Classification of the choroidal atrophies

Cross-Sectional Analysis of Outer Retinal Tubulation in Inherited Retinal Diseases: A Multicenter Study

PURPOSE

This study aims to explore genetic variants that potentially lead to outer retinal tubulation (ORT), estimate the prevalence of ORT in these candidate genes, and investigate the clinical etiology of ORT in patients with inherited retinal diseases (IRDs), with respect to each gene.

DESIGN

Retrospective cohort study.

METHODS

A retrospective cross-sectional review was conducted on 565 patients with molecular diagnoses of IRD, confirming the presence of ORT as noted in each patient's respective spectral-domain optical coherence tomography (SD-OCT) imaging. Using SD-OCT imaging, the presence of ORT was analyzed in relation to specific genetic variants and phenotypic characteristics. Outcomes included the observed ORT frequencies across 2 gene-specific cohorts: non-retinal pigment epithelium (RPE)-specific genes, and RPE-specific genes; and to investigate the analogous characteristics caused by variants in these genes.

RESULTS

Among the 565 patients included in this study, 104 exhibited ORT on SD-OCT. We observed ORT frequencies among the following genes from our patient cohort: 100% (23/23) for CHM, 100% (2/2) for PNPLA6, 100% (4/4) for RCBTB1, 100% for mtDNA [100% (4/4) for MT-TL1 and 100% (1/1) for mtDNA deletion], 100% (1/1) for OAT, 95.2% (20/21) for CYP4V2, 72.7% (8/11) for CHM female carriers, 66.7% (2/3) for C1QTNF5, 57.1% (8/14) for PROM1, 53.8% (7/13) for PRPH2, 42.9% (3/7) for CERKL, 28.6% (2/7) for CDHR1, 20% (1/5) for RPE65, 4% (18/445) for ABCA4. In contrast, ORT was not observed in any patients with photoreceptor-specific gene variants, such as RHO (n = 13), USH2A (n = 118), EYS (n = 70), PDE6B (n = 10), PDE6A (n = 4), and others.

CONCLUSIONS

These results illustrate a compelling association between the presence of ORT and IRDs caused by variants in RPE-specific genes, as well as non-RPE-specific genes. In contrast, IRDs caused by photoreceptor-specific genes are typically not associated with ORT occurrence. Further analysis revealed that ORT tends to manifest in IRDs with milder intraretinal pigment migration (IPM), a finding that is typically associated with RPE-specific genes. These findings regarding ORT, genetic factors, atrophic patterns in the fundus, and IPM provide valuable insight into the complex etiology of IRDs. Future prospective studies are needed to further explore the association and underlying mechanisms of ORT in these contexts.

Prevalence and optical coherence tomography analyses of outer retinal tubulations in Chinese population with inherited retinal diseases

BACKGROUND

To investigate the prevalence of outer retinal tubulation (ORT) and its correlations with optical coherence tomography (OCT) parameters in Chinese population with inherited retinal diseases (IRDs).

METHODS

This retrospective study enrolled consecutive patients identified with IRDs and referred for genetic testing between February 2016 and April 2021. Clinical characteristics from medical records and features of cross-sectional B-scans were reviewed and analysed. The associations of patient-specific and ocular features with the presence of ORT were evaluated using univariate and multivariate analyses.

RESULTS

Two hundred and three patients (401 eyes) with a mean age of 49.7 ± 16.7 years were enrolled. ORT was observed in 41 eyes (10.2%), including 26 of 28 eyes (92.9%) with Bietti crystalline corneoretinal dystrophy (BCD), 14 of 338 eyes (4.1%) with retinitis pigmentosa (RP), and 1 of 26 eyes (3.8%) in eyes with cone-rod dystrophy. Eyes with ORT showed significantly worse visual acuity than those without ORT (P = 0.002). Multivariate analysis indicated that the presence of ORT was positively correlated with choroidal atrophy and inner nuclear layer (INL) cysts (P < 0.01). ORTs were detected more frequently in eyes with BCD than RP (P = 0.024), most of which located exclusively within the extrafoveal area. Large choroidal vessels were detected underneath the corresponding ORTs in both patients with BCD and RP.

CONCLUSIONS

The prevalence of ORT varies among different IRDs phenotypes, with the highest prevalence in BCD. The presence of choroidal atrophy and INL cysts may be associated with an increased risk of ORT formation in patients with IRD.

