Crystalline retinopathy

HYPERREFLECTIVE DEPOSITION IN THE BACKGROUND OF ADVANCED STARGARDT DISEASE

PURPOSE

To describe an unusual manifestation of hyperreflective deposits in the subretinal space in a group of patients with clinically and genetically confirmed Stargardt disease.

METHODS

Retrospective review of color fundus, autofluorescence, infrared reflectance, red-free images, and spectral domain optical coherence tomography in 296 clinically diagnosed and genetically confirmed (2 expected disease-causing mutations in ABCA4) patients with Stargardt disease. Full-field electroretinogram (ffERG), medical history, and genotype data (in silico predictions) were further analyzed from the selected cohort.

RESULTS

Eight of 296 patients (2.7%) were found to exhibit small crystalline deposits that were detectable on certain imaging modalities, such as color, infrared reflectance and red-free images, but not autofluorescence. The deposits were most prevalent in the superior region of the macula, and spectral domain optical coherence tomography revealed their presence in the subretinal space. All patients presented with these findings at a notably advanced disease stage with abnormal ffERG and a high proportion of highly deleterious ABCA4 alleles.

CONCLUSION

Hyperreflective subretinal deposits may be a manifestation of advanced ABCA4 disease, particularly in regions susceptible to disease-related changes, such as lipofuscin accumulation.

Objective Determination of Retinal Function in Bietti Crystalline Retinopathy

A 44-year-old female patient without any known systemic or ocular disease presented with progressive visual loss and night vision disturbance. Visual acuity was 0.6 in the right eye and 0.2 in the left eye. Tiny, yellow crystalline deposits were seen on fundus examination. In addition, areas of retinal pigment epithelium and choriocapillaris atrophy were detected. Rod and cone responses were depressed in full-field flash electroretinogram. Multifocal electroretinogram testing showed severe foveal function disturbance with less severe but still depressed responses toward the periphery. Multiple hyperreflective lesions were detected in the retina in optical coherence tomography. We aimed to present the role of ocular electrophysiology by comparing the patient’s signs and symptoms with her ocular electrophysiological test results.

An atypical form of Bietti crystalline dystrophy

PURPOSE

To describe clinical and functional features of a patient with Bietti crystalline dystrophy and atypical electroretinogram responses.

METHODS

The patient underwent a thorough medical anamnesis, genetic counseling, peripheral blood draw for CYP4V2 gene analysis and electron microscopy, and a complete ophthalmological assessment including optical coherence tomography, indocyanine green angiography, microperimetry, full-field electroretinogram and multifocal electroretinogram.

RESULTS

The most striking features of the retina were deposits of yellowish-white glistening crystals and focal lobular areas of choriocapillary atrophy at the posterior pole and midperiphery. The full-field electroretinogram was normal and the multifocal electroretinogram showed extinguished central recordings. Mutation analysis revealed a homozygous c. 332T>C p.I111T mutation in exon 3 of the CYP4V2 gene. Typical cytoplasmic inclusions containing crystalline-like structure and large degenerative lysosomes were seen on electron microscopy of peripheral leukocytes.

CONCLUSION

Here we describe a patient with Bietti crystalline dystrophy with a CYP4V2 gene mutation and typical leukocyte inclusions who showed the classical retinal lesions but had a normal electroretinogram. This suggests the existence of less severe forms of BCD related to relatively mild CYP4V2 mutations.

Bietti crystalline retinal dystrophy with subfoveal neurosensory detachment and congenital tortuosity of retinal vessels: case report

