Unusual OCT findings in a patient with CABP4-associated cone-rod synaptic disorder

PURPOSE

Bi-allelic variants in CABP4 are associated with congenital cone-rod synaptic disorder, which has also been classified, electrophysiologically, as incomplete congenital stationary night blindness (iCSNB). We describe clinical findings in a patient who demonstrated an unusual macular optical coherence tomography (OCT) phenotype, not previously reported in this condition.

METHODS

Our patient underwent multimodal retinal imaging, international standard full-field ERG testing and whole genome sequencing.

RESULTS

The patient was a 60-year-old woman with non-progressive visual impairment since birth, nystagmus and preference for dim lighting. Clinical fundus examination was unremarkable. OCT imaging revealed a hypo-reflective zone under an elevated fovea in both eyes. ERGs showed an electronegative DA10 response, with severely abnormal light-adapted responses. Whole genome sequencing revealed homozygosity for a known pathogenic variant in CABP4. No variants were found in other genes that could explain the patient's phenotype.

CONCLUSIONS

OCT findings of foveal elevation and an underlying hypo-reflective zone are novel in this condition. Whilst the clinical history was similar to achromatopsia and other cone dysfunction syndromes, ERG findings suggested disease associated with CACNA1F or CABP4. As CACNA1F is X-linked, CABP4 was more likely, and confirmed on genetic testing. The patient saw better in dim light, confirming that night blindness is not a feature of CABP4-associated disease. Our case highlights the value of ERGs in discriminating between causes of cone dysfunction, and extends the range of retinal imaging phenotypes reported in this disorder.

Comprehensive Genotyping and Phenotyping Analysis of GUCY2D-Associated Rod- and Cone-Dominated Dystrophies

PURPOSE

To describe the genetic and clinical spectrum of GUCY2D-associated retinopathies and to accurately establish their prevalence in a large cohort of patients.

DESIGN

Retrospective case series.

METHODS

Institutional study of 47 patients from 27 unrelated families with retinal dystrophies carrying disease-causing GUCY2D variants from the Fundación Jiménez Díaz hospital dataset of 8000 patients. Patients underwent ophthalmological examination and molecular testing by Sanger or exome sequencing approaches. Statistical and principal component analyses were performed to determine genotype-phenotype correlations.

RESULTS

Four clinically different associated phenotypes were identified: 66.7% of families with cone/cone-rod dystrophy, 22.2% with Leber congenital amaurosis, 7.4% with early-onset retinitis pigmentosa, and 3.7% with congenital night blindness. Twenty-three disease-causing GUCY2D variants were identified, including 6 novel variants. Biallelic variants accounted for 28% of patients, whereas most carried dominant alleles associated with cone/cone-rod dystrophy. The disease onset had statistically significant differences according to the functional variant effect. Patients carrying GUCY2D variants were projected into 3 subgroups by allelic combination, disease onset, and presence of nystagmus or night blindness. In contrast to patients with the most severe phenotype of Leber congenital amaurosis, 7 patients with biallelic GUCY2D had a later and milder rod form with night blindness in infancy as the first symptom.

CONCLUSIONS

This study represents the largest GUCY2D cohort in which 4 distinctly different phenotypes were identified, including rare intermediate presentations of rod-dominated retinopathies. We established that GUCY2D is linked to about 1% of approximately 3000 molecularly characterized families of our cohort. All of these findings are critical for defining cohorts for inclusion in future clinical trials.

Genetic analysis and clinical features of three Chinese patients with Oguchi disease

BACKGROUND

Oguchi disease is a rare autosomal recessive form of congenital stationary night blindness caused by disease-causing variants in the rhodopsin kinase gene (GRK1) or the arrestin gene (SAG). Our study aims to describe the clinical features and identify the genetic defects for three Chinese patients with Oguchi disease.

METHODS

We conducted detailed ophthalmologic examinations for three patients from three unrelated non-consanguineous Chinese families. Targeted next-generation sequencing (targeted NGS) and copy number variations (CNVs) analysis were applied to screen pathogenic variants. Sanger sequencing validation, quantitative real-time PCR (qPCR), and segregation analysis were further performed for confirmation. Subsequently, a combined genetic and structural biology approach was used to infer the likely functional consequences of novel variants.

RESULTS

All three patients presented with typical clinical features of Oguchi disease, including night blindness, characteristic fundus appearance (Mizuo-Nakamura phenomenon), attenuated rod responses, and negative ERG waveforms. Their visual acuity and visual field were normal. Genetic analysis revealed two pathogenic variants in SAG and four pathogenic variants in GRK1. Patient 1 was identified to harbor compound heterozygous SAG variants c.874C > T (p.R292*) and exon2 deletion. Compound heterozygous GRK1 variants c.55C > T (p.R19*) and c.1412delC (p.P471Lfs*52) were found in patient 2. In patient 3, compound heterozygous GRK1 variants c.946C > A (p.R316S) and c.1388 T > C (p. L463P) were detected.

CONCLUSIONS

We reported the first two Chinese Oguchi patients with novel GRK1 pathogenic variants (P471Lfs*52, R316S, L463P) and one Oguchi case with SAG, indicating both GRK1 and SAG are important causative genes in Chinese Oguchi patients.

A Japanese boy with Bardet-Biedl syndrome caused by a novel homozygous variant in the ARL6 gene who was initially diagnosed with retinitis punctata albescens: A case report

PURPOSE

Bardet-Biedl Syndrome (BBS) is an autosomal recessive systemic disorder characterized by retinitis pigmentosa, polydactyly, obesity, intellectual disability, renal impairments, and hypogonadism. The purpose of this study was to determine the ocular characteristics of a boy with BBS caused by a novel homozygous variant in the ARL6 (alternative named BBS3) gene who had been originally diagnosed with retinitis punctata albescens.

METHODS

This was an observational case study. The patient underwent ophthalmological examinations, electroretinography, and genetic analyses using whole-exome sequencing.

