Peripheral Visual Field Constriction Research Articles

The Curious Case of Night Blindness: A Rare Case Report

Introduction: Gyrate Atrophy of the choroid and the retina is a rare autosomal recessive disorder caused by a mutation in ornithine aminotransferase. Case Report: We present an interesting case of a 55-year-old male who presented to us with complaints of night blindness, increase in number of minus glasses, senile cataract in both eyes, constriction of peripheral visual field and chorioretinal atrophic lesions in both eyes. Blood investigation revealed raised plasma ornithine levels at 690 micromole/L (normal range 30-90 micromole/L). There is progressive night blindness and visual field constriction due to progressive chorioretinal degeneration. It has now progressed to diminution of central visual acuity due to progressive macular and glaucomatous changes and cataract formation. Conclusion: There is history of blindness in two out of 6 more siblings which indicates a hereditary pattern.

Usher Syndrome: A Case Report of Two Brothers

Purpose: To report a case of Usher’s syndrome in two brothers. Case Report: Two brothers, 24 and 26 years of age, presented to Chittagong eye infirmary and training complex with the complaints of gradual diminution of vision in both eyes, especially at night. Their ocular examination revealed best corrected visual acuity of 6/36 in right eye and 6/24 in left eye. Dilated fundus evaluation showed pigmentary retinopathy. Perimetry revealed peripheral visual field constriction. Their systemic examination revealed sensorineural hearing loss. These clinical findings supported the diagnosis of Usher syndrome Type 1. The patients were advised for low vision aids to improve their quality of life and counseling regarding the prognosis of the disease was done with the patient’s family members. Conclusion: Early detection and appropriate intervention will help preserve the residual vision.

周辺視野の狭窄が自動車運転時における速度感覚に及ぼす影響

周辺視野の狭窄が自動車運転時における速度感覚に及ぼす影響

Role of Taurine Transporter in the Retinal Uptake of Vigabatrin.

Vigabatrin (VGB) is a first-line drug used for treatment of infantile spasms. On therapeutic dose, VGB accumulates in the retina causing permanent peripheral visual field constriction. The mechanism involved in retinal accumulation of VGB is ambiguous. In the present study, mechanism of VGB transport into retina was evaluated. VGB uptake into retina was studied in vitro using human adult retinal pigment epithelial (ARPE-19) cells as a model for outer blood retinal barrier. The VGB cell uptake studies demonstrated saturation kinetics with Km value of 13.1mM and uptake was significantly increased at pH7.4 and hyperosmolar conditions indicating involvement of carrier-mediated Na+-Cl--dependent transporter. In the presence of taurine transporter (TauT) substrates (taurine and GABA) and inhibitor guanidinoethyl sulfonate (GES), the uptake of VGB decreased significantly demonstrating contribution of TauT. The VGB retinal levels in rats were decreased by 1.5- and 1.3-folds on chronic administration of GES and taurine, respectively. In conclusion, this study demonstrated the TauT involvement in VGB uptake and accumulation in retina.

Transcriptome analysis in mice treated with vigabatrin identifies dysregulation of genes associated with retinal signaling circuitry

Vigabatrin (VGB; γ-vinyl-GABA) is an antiepileptic drug that elevates CNS GABA via irreversible inactivation of the GABA catabolic enzyme GABA-transaminase. VGB’s clinical utility, however, can be curtailed by peripheral visual field constriction (pVFC) and thinning of the retinal nerve fiber layer (RNFL). Earlier studies from our laboratory revealed disruptions of autophagy by VGB. Here, we tested the hypothesis that VGB administration to animals would reveal alterations of gene expression in VGB-treated retina that associated with autophagy. VGB (140 mg/kg/d; subcutaneous minipump) was continuously administered to mice (n = 6 each VGB/vehicle) for 12 days, after which animals were euthanized. Retina was isolated for transcriptome (RNAseq) analysis and further validation using qRT-PCR and immunohistochemistry (IHC). For 112 differentially expressed retinal genes (RNAseq), two databases (Gene Ontology; Kyoto Encyclopedia of Genes and Genomes) were used to identify genes associated with visual function. Twenty four genes were subjected to qRT-PCR validation, and five (Gb5, Bdnf, Cplx9, Crh, Sox9) revealed significant dysregulation. IHC of fixed retinas verified significant down-regulation of Gb5 in photoreceptor cells. All of these genes have been previously shown to play a role in retinal function/circuitry signaling. Minimal impact of VGB on retinal autophagic gene expression was observed. This is the first transcriptome analysis of retinal gene expression associated with VGB intake, highlighting potential novel molecular targets potentially related to VGB’s well known ocular toxicity.