A 34-year-old man presented with reduction and distortion of vision in both the eyes. The best-corrected vision was 20/20 parts, N6 in either eye. The external and slit lamp examination of both the eyes was unremarkable. The fundus examination showed multiple intraretinal crystalline deposits at the posterior pole, extending up to midperiphery, tortuous retinal blood vessels with S-shaped deflections, and absent foveal reflex in both the eyes. There were no corneal crystals, and the color vision was defective in both the eyes. Fundus autofluorescence and fundus fluorescein angiogram (FFA) were suggestive of geographic areas of retinal pigment epithelium (RPE) and choriocapillary (CC) loss. OCT revealed subfoveal neurosensory detachment. Flash ERG and EOG were normal except for a slight decrease in amplitude and delay in latency of pattern ERG waveforms. The Humphrey's visual field showed paracentral scotoma with reduction in the amplitude of waveforms from the corresponding area in the multifocal ERG in both the eyes. Systemic evaluation for crystalline retinopathy was unremarkable. He was diagnosed to be a case of Bietti crystalline retinopathy (local/regional variant). The subfoveal neurosensory detachment could represent early RPE dysfunction caused by these crystals and could account for the mild visual disturbance in both the eyes. Retinal vascular tortuosity and neurosensory detachment seen in this case is the first time to be reported in literature.

Electrophysiological findings in Bietti's crystalline dystrophy

PURPOSE

The aim was to investigate multifocal electroretinogram (mfERG) findings in Bietti's crystalline dystrophy (BCD) using a retrospective, non-interventional, consecutive case series.

METHODS

Five patients, two women and three men (mean age 31.8 years), clinically diagnosed with BCD underwent full-field electroretinogram (ffERG) and mfERG using Burian Allen bipolar contact lens electrode on the VERIS Science 5.2.1X system. The ffERG and mfERG parameters of patients with Bietti's crystalline dystrophy were compared with age-matched normal subjects. The N1, P1 amplitudes and implicit times of the mfERG for the six concentric rings were analysed.

RESULTS

The ffERG showed significant decreases in the amplitude of the scotopic and photopic responses in all patients; however, implicit times were only mildly prolonged. Rod response implicit times appeared to be more affected than the cone responses. The N1 and P1 amplitudes of mfERG showed a significant decrease in all rings in all patients. N1 implicit times were significantly delayed in rings 3, 4 and 5. The P1 implicit time was significantly delayed in all rings except 1 and 6.

CONCLUSION

The mfERG in Bietti's crystalline dystrophy can provide insight into the functional retina and objectively help to quantify the extent of retinal damage.

Evolution of Cellular Inclusions in Bietti's Crystalline Dystrophy

Bietti's crystalline dystrophy (BCD) consists of small, yellow-white, glistening intraretinal crystals in the posterior pole, tapetoretinal degeneration with atrophy of the retinal pigment epithelium (RPE) and “sclerosis” of the choroid; in addition, sparking yellow crystals in the superficial marginal cornea are also found in many patients. BCD is inherited as an autosomal-recessive trait (4q35-tel) and usually has its onset in the third decade of life. This review focuses on the ultrastructure of cellular crystals and lipid inclusions of BCD.

Evolution of Cellular Inclusions in Bietti's Crystalline Dystrophy

Bietti's crystalline dystrophy (BCD) consists of small, yellow-white, glistening intraretinal crystals in the posterior pole, tapetoretinal degeneration with atrophy of the retinal pigment epithelium (RPE) and "sclerosis" of the choroid; in addition, sparking yellow crystals in the superficial marginal cornea are also found in many patients. BCD is inherited as an autosomal-recessive trait (4q35-tel) and usually has its onset in the third decade of life. This review focuses on the ultrastructure of cellular crystals and lipid inclusions of BCD.

A case of Bietti crystalline dystrophy with preserved visual acuity and extinguished electroretinogram: a case report

INTRODUCTION

Progressive night blindness and constriction of the visual fields are features of Bietti crystalline corneoretinal dystrophy, but here we report a case with the most probable diagnosis of Bietti crystalline dystrophy and good central visual acuity and severely decreased electroretinogram.

CASE PRESENTATION

The patient was a 28-year-old woman with complaint of decreased vision without night blindness. Her both eyes visual acuity were 20/25 with plano refraction. Fundus examination showed intraretinal crystals distributed in the posterior pole and also midperiphery. Fullfield electroretinogram showed decreased scotopic a and b-wave amplitudes.

CONCLUSION

In our patient central foveal region was relatively intact; and this can explain subnormal visual acuity. Although visual acuity was nearly spared, electroretinogram was extremely affected.