RESULTS

A 7-year-old boy was examined in our hospital with complaints of a progressive reduction of his visual acuity and night blindness in both eyes. There was no family history of eye diseases and no consanguineous marriage. Fundus examinations showed numerous white spots in the deep retina and retinal pigment epithelium. Fundus autofluorescence showed hypofluorescence consistent with these spots. Both the scotopic and photopic components of the full-field electroretinographies were non-detectable. Based on these clinical findings, this boy was suspected to have retinitis punctata albescens. Subsequent genetic testing using whole-exome sequencing revealed a novel homozygous variants in the ARL6/BBS3 gene (NM_001278293.3:c.528G>A, (p.Trp176Ter)). A systemic examination by the pediatric department revealed that this boy had a history of a surgical excision of polydactyly on his left foot when he was born, and that he was mildly obese. There were no prominent intellectual or gonadal dysfunctions, no craniofacial or dental abnormalities, no congenital heart disease, and no hearing impairment. He was then clinically and genetically diagnosed with BBS.

CONCLUSION AND IMPORTANCE

In children with night blindness and progressive visual dysfunction, it is important for ophthalmologists to consult clinical geneticists and pediatricians to rule out the possibility of systemic diseases such as BBS.

Association of Missense Variants in VSX2 With a Peculiar Form of Congenital Stationary Night Blindness Affecting All Bipolar Cells

Importance

Congenital stationary night blindness (CSNB) is an inherited stationary retinal disorder that is clinically and genetically heterogeneous. To date, the genetic association between some cases with CSNB and an unusual complex clinical picture is unclear.

Objective

To describe an unreported CSNB phenotype and the associated gene defect in 3 patients from 2 unrelated families.

Design, Setting, and Participants

This retrospective case series was conducted in 2021 and 2022 at a national referral center for rare ocular diseases. Data for 3 patients from a cohort of 140 genetically unsolved CSNB cases were analyzed clinically and genetically.

Exposures

Complete ocular examination including full-field electroretinography and multimodal fundus imaging (spectral-domain optical coherence tomography, color, infrared reflectance, and short-wavelength autofluorescence photographs) were performed. The gene defect was identified by exome sequencing and confirmed by Sanger sequencing and co-segregation analysis in 1 family. Screening was performed for genetically unsolved CSNB cases for VSX2 variants by direct Sanger sequencing.

Main Outcomes and Measures

Ocular and molecular biology findings.

Results

The series included 3 patients whose clinical investigations occurred at ages in the early 30s, younger than 12 years, and in the mid 40s. They had nystagmus, low stable visual acuity, and myopia from birth and experienced night blindness. Two older patients had bilateral lens luxation and underwent lens extraction. Full-field electroretinography revealed an electronegative Schubert-Bornschein appearance, combining characteristics of incomplete and complete CSNB, affecting the function of rod and cone ON- and OFF-bipolar cells. Exome sequencing and co-segregation analysis in a consanguineous family with 2 affected members identified a homozygous variant in VSX2. Subsequently, screening of the CSNB cohort identified another unrelated patient harboring a distinct VSX2 variant.

Conclusions and Relevance

This case series revealed a peculiar pan-bipolar cell retinopathy with lens luxation associated with variants in VSX2. Clinicians should be aware of this association and VSX2 added to CSNB diagnostic gene panels.

Presentation of TRPM1-Associated Congenital Stationary Night Blindness in Children

IMPORTANCE

Congenital stationary night blindness (CSNB) implies a stable condition, with the major symptom being nyctalopia present at birth. Pediatric clinical presentation and the course of different genetic subtypes of CSNB have not, to our knowledge, been well described in the era of molecular genetic diagnosis.

OBJECTIVE

To describe the presentation and longitudinal clinical characteristics of pediatric patients with molecularly confirmed TRPM1-associated complete CSNB (cCSNB).

DESIGN, SETTING, PARTICIPANTS

This study was conducted at the University of Iowa from January 1, 1990, to July 1, 2015, and was a retrospective, longitudinal case series of 7 children (5 [71.4%] female) with TRPM1-associated cCSNB followed up for a mean (SD) of 11.1 (2.8) years.

MAIN OUTCOMES AND MEASURES

History, ophthalmologic examination findings, full-field electroretinogram (ffERG) results, full-field stimulus threshold testing results, Goldmann visual field results, optical coherence tomography results, and molecular genetic results were evaluated. Presenting symptoms and signs, the correlation of refractive error with electroretinography, and clinical evolution were analyzed.

RESULTS

Seven patients (5 [71.4%] female) presented early in childhood with strabismus (n = 6 [86%]), myopia (n = 5 [71%]), and/or nystagmus (n = 3 [43%]). The mean (SD) age at presentation was 8 (4) months and for receiving a diagnosis by ffERG was 7.3 years, with molecular diagnosis at 9.7 years. The mean (SD) length of follow-up was 11 (2.8) years. The best-corrected visual acuity at the most recent visit averaged 20/30 in the better-seeing eye (range, 20/20-20/60). The mean (SD) initial refraction was -2.80 (4.42) diopters (D) and the mean refraction at the most recent visit was -8.75 (3.53) D (range, -4.00 to -13.75 D), with the greatest rate of myopic shift before age 5 years. Full-field electroretinogram results were electronegative, consistent with cCSNB, without a significant change in amplitude over time. No patient or parent noted night blindness at presentation; however, subjective nyctalopia was eventually reported in 5 of 7 patients (71%). The full-field stimulus threshold testing results were moderately subnormal (-29.7 [3.8] dB; normal -59.8 [4.0] dB). Goldmann visual field results were significant for full I-4e, but constricted I-2e isopter. Eight different mutations or rare variants in TRPM1 predicted to be pathogenic were detected, with 3 novel variants.

CONCLUSIONS AND RELEVANCE

Children with TRPM1-associated cCSNB presented before school age with progressive myopia as well as strabismus and nystagmus (but not nyctalopia), with stable, electronegative ffERG results, mildly subnormal full-field stimulus threshold testing results, and a constricted I2e isopter on perimetry. These findings suggest that ffERG and cCSNB genetic testing should be considered for children who present with early-onset myopia, especially in the presence of strabismus and/or nystagmus, and that TRPM1-associated cCSNB is a channelopathy that may present without complaints of night blindness in childhood.

