On- and off-responses in the photopic electroretinogram in complete-type congenital stationary night blindness

We examined the on- and off-responses of the photopic electroretinogram in patients with complete congenital stationary night blindness. Standard flash electroretinograms as well as those produced in a ganzfeld modified for long-duration light stimuli (500 msec) permitted the separation of on- and off-responses in four patients and four normal subjects. The amplitude and latency of the electroretinogram on- response (a- and b-waves) and off-response (d-wave) in addition to the oscillatory potentials of the off-response in normal subjects and patients were compared. The abnormal on-response was demonstrated in all the patients, and the offresponse with its oscillatory potentials were preserved. We showed that the second portion of the off-response (of inner retinal origin) is normal. If congenital stationary night blindness is a defect of depolarizing bipolar cells, these results preclude input of the depolarizing bipolar cells and support the hyperpolarizing bipolar cells as the cellular origin of the off-response electroretinogram.     

Oscillatory potentials and pattern electroretinogram: are they related?

The possible relationship between the pattern electroretinogram (ERG) and oscillatory potentials was investigated in two patients with night blindness. One patient had congenital stationary night blindness of Schubert-Bornschein type, and the other had Oguchi's disease. Both had normal visual acuity, normal mass photopic (cone) ERG and normal local macular ERG. In each patient, scotopic (rod) ERG after 20-minute dark adaptation was nonrecordable and the single bright flash ERG was of the negative type. The difference between the ERG pattern of the two patients was found in the oscillatory potentials. The patient with congenital stationary night blindness showed no oscillatory potentials, whereas the patient with Oguchi's disease had good oscillatory potentials. The pattern ERG in both patients was normal. Based on the data of these two patients, it was thought that the pattern ERG is not closely related to the oscillatory potentials and may have different mechanisms of generation.     

Congenital stationary night blindness

Congenital stationary night blindness (CSNB) seems to be a very rare condition in Scandinavia. From Denmark a 7-generation family with the dominant form was published in 1909, and one family with the X-linked recessive form was reported from Norway. On going through the files of the National Eye Clinic for Visually Impaired, 7 patients were found (1 dominant, 4 X-linked recessive, 1 simplex case and 1 autosomal recessive). Including anamnestic information on relatives, 17 patients had a diagnosis of CSNB. The clinical findings in these cases are reported with stress on alteration in ERG, dark adaptation and the optic discs. The loss of oscillatory potentials in a carrier of CSNB is described. The provisional findings seem to indicate that 3 genetic variants are present in the Danish population. The real prevalence is estimated considerably higher than 17 out of 5 million.     

完全型X连锁先天性静止性夜盲临床和基因研究

目的 明确一国人家族遗传性完全型X连锁先天性静止性夜盲(CSNB)的诊断，并检定致病基因突变。 方法 对一CSNB家系进行临床研究和系谱分析。采集家族中5位患者和16位正常人的静脉血并提取基因组DNA。通过连锁分析确定该病致病基因的染色体位点后，应用聚合酶链反应（PCR）扩增候选基因外显子及其侧翼，直接测序确定致病的基因突变。采用PCR直接测序法进行群体分析。对照组包括正常人群对照和家族内正常对照，按照一定标准入选。 结果 该CSNB家系家族中所有患者NYX基因外显子2发生了错义突变，核苷酸772位的腺嘌呤被胞嘧啶取代（A772C）；对应的苏氨酸改变为脯氨酸 (T258P)，女性携带者均为杂合。家族中正常人及110名正常人群对照均未发现该突变。 结论NYX新突变A772C (T258P )和该家系X连锁CSNB相关。(中华眼底病杂志，2007，23：184-188)     

Cone function in congenital nyctalopia

A patient with congenital stationary night blindness (CSNB) (Schubert-Bornschein type) transmitted as an autosomal recessive trait was studied with several tests of electrical function as well as a variety of psychophysical procedures. Comparison of the patient's present findings with those obtained 23 years earlier showed that while rod thresholds have remained the same, cone sensitivity has decreased. Subjective flicker thresholds obtained following a bleach were unchanged during the course of dark adaptation. The absence of rod-cone interaction, together with an absent scotopic b-wave, implies that the defect is in the mid-retinal layers. Further, the absence of oscillatory potentials in the photopic electroretinogram (ERG) suggests that the interplexiform cell may be implicated in some manner. The focal ERG of the CSNB patient showed normal amplitude and normal phase delays, supporting the idea that the focal ERG samples primarily cone photoreceptor activity.     

Affected females in X-linked congenital stationary night blindness.