Bietti's crystalline dystrophy in Asians: clinical, angiographic and electrophysiological characteristics

This article describes nine Chinese patients with Bietti's crystalline dystrophy, including two families, one consisting of three siblings and the other a pair of sisters. All patients had the classic refractile deposits located in all layers of the retina, with varying degrees of pigment epithelium atrophy. However, paralimbal crystals were not seen in the anterior corneal stroma. We describe clinical, angiographical and electrophysiological characteristics, and also review the literature on Bietti's crystalline dystrophy. All patients had full eye examination, including best corrected visual acuity, biomicroscopy, applanation tonometry and dilated funduscopy. Fluorescein angiography and indocyanine green angiography were performed, together with visual fields and electrophysiologic studies. All nine of our patients were phenotypically heterogeneous, with varying age and symptoms at presentation, as well as different degrees of progression. Age was not found to be a predictor of severity. The differences in disease severity, even within sibling groups, suggested that perhaps other factors were at play in phenotypic expression. We found that in early ICGA, all stages of BCD had delayed choroidal filling, which has not been previously described. We also observed a relative derangement of inner choroidal circulation as evidenced by late hypofluorescence on the ICGA. However, it is as yet unclear whether this circulatory disturbance is due to primary involvement of the posterior ciliary arteries, or secondary to choroidal and/or retinal pigment epithelial atrophy. While the FA and ICGA findings were similar, we found that the true extent of the atrophic areas was better delineated by ICGA. ICGA was also superior in outlining the degree and extent of choroidal vascular compromise.

Clinical and genetic heterogeneity of crystalline retinopathies: report of two families without bietti crystalline dystrophy

PURPOSE

To report variations in the inheritance pattern and clinical presentation of crystalline retinopathies.

METHODS

Two different families with crystalline retinopathy were studied with a complete family history and ophthalmologic examination including Goldmann kinetic perimetry and electroretinography. Genetic studies were performed in one of the families.

RESULTS

One of the families had a clearly autosomal dominant mode of inheritance while the other family most likely follows an autosomal recessive pattern. Several members in each family had significant retinal pigment epithelial atrophy, intraretinal crystals, relatively pink optic nerves, and paracentral visual field defects, all of which are clinical features resembling those of Bietti crystalline retinopathy. Examination of peripheral leukocytes using transmission electron microscopy in selected affected members showed no evidence of classical lysosomal crystals that are characteristics for Bietti crystalline retinopathy. No pathogenic mutations were identified in the CYP4V2 gene.

CONCLUSIONS

Not all crystalline retinopathies are Bietti's. Further genetic, biochemical, and pathologic studies are required to better differentiate between these retinopathies.

CYP4V2 mutations in two Japanese patients with Bietti's crystalline dystrophy

Bietti's crystalline dystrophy (BCD) is an autosomal-recessive retinal dystrophy characterized by numerous glistening intraretinal dots scattered over the fundus, particularly in the posterior pole. The purpose of this study was to report mutations in the CYP4V2 gene (encoding a ubiquitously-expressed 525-amino acid sequence belonging to the CYP450 family) and to investigate the impact of the mutation on pre-mRNA splicing. DNA and RNA analyses were conducted using blood samples from two unrelated Japanese patients with BCD (a 46-year-old female and a 52-year-old male). In the female patient, a homozygous deletion/insertion mutation (g.IVS6-8_-1delc.802_810del/insGC) including the 3 -acceptor splice site was identified. Reverse transcription-PCR analysis revealed that the complete length of exon 7 (186 bp), is skipped, resulting in the in-frame deletion mutation (p.V268_E329del). Conversely, the male patient was a compound heterozygote for the deletion/insertion and novel nonsense (p.W340X) mutations. Clinically, the female patient had decreased visual acuity, constriction of visual fields, severely reduced amplitudes in both rod and cone electroretinograms (ERGs). Despite being 6 years older, the male patient presented with milder clinical manifestations having good visual acuity and substantial amplitudes in both rod and cone ERGs. Because the CYP4V2 truncated protein with the p.W340X mutation lacks 186 amino acids at the C-terminus, if expressed, it retains 62 amino acids encoded in exon 7, which are important for enzymatic activity. In the male patient, expression of both mutant alleles may compensate for the malfunction of each mutated protein and could explain why a milder form of BCD results from compound heterozygosity.

