sanger sequencing and cosegregation analysis. We describe a novel mutation c.861_862insGCTT in CHM gene in a Chinese pedigree with choroideraemia. Our study emphasizes the utilization of next-generation sequencing in the diagnosis and genetic analysis of retinal diseases.

Chronically shortened rod outer segments accompany photoreceptor cell death in Choroideremia.

X-linked choroideremia (CHM) is a disease characterized by gradual retinal degeneration caused by loss of the Rab Escort Protein, REP1. Despite partial compensation by REP2 the disease is characterized by prenylation defects in multiple members of the Rab protein family that are master regulators of membrane traffic. Remarkably, the eye is the only organ affected in CHM patients, possibly because of the huge membrane traffic burden of the post mitotic photoreceptors, which synthesise outer segments, and the adjacent retinal pigment epithelium that degrades the spent portions each day. In this study, we aimed to identify defects in membrane traffic that might lead to photoreceptor cell death in CHM. In a heterozygous null female mouse model of CHM (Chmnull/WT), degeneration of the photoreceptor layer was clearly evident from increased numbers of TUNEL positive cells compared to age matched controls, small numbers of cells exhibiting signs of mitochondrial stress and greatly increased microglial infiltration. However, most rod photoreceptors exhibited remarkably normal morphology with well-formed outer segments and no discernible accumulation of transport vesicles in the inner segment. The major evidence of membrane trafficking defects was a shortening of rod outer segments that was evident at 2 months of age but remained constant over the period during which the cells die. A decrease in rhodopsin density found in the outer segment may underlie the outer segment shortening but does not lead to rhodopsin accumulation in the inner segment. Our data argue against defects in rhodopsin transport or outer segment renewal as triggers of cell death in CHM.

A putative frameshift variant in the CHM gene is associated with an unexpected splicing alteration in a choroideremia patient.

BACKGROUND: Due to the limited availability of mRNA analysis data, the number of exonic variants resulting in splicing impairment is underestimated although aberrant splicing correction is a promising therapeutic option to treat monogenic diseases, including choroideremia (CHM), a rare X-linked eye disorder arising from sequence alteration of the CHM gene. Herein we report an exonic frameshift variant associated with an mRNA splicing alteration that leads to a CHM hypomorphic allele. METHODS: Total RNA and genomic DNA were extracted from peripheral blood of a patient affected by a mild form of CHM. The CHM gene was analyzed by PCR-based methods and Sanger sequencing. RESULTS: Besides the known c.1335dup frameshift variant, mRNA analysis revealed a splicing alteration that restored the reading frame of the mutant transcript, likely leading to an aberrant protein with residual activity. Bioinformatic analyses identified novel putative exonic splicing enhancer elements and provided clues that also pre-mRNA secondary structure should be taken into account when exploring splicing mechanisms. CONCLUSION: A careful molecular characterization of the c.1335dup variant's effect explains the relationship between genotype and phenotype severity in a CHM patient and provides new perspectives for the study of therapeutic strategies based on splicing correction in human diseases.

Autofluorescence in female carriers with choroideremia: A familial case with a novel mutation in the CHM gene.

BACKGROUND: Choroideremia is an X-linked chorioretinal dystrophy caused by mutations in the CHM gene. The main differential diagnosis is X-linked retinitis pigmentosa. Clinically, male patients that are affected by these two diseases have similar symptoms. This work aims to report a familial case of choroideremia initially diagnosed as X-linked retinitis pigmentosa with a novel mutation in the CHM gene, and the relevance of fundus autofluorescence (FAF) in female carriers. MATERIALS AND METHODS: A complete ophthalmological evaluation was done in a 37-year-old woman and her 53-year-old maternal uncle; the uncle had been diagnosed previously with X-linked retinitis pigmentosa. A visual field test, FAF imaging, full-field electroretinography, and a genetic test were performed. RESULTS: In the proband, the fundoscopy revealed diffuse changes in the retinal pigment epithelium in both eyes, and the FAF showed a speckled pattern of low- and high-density. The maternal uncle's ophthalmological evaluation showed choroidal and retinal atrophy consistent with choroideremia. The molecular analysis revealed a pathogenic variant in the CHM gene, c.190-1 G > T. CONCLUSIONS: In female carriers of choroideremia and X-linked retinitis pigmentosa, differential diagnosis may be challenging. A speckled pattern of low- and high-density in autofluorescence is commonly found in female carriers of choroideremia. FAF is a powerful tool for making a correct clinical diagnosis because the pattern in FAF is much more apparent than the visible retinal changes obtained by fundoscopy. Although it is crucial to perform molecular analysis to confirm the diagnosis, FAF is useful when genetic testing may not be readily available.

A novel SVA retrotransposon insertion in the CHM gene results in loss of REP-1 causing choroideremia.

BACKGROUND: Choroideremia is an X-linked retinal disease characterized by progressive atrophy of the choroid and retinal pigment epithelium caused by mutations in the CHM gene. SVA (SINE-R/VNTR/Alu) elements are a type of non-autonomous retrotransposon that occasionally self-replicate, reinsert randomly into a gene, and cause disease. Intragenic SVA insertions have been reported as the mechanism underlying a number of diseases including a syndromic form of retinal dystrophy, but have never been found in CHM. MATERIALS AND METHODS: Here we identified and characterized a novel hemizygous SVA insertion, c.97_98inSVA (p.Arg33insSVA), in exon 2 of CHM in a male choroideremia patient. The SVA insertion's impact was evaluated by establishing a patient-derived lymphoblastoid cell line as a source of RNA for mRNA analysis of the CHM transcript, and protein for immunoblot analysis of Rab Escort Protein 1 (REP-1). RESULTS: Immunoblot analysis revealed the absence of REP-1 protein, while a smaller than expected PCR product was amplified from cDNA. Sequencing of this PCR product showed skipping of exon 2, denoted r.50_116del. Ophthalmic examination including psychophysical tests, visual electrophysiology, and fundus imaging showed the patient's phenotype was consistent with severe early manifestations of choroideremia. CONCLUSIONS: This case is the first report of a SVA insertion in the CHM gene causing choroideremia.

