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Biomedical subjects

N R Miller

Publications and source records attributed to N R Miller.

At least 37 records · Page 2Linked to original sources
PubMed2001

Clinical spectrum of posterior ischemic optic neuropathy.

PURPOSE: To describe the systemic and visual characteristics and prognosis in patients with posterior ischemic optic neuropathy (PION). DESIGN: Observational case series. METHODS: Retrospective chart review in a multicenter setting. Seventy-two patients (98 eyes) with a clinical diagnosis of PION. Co-morbid systemic diseases and visual function were recorded at both initial presentation and after mean visual follow-up of 4.1 years and systemic follow-up of 5.4 years. RESULTS: PION occurred in three main settings: in the perioperative period following a variety of surgical procedures (28 patients), associated with giant cell (temporal) arteritis (6 patients), and associated with nonarteritic systemic vascular disease (38 patients). Patients with perioperative and arteritic PION were more likely to have severe, bilateral visual loss that did not improve. Among eyes with nonarteritic PION, 34% experienced improvement in vision, 28% remained stable, and 38% worsened. Among patients with nonarteritic PION, carotid artery disease and a history of stroke (with or without carotid artery disease) were both associated with a statistically significant increased risk of poor final visual outcome. CONCLUSIONS: There are three distinct subtypes of PION: perioperative, arteritic, and nonarteritic. Patients with PION that is unassociated with surgery should undergo an evaluation for systemic vascular diseases, including giant cell arteritis, that may or may not be apparent at the time of vision loss. The visual prognosis for patients with perioperative or arteritic PION is poor, whereas that for nonarteritic PION is similar to that for patients with nonarteritic AION.

Adolescent↗
PubMed2001

Optic nerve protection, regeneration, and repair in the 21st century: LVIII Edward Jackson Memorial lecture.

PURPOSE: To present the current status and clinical implications of optic nerve protection, repair, and regeneration after experimental injury in mammals, including nonhuman primates. DESIGN: Optic nerve and neuro-ophthalmology experimental study review. METHOD: Synthesis of experimental data regarding experimental studies of optic nerve protection, repair, and regeneration. RESULTS: Under certain conditions, mammalian retinal ganglion cells can be prevented from dying despite injury to the cell bodies or their axons, injured mammalian retinal ganglion cells whose axons have degenerated can be induced to extend new axons, and regenerating axons can reach their correct targets in the central nervous system. In addition, stem cells can be induced to become retinal ganglion cells. CONCLUSIONS: It may soon be possible to preserve and restore vision in persons whose sight is threatened or has been lost from disease or damage to the optic nerve.

Animals↗
PubMed2001

Visual manifestations of temporal arteritis.

Visual difficulties are common in patients with temporal arteritis. They may be the presenting manifestation of the disease or may occur at any time during its course. The visual deficits that occur in patients with temporal arteritis are most often loss of visual acuity or visual field; however, some patients develop double vision or other symptoms of ocular motor dysfunction. Knowledge of the visual deficits associated with temporal arteritis can aid in the diagnosis of the disorder, and early diagnosis of temporal arteritis can often prevent such deficits from developing.

Giant Cell Arteritis↗
PubMed2001

Visual function is stable in patients who continue long-term vigabatrin therapy: implications for clinical decision making.

PURPOSE: Vigabatrin (VGB) has been shown to cause visual field constriction and other forms of mild visual dysfunction. We determined the safety of continuing VGB therapy in patients who had received prolonged treatment (>2 years) with the drug by serially monitoring changes in visual function over a 1-year period of continued therapy. We also followed up patients who discontinued VGB to see whether alternative therapies are effective. METHODS: Fifteen of 17 patients who continued VGB therapy had visual-function testing (visual acuity, color vision, kinetic and static perimetry) every 3 months for 1 year. Eighteen patients who discontinued VGB were given alternative antiepileptic drugs (AEDs); their seizure responses were measured after > or =3 months of treatment. RESULTS: Patients continuing VGB showed no worsening of visual acuity, color vision, or visual-field constriction beyond that measured in the initial test. Many patients who discontinued VGB had good seizure control with either newer or previously unsuccessful AEDs. CONCLUSIONS: For patients who have an excellent response to VGB and only mild visual changes, continued therapy may be safe with close visual monitoring. Patients who do not have a significant reduction in seizures or who experience considerable visual dysfunction with VGB may respond well to alternative therapies.

Adult↗
PubMed2001

Recurrent ectopic craniopharyngioma.

A 66-year-old woman developed an asymptomatic mass in the right frontal lobe 5 years after undergoing a right frontal craniotomy and removal of a craniopharyngioma. The mass progressively enlarged over the next 3 years, during which time it became multiloculated and partially cystic. Repeat craniotomy was performed 8 years after the original operation, at which time the mass was found to be an ectopic craniopharyngioma. The lesion probably resulted from seeding of tumour cells along the surgical tract at the time of the initial surgery.

Aged↗
PubMed2001

Traumatic optic neuropathy: a review of 61 patients.

The outcome of traumatic optic neuropathy was evaluated following penetrating and blunt injuries to assess the effect of treatment options, including high-dose steroids, surgical intervention, and observation alone. Factors that affected improvement in visual acuity were identified and quantified. Sixty-one consecutive, nonrandomized patients presenting with visual loss after facial trauma between 1984 and 1996 were assessed for outcome. Pretreatment and posttreatment visual acuities were compared using a standard ophthalmologic conversion from the values of no light perception, light perception, hand motion, finger counting, and 20/800 down to 20/15 to a logarithm of the minimum angle of resolution (log MAR). The percentage of patients showing visual improvement and the degree of improvement were calculated for each patient group and treatment method. Measurements of visual acuity are in log MAR units +/- standard error of the mean. Patients who sustained penetrating facial trauma (n = 21) had worse outcomes than patients with blunt trauma (n = 40). Improvement in visual acuity after treatment was seen in 19 percent of patients with penetrating trauma compared with 45 percent of patients with blunt trauma (p < 0.05). Furthermore, patients with penetrating trauma improved less than those with blunt trauma, with a mean improvement of 0.4 +/- 0.23 log MAR compared with 1.1 +/- 0.24 in blunt-trauma patients (p = 0.03). The patients with blunt trauma underwent further study. There was no significant difference in improvement of visual acuity in patients treated with surgical versus nonsurgical methods; however, 83 percent of patients without orbital fractures had improvement compared with 38 percent of patients with orbital fractures (p < 0.05). The mean improvement in patients without orbital fractures was 1.8 +/- 0.65 log MAR compared with 0.95 +/- 0.26 in patients with orbital fractures (p = 0.1). Twenty-seven percent of patients who had no light perception on presentation experienced improvement in visual acuity after treatment compared with 100 percent of patients who had light perception on admission (p < 