BIETTI’S CRYSTALLINE CORNEORETINAL DYSTROPHY: A CROSS-SECTIONAL STUDY

OBJECTIVE

To evaluate the prevalence of Bietti's corneoretinal dystrophy (BCD) in a reference population of retinitis pigmentosa (RP), and to document the disease course clinically and angiographically by a cross-sectional approach.

METHODS

Two hundred seven consecutive RP patients were ascertained within a 3-year period. All patients had a complete eye examination, including fluorescein and indocyanine green angiography (FA, ICG). Blood samples were collected for electron microscopy evaluation of circulating lymphocytes of BCD patients.

RESULTS

Six patients were diagnosed with BCD. Prevalence was 3% of nonsyndromic RP cases. Limbal corneal and intraretinal crystals were found in all cases. In the early phase of BCD, ICG revealed focal lobular areas of choriocapillary atrophy at the equator, with concomitant retinal pigment epithelium (RPE) changes at the posterior pole on FA. These lesions gradually progressed both anteriorly and posteriorly, sparing an incomplete peripapillary ring and macular island until late in the disease. Progressive sclerosis of ciliary and choroidal arteries was noted upon ICG. The presence of lysosomal crystals was documented in a subpopulation of circulating lymphocytes that seemed to increase with age.

CONCLUSION

The present study is the first to assess BCD prevalence in a population of retinitis pigmentosa patients, to describe clinically and angiographically its evolution from first symptom to legal blindness, and to localize the first fundus alterations not only at the posterior pole but also at the equator.

Clinical and functional findings in crystalline retinopathy

BACKGROUND

Crystalline retinopathy is an infrequently encountered disorder characterized by reflective retinal crystalline deposits. The clinical findings of seven patients with crystalline retinopathy are documented.

METHODS

Clinical features of crystalline retinopathy were studied retrospectively in seven patients, three of whom were followed up for 2 to 5 years.

RESULTS

Six patients had a similar fundus appearance, that is, the reflective yellow deposits located mainly in the deep retina with retinal pigment epithelium atrophy throughout the posterior pole and mid-peripheral retina and with choriocapillaris atrophy at the posterior pole. However, the results from electroretinogram responses were markedly variable. Two of the patients showed marked electroretinogram functional impairment. In addition, other sibling patients only 3 years apart in age had different degrees of disease expression.

CONCLUSION

There is considerable variability in functional manifestations among patients with crystalline retinopathy, even in intrafamilial cases.

The differential diagnosis of crystals in the retina

Crystalline deposits in the retina may be associated with a wide variety of systemic disorders such as oxalosis, cystinosis, hyperornithinaemia and Sjögren-Larsson syndrome. Refractile crystalline deposits may also be a manifestation of drug toxicity like the antineoplastic agent tamoxifen, the anesthetic methoxyflurane and the oral tanning agent canthaxanthine. Crystals may also occur in drug abusers who inject multiple crushed tablets of methadone or meperidine intravenously (talc retinopathy). The differential diagnosis of retinal crystals also includes primary ocular diseases like Bietti's crystalline retinopathy, calcified macular drusen, idiopathic parafoveal telangiectasis and longstanding retinal detachment. This article will review the most common causes of crystalline retinopathies, their etiologies, pathologies and clinical characteristics.

Rod and cone a-waves in three cases of Bietti crystalline chorioretinal dystrophy

PURPOSE

To estimate retinal function in Bietti crystalline chorioretinal dystrophy using the electroretinogram.

METHODS

In this observational case series, the scotopic and photopic electroretinograms in three Japanese female patients (case 1, 55 years old; case 2, 56 years old; case 3, 47 years old) who showed bilateral crystalline retinal deposits but no corneal deposits were recorded. The rod and cone a-waves were analyzed by using the method described by Hood and Birch (1995, 1997). The parameters Rm(p3) (maximum a-wave amplitude) and S (sensitivity) were calculated.