Intracranial hypertension as an initial clinical manifestation of Systemic Lupus Erythematosus

Abstract Background Systemic Lupus Erythematosus (SLE) is an auto-immune systemic disorder that may affect multiple organ systems including central nervous system. Although involvement of the nervous system and eye is not uncommon in SLE, the presence of intracranial hypertension (IH) with papilledema in SLE a rare occurrence and it requires high level of suspicion to be diagnosed, especially when the combination of IH and papilledema is the initial presentation of SLE. Case presentation A 21-year-old female presented with a month long history of progressively deteriorating bilateral frontotemporal headache of throbbing quality. In neurological examination the only finding was bilateral papilledema with mild peripheral visual field Constriction. A brain Magnetic Resonance Imaging (MRI), MR angiography and venography showed no abnormal findings. Cerebrospinal fluid (CSF) analysis revealed a high opening pressure (320 mm H2O) with normal CSF indices. She also had normocytic, normochromic anemia, mild thrombocytopenia, increased quantitative CRP, ESR and LE cell was also reported. Upon further work-up, it was revealed that she had positive ANA and Anti-ds-DNA, decreased level of complement C3 and C4. She, with SLE, was treated with corticosteroid which resulted in significant improvement in patient's manifestation of IH. Conclusions The association of IH and SLE has already been established and one should be aware of this coexistence and in IH cases, SLE should also be considered as an underlying cause and subsequently appropriate diagnostic tests should be performed.

Intravitreal Pharmacotherapy in the Treatment of Retinitis Pigmentosa-related Cystoid Macular Oedema

Peripheral visual field constriction and night blindness are the main features of retinitis pigmentosa (RP). However, central vision is often impaired dramatically even in the early stages of the disease when macular complications such as cystoid macular oedema (CME) occur. The pathogenesis of RP-related CME is still not well explained. Therefore, several treatment alternatives such as topical, oral and systemic pharmacotherapy; laser photocoagulation and even vitreoretinal surgery are employed by the clinicians. In this review, we summarise the clinical data on intravitreal pharmacotherapeutic agents and focus mainly on the steroids and anti-vascular endothelial growth factor agents.

Spare the Rod, Spoil the Degeneration

Ahost of retinal degenerations, including many types of retinitis pigmentosa, follow a pattern of rod loss followed by cone loss. The rod loss may take many years, causing problems with night vision and peripheral visual field constriction. Only after signif icant rod loss occurs does cone loss ensue, with its devastating loss of central vision. The pathophysiology for some of these degenerations has been elucidated. In many of these diseases, the underlying genetic pathology is limited to the rods. So, why at the end of the process do we

Vigabatrin-Induced Retinal Toxicity Is Partially Mediated by Signaling in Rod and Cone Photoreceptors

Vigabatrin (VGB) is a commonly prescribed antiepileptic drug designed to inhibit GABA-transaminase, effectively halting seizures. Unfortunately, VGB treatment is also associated with the highest frequencies of peripheral visual field constriction of any of the antiepileptic drugs and the mechanisms that lead to these visual field defects are uncertain. Recent studies have demonstrated light exposure exacerbates vigabatrin-induced retinal toxicity. We further assessed this relationship by examining the effects of vigabatrin treatment on the retinal structures of mice with genetically altered photoreception. In keeping with previous studies, we detected increased toxicity in mice exposed to continuous light. To study whether cone or rod photoreceptor function was involved in the pathway to toxicity, we tested mice with mutations in the cone-specific Gnat2 or rod-specific Pde6g genes, and found the mutations significantly reduced VGB toxicity. Our results confirm light is a significant enhancer of vigabatrin toxicity and that a portion of this is mediated, directly or indirectly, by phototransduction signaling in rod and cone photoreceptors.