Goldmann-Favre Vitreoretinal Degeneration

PURPOSE

To describe a case of Goldmann-Favre vitreoretinal degeneration with typical clinical findings.

METHODS

The case report of a healthy 47-year-old woman with typical clinical findings of Goldmann-Favre vitreoretinal degeneration is presented. She had complaints of reduced visual acuity and night blindness. Her parents were first cousins.

RESULTS

Fundus examination revealed annular pigmentary degenerative changes, macular edema, and peripheral retinoschisis in both eyes. Electroretinography results were abnormal. Optical coherence tomography scans revealed hyporeflective spaces in the macular area and irregularities of the chorioretinal complex in the degenerative pigmentary areas.

CONCLUSIONS

Typical fundus findings combined with night blindness and electroretinogram abnormalities permited the diagnosis of Goldmann-Favre vitreoretinal degeneration.

Mizuo-Nakamura Phenomena

A 21-year-old male presented with a chief complaint of night blindness since early childhood. The patient had no history of hemeralopia or photophobia, and no family history of such illness or use of glasses. On examination, his visual acuity was 6/6 in both eyes. Pupils were reacting normally. Dilated fundus examination revealed diffuse golden-yellow sheen throughout the fundus with prominent retinal vasculature, but arteries and veins were less distinguishable. Choroidal vessels were not visible. The patient was then patched and dark adapted for 6 hours. The dark-adapted fundus showed the disappearance of the golden sheen with normal visible choroidal and retinal vasculature. This characteristic phenomenon observed on fundus examination from dark-adapted state to light adaptation is known as Mizuo-Nakamura phenomenon. Although this phenomenon is classical of Oguchi disease, it is also seen in X-linked cone dystrophy and X-linked retinoschisis. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:1068.].

Paraneoplastic retinopathy associated with systemic follicular cell lymphoma

The authors describe two rare cases of autoimmune retinopathy associated with follicular cell lymphoma, including a 54-year-old man who experienced nyctalopia for 1 year (patient 1) and a 59-year-old man who had bilateral loss of central vision for 6 months (patient 2). Visual field testing of patient 1 revealed nonspecific defects, and multifocal electroretinogram (ERG) testing showed mildly subnormal amplitudes more pronounced in the left than the right eye. Serologic testing detected antibodies against a 47-kD protein, presumed to be alpha-enolase. Goldmann perimetry of patient 2 showed dense central scotomas, and a full-field ERG revealed reduced amplitudes of bright scotopic responses. Serological testing yielded anti-bipolar cell antibodies. A variable presentation of autoimmune retinopathy can occur in the setting of follicular cell lymphoma. Disparate serum autoantibodies may have mediated the pathogenesis of retinal degeneration in these two patients and could explain the difference in course and severity of retinopathy.

The first case of Oguchi disease, type 2 in a Polish patient with confirmed GRK1 gene mutation

Oguchi disease type 2 is a rare autosomal recessive form of congenital stationary night blindness. A typical feature of this disorder is a golden-brown discoloration of the fundus called Mizuo-Nakamura phenomenon, which disappears after prolonged dark adaptation and reappears shortly after the onset of light.

MATERIAL AND METHODS

A 13-year-old boy exhibiting the clinical features of congenital stationary night blindness, was examined. Ophthalmic examination including slit-lamp biomicroscopy, perimetry and funduscopy was performed. Additionally, the full-field electroretinography and molecular testing for congenital stationary night blindness using the Single Nucleotide Polymorphism microarray technique were performed.

RESULTS

The ophthalmic examination showed normal visual acuity, normal anterior segment of both eyes and full visual fields. The eye fundus examination showed a typical golden-brownish discoloration of the peripheral retina (disappearing after long dark adaptation) with no pigment deposits. Full-field electroretinography showed reduced amplitudes of both waves under scotopic conditions, while under photopic conditions both shape and parameters of the record were within the normal limits. The Single Nucleotide Polymorphism microarray revealed a homozygous deletion: c.1607161 OdelCGGA in GRK1 gene. This frameshift mutation introduces a stop codon (p.Asp537Valfs*542) and results in deletion of terminal 22 amino acid residues of retinal kinase protein.

CONCLUSIONS

This is the first molecular evidence for GRK1 gene mutation in a Polish patient with Oguchi disease type 2. The identification of the c.1607_1610delCGGA mutation in a patient with Oguchi disease confirms the pathogenicity of this variant.

Risk factors associated with night vision disturbances after phakic intraocular lens implantation

PURPOSE

To investigate the incidence and severity of night vision disturbances after implantable collamer lens surgery and to analyze the risk factors.

DESIGN

Retrospective, noncomparative study.

METHODS

Medical charts from 50 eyes of 25 patients who underwent implantable collamer lens implantation were retrospectively reviewed. The incidence and severity of night vision disturbances were evaluated using questionnaires administered 6 months after surgery. Univariate simple and multiple logistic regression analyses were used to detect risk factors associated with postoperative night vision disturbances. Potential risk factors included in the analysis were keratometric value, anterior chamber depth, postoperative residual refractive error, higher-order aberrations, preoperative and postoperative mesopic pupil size, the difference between preoperative and postoperative mesopic pupil size, the difference between mesopic pupil size and implantable collamer lens optic zone diameter, white-to-white diameter, sulcus-to-sulcus diameter, and postoperative implantable collamer lens vaulting. The power, size, optic zone diameter, and toricity of the implantable collamer lens were also included as variables.

RESULTS

The incidence of night vision disturbances was 34.0% for halos and 26.0% for glare. Halos were found to be significantly related to the difference between mesopic pupil size and implantable collamer lens optic zone diameter (P = .013), white-to-white diameter of the cornea (P = .028), and implantable collamer lens optic zone diameter (P = .030). For glare, toricity of the implantable collamer lens was revealed as a significant risk factor (P = .047).