RESULTS

In case 1, the rod Rm(p3) was decreased in both eyes. The rod S in the right eye was within the normal range, but that in the left eye was significantly reduced. Although the cone Rm(p3) was decreased, the cone S was within the normal range. In case 2, the rod and cone Rm(p3) was reduced, but the rod and cone S was within the normal range in both eyes. In case 3, the rod and cone Rm(p3) and S were within the normal range.

CONCLUSIONS

Electroretinograms illustrated different disease stages, however, no eye with normal Rm(p3) and decreased S was found in rods and cones. In the early stages of this disease, decreased numbers of photoreceptors and/or outer segment shortening may be present while phototransduction remains normal. As the damage to the retina progresses, phototransduction becomes severely affected. Because reduced cone S was not observed in our cases, cones may be less involved than rods in this disease.

Juvenile macular dystrophy associated with deficient activity of fatty aldehyde dehydrogenase in Sjögren-Larsson syndrome

PURPOSE

To report the ocular manifestations associated with the Sjögren-Larsson syndrome in a series of patients with proven fatty aldehyde dehydrogenase deficiency. To emphasize the clinical importance of the ophthalmological features of the Sjögren-Larsson syndrome. To discuss the metabolic disturbances that might give rise to the ophthalmological picture.

METHODS

Fifteen patients with Sjögren-Larsson syndrome underwent a standardized ophthalmological examination. In patients of appropriate age, and who were able to cooperate, additional investigations were performed.

RESULTS

All patients exhibited bilateral, glistening yellow-white crystalline deposits that were located in the innermost retinal layers and appeared during the first 2 years of life. Repeated fundus photography in individual patients showed that the dots became more numerous as the patients got older. Photophobia, subnormal visual acuity, myopia, and astigmatism were found in most of the patients. Fluorescein angiography was performed in three patients and showed a mottled hyperfluorescence of the retinal pigment epithelium, without leakage. Color vision, electroretinography, and electro-oculography could be performed in only a small number of patients and showed no abnormalities. Visual evoked potentials were found to be abnormal in six of eight patients.

CONCLUSIONS

In Sjögren-Larsson syndrome, patients exhibit highly characteristic bilateral, glistening yellow-white retinal dots from the age of 1 to 2 years onward. The number of dots increases with age. The extent of the macular abnormality does not correlate with the severity of the ichthyosis or with the severity of the neurological abnormalities. A high percentage of patients shows additional ocular signs and symptoms, notably marked photophobia.

Nondetectable S-cone electroretinogram in a patient with crystalline retinopathy

We examined cone and rod electroretinograms to ganzfeld stimuli in a patient with crystalline retinopathy. The 54-year-old man complained of night blindness, blurred vision, and metamorphopsia in both eyes. His visual acuity was 10/200 in the right eye and 10/20 in the left eye; his subjective dark-adaptation threshold was elevated 1 log unit, and he made one tritan error on the Farnsworth Panel D-15. Specular microscopic examinations revealed tiny crystalline deposits in the limbal cornea bilaterally. Ophthalmoscopically, crystalline deposits were found in the posterior fundi. His light-adapted cone electroretinograms to white stimuli were diminished (about 30% of those of normal controls), with normal implicit times. His dark-adapted rod electroretinogram amplitudes were 10% of those of normal controls. The S-cone electroretinogram was not detectable to different spectral stimuli with strong white background, while the L-M-cone responses appeared normal in waveforms with reduced amplitude. These ERG results indicated that the patient's S-cone system is more highly impaired than the L-M-cone system, supporting the psychophysical evidence that the S-cone system is more vulnerable than other cone systems in retinal diseases.

Clinical biochemical and pathologic correlations in Bietti's crystalline dystrophy

We examined three affected members of a Chinese-American family with Bietti's crystalline retinopathy. The clinical characteristics of a 24-year-old proband are contrasted to the clinical findings of her grandmother, for whom we have 26 years of follow-up data. Lymphocytes and fibroblasts from a skin biopsy of the grandmother contained crystalline lysosomal material, which supports the diagnosis. Biochemical studies of the crystalline lysosomal material failed to identify the stored compounds but did not show them to be cholesterol or cholesterol ester. Finally, histopathologic studies performed for this condition demonstrated advanced panchorioretinal atrophy, with crystals and complex lipid inclusions seen in choroidal fibroblasts.