Paramacular Choriocapillaris Atrophy

In this paper, a review of a rare case of paramacular choriocapillaris atrophy with a foveal-sparing phenotype is carried out. The 73-year-old patient stated that they had impaired vision and photophobia in both eyes during a regular ophthalmological examination, denying visual field defects and night blindness. A complete ophthalmological examination (best-corrected visual acuity, applanation tonometry, and biomicroscopy of anterior and posterior segments) and diagnostic tests, including fundus autofluorescence, fluorescein angiography, optical coherence tomography with angiography, computerized perimetry, and electroretinography, were carried out. The underlying genetic pattern is unclear, which points to paramacular choriocapillaris atrophy. According to recent research on histology, pathologies categorized as regional choroidal dystrophies are caused by alterations at the level of the retinal pigment epithelium. Despite the unresolved etiopathogenetic mechanism of foveal sparing in central choroidal and retinal dystrophies, a highly variable disease phenotype with spared fovea and central visual acuity present in a variety of heterogeneous dystrophies supports a disease-independent mechanism that allows the survival of foveal cones. The related preservation of BCVA has implications for individual prognosis and influences how treatment trials for choroidal and retinal dystrophies are designed.

Clinical Manifestations and Genetic Analysis of 5 Korean Choroideremia Patients Initially Diagnosed With Retinitis Pigmentosa

BACKGROUND

To investigate the clinical findings of choroideremia patients and perform genetic analysis by whole-exome sequencing (WES).

METHODS

A total of 94 patients initially diagnosed with retinitis pigmentosa (RP) at another hospital, and who visited our hospital for genetic analysis by WES, were included in the study, along with 64 family members. All subjects underwent comprehensive ophthalmic evaluation, including best-corrected visual acuity, slit lamp examination, fundus photography, fundus autofluorescence (FAF), fluorescein angiography (FAG), visual field (VF), electroretinogram (ERG), and optical coherence tomography (OCT).

RESULTS

In six male patients with suspected choroideremia, extensive retinal pigment epithelium (RPE) and severe loss of choroid were observed in the fundus, but not in the macula. CHM gene mutation was confirmed in five patients. A novel single nucleotide variant at a splice site was observed in one patient. OCT showed marked thinning of the outernuclear layer and choroid, except in the macula. FAF showed a small area of hyperfluorescence in the posterior pole. In addition, characteristic interlaminar bridges were observed in four patients. On FAG, hypofluorescence was seen up to the far-peripheral retina in five patients.

CONCLUSION

Of the 94 patients initially diagnosed with RP, CHM mutation was identified in five (5.3%) by WES. Choroideremia should be considered as a differential diagnosis of RP. WES would be useful for identifying the causes of hereditary retinal disease.

Macular Colobomata: Comparison of Clinical and Optical Coherence Tomography Features With Serologic Results

PURPOSE

To assess the correlation between the morphologic features and serology in eyes with macular colobomata (MC).

DESIGN

Retrospective comparative case series.

METHODS

Setting: Institutional.

STUDY POPULATION

Patients presenting with MC to the retina clinic over a period of 2 years (January 2016 to December 2017). Interventional/Observational Procedure: Color fundus and swept-source optical coherence tomography (SSOCT) features were reviewed and assessed in 3 groups based on the serum IgG results: positive for Toxoplasma, positive for cytomegalovirus (CMV), and serology negative.

MAIN OUTCOME MEASURE

Morphologic features on clinical and OCT-based examination.

RESULTS

A total of 49 eyes of 27 patients were recruited. The mean age was 24.8 ± 14.9 years (range 7-60 years). While the lesion size, the presence of satellite lesions, choroidal excavation, and choroidal lacunae (large choroidal vessels) on SSOCT differed significantly among the groups, pigmentation, retinal fibrosis, shape, retinal vessel pattern, and choroidal vessel visibility did not vary significantly. The lesions in CMV serology-positive cases were mostly solitary (n = 8/8), large (n = 5/8) and deeply excavated (n = 8/8). The lesions in Toxoplasma serology-positive cases were mostly flat to shallow (n = 18/26), medium-sized (n = 19/26), and either a solitary lesion (n = 17/26) or multiple satellite lesions (n = 9/26). The lesions in serology-negative cases were mostly small to medium (n = 13/15), solitary (n = 15/15), deeply excavated lesions (n = 11/15) with choroidal lacunae (n = 8/15).