CONCLUSIONS

Although not severe, the incidence of night vision disturbances after implantable collamer lens implantation was not negligible. Possible risk factors for night vision disturbances include implantable collamer lens optic zone diameter, the difference between mesopic pupil size and implantable collamer lens optic zone diameter, and white-to-white diameter of the cornea for causing halos, and the toricity of the implantable collamer lens for causing glare.

Assessing retinal structure in complete congenital stationary night blindness and Oguchi disease

PURPOSE

To examine retinal structure and changes in photoreceptor intensity after dark adaptation in patients with complete congenital stationary night blindness and Oguchi disease.

DESIGN

Prospective, observational case series.

METHODS

We recruited 3 patients with complete congenital stationary night blindness caused by mutations in GRM6, 2 brothers with Oguchi disease caused by mutations in GRK1, and 1 normal control. Retinal thickness was measured from optical coherence tomography images. Integrity of the rod and cone mosaic was assessed using adaptive optics scanning light ophthalmoscopy. We imaged 5 of the patients after a period of dark adaptation and examined layer reflectivity on optical coherence tomography in a patient with Oguchi disease under light- and dark-adapted conditions.

RESULTS

Retinal thickness was reduced in the parafoveal region in patients with GRM6 mutations as a result of decreased thickness of the inner retinal layers. All patients had normal photoreceptor density at all locations analyzed. On removal from dark adaptation, the intensity of the rods (but not cones) in the patients with Oguchi disease gradually and significantly increased. In 1 Oguchi disease patient, the outer segment layer contrast on optical coherence tomography was 4-fold higher under dark-adapted versus light-adapted conditions.

CONCLUSIONS

The selective thinning of the inner retinal layers in patients with GRM6 mutations suggests either reduced bipolar or ganglion cell numbers or altered synaptic structure in the inner retina. Our finding that rods, but not cones, change intensity after dark adaptation suggests that fundus changes in Oguchi disease are the result of changes within the rods as opposed to changes at a different retinal locus.

[Clinical features of congenital stationary night blindness]

OBJECTIVE

To explore the clinical features of Chinese patients with congenital stationary night blindness (CSNB).

METHODS

An observational serial case study was conducted for 22 patients diagnosed as CSNB at Department of Ophthalmology, Peking Union Medical College Hospital from December 2003 through December 2011. Sixteen patients (72.7%) were males and 6 patients (27.3%) were females. Their age range was 4-73 years old. All of them underwent detailed ocular examinations including electroretinogram (ERG). Thirteen patients underwent optical coherence tomography (OCT) while 9 had visual field (VF) testing. Medical and family history was recorded.

RESULTS

Seven patients had a positive family history. Thirteen patients (59.1%) complained of a poor night vision. Best corrected visual acuity was < 0.8 in both eyes for 16 patients (72.7%). There were nystagmus (n = 4) and strabismus (n = 4). Except for 1 complicated with background diabetic retinopathy, all other patients showed normal or myopic fundi. Nine patients revealed peripheral visual field defects. Twenty-one (95.5%) patients had Schubert-Bornstein type negative ERG while another one had Riggs type ERG. Among 21 Schubert-Bornstein type patients, 13 (61.9%) patients showed complete type CSNB and 8 (38.1%) were of incomplete CSNB. Before referral to our tertiary hospital, only 2 patients were suspected as CSNB. The common primary diagnoses included pathogenic myopia, amblyopia and retinitis pigmentosa.

CONCLUSION

CSNB is frequently misdiagnosed in China. Poor visual acuity is one of the major complaints. And around 50% CSNB patients experience night vision problem. Complete CSNB is more common than incomplete type in China.

Longitudinal assessment of retinal structure and function reveals a rod-cone degeneration in a guinea pig model initially presented as night blind

We have previously reported a naturally occurring retinopathy in a population of guinea pigs, where the affected animals presented a defect of the rod-mediated vision. The purpose of this study was to investigate if the mutants were affected with a stationary or degenerative retinopathy and to identify the cellular origin of this unique disorder. Electroretinogram (ERG) [postnatal day 1 (P1) to P450], light (LM) and electron microscopy (EM) [P5, P150, P450], and immunohistochemistry [P30, P150, P450] were evaluated from normal and mutant animals. Irrespective of age, the scotopic ERGs of mutants could only be evoked by bright flashes, and the resulting ERGs were of photopic waveform. Interestingly, the amplitude of the cone and the rod/cone a-waves was always of smaller amplitude in mutants, but this difference tended to decrease with age. In contrast, the b-waves were of larger amplitude than normal in photopic ERGs obtained prior to age 25 (days) and prior to age 10 for rod/cone ERGs. LM revealed, in mutants, an absence of the outer segment layer (OSL) with a reduction in the outer nuclear layer (ONL) thickness. EM disclosed the presence of cone outer segment (OS) while no rod OS could be evidenced. Immunohistochemistry revealed the presence of rhodopsin, both cone opsins as well as normal synaptophysin immunoreactivity. Finally, neither the retinal structure nor the function in the mutants achieved normal development. Results suggest that mutant animals are suffering from a degenerative retinal disorder that affects the structure and function of rods and cones.

Vitamin A deficiency (VAD) after a duodenal switch procedure: a case report

Vitamin A deficiency (VAD) after bariatric surgery is a well-documented complication. Clinical signs of VAD deficiency are significant if the vitamin A level is below 100 mug/L (4 mumol/L). Main symptom of VAD is nyctalopia. It has been described in several reports after malabsorptive bariatric procedures. We report a 52-year-old man with VAD complained of night blindness and optic neuropathy after undergoing a duodenal switch procedure. The case illustrates the necessity of lifelong vitamin supplementation after malabsorptive bariatric operations.

A family with vitreo-tapeto-retino-choroidal degeneration with dominant transmission

A family with vitreo-tapeto-retino-choroidal degeneration is presented. Five members of a sibship of nine and their mother are affected. Retinal changes in the form of macular degeneration and peripheral preretinal membranes are the most prominent features. Other manifestations are vitreous degeneration, optic atrophy, equatorial pigmentation, and complicated cataract. The heredity is probably autosomal dominant. Comparisons are made with the well-known hereditary vitreo-retinal degenerations, in particular with Wagner's disease. Above all, the extensive macular degeneration in two of the patients, involving the retina, the pigment epithelium, and the choriocapillaris, distinguishes the present disorder from the above-mentioned.