Most heterozygous (carrier) females in families with X-linked congenital stationary night blindness are asymptomatic. Several anecdotal cases of manifesting females in X-linked congenital stationary night blindness have been reported, but few clinical details are available. The authors report clinical, electroretinographic, and dark adaptation studies of four affected females from a five-generation family with X-linked congenital stationary night blindness. Each of the manifesting females was the daughter of a different, asymptomatic, carrier mother. None of the 14 daughters of the 9 affected males showed signs or symptoms of congenital stationary night blindness. Uneven X-chromosomal lyonization is the most likely reason for these females manifesting this X-linked disorder.     

Loss of electroretinographic oscillatory potentials, optic atrophy, and dysplasia in congenital stationary night blindness

New criteria for diagnosing congenital stationary night blindness include loss of the oscillatory potentials in the photopic and bright-flash dark-adapted electroretinogram, and atrophy or dysplastic changes, or both, in the optic nerve head. Ten patients (seven male and three female, ranging in age from 6 to 19 years) had typical findings of congenital stationary night blindness including congenital nonprogressive nyctalopia, no pigmentary retinopathy, and full visual fields consistent with myopia. Visual acuities ranged from 20/30 to 20/60, though one patient had a visual acuity of 20/200. Most patients had histories of strabismus. The photopic electroretinograms were subnormal. Of the male patients, five had tilted optic disks with temporal portions of the nerve missing, and two had misshapen nerve heads. The three female patients had pallor of the optic disk without evidence of tilt.     

X-chromosomal hereditary night blindness: detection of carriers by segregation analysis with linked DNA markers

Congenital stationary night blindness is a rare disease with autosomal dominant, autosomal recessive, or X-linked recessive inheritance. The X-chromosomal form is frequently associated with myopia. Female carriers have no symptoms of visual impairment and therefore cannot be identified clinically. The close link recently described between the disease locus and the DXS7 locus, mapped in Xp11.3, as well as other marker loci from this chromosomal region, permits indirect genotype analysis and thus identification of the carriers; with the information thus obtained, improved genetic counseling is possible. The authors studied a large Swiss family with the X-linked trait. Segregation analysis was performed with DXS7 as well as two flanking markers, DXS255 and OTC. It was thus possible to determine the degree or probability of several female members of the family being carriers.     

A survey of hereditary aspects of pigmentary retinal dystrophies

A study of 707 cases of retinitis pigmentosa and choroideraemia presenting over 12 years were classified according to their modes of inheritance-439 autosomal recessive (62%), 193 autosomal dominant (27%), 75 X-linked (10.7%). The patients with autosomal recessive transmission included 58 Usher syndrome, 12 Laurence-Moon-Bardet-Biedl syndrome and 33 Leber's congenital amaurosis. Another 37 had an early onset with macular degeneration and 31 were of late onset with pericentral dystrophy. Forty two were offspring of consanguineous parents. Of 193 individuals (78 families) with autosomal dominant inheritance, 20% had night blindness from early childhood. With X-linked transmission, 33 males and 31 female carriers comprised the retinitis pigmentosa group and eight males and three carrier females, choroideraemia. Almost all this X-linked group were of British ancestry. Of patients originating from the Mediterranean area, 94% had autosomal recessive disease.     

A survey of hereditary aspects of pigmentary retinal dystrophies

A study of 707 cases of retinitis pigmentosa and choroideraemia presenting over 12 years were classified according to their modes of inheritance--439 autosomal recessive (62%), 193 autosomal dominant (27%), 75 X-linked (10.7%). The patients with autosomal recessive transmission included 58 Usher syndrome, 12 Laurence-Moon-Bardet-Biedl syndrome and 33 Leber's congenital amaurosis. Another 37 had an early onset with macular degeneration and 31 were of late onset with pericentral dystrophy. Forty two were offspring of consanguineous parents. Of 193 individuals (78 families) with autosomal dominant inheritance, 20% had night blindness from early childhood. With X-linked transmission, 33 males and 31 female carriers comprised the retinitis pigmentosa group and eight males and three carrier females, choroideraemia. Almost all this X-linked group were of British ancestry. Of patients originating from the Mediterranean area, 94% had autosomal recessive disease.     