CONCLUSIONS

The clinical and SSOCT features such as the lesion size, the presence of satellite lesions, choroidal excavation, and choroidal lacunae can provide a clue toward the etiology of macular colobomata.

High-Resolution Retinal Imaging Reveals Preserved Cone Photoreceptor Density and Choroidal Thickness in Female Carriers of Choroideremia

BACKGROUND AND OBJECTIVE

To characterize the photoreceptors and choroidal morphology of heterozygous female carriers of choroideremia who typically do not have any visual defects but can have severe funduscopic changes.

PATIENTS AND METHODS

This was a clinical case series study. Detailed ophthalmic examinations were performed on six female carriers from four families with choroideremia. The subfoveal choroidal thickness (SFCT) was determined by spectral-domain optical coherence tomography (SD-OCT) and the cone photoreceptor density by adaptive optics (AO) retinal imaging. SFCT and cone densities of the carriers were compared to that of normal eyes of healthy subjects.

RESULTS

The mean age of the carriers was 42.5 years. Fundus photographs showed diffuse, patchy depigmentation; however, the SFCT was within the normal limits. AO retinal imaging revealed preserved cone densities at temporal eccentricities from 2 to 8 angular degrees.

CONCLUSIONS

The findings indicate that despite the presence of distinctive depigmentation of the retinal pigment epithelium in female carriers of choroideremia, their cone photoreceptor densities and SFCT are well-preserved. These observations may account for the good visual acuity and lack of an awareness of visual disturbances. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:76-85.].

Genetic testing for central areolar choroidal dystrophy

We studied the scientific literature and disease guidelines in order to summarize the clinical utility of the genetic test for central areolar choroidal dystrophy (CACD). CACD is mostly inherited in an autosomal dominant manner. Transmission is rarely autosomal recessive. Overall prevalence is currently 1-9 per 100 000. CACD is caused by mutations in the PRPH2 and GUCY2D genes. Clinical diagnosis is based on clinical findings, ophthalmological examination, fluorescein angiography, electroretinography (showing cone dystrophy) and stereo fundus photography. The genetic test is useful for confirming diagnosis, and for differential diagnosis, couple risk assessment and access to clinical trials.

POSTERIOR POLAR ANNULAR CHOROIDAL DYSTROPHY: A CASE SERIES

PURPOSE

To describe the multimodal imaging findings of posterior polar annular choroidal dystrophy (PPACD).

METHODS

Retrospective case series of 2 patients diagnosed with PPACD. Spectral-domain optical coherence tomography, fundus autofluorescence, and fluorescein angiography findings of PPACD are described. Electroretinography results are also presented.

RESULTS

Both patients presented with bilateral peripapillary atrophy extending to involve the temporal arcades in an annular, foveal sparing pattern. Both cases demonstrated outer retinal atrophy with foveal sparing on spectral-domain optical coherence tomography, and fluorescein angiography illustrated corresponding window defects with late staining. Fundus autofluorescence showed hypoautofluorescence in the center of atrophic areas but hyperautofluorescence at the leading edge. Electroretinography findings included cone loss with rod preservation. Inflammatory and infectious workup was unremarkable in both cases.

CONCLUSION

This report describes the multimodal imaging findings of a rare and poorly described chorioretinal disorder, PPACD, and will serve to guide clinicians regarding the evaluation and management of this elusive condition.

Optical coherence tomography angiography and fundus autofluorescence in the eyes with choroideremia

A 65-year-old man with presumed choroideremia with preserved central vision was examined by fundus autofluorescence (FAF) and optical coherence tomography angiography (OCTA). FAF showed an isolated area of hyperautofluorescence that involved the fovea. Although the choroid capillary slab of the OCTA showed the medium and large choroidal vessels inferior to the area of retinal pigment epithelium (RPE) atrophy, the choriocapillaris was visible in a relatively wider area than the hyperautofluorescent area in the FAF images. FAF and OCTA images allowed us to detect damage of the RPE before the choriocapillaris atrophy in a case of presumed choroideremia with preserved central vision.