Cellular phone use while driving at night

OBJECTIVE

Use of a cellular phone has been shown to negatively affect one's attention to the driving task, leading to an increase in crash risk. At any given daylight hour, about 6% of US drivers are actively talking on a hand-held cell phone. However, previous surveys have focused only on cell phone use during the day. Driving at night has been shown to be a riskier activity than driving during the day. The purpose of the current study was to assess the rate of hand-held cellular phone use while driving at night, using specialized night vision equipment.

METHODS

In 2006, two statewide direct observation survey waves of nighttime cellular phone use were conducted in Indiana utilizing specialized night vision equipment. Combined results of driver hand-held cellular phone use from both waves are presented in this manuscript.

RESULTS

The rates of nighttime cell phone use were similar to results found in previous daytime studies. The overall rate of nighttime hand-held cellular phone use was 5.8 +/- 0.6%. Cellular phone use was highest for females and for younger drivers. In fact, the highest rate observed during the study (of 11.9%) was for 16-to 29-year-old females.

CONCLUSIONS

The high level of cellular phone use found within the young age group, coupled with the increased crash risk associated with cellular phone use, nighttime driving, and for young drivers in general, suggests that this issue may become an important transportation-related concern.

Fundus albipunctatus in a patient with achondroplasia

We describe a patient with achondroplasia who presented with defective night vision due to fundus albipunctatus. We found no previous report of the association in a search of the literature.

A case of Oguchi's disease with diabetic retinopathy

A 50-year-old Iranian diabetic woman with night blindness was referred to our clinic. Complete ophthalmic examination including ophthalmoscopy after dark adaptation and paraclinic evaluations such as fluorescein angiography and electroretinography were performed. Retinal neovascularization and preretinal haemorrhages compatible with high-risk characteristic proliferative diabetic retinopathy were observed bilaterally. In addition, a golden-yellowish discoloration of posterior pole was noted in her both eyes. The diagnosis of Oguchi's disease was made when this discoloration disappeared after dark adaptation for 3 h. Electroretinograms also confirmed the diagnosis by showing a slow negative wave followed by a slow positive wave in the photopic condition and absent a- and b-waves in the scotopic state. We concluded that proliferative diabetic retinopathy might occur in a patient with Oguchi's disease. This report represents this association in an Iranian patient for the first time.

Negative electroretinogram in the differential diagnosis of malingering of night blindness in the military

OBJECTIVE

We evaluated the value of unusual electroretinogram (ERG) findings (negative ERG, which is selective reduction in the amplitude of the b-wave) in the differential diagnosis of night blindness in the military.

METHODS

We surveyed 3 years of data. Presumptive and final clinical diagnoses before and after negative ERG recordings were evaluated.

RESULTS

A total of 495 ERGs were included. The mean age was 22 +/- 2.5 years (range, 20-33 years). Twenty-two patients (4.4%) had negative ERG. Final clinical diagnoses could be made for all except two patients (9%). The diagnoses were congenital stationary night blindness (CSNB) (14 patients), X-linked juvenile retinoschisis (five patients), and muscular dystrophy (one patient). Seven (50%) of 14 patients with CSNB had normal fundal appearance, symptoms of night blindness, and a presumptive clinical diagnosis of malingering before the ERG test.

CONCLUSION

Negative ERG may prevent misdiagnosis of malingering for patients with CSNB with normal fundal appearance in the military.

The dilemma of the late-onset “Dystrophy”

A case of late-onset (age 51) visual loss and night-blindness is presented to illustrate the challenges of diagnosis. This patient had anti-enolase antibodies, and demonstrates the importance of auto-immune retinopathy as a potential cause of late-onset retinal "dystrophy."

Syndrome d’Oguchi ou cécité nocturne congénitale stationnaire : à propos d’un cas

INTRODUCTION

Oguchi disease, originally described in Japanese people, is a rare form of stationary night blindness in patients with normal acuity.

OBSERVATION

We report the case of an 8-year-old girl who presented with an abnormal terrified behavior in the dark. Thorough questioning revealed hemeralopia. Her clinical examination (visual acuity, Goldmann visual field, and color vision) were normal. The fundus examination showed golden-brown color, grayish, almost greenish yellow discoloration in the peripheral area with no osteoclast. This abnormality disappeared after prolonged dark adaptation. The electroretinogram showed a reduced b wave amplitude under scotopic conditions. Her parents were cousins.

CONCLUSION

This diagnosis should be suggested when hemeralopia is associated with typical fundus aspect resolving after dark adaptation (so called Mizuo-Nakamura phenomenon). The long-term prognosis in these patients is good in the absence of clinical progression. This is a genetic autosomal recessive disease caused by mutations in the gene coding for arrestin located in 2q37.1.

Electroretinographic assessment and diagnostic reappraisal of children with visual dysfunction: A prospective study

PURPOSE

To assess the presence or absence of a retinal cause of visual impairment using electroretinography (ERG) in children with no obvious discernable cause on ocular examination.

DESIGN

Prospective observational case series.

MATERIALS AND METHODS

A prospective study was carried out involving 120 children with the mean age 4.4+/-3.2 years with visual dysfunction. All children underwent ERG under general anesthesia using a special handheld mini-Ganzfeld (Kurbisfeld) dome.

RESULTS

Fifty-two (43.3%) children were male and 68 (56.7%) were female. The clinical diagnosis was as follows: Leber's congenital amaurosis (LCA) (n=47), achromatopsia (n=25), congenital stationary night blindness (CSNB) (n=9) and others (unclassifiable, n=39). The visual acuity ranged from perception of light (PL) to PL with projection in children with LCA. In the rest (n=73), some sort of visually guided behavior was discernable. Following ERG, a diagnostic reappraisal resulted as follows: LCA (n=49), achromatopsia (n=28), CSNB (n=4), cone-rod dystrophy (n=22), rod-cone degeneration (n=7), normal (n=8) and others (unclassifiable, n=2). Except for the two unclassifiable cases, ERG was successful in the diagnosis or exclusion of retinal dysfunction in the rest. By Pearson Chi-square test, there was a statistically significant association between the clinical and ERG diagnosis (P < 0.001).