Understanding and interpreting vision safety issues with vigabatrin therapy

Vigabatrin is an irreversible inhibitor of γ-aminobutyric acid (GABA) transaminase. It is effective as adjunctive therapy for adult patients with refractory complex partial seizures (rCPS) who have inadequately responded to several alternative treatments and as monotherapy for children aged 1 month to 2 years with infantile spasms. The well-documented safety profile of vigabatrin includes risk of retinopathy characterized by irreversible, bilateral, concentric peripheral visual field constriction. Thus, monitoring of visual function to understand the occurrence and manage the potential consequences of peripheral visual field defects (pVFDs) is now required for all patients who receive vigabatrin. However, screening for pVFDs for patients with epilepsy was conducted only after the association between vigabatrin and pVFDs was established. We examined the potential association between pVFDs and epilepsy in vigabatrin-naïve patients and attempted to identify confounding factors (e.g., concomitant medications, method of vision assessment) to more accurately delineate the prevalence of pVFDs directly associated with vigabatrin. Results of a prospective cohort study as well as several case series and case reports suggest that bilateral visual field constriction is not restricted to patients exposed to vigabatrin but has also been detected, although much less frequently, in vigabatrin-naïve patients with epilepsy, including those who received treatment with other GABAergic antiepileptic therapy. We also reviewed published data suggesting an association between vigabatrin-associated retinal toxicity and taurine deficiency, as well as the potential role of taurine in the prevention of this retinopathy.

Idiopathic intracranial hypertension in Dubai: nature and prognosis

To evaluate the nature and course of idiopathic intracranial hypertension (IIH) in Dubai, UAE. In a retrospective study the medical records of 50 patients with IIH were reviewed. All of them were diagnosed according to the Modified Dandy Criteria. There were 46 (92%) women. Mean age at presentation was 35.7 years. Obesity was the commonest associated factor (32%). Headache was reported in 98% followed by double vision (32%). Papilledema was present in all patients at the time of examination (100%). Perimetric study showed mild peripheral visual field constriction in 56%. Only two patients showed severe field constriction and one of them deteriorated rapidly and she became blind. The mean cerebrospinal fluid pressure was 302.5 mmH(2)O. The visual status improved significantly throughout the follow-up period. Idiopathic intracranial hypertension has relatively benign course in this part of the world and more aggressive treatment is not recommended.

Retinal function abnormalities in patients treated with vigabatrin.

To evaluate central and peripheral retinal function in patients treated with vigabatrin, an antiepileptic drug associated with peripheral visual field constriction (VFC). Six patients with epilepsy treated with vigabatrin as add-on therapy for at least 3 years were included in this observational case series. All patients underwent a clinical ophthalmologic examination, color vision testing, standard perimetry, and full-field and focal foveal cone electroretinography. Four patients, 3 of whom had VFC, completed specialized computerized static light- and dark-adapted perimetry. In 9 of 11 eyes tested, foveal cone electroretinographic amplitudes were at or below the lower limit of normal. Dark-adapted perimetry demonstrated abnormal rod-derived visual fields in the 3 patients with vigabatrin-attributed VFC, whereas rod-derived thresholds were within normal limits throughout the visual field in the patient who did not have VFC. Our results suggest that vigabatrin not only impairs peripheral cone-derived function as manifested by VFC but also affects foveal cone electroretinographic amplitudes and rod-derived visual fields. The clinical dilemma regarding the use of vigabatrin therapy is further complicated since central as well as peripheral visual function seems to be adversely affected.