Generalized choriocapillaris dystrophy, a distinct phenotype in the spectrum of ABCA4-associated retinopathies

PURPOSE

We describe a particular form of autosomal recessive generalized choriocapillaris dystrophy phenotype associated with ABCA4 mutations.

METHODS

A cohort of 30 patients with identified ABCA4 mutations and a distinct phenotype was studied. A retrospective review of history, fundus photographs, electroretinography, visual field testing, dark adaptometry, and optical coherence tomography was performed. Genetic analyses were performed by ABCA4 microarray analysis, high resolution melting, and/or next generation sequencing of all protein-coding sequences of the ABCA4 gene.

RESULTS

The earliest recorded manifestation of ABCA4-associated disease was a central bull's eye type of macular dystrophy that progressed to chorioretinal atrophy of the macula with coarse rounded hyperpigmentations and expanding involvement of the periphery. The mean age at first presentation was 10.3 years, the longest follow-up was 61 years. All patients had two ABCA4 mutations identified, confirming the molecular genetic diagnosis of an ABCA4-associated disease. Most patients harbored at least one mutation classified as "severe," the most common of which was the p.N965S variant that had been found previously at a high frequency among patients with ABCA4-associated retinal dystrophies in Denmark.

CONCLUSIONS

Generalized choriocapillaris dystrophy is a progressive ABCA4-associated phenotype characterized by early-onset macular dystrophy that disperses and expands to widespread end-stage chorioretinal atrophy with profound visual loss. All cases in this study were confirmed as harboring two ABCA4 mutations. Most of the ABCA4 mutations were classified as "severe" explaining the early onset, panretinal degeneration, and fast progression of the disease.

Blood-aqueous barrier function in a patient with choroideremia

The purpose was to determine whether there was a breakdown of the blood-aqueous barrier in a patient with choroideremia. A 27-year-old man with typical choroideremia underwent standardized ophthalmo-logical evaluation, including quantitative measurement of aqueous flare intensity, by a laser flare-cell meter. The results showed areas of atrophy of the choriocapillaries and retinal pigment epithelium in the mid-periphery and posterior pole, although not in the macula. Fluorescein angiography showed areas of loss of the choriocapillaries and retinal pigment epithelium. The fovea was spared with a surrounding zone of hy-perfluorescence. Electroretinography showed a subnormal photopic amplitude and extinguished scotopic response. Electrooculography revealed that the light peak/dark trough ratio was reduced. Goldmann perimetry showed constricted peripheral fields. Laser photometry showed an increase in the aqueous flare intensity in both eyes, as compared with normal subjects. We conclude that the function of the blood-aqueous barrier might be affected in patients with choroideremia.

CHM gene molecular analysis and X-chromosome inactivation pattern determination in two families with choroideremia

Choroideremia is an X-linked recessive retinal dystrophy characterized by progressive loss of the photoreceptor, the retinal pigment epithelium, and the choriocapillaris layers which ultimately can result in blindness by the fifth decade of life. The disease is caused by mutations in the gene CHM, which encodes a protein involved in the regulation of intracellular vesicular traffic. Typically, hemizygous males are affected by the disease and female carriers are asymptomatic with only a diffuse mottled pattern of hyperpigmentation on funduscopy. Uncommon instances of fully affected females have been described previously and these cases are proposed to arise from an skewed Lyonization mechanism preferentially inactivating the X chromosome carrying the normal CHM allele. In this work, the clinical and molecular features of two Mexican families with choroideremia are described. A novel and a previously described CHM mutation were identified. X-chromosome inactivation assays were performed in a total of 12 heterozygous carriers from the two families. In an affected female from family A, a random X-inactivation pattern was demonstrated; on the other hand, in a female carrier from family B displaying a conspicuous pattern of pigment epithelium mottling at the peripheral retina, a skewed X-inactivation pattern was found. However, the X-chromosome preferentially inactivated in this female was the one carrying the mutated allele. Our results add to the genotypic spectrum in choroideremia and does not support a correlation between X-inactivation status and abnormal retinal phenotype in heterozygous female carriers from these two families.

Choroideremia: variability of clinical and electrophysiological characteristics and first report of a negative electroretinogram

PURPOSE

To analyze the variability of clinical and electrophysiological characteristics in X-linked choroideremia and provide the first report of a negative electroretinogram in choroideremia.

DESIGN

Retrospective study.

PARTICIPANTS

The records of 18 male patients with choroideremia and 8 female carriers were evaluated.