CONCLUSION

LCA was the commonest cause of visual dysfunction in our series. A statistically significant correlation between clinical and electrophysiological diagnosis was seen. ERG helped in firmly establishing the presence or absence of global retinal dysfunction in the majority (118/120) of pediatric patients with visual dysfunction.

Rapid detection of SAG 926delA mutation using real-time polymerase chain reaction

PURPOSE

Mutation 926delA of the arrestin/S-antigen SAG gene is the main cause of Oguchi disease in the Japanese. The purpose of this study was to develop a rapid diagnostic assay to detect mutations in the SAG gene.

METHODS

Two sequence-specific primers and fluorophore-labeled probes for exon 11 of the SAG gene were designed, and the region spanning the mutations was amplified by polymerase chain reaction (PCR) using the LightCycler detection system (Roche Diagnostics, Mannheim, Germany). The mutations were then identified by melting curve analyses of the hybrid formed between the PCR product and a specific fluorescent probe.

RESULTS

We clearly distinguished each SAG genotype (homozygous and heterozygous 926delA and wild type) by the distinct melting peaks at different temperatures. One thermal cycling required approximately 54 min to process, and the results were 100% in concordance with the genotypes determined by DNA sequencing.

CONCLUSIONS

We have succeeded in developing a rapid method to detect the most frequent mutation in the SAG gene. This method will help in identifying gene mutations associated with Oguchi disease with a rapid and reliable identification or the exclusion of the frequent mutations in the SAG gene.

A teenager with nightblindness and cystic maculopathy: enhanced S cone syndrome (Goldmann-Favre syndrome)

Poor night vision and pigmentary retinopathy are hallmarks of retinitis pigmentosa, but variations in the type of pigmentation and in the characteristics of the electroretinogram (ERG) can point to other diagnoses. The case below (enhanced S cone syndrome) is a good example of this, and demonstrates the diagnostic importance of clinical electrophysiology.

Retinitis pigmentosa

Retinitis pigmentosa (RP) is an inherited retinal dystrophy caused by the loss of photoreceptors and characterized by retinal pigment deposits visible on fundus examination. Prevalence of non syndromic RP is approximately 1/4,000. The most common form of RP is a rod-cone dystrophy, in which the first symptom is night blindness, followed by the progressive loss in the peripheral visual field in daylight, and eventually leading to blindness after several decades. Some extreme cases may have a rapid evolution over two decades or a slow progression that never leads to blindness. In some cases, the clinical presentation is a cone-rod dystrophy, in which the decrease in visual acuity predominates over the visual field loss. RP is usually non syndromic but there are also many syndromic forms, the most frequent being Usher syndrome. To date, 45 causative genes/loci have been identified in non syndromic RP (for the autosomal dominant, autosomal recessive, X-linked, and digenic forms). Clinical diagnosis is based on the presence of night blindness and peripheral visual field defects, lesions in the fundus, hypovolted electroretinogram traces, and progressive worsening of these signs. Molecular diagnosis can be made for some genes, but is not usually performed due to the tremendous genetic heterogeneity of the disease. Genetic counseling is always advised. Currently, there is no therapy that stops the evolution of the disease or restores the vision, so the visual prognosis is poor. The therapeutic approach is restricted to slowing down the degenerative process by sunlight protection and vitaminotherapy, treating the complications (cataract and macular edema), and helping patients to cope with the social and psychological impact of blindness. However, new therapeutic strategies are emerging from intensive research (gene therapy, neuroprotection, retinal prosthesis).

[Fundus albipunctatus incidentally discovered in a black African man]

Fundus albipunctatus is a recessive autosomal disease classified as one of the causes of congenital stationary night blindness. It is characterized by early hemeralopia beginning in infancy. We report the incidental discovery of the disease in a 23-year-old black African man with late hemeralopia onset. During the 4 years of follow-up, visual acuity, ERG, and visual field remained normal. We underline the possibility of late hemeralopia onset and discuss the possible progressive features of this disease. Progression may be conditioned by the mutation of the RDH5 gene, which codes for retinol dehydrogenase-5.

[Congenital stationary night blindness]

Congenital stationary night blindness (CSNB) is a group of genetically heterogeneous retinopathy with characterized clinical and visual electrophysiological abnormality. Five candidate genes associated with the disease have been identified. Clinical, electrophysiological and molecular genetics about CSNB are reviewed in this paper.

Verkehrsophthalmologie

Assessment of an individual's ability to drive in road traffic is an important part of the ophthalmologist's work. It fulfils the ophthalmologist's duty to care for the patient and increases general road traffic safety. This assessment requires testing of visual acuity, visual field, mesopic vision and glare, motility, binocular vision and colour vision. Also the optical media and the fundus have to be examined. If an optical aid is necessary, it should be suitable for use in road traffic. In some cases restrictions are necessary, which should be noted in the driver's licence. Testing of visual function has to be performed with standardised procedures according to the recommendations of DOG and BVA. This article will provide readers with an overview of current practices in assessing the ability to drive in road traffic and enable them to render an accurate professional opinion regarding driver's licences.

Erworbene vorübergehende Nachtblindheit bei Vitamin-A- und Zinkmangel bei Anorexia nervosa neun Jahre nach Nierentransplantation

BACKGROUND

Vitamin and trace element deficiencies may cause visual disturbances. Before starting a substitutional therapy, specific investigations should be performed.

HISTORY AND SIGNS

We present a kidney-transplanted patient who suffered for 6 months from night blindness. The electroretinography showed a severe decrease of the rod activity. Except for an irregular pigmentation in the far periphery, the fundus appeared normal. These findings were indicative of a vitamin A and zinc deficiency. The laboratory tests showed decreased vitamin A and zinc serum levels.