Recent developments in idiopathic intracranial hypertension (IIH)

Idiopathic intracranial hypertension is a disease with a predilection for young obese women. The most common symptoms are headache, transient visual obscuration and pulsatile tinnitus. The only focal neurologic finding is false-localizing 6th cranial nerve palsy. Papilledema is usually present and this can lead to optic atrophy with progressive permanent visual loss. The earliest visual loss is constriction of peripheral visual field, usually starting with the inferior nasal quadrant. Numerous theories have been entertained as to the pathogenesis but this still remains an open controversy. The most prevalent current theories involve increased resistance to cerebrospinal fluid reabsorption at the arachnoid granulations, either from intrinsic disease in the granulations or secondary to elevated pressure in the dural venous sinuses into which the cerebrospinal fluid is absorbed across the granulations. The syndrome of idiopathic intracranial hypertension was long ago recognized as a complication of recurrent otitis media with resultant thrombosis of the transverse and sigmoid dural venous sinuses. Cases secondary to dural venous sinus thrombosis are seldom encountered today because the incidence of chronic otitis is much less than in the past. The prevalent concept has been that the idiopathic cases in obese young women were not associated with pathology in the dural venous sinuses. A recent study using ATECO MR venography, which the authors claim to be more reliable than even conventional catheter venography, has demonstrated stenosis of the transverse and sigmoid dural venous sinuses distinguishes cases of idiopathic intracranial hypertension from controls with a high degree of sensitivity and specificity. The authors believe the stenosis is secondary to intracranial hypertension but that it may further aggravate the hypertension when it occurs.

Clinical and Genetic Features of Choroideremia

Background: Choroideremia is an X-linked hereditary eye disease that causes progressive degeneration of the choroid and retina and frequently leads to legal blindness in later life. Recent molecular genetic studies have revealed mutations involving the Rab escort protein (REP-1) gene localized at Xq 21. Clinical Features: The clinical picture and rate of progression may vary among affected individuals in different families and within the same family. Usually, hemizygous males develop night blindness in their teenage years, followed by progressive peripheral visual field constriction and visual disability in late age. Heterozygous female carriers are mostly asymptomatic, but their fundi show characteristic pigment changes in the midperiphery closely resembling the fine mottling observed in the initial stage of the disease in males. Molecular Genetics: Assessment of the REP-1 gene in European and Japanese choroideremia patients has revealed a wide variety of mutations, including gross deletions and point mutations such as nonsense, frameshift, and splice-site mutations. All these mutations are thought to fail in intact REP-1 protein synthesis. Conclusions: The recent molecular studies may open a new chapter in the research on choroideremia as well as diagnosis and genetic counseling.

Symptomatic and asymptomatic visual loss in patients taking vigabatrin

Purpose To investigate the clinical, perimetric, and electrophysiologic findings in patients with visual field loss on long-term treatment with the antiepileptic medication vigabatrin. Design Consecutive observational case series. Participants Forty-one consecutive subjects taking vigabatrin referred for screening ophthalmologic assessment were studied. Twelve subjects with evidence of peripheral visual field constriction are presented. Methods Twelve subjects with evidence of peripheral visual field constriction on 60-4 perimetry underwent central 30-2 and blue-on-yellow (B/Y) perimetry, as well as electroretinography (ERG), electro-oculography (EOG), and visual-evoked potential (VEP) testing. Main outcome measures Visual acuity; fundus abnormalities; visual field loss; and ERG, EOG, or VEP abnormalities were the main outcome measures. Results Eight of the 12 subjects with constricted visual fields were asymptomatic. The central 30-2 perimetry demonstrated bilateral visual field constriction in 9 of 12 patients and the B/Y perimetry in 8 of 9 patients tested. Of the ten patients tested electrophysiologically, four had abnormal ERGs, five had abnormal EOGs, and three had delayed VEPs. Conclusions The incidence of visual field constriction in patients taking vigabatrin may be higher, and asymptomatic visual field loss more common, than reported previously. The authors postulate a possible Muller cell dysfunction in the peripheral retina. Patients taking vigabatrin should have regular peripheral visual field examinations.

Late visual field changes following cryotherapy for retinopathy of prematurity stage 3.