METHODS

The data were reviewed regarding visual acuity (VA), color vision, perimetry, fundus autofluorescence, and full-field electroretinography (according to standards of the International Society for Clinical Electrophysiology of Vision).

MAIN OUTCOME MEASURES

Morphological and functional phenotype characteristics, fundus autofluorescence, electroretinography, and Rab escort protein 1 (REP-1) mutations.

RESULTS

Four unrelated families with choroideremia (9 affected males, 7 carriers) and 10 unrelated individuals (9 affected males, 1 carrier) were included. Mutational analysis, performed in 2 families and 3 individual males, revealed REP-1 mutations in all except 1 male. The age of the males ranged from 5.9 to 63.0 years (mean, 33.9), and VA ranged from hand movements to 1.0 (median, 0.7). Fundus autofluorescence (n = 7) showed defects in the retinal pigment epithelium in all males. Electroretinography (n = 13) was almost undetectable in 6 males and reduced in 6, indicating a rod-cone dystrophy. A further male showed a negative electroretinogram, with a b:a wave ratio of 0.5. Visual acuity of the 8 carriers (age, 4.8-56.8 years [mean, 24.0]) ranged from light perception to 1.2 (median, 1.0). Light perception was present in 1 carrier manifesting choroideremia with distinct chorioretinal atrophy. Pigmentary stippling, seen in the other carriers, was seen in fundus autofluorescence (n = 1) with a distinct speckled pattern. Electroretinograms were normal in 6 of 7 and reduced in the manifesting carrier. Defects in color vision and visual field were found in affected males and in the female carriers.

CONCLUSIONS

The phenotype of choroideremia presents with high variability. In addition to the previously reported findings, we observed a negative electroretinogram, indicating a postreceptoral retinal dysfunction, in 1 affected male; severe course of choroideremia with early blindness in 1 manifesting carrier; color vision deficits in the majority of affected males and carriers; and characteristic alterations in fundus autofluorescence.

Various glaucomatous optic nerve appearances. A color Doppler imaging study of retrobulbar circulation

PURPOSE

The purpose of this study was to observe the blood flow velocity in the retrobulbar vessels of patients with glaucoma with different appearances of optic discs.

METHODS

Patients with four different disc appearances (focal ischemic discs, myopic glaucomatous discs, senile sclerotic discs, and discs with a generalized enlargement of the cup) were selected from a pool of optic disc photographs. No clinical information from the patients was available during the selection. Color Doppler imaging (CDI) was performed in those patients whose discs clearly belonged to one of the disc patterns. The peak systolic and end diastolic velocity were measured and the resistance index calculated from the central retinal artery, short posterior ciliary arteries and ophthalmic artery.

RESULTS

Color Doppler imaging was performed in 24 patients with focal ischemic discs, 26 patients with myopic glaucomatous discs, 16 patients with senile sclerotic discs, and 16 patients with generalized enlargements of the cup. The patients with senile sclerotic discs had statistically significantly lower diastolic velocity and a higher resistance index in their ophthalmic, central retinal and the mean of the short posterior ciliary arteries sampled. These statistical differences persisted for the ophthalmic artery even after correcting the values for the age differences between the groups.

CONCLUSIONS

Patients with senile sclerotic discs seem to have greater circulatory abnormalities in their retrobulbar vessels studied with color Doppler imaging that are compatible with a higher downstream resistance in these vessels. These circulatory abnormalities could be related to the pathogenesis of the glaucoma in these patients.

A point mutation in the RDS-peripherin gene in a Spanish family with central areolar choroidal dystrophy

The RDS-peripherin gene encodes a photoreceptor-specific protein that is localized in the outer segment disc membranes of both rods and cones. We screened a Spanish family with central areolar choroidal dystrophy for mutations in candidate genes. A base substitution was identified in the RDS-peripherin gene of one patient and DNA sequencing revealed a C-to-T transition in codon 172, arginine being substituted by tryptophan. The mutation was also detected in two asymptomatic family members who showed irregular pigmentation in the retinal pigment epithelium (RPE). The phenotype is similar to other macular dystrophies caused by mutation in the RDS-peripherin gene.