Optical Coherence Tomography Angiography (OCT-A) in Choroideremia (CHM) carriers.

Purposes: To explore OCT-A abnormalities in CHM carriersMethods: CHM carriers and age-matched controls were consecutively enrolled at the Eye Clinic in Florence. All patients underwent a complete ophthalmic examination, fundus photography, fundus autofluorescence (FAF) and OCT examinations. OCT-A images of the superficial capillary plexus (SCP), deep capillary plexus (DCP) and choriocapillaris slab (CC) were acquired and analyzed using ImageJ software to detect and quantify vascular density.Results: Six patients (12 eyes) and 8 age-matched controls (16 eyes) were included in our study. The mean age was 45.5 ± 16.3 years (range 15-61) for the CHM carriers and 46.6 ± 12.2 (range 18-54) for controls. All CHM carriers showed fundus abnormalities. The detected mean central retinal thickness (CRT) (220 ± 18.34 vs 227 ± 15.46; p = .342) and choroidal central thickness (CCT) (271 ± 54.28 vs 275 ± 38.36; p = .760) did not differ between the carrier and the control group, respectively. Quantitative analysis of the inner retinal vasculature disclosed no significant difference of both SCP (p = .437) and DCP (p = .859) vessel density compared to the control group. Of note, a mild reduction on the vascular flow of the CC could be detected in the carrier group compared to the control group (78.896 ± 13.972 vs 80.008 ± 10.862; p = .045).Conclusions: OCT-A allows us to underline the role of the retinal pigment epithelium in the CHM pathophysiology. Central inner retinal and choriocapillaris vascularization were preserved although the RPE was always involved in the CHM carrier: this could support a secondary role of vascular impairment in the natural history of the disease.

A distinct retinal pigment epithelial cell autofluorescence pattern in choroideremia predicts early involvement of overlying photoreceptors.

PURPOSE: Choroideremia is an X-linked retinal disease characterized by early retinal pigment epithelium (RPE) loss and subsequent retinal degeneration. The RPE adopts either a smooth or mottled appearance on fundus autofluorescence (FAF). It is not known how RPE changes predict the health of the overlying ellipsoid zone (EZ). METHODS: A retrospective review of FAF and optical coherence tomography (OCT) images from 20 patients with choroideremia was performed. The percentage of intact EZ in each smooth and mottled FAF region was determined using one horizontal trans-foveal OCT section. RESULTS: Fourteen out of 20 patients had distinct smooth and mottled areas in both eyes and were included in the sub-analysis. On average, 62.5 ± 10.1% of the EZ in each smooth region of the right eyes was intact compared to 10.0 ± 4.3% in the mottled areas. The same trend was observed in left eyes: 76.5 ± 7.2% of the EZ was intact in the smooth regions versus 9.8 ± 3.9% in the mottled areas (two-way anova, p < 0.0001). Thus, the mottled FAF regions were associated with EZ disruption more so than the smooth areas. CONCLUSION: Retinal pigment epithelium (RPE) changes correlate with the health of the overlying EZ in choroideremia. The smooth FAF region likely represents early stages of the disease, with most of the area containing preserved EZ, whereas the mottled zone indicates more advanced stages and has mostly disrupted EZ. Because of the clear relationship between FAF findings and EZ integrity, FAF imaging can be used to monitor disease progression and identify areas of preserved EZ that could be rescued by gene therapy.

Cone Structure Persists Beyond Margins of Short-Wavelength Autofluorescence in Choroideremia.

Purpose: We studied the relationship between structure and function of the choriocapillaris (CC), retinal pigment epithelium (RPE), and photoreceptors in patients with choroideremia (CHM). Methods: Six CHM patients (12 eyes) and four normal subjects (six eyes) were studied with fundus-guided microperimetry, confocal and nonconfocal adaptive optics scanning laser ophthalmoscopy (AOSLO), near-infrared and color fundus photos, short wavelength fundus autofluorescence (SW-AF), and swept-source optical coherence tomography (SS-OCT) and angiography (SS-OCTA) images. Cone spacing was represented using Z-scores (standard deviations from the mean at that eccentricity). CC flow voids were defined using a threshold of 1 SD below the normal mean. Results: Cone spacing Z-scores were not significantly correlated with distance from the borders of preserved RPE, determined using either the SS-OCT or SW-AF scans. Cone spacing Z-scores were significantly correlated with CC flow voids and retinal sensitivity. Flow voids were abnormal in regions of preserved RPE and increased progressively from within -2° of the preserved area to +2° beyond the border. Visual sensitivity decreased as CC flow voids increased approaching and beyond the border of preserved structure. Conclusions: In CHM, cone spacing Z-scores correlated with CC flow voids, and were negatively correlated with retinal sensitivity, suggesting cone degeneration accompanied reduced CC perfusion. Functional cones were found outside the presumed borders of preserved outer-retina/RPE as defined by SW-AF, but not outside the borders determined by SS-OCT. The use of SW-AF to identify the border of preserved structures may underestimate regions with cells that may be amenable to treatment.