The correlation between cryoscars and visual field defects following cryoablation was studied. A Humphrey 120 full field screening test was performed in 10 children (15 eyes) who were treated by cryotherapy between 10 and 14 years previously for retinopathy of prematurity (ROP) stage 3. In eight eyes treated by cryoablation through 360 degrees in zone I or II, a moderate circumferential peripheral visual field constriction was found. In seven other eyes, cryotreated up to 180 degrees only in the temporal retina (zone III), a nasal field constriction was noted. There was no evidence of late development of retinal tears or retinal detachment. The correlation between the primary cryoapplications, late chorioretinal cryoscars, and the visual field changes was evaluated. Late chorioretinal scars following cryotherapy for ROP stage 3 are associated with visual field defects, but as these defects are at the periphery of the visual field they do not cause any subjective derangements 10-14 years after treatment.

Red krypton and blue-green argon laser diabetic panretinal photocoagulation

Eyes with three or four diabetic retinopathy risk factors received laser panretinal photocoagulation with random selection of either blue-green argon (42 eyes) or red krypton (40 eyes) laser to determine if one laser was superior to the other. After 6 months, visual acuity preservation or improvement was obtained in 33 (79%) argon- and 34 (84%) krypton-treated eyes. Peripheral IV-4e visual field constriction of 7% occurred with argon and 10% with krypton. Vitreous hemorrhaging after treatment occurred in 1 argon- and in 6 krypton-treated eyes. Complete disc neovascular regression was obtained in 27 (67%) of 40 argon- and 19 (56%) of 34 krypton-treated eyes, with partial regression occurring in 8 (20%) argon- and 8 (24%) krypton-treated eyes. The two treatments produced essentially equal results.

Ophthalmology

<h3>Diabetic Retinopathy</h3> One of the most important aspects in the treatment of eye diseases is the effect of photocoagulation on diabetic retinopathy. The collaborative study of the National Eye Institute has provided important and significant results.¹ For the first time the treatment of this condition has been put on a firm scientific basis. Additional follow-up studies have now confirmed previous reports that photocoagulation as used in the study protocol reduces the risk of severe visual loss by 50% or more. Harmful effects (decrease of vision by one or more lines, constriction of peripheral visual field) were also observed (especially when the treatment was performed with a xenon arc coagulator). However, the two-year risk of severe visual loss without treatment outweighs the harmful treatment effects in two groups: (1) in eyes with new vessels on or within one disc diameter of the optic disc equaling or exceeding one-fourth to one-third

Photocoagulation Treatment of Proliferative Diabetic Retinopathy: Clinical Application of Diabetic Retinopathy Study (DRS) Findings, DRS Report Number 8

Additional follow-up confirms previous reports1–4 from the Diabetic Retinopathy Study (DRS) that photocoagulation, as used in the study, reduces the risk of severe visual loss by 50% or more. Decreases of visual acuity of one or more lines and constriction of peripheral visual field due to treatment were also observed in some eyes. These harmful effects were more frequent and more severe following the DRS xenon technique.3,4 The two-year risk of severe visual loss without treatment outweighs the risk of harmful treatment effects for two groups of eyes: (1) eyes with new vessels and preretinal or vitreous hemorrhage; and (2) eyes with new vessels on or within one disc diameter of the optic disc (NVD) equaling or exceeding 1/4 to 1/3 disc area in extent, (Fig 1), even in the absence of preretinal or vitreous hemorrhage. For eyes with these characteristics, prompt treatment is usually advisable. For eyes with less severe retinopathy, DRS findings do not provide a clear choice between prompt treatment or deferral unless progression to these more severe stages occurs.

Photocoagulation Treatment of Proliferative Diabetic Retinopathy: The Second Report of Diabetic Retinopathy Study Findings

Data from the Diabetic Retinopathy Study (DRS) show that photocoagulad inhibited the progression of retinopathy. These beneficial effects were noted to some degree in all those stages of diabetic retinopathy which were included in the Study. Some deleterious effects of treatment were also found, including losses of visual acuity and constriction of peripheral visual field. The risk of these harmful effects was considered acceptable in eyes with retinopathy in the moderate or severe retinopathy in the moderate or severe proliferative stage when the risk of severe visual loss without treatment was great. In early proliferative or severe nonproliferative retinopathy, when the risk of severe visual loss without treatment was less, the risks of harmful treatment effects assumed greater importance. In these earlier stages, DRS findings have not led to a clear choice between prompt treatment and deferral of treatment unless and until progression to a more severe stage occurs.