Full-field electroretinograms in patients with central areolar choroidal dystrophy

Patients with central areolar choroidal dystrophy are often difficult to diagnose because they are similar in fundus appearance to other retinal disorders. Nineteen patients with the diagnosis were studied in order to estimate the diagnostic and prognostic value of full-field electroretinography in this disorder. Our results showed that the cone b-wave amplitude in the ERG is decreased, that there is a progression in this decrease during a follow-up period of 5 years, and that the cone b-wave implicit time is prolonged. Central areolar choroidal dystrophy is considered to be primarily a choroidal disease. Our results indicate that it also affects most or all of the retinal cones. Further, our observations suggest that the disease is slowly progressive and that full-field electroretinography is of value in its early diagnosis.

Prevalence of angioid streaks and other ocular complications of Paget's disease of bone

Seventy randomly selected patients with Paget's disease of bone were examined for ocular complications. The prevalence of macular degeneration and cataract was 24.3%. Only one patient was found to have angioid streaks. Eight patients had peripapillary chorioretinal atrophy. These findings suggest that the prevalence of serious ocular complications of Paget's disease is not as high as previously thought. The significance of peripapillary chorioretinal atrophy requires further evaluation.

Electroretinograms and pattern visually evoked cortical potentials in central areolar choroidal dystrophy

We describe three patients with central areolar choroidal dystrophy whose electroretinograms (ERGs) and pattern visually evoked cortical potentials (VECPs) confirmed their macular dysfunction. Visual fields measured by Goldmann perimetry showed central relative scotomata corresponding to a dystrophic lesion. Dark adaptation curves were slightly abnormal either in the first curve or in the second curve, depending on the visual acuity. Color vision was disturbed irregularly. Fluorescein angiography revealed a loss of the choriocapillaries, and a hyperfluorescent border outlined the dystrophic lesion. Single-flash dark-adapted ERGs and scotopic ERGs were almost normal, while photopic and flicker ERGs showed slightly attenuated amplitudes. Conversely, VECPs to pattern reversal stimulation were greatly affected for both transient and steady-state stimuli. We conclude that, in central areolar choroidal dystrophy, pattern VECPs can provide more information on macular dysfunction than does the ERG.

Helicoid peripapillary chorioretinal degeneration

Study of a father and son who had helicoid peripapillary chorioretinal degeneration suggests that a progressive tearing and retraction of the retinal pigment epithelium or of Bruch's membrane around the optic disk may be involved in the disorder's pathogenesis. We presume that this tearing results primarily from dysplastic abnormalities of the retinal pigment epithelium that surrounds the optic disk. The dystrophic lesions progress slowly and may affect the macula and even the peripheral retina.

Histopathologic observations in choroideremia with emphasis on vascular changes of the uveal tract

The patient presented is a member of a four-generation kindred that has exhibited progressive retinal degenerative changes of choroideremia in an X-linked pattern. The patient was seen initially at age 44 with clinical retinal findings consistent with choroidal sclerosis. Over a 20-year interval of observation, the findings evolved into a clinical picture consistent with choroideremia. The patient died at age 66. Both eyes were obtained at autopsy. The histologic findings included extensive chorioretinal atrophy and epiretinal membrane formation. Additionally, Bruch's membrane was calcified and disrupted. Retinal (glial) cells had migrated through the ruptures in Bruch's membrane. There was production of thin and thicker basement membranes by glial (Müller) cells on the choroidal (collagenous) side of Bruch's membrane. There was hypoproduction of basement membrane by vascular endothelial cells and their pericytes both in the posterior uveal tract associated with loss of retinal pigment epithelial (RPE) cells and overlying retina and in the anterior uveal tract associated with loss of dilator muscle and flattening of the iris pigment epithelium. The finding of vascular endothelial cell abnormalities throughout the uveal tract strongly supports the concept that the primary defect in choroideremia lies with the uveal vessels rather than the RPE.