A potential spontaneous rat model of X-linked congenital stationary night blindness

Purpose: To describe a possible spontaneous rat model of X-linked congenital stationary night blindness (CSNB). Methods: Experimental animals were generated by mating the affected animal to normal rats, and from interbreeding littermates. To define the inheritance pattern, full-field electroretinograms (ERGs) were recorded from all progeny. Results: During the course of other experiments, an affected male rat was identified by a reduced amplitude ERG b-wave. When this rat was mated to normal Sprague–Dawley rats, all of the F1 progeny had normal ERG waveforms. When F1 offspring were interbred, 51% of the male offspring had b-wave reductions while all female offspring had normal ERG waveforms. When F1 females were backcrossed to the original affected male, b-wave reductions were noted in both male and female offspring; overall, 46.8% of the backcross progeny exhibited a b-wave reduction. In affected animals, the b-wave was selectively affected as the a-wave appeared to retain normal amplitude and kinetics at 1–4 months old. Cone ERGs were significantly reduced in amplitude and somewhat delayed. Similar ERG results were also obtained under the same stimulus conditions from human patients with complete CSNB (CSNB1). Conclusions: The inheritance pattern is consistent with an X-linked recessive trait. The electrophysiological results suggest that this mutant rat line may provide another model for CSNB1.     

Possible pathogenesis of congenital stationary night blindness

We reported a case of congenital stationary night blindness (CSNB) who showed Schubert-Bornschein type electroretinogram (ERG) in the right eye and nearly normal ERG in the left eye with absolute glaucoma. From the electrophysiological findings of both eyes and histological findings of the enucleated eye, we concluded that the mechanism of night blindness in CSNB is an abnormal inhibition in the bipolar cell layer. The experiments in rabbits by vincristine intravenous and intravitreous administrations did not give rise to a negative type ERG, but to a decrease of the amplitude of all ERG components. The lesion of CSNB which was reported to be responsible in the synaptic terminal by Ripps et al could not be confirmed.     

Changes in the DC electroretinogram in Briard dogs with hereditary congenital night blindness and partial day blindness.

Five Briard dogs, 7-12 months old, with congenital night blindness and severely reduced day vision (offspring of a sister and brother with congenital and supposedly stationary night blindness but with normal or nearly normal day vision) and three normal control dogs were studied by means of direct current (DC) electroretinography in order to analyse fast and slow retinal and pigment epithelial (RPE) potentials. No definite a- and b-waves were seen in the affected dogs in the dark-adapted state, which indicates severely impaired rod function. All affected dogs responded to 30 Hz flickering light in the light-adapted state, although with an amplitude reduced by 50-70%. Thus, cone function was better preserved than rod function. The control dogs showed a small c-wave and a deep negative trough between the b- and c-waves, indicating that slow PIII from the Müller cells, as well as the photoreceptor potential, are very prominent. In the affected dogs, there was no c-wave, but from a stimulus intensity of 3 log U above the normal b-wave threshold, a slow negative potential appeared, the latency and peak time of which were very long, 5-7 and 11-15 sec, respectively. With increasing stimulus intensities, both parameters decreased substantially, whereas the amplitude increased to a maximum of 2400 microV. In the light-adapted state, the dog with the best day vision showed a negative potential of short duration (peak time about 0.2 sec), followed by a positive potential (peak time about 1.2 sec).(ABSTRACT TRUNCATED AT 250 WORDS)     

A distinctive form of congenital stationary night blindness with cone ON-pathway dysfunction

PURPOSE: To characterize a distinctive form of congenital stationary night blindness (CSNB). DESIGN: Observational case report. PARTICIPANTS: A 30-year-old male with a history of night blindness, several members of his family, a patient with "complete" congenital stationary night blindness (CSNB1), and groups of age-similar control subjects. METHODS: Rod-system function was evaluated by measuring psychophysical dark-adapted thresholds, by recording dark-adapted electroretinograms (ERGs), and by fundus reflectometry. Cone-system function was evaluated by recording light-adapted ERGs, including those to sawtooth flicker, and by recording light-adapted visually evoked potentials (VEPs) to luminance increments and decrements. MAIN OUTCOME MEASURES: Dark-adapted thresholds, ERGs, rhodopsin double densities, Goldmann visual fields, and VEPs. RESULTS: The patient's visual acuity, visual fields, and color vision were normal. His peripheral dark-adapted thresholds were rod-mediated but elevated by approximately 3 log units above normal. Rhodopsin double density and bleaching recovery were normal. His dark-adapted maximal-flash ERG showed a "negative" waveform, in which the b-wave was more reduced in amplitude than the a-wave, although the a-wave amplitude was also reduced. The rod photoreceptors contributed to the patient's dark-adapted ERGs, as illustrated by the unequal responses to cone-matched stimuli. The patient's cone-mediated thresholds for long-wavelength stimuli were within the normal range. However, his light-adapted brief-flash b-wave was abnormal in amplitude and implicit time. Selective abnormalities of the ON responses of the cone system were apparent in the patient's reduced b-wave amplitude to rapid-on flicker with a normal response to rapid-off flicker, and his prolonged VEP latencies to increments but not to decrements. CONCLUSIONS: The overall pattern of findings distinguishes this patient from previously described forms of CSNB. The results suggest that two factors likely contribute to the patient's night blindness: (1) a rod phototransduction defect and (2) a postreceptoral defect. The results also indicate dysfunction within the cone ON pathway.     