Autosomal dominant crystalline dystrophy

A black woman was identified with a tapetoretinal degeneration with sparkling intraretinal crystals, retinal pigment epithelial and choroidal atrophy, night blindness, color vision abnormalities, and paracentral scotomas. This constellation of findings is most consistent with the diagnosis of Bietti's crystalline dystrophy. Eight other family members were identified with intraretinal crystals similar to those seen in the proband but in varying degrees of progression. Transmission electron microscopy of circulating lymphocytes in several patients demonstrated crystals and granular osmophilic material of unknown composition contained within abnormal lysosomes. These crystals are similar in appearance and location to those seen in cholesterol ester storage disease. This family demonstrates an autosomal dominant inheritance pattern, as well as other differences from classic Bietti's crystalline dystrophy. The authors, therefore, suggest that this new entity be named autosomal dominant crystalline dystrophy.

Prevalence and mode of inheritance of major genetic eye diseases in China

The prevalence and mode of inheritance of major genetic eye diseases have been investigated in China since the establishment of the Section of Ophthalmic Genetics of the Chinese Society of Genetics. Mass screening of genetic eye diseases has been undertaken in many districts in China, covering more than 700,000 people, and more than 5000 pedigrees of genetic eye diseases have been collected and analysed all over China. Based on these data, the prevalence and mode of inheritance of dyschromatopsia, degenerative myopia, retinitis pigmentosa, congenital ptosis, congenital microphthalmos, congenital cataract, congenital glaucoma, Leber's optic atrophy, corneal dystrophy, congenital nystagmus, coloboma of the eye, congenital aniridia, retinoblastoma, macular dystrophy, simple myopia, primary glaucoma, and strabismus have been investigated, and the results are presented.

Bietti's tapetoretinal degeneration with marginal corneal dystrophy (crystalline retinopathy): case report

A patient with Bietti's tapetoretinal degeneration and marginal corneal dystrophy is reported on. Refractile deposits found in both the retina and cornea are the most striking feature of this condition. Apart from a slight reduction in left visual acuity there were no visual symptoms. The dark adapted electroretinogram was abnormal. No metabolic disturbance was detected.

Bietti's crystalline retinopathy

The authors reported a case of Bietti's crystalline retinopathy in 1981. In the present paper they report three additional cases studying the stages of this disease and the clinical findings at each stage. Conclusions obtained are as follows: This disease is a type of total RPE-choriocapillaris dystrophy, the process of which starts at the posterior pole. This disease can be divided into three stages, based on the clinical findings: Stage 1: RPE atrophy with uniform fine white crystalline deposits is observed at the macular area. Stage 2: RPE atrophy extends beyond the posterior pole. Choriocapillaris atrophy in addition to the RPE atrophy appears markedly at the posterior pole. Crystalline deposits in the lesion vary in shape and size and have a tendency to conflue. The number of crystalline deposits is less in the advanced atrophic areas of the RPE-choriocapillaris complex. Stage 3: RPE-choriocapillaris complex atrophy is observed throughout the fundus. The total number of crystalline deposits decreases because the crystalline deposits that disappear number more than those that appear in Stage 3. Crystalline deposits which are observed at the corneal limbus are possibly prominent in the advanced stage of atrophy of the RPE-choriocapillaris complex.

Yellowish flecks in Leber's congenital amaurosis

The fundus abnormalities of Leber's congenital amaurosis are extremely variable, from normal to salt-and-pepper changes to typical retinitis pigmentosa. A less commonly seen appearance is that of multiple, irregular shaped, yellowish white flecks deep in the midperipheral retina in a periarteriolar distribution. The nasal fundus as well as the posterior pole are spared. Such a case is presented along with a four-year follow-up together with the fluorescein angiographic findings. The flecks appear to be specific for this entity.