Ornithine delta-aminotransferase activity in retina and other tissues

Ornithine delta-aminotransferase (OAT) activity was determined in liver, kidney, brain, retina and ciliary body-iris of rat, rabbit, calf and human. OAT activities (nanomoles delta 1-pyrroline-5-carboxylate/mg protein/hr) in retina were (mean +/- SE) 324 +/- 43, 240 +/- 24, 234 +/- 26 and 218 +/- 22 respectively in rat, rabbit, calf and human. The OAT activities in retina were three times higher than in brain and 80% of that of liver. 2-oxoglutarate was the preferred amino acceptor substrate for OAT activity. In rat retina the activities of OAT with glyoxalate, beta-hydroxypyruvate, pyruvate, and oxaloacetate were 51, 44, 30, and 30% of that of 2-oxoglutarate respectively. A lack of substrate OAT specificity indicates OAT deficiency such as occur in gyrate atrophy of the choroid and retina could impair metabolism of ketoacids. A candidate for possible toxicity to the retina in OAT deficiency is glyoxalate. Arginine glycine transamidinase activity was not detectable in human retina, thus a previously postulated creatine phosphate deprivation in OAT deficiency may not be applicable to the pathogenesis of the disease.

Metabolic tapetoretinal degenerations

There are a number of metabolic diseases which cause tapetoretinal degeneration, suggesting that pure pigmentary retinopathy may also be metabolic in nature. On the other hand tapetoretinal degenerations may have various modes of inheritance, so we may conclude that the metabolic disorder at the basis of these diseases is not unique and that tapetoretinal degenerations are heterogenic. In this article, some 450 published reports on tapetoretinal degenerations are reviewed. Based on these reports, the clinical and ocular manifestations, laboratory and histopathological findings, inheritance patterns, and treatments of various syndromes characterized by tapetoretinal degenerations are described. It is hoped that the gathering together of this information in one source will acid in the future understanding of metabolically based eye disease.

The disciform response: an historical perspective

This paper is a survey of the literature in an attempt to provide the basis for our current understanding of the disciform process. Particular emphasis is placed on its pathogenesis and the role of subretinal neovascularization. No two lesions appear exactly alike because of the many stages and combinations possible. Gass (1967) has delineated the broad spectrum with the many different clinical manifestations of this disease process. Verhoeff and Grossman (1937) provided the histopathologic basis for our understanding of the disciform process. The histologic correlation of the clinical "predisciform" state would seem to offer the most promising information for understanding the pathogenesis of the disciform process (Frank et al. 1973; Green and Key 1977; Kornweig 1967; Sarks 1973 and 1976; Small et al. 1976; Zauberman 1970). It is hoped that this literature review has sufficiently emphasized the inherent deficiencies of strictly clinical studies and the need for an appropriate experimental animal model (Ryan 1979).

Subretinal neovascularization with geographic (serpiginous) choroiditis

Three patients with geographic choroiditis developed subretinal neovascular membranes associated with subretinal hemorrhage and serous elevation of the retina. Proximity of the membrane to the foveal avascular zone prevented photocoagulation of the neovascular membrane in one patient. Central visual acuity remained 6/60 (20/200) despite systemic corticosteroid therapy. The neovascular membranes in the other two patients were obliterated by argon laser photocoagulation with preservation of central vision. The inflammatory process of geographic choroiditis can disrupt Bruch's membrane, allowing occasional choroidal vascular growth. Concomitant destruction of choroidal vessels may account for rarity of subretinal neovascularization in geographic choroiditis.

Amino-acid metabolism and liver ultrastructure in hyperornithinemia with gyrate atrophy of the choroid and retina

Three patients with the rare hyperornithinemia with gyrate atrophy of the choroid and retina (HOGA) syndrome were studied to elucidate the metabolic derangement and its pathologic concomitants. Tenfold elevations of blood ornithine levels, decreases in lysine levels, and hitherto unreported decreases in blood glutamate and glutamine concentration were observed. The output of ornithine from muscle kidney and splanchnic beds was curtailed or reversed after intravenous glucose. Levels of ornithine in venous blood declined after oral glucose, and rose after intravenous arginine. Increased amounts of 3-amino-2-piperidone were found in the urine, but these did not increase after the arginine-induced increase in ornithine levels. Liver biopsies in two patients revealed a marked alteration in mitochondrial ultrastructure. These studies extend the knowledge of the metabolic and pathologic derangements in HOGA. These findings are consistent with a disorder of ornithine-ketoacid transaminase, but such a disorder might not account for all the observations.

Hyperornithinemia and gyrate atrophy of the choroid and retina

The diagnosis of hyperornithinemia and gyrate atrophy (HOGA) depends upon the presence of five characteristic features: (1) typical chorioretinal lesions, (2) high myopia, (3) cataracts, (4) hyperornithinemia, and (5) autosomal recessive inheritance. We have seen three patients and described four new findings: (1) decreased whole blood glutamic acid, (2) low normal intelligence, (3) hepatic mitochondrial changes, and (4) urinary excretion of ornithine methyl ester. Investigations of amino acid metabolism in vivo are consistent with the presence of a defect in ornithine keto-acid transaminase.

Familial bilateral macular colobomata

A mother and daugher had a life-long history of poor vision and photophobia, bilateral macular colobomata, and retinal pigment epithelial abnormalities; psychoelectrophysiological testing indicated extensive loss of cone or cone-rod function. These cases suggest this is a genetically determined condition unrelated to infection.

A histologic study of regional choroidal dystrophy

Light and electron microscopy studies of eyes removed from an 84-year-old man after death indicated a normal optic nerve despite severe peripapillary choroidal atrophy. In the area of atrophy, the choriocapillaris, retinal pigment epithelium, and photoreceptors were absent and there was a marked decrease in choroidal arteries and veins. Bruch's membrane was intact except for several breaks in the peripapillary region. Müller cells, in the region of atrophy, produced an aberrant, thick basement membrane either in the outer layers of the neurosensory retina or directly applied to Bruch's membrane. On the basis of this study, we postulate that the primary abnormality in this disease is of the choroidal vasculature.

Fluorescein angiography of the hereditary choroidal dystrophies

The hereditary choroidal dystrophies are divided into (1) geographic choroidal dystrophies (central areolar, peripapillary, generalised), (2) gyrate atrophy, and (3) choroideremia. Each of these disorders is discussed with regard to mode of inheritance, age of onset, symptoms, fundus appearance, and visual function testing. A typical case history of each disorder is presented together with fluorescein angiography, and the fluorescein angiographic findings are related to our present understanding of these diseases. Fluorescein angiography was found to be most helpful in diagnosing the early cases, by confirming the absence of the choriocapillaris, and in demonstrating either a local or general abnormality. The role of fluorescein angiography in understanding the aetiology of choroidan dystrophies is discussed.

The late stage of serpiginous (geographic) choroiditis

Serpiginous and geographic choroiditis, one and the same disease, is characterized by episodic involvement of the pigment epithelium and choroid. Each new lesion passes through an acute phase into an atrophic and scarring one. We observed 20 patients, some with long-term follow-up; some had eventual widespread involvement of both posterior poles. There was no basis for the disease, and treatment did not affect its course. In the patients with long-term disease there was widespread atrophy of the choroid and pigment epithelium and variable amounts of pigment clumping and subretinal fibrous tissue deposition. In nine patients discrete peripheral patches of atrophy were also found. In some eyes the atrophy at the posterior pole had become so confluent that the condition could have been mistaken superficially for a primary choroidal dystrophy. The uninvolved areas appeared to be normal. The electroretinogram and electrooculogram were only affected when extensive disease was present.

Central areolar pigment epithelial dystrophy

We examined nine members of a family with a unique hereditary macular dystrophy by using stereoscopic color photography, fluorescein angiography, electroretinography, electro-oculography, dark adaptation, H-R-R color plates, and the Farnsworth-Munsell 100-hue test. The disorder was transmitted as an autosomal-dominant trait with increased penetrance and variable expression. Four of the family members, representing three successive generations, exhibited defects in macular pigmentation ranging from a 1-disk diameter excavation to a more subtle central loss of macular pigment. Only one eye with macular hemorrhage had decreased visual acuity; visual acuity in this eye was 20/25 when the hemorrhage resolved. All other retinal function studies were normal. The unusual nonprogressive areolar depigmentation of the central macula together with normal retinal functions made it impossible to classify this disorder, and indicated a new and unreported dominant macular dystrophy, central areolar pigment epithelial dystrophy.

Serpiginous (geographic) choroiditis

The rare pathological condition of serpiginous choroiditis is discussed on the basis of four observations. The authors discuss the different views advanced in the literature in regard to the aetiology. They advance arguments in favor of an inflammatory pathogenesis. The problems of the differential diagnosis are also considered in some detail.

Fluorescein study of a family with angioid streaks and pseudoxanthoma elasticum

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Gyrate atrophy of the choroid and retina associated with hyperornithinaemia

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Differential diagnosis between the primary total choroidal vascular atrophies

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Senile choroidal sclerosis

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