THERAPY AND OUTCOME

After three months of substitutional therapy the electroretinogram had normalized and the patient was free of symptoms.

CONCLUSIONS

Visual disturbances due to vitamin and trace element deficiencies are rare in Europe. If suspected, since the diagnosis and the treatment of nutritional deficiencies are simple, specific investigations and a substitutional therapy should be initiated.

Dysfunction of transmission in the inner retina: incidence and clinical causes of negative electroretinogram

BACKGROUND

Only limited data exist on the incidence of negative electroretinograms (ERG) in clinical practice. The purpose of this study is therefore to determine the incidence and clinical causes of a negative ERG in a tertiary care centre focused on inherited and acquired retinal degenerations.

METHODS

All ERGs recorded (in accordance with ISCEV standards) in our electrophysiological laboratory from 1992 to 2004 were retrospectively reviewed. The negative ERGs (criterion: ERG with b:a wave ratio<or=1 in the scotopic standard combined response in at least one eye) were analysed in the context of further clinical results. The photopic ON- and OFF-responses were recorded with long duration (200 ms) stimuli.

RESULTS

A total of 1999 ERGs from 1644 patients were performed during the study period. 47/1644 patients (2.9%) presented with a negative ERG and were included in the study. Clinical diagnoses included inherited retinal dystrophies [X-linked congenital retinoschisis (XRS) (n=17), congenital stationary night blindness (CSNB) (n=6), retinitis pigmentosa (RP) (n=6), cone (-rod) dystrophy (n=5), choroideremia (n=1), Müller cell sheen dystrophy (MCSD) (n=1)] and acquired retinopathies (melanoma-associated retinopathy (MAR) (n=1), vigabatrin retinotoxicity (n=1)). In nine patients a definitive diagnosis could not be established. Unilateral negative ERGs were seen in 10/37 patients where ERG was bilaterally recorded. The fellow eye presented with a b:a wave ratio >1 (8 eyes) or ERG responses were not detectable (2 eyes). Photopic ON- and OFF-responses were recorded in 38 eyes of 29 patients and 32/38 eyes presented with a negative ERG. The ON-response was reduced in 25/32 eyes, whereas the OFF-response was reduced in only 11/32 eyes.

CONCLUSIONS

The incidence of a negative ERG can differ between the laboratories depending on the causes for ERG recording and was in our laboratory 2.9% in a consecutive series of patients with inherited or acquired retinal degenerations. A disorder characteristically associated with negative ERG (e.g. XRS, CSNB, MAR) was diagnosed in 53% of these patients, whereas in 47% the negative ERG indicated an unexpected post-receptoral dysfunction, e.g. in cone (-rod) dystrophy or RP. The ON-bipolar pathway was affected in most cases.

Is Optic Nerve Fibre Mis-Routing a Feature of Congenital Stationary Night Blindness?

PURPOSE

To determine whether patients with congenital stationary night blindness (CSNB) have electrophysiological evidence of optic nerve fibre mis-routing similar to that found in patients with ocular albinism (OA).

METHOD

We recorded the Pattern Onset VEP using a protocol optimised to detect mis-routing of optic nerve fibres in older children and adults. We tested 20 patients (age 15-69 yrs) with X-linked or autosomal recessive CSNB, 14 patients (age 9-56 yrs) with OA and 13 normally pigmented volunteers (age 21-66 yrs). We measured the amplitude and latency of the CI component at the occipital midline and over left and right occipital hemispheres. We also assessed the computed inter-hemispheric "difference" signal. Subjects with CSNB were classified as having the "complete" or "incomplete" phenotype on the basis of their ERG characteristics. Members of X-linked CSNB pedigrees underwent mutation screening of the NYX and CACNA1F genes.

RESULTS

CI was significantly smaller over the ipsilateral hemisphere and more prominent over the contralateral hemisphere in OA patients compared with both controls and CSNB patients. In CSNB patients CI response amplitudes were not significantly different from controls but peak latency was prolonged at all three electrodes compared with controls. The inter-hemispheric "difference" signal was abnormal for the OA group but not for the CSNB group. Contralateral dominance of CI could be identified in the majority of OA patients and the "difference" signal was opposite in polarity for left compared with right eye stimulation in every patient in this group. Only 3 of 20 patients with CSNB showed significant inter-hemispheric asymmetry similar to that seen in the OA patients. All 3 CSNB patients with evidence for optic nerve fibre mis-routing had X-linked pedigrees: 2 had an identified mutation in the NYX gene but no mutation in either the NYX or CACNA1F genes was identified in the third. VEP evidence of optic nerve fibre mis-routing was present in 3 of the 11 subjects with "complete" phenotype and none of the 9 patients with "incomplete" phenotype CSNB.

CONCLUSION

Mis-routing of optic nerve fibres does occur in CSNB but we found evidence of it in only 15% of our patients.

Predicting patients' night vision complaints with wavefront technology

PURPOSE

To evaluate the accuracy of the diagnostic capabilities of optical metrics generated from wavefront measurements in relationship to post-laser-assisted in situ keratomileusis (LASIK) visual complaints as expressed and drawn by patients.

DESIGN

Retrospective analysis and observational case series.

METHODS

Patient wavefront data from an investigational device exemption study for wavefront-guided ablations were used to derive normative modulation transfer function (MTF), encircled energy (EE), and Strehl ratio. These optical metrics and their point-spread functions (PSF) were compared with data from five postoperative patients with night vision complaints. Patients were asked to draw their symptoms, which were elicited by testing with a Fenthoff muscle light, while using their best-corrected distance vision.

RESULTS

The MTF, EE, and Strehl ratio of most patients were markedly different from those of the averages of 208 normal myopic eyes before and after LASIK surgery. The spatial extent of the PSF correlated positively with the severity of the visual complaints. Wavefront-derived PSFs were markedly similar to the patients' drawings.

CONCLUSIONS

The results of this study demonstrate the diagnostic capability of the wavefront system in predicting visual symptoms and complaints of patients with high-order aberrations. Objective visual metrics from patients with night vision complaints were different from those of normal myopic eyes that had undergone LASIK procedures.

Glare sensitivity and professional drivers' safety: a case of rod-cone dystrophy with negative electroretinogram

BACKGROUND

To obtain a driver's licence certain requirements for visual acuity and visual field have to be fulfilled. Mesopic contrast and glare sensitivity are not regularly tested and are not crucial to passing the driving test.

CASE REPORT

We report a case of a 39-year-old professional bus driver whose only complaint was increased glare sensitivity. After he had been involved in four traffic accidents, ophthalmological investigations revealed binocular annular scotomata and night blindness, leading to the diagnosis of rod-cone dystrophy.

DISCUSSION

Enhanced glare sensitivity is a common complaint in elderly people or people with the beginnings of cataract but may also represent an initial symptom of a retinal disorder. It is therefore advisable for traffic safety if drivers with such complaints undergo a complete ophthalmological investigation including visual field testing.

Clinical manifestations of a unique X-linked retinal disorder in a large New Zealand family with a novel mutation in CACNA1F, the gene responsible for CSNB2

PURPOSE

To describe the phenotype in a New Zealand family with an unusual severe X-linked retinal disorder with a novel I745T mutation in CACNA1F, the gene responsible for incomplete congenital stationary night blindness (CSNB2).

METHODS

Members of the family tree were invited for clinical, psychophysical and electrodiagnostic evaluation.

RESULTS

Male family members had severe non-progressive visual impairment, abnormal colour vision, congenital nystagmus, hyperopia and normal fundi. Some were intellectually disabled. Female family members had congenital nystagmus and decreased visual acuity frequently associated with high myopia. Electroretinograms (ERG) identified reduced rod and cone responses with negative waveform in male and female family members, with atypical features for CSNB2.

CONCLUSIONS

Although there were similarities to CSNB2, distinctive features in male family members included severity of phenotype, and association of intellectual disability. Moreover, all female heterozygotes had clinical and ERG abnormalities. CACNA1F encodes the Ca(v)1.4 alpha1 subunit of a voltage-gated calcium channel, which may mediate neurotransmitter release from photoreceptors. Molecular analyses, reported separately, identified a novel I745T CACNA1F mutation that was associated in vitro with major alterations in gating and kinetics of the Ca(v)1.4 channel. It is speculated that the unique phenotype described in this family may reflect similarly altered function of Ca(v)1.4 channel activity in vivo.

Clinical features of Japanese families with a 402delT or a 555-556delAG mutation in choroideremia gene

PURPOSE

To characterize the clinical features of two Japanese families with choroideremia associated with a 402delT and a 555-556delAG mutation in the choroideremia gene (CHM).

METHODS

Four affected members and one obligate carrier from two Japanese families with choroideremia were studied. To detect mutations of the CHM gene, the products of polymerase chain reaction were directly sequenced in both directions. The ophthalmologic examination included best-corrected visual acuity, slit-lamp examination, fundus examination, kinetic perimetry, electroretinography, and fluorescein angiography.

RESULTS

A 402delT and a 555-556delAG mutation were found in two Japanese families with choroideremia. All affected members had night-blindness, progressive constriction of the visual field, chorioretinal atrophy, and mottled appearance of the retinal pigment epithelium. The obligate carrier had mild patchy areas of retinal pigment epithelial atrophy with no visual symptoms.

CONCLUSION

The authors found a 402delT and a 555-556delAG mutation in the CHM gene, one of which (402delT) is a novel mutation. They conclude that these mutations cause choroideremia in Japanese families.

[Flash full-field electroretinography in diseases with night blindness]

PURPOSE

The aim of this study is to present similarities and differences of electroretinograms in early stages of retinal diseases with nyctalopia.

MATERIAL AND METHODS

Flash full-field electroretinography was done according to ISCEV standards and also with chromatic stimulations in patients with nyctalopia, who were diagnosed as various forms of congenital stationary night blindness and various types of retinitis pigmentosa, choroideremia, gyrate atrophy and also in patients with nyctalopia, because of unknown reason. ERG results were compared with normal values and with each other.

RESULTS

In diseases with nyctalopia the function of peripheral retina is markedly abnormal and scotopic ERG is significantly reduced or even absent. In retinitis pigmentosa a-wave is small or absent especially scotopic but photopic ERG is also abnormal. Well preserved a-wave distinguished ERG of patients with stationary night blindness from the other progressive diseases of retina or choroid.

CONCLUSIONS

In patients with nyctalopia using ERG is possible to obtain which retinal elements do not work but it is only start point to following diagnostic examinations, to make proper final diagnosis.

A novel IMPDH1 mutation (Arg231Pro) in a family with a severe form of autosomal dominant retinitis pigmentosa

PURPOSE

To define ophthalmic findings in a family with autosomal dominant retinitis pigmentosa and a novel IMPDH1 gene mutation.

DESIGN

Genetic and observational family study.

PARTICIPANTS

Sixteen affected members of a family with autosomal dominant retinitis pigmentosa.

METHODS

Ophthalmic examination, including best-corrected visual acuity (VA), slit-lamp biomicroscopy, direct and indirect ophthalmoscopy, Goldmann kinetic perimetry, and electroretinography were performed. Deoxyribonucleic acid single-strand conformation polymorphism (SSCP) analysis was done. Abnormal polymerase chain reaction products identified by SSCP analysis were sequenced bidirectionally.

RESULTS

All affected patients had the onset of night blindness within the first decade of life. Ocular findings were characterized by diffuse retinal pigmentary degenerative changes, marked restriction of peripheral visual fields, severe loss of VA, nondetectable electroretinography amplitudes, and a high frequency of posterior subcapsular lens opacities. Affected members were observed to harbor a novel IMPDH1 gene mutation.

CONCLUSION

A novel IMPDH1 gene mutation (Arg231Pro) was associated with a severe form of autosomal dominant retinitis pigmentosa. Families affected with a severe form of this genetic subtype should be investigated for a mutation in the IMPDH1 gene.