Abnormalities of the long flash ERG in congenital stationary night blindness of the Schubert-Bornschein type

We investigated abnormalities of the retinal cone ON- and OFF-pathways in 24 males with Schubert-Bornschein congenital stationary night blindness (CSNB). Substantial differences were found between both CSNB types. In incomplete type, a-, b- and d-waves were reduced and delayed, whereas in complete type only the b-wave showed significant changes. Oscillatory potentials (OPs) were not discernible from noise in incomplete CSNB and showed significant peak alterations of the ON-OPs only in complete CSNB. In the complete CSNB type, the ON pathway appeared to be mainly affected. In the incomplete CSNB form marked involvement of both the ON and the OFF pathways was noted.     

Norrie disease and exudative vitreoretinopathy in families with affected female carriers.

PURPOSE: Norrie disease (ND) is a rare X-linked recessive disorder characterized by congenital blindness, which is often associated with sensorineural hearing loss and mental retardation. X-linked familial exudative vitreoretinopathy (FEVR) is a hereditary disorder characterized by an abnormality of the peripheral retina and is not associated with systemic diseases. X-linked recessive disorders generally do not affect females. Here we show that female carriers can be associated with manifestation of an X-linked disorder. METHODS: A four-generation family with an affected female, and a history of congenital blindness and hearing loss, was identified through the pro-band. A second family, with a full-term female infant, was evaluated through ophthalmic examinations and found to exhibit ocular features, such as retinal folds, retinal detachment and peripheral exudates. Peripheral blood specimens were collected from several affected and unaffected family members. DNA was extracted and analyzed by single-strand conformation polymorphism (SSCP) following polymerase chain reaction (PCR) amplification of the exons of the Norrie disease gene. The amplified products were sequenced by the dideoxy chain termination method. RESULTS: In an X-linked four-generation family, a novel missense (A118D) mutation in the third exon of the Norrie disease gene, was identified. The mutation was transmitted through three generations and cosegregated with the disease. The affected maternal grandmother and the unaffected mother carried the same mutation in one of their alleles. In an unrelated sporadic family, a heterozygous missense mutation (C96Y) was identified in the third exon of the Norrie disease gene in an affected individual. Analysis of exon-1 and 2 of the Norrie disease gene did not reveal any additional sequence alterations in these families. The mutations were not detected in the unaffected family members and the 116 normal unrelated controls, suggesting that they are likely to be the pathogenic mutations. CONCLUSIONS: The results further strengthen the proposal that X-linked disorders can occur in female carriers, due likely to an unfavorable X-inactivation.     

Negative-type electroretinogram from cisplatin toxicity

A 68-year-old woman with ovarian cancer suffered a loss of visual acuity and color perception after inadvertent overdosage with the antineoplastic agent cisplatin. Her acuity returned to normal but a tritan color defect persisted more than a year later. Her electroretinogram was stable between 7 weeks and 15 months after cisplatin administration, with a negative-type scotopic response, but also reduced cone b waves and a loss of some scotopic oscillatory potentials. With light stimuli between 10 and 100 ms in duration, the photopic on-responses were markedly reduced while the off-responses were normal or close to it. This case suggests that cisplatin may selectively injure on-pathways in the retina and indicates the need to expand the list of disorders that may cause a negative-type electroretinogram.Abbreviations CSNB congenital stationary night blindness     

ERG characteristics of congenital stationary night blindness

The ERGs of 9 cases (18 eyes) of congenital stationary night blindness with normal fundi or myopia were tested. All eyes showed nonrecordable rod ERG and cone ERG with normal a-wave. Scotopic mixed ERGs were of the negative type in 7 eyes and of the subnormal type in 11 eyes. The b/a ratio was reduced in all eyes. The ERG characteristics are useful for the classification, estimation of the probable location of the lesion, and differential diagnosis of the disease.     

Aland island eye disease: clinical and electrophysiological studies of a Welsh family.

Clinical and molecular genetic studies were performed on a single, large, white family, in which congenital nystagmus and moderate to high refractive error segregated as a sex linked trait with manifestation in some female carriers. In this family, affected males demonstrate myopia, but a high proportion of female carriers, and some of the possibly affected males, show hypermetropia. Clinical ophthalmic examination and electrodiagnostic studies of retinal function were fully compatible with a diagnosis of either incomplete congenital stationary night blindness or of Aland island eye disease. Previous studies have mapped both disorders to the proximal short arm of the X chromosome: our molecular studies support this localisation. Incomplete congenital stationary nightblindness and Aland Island eye disease could be considered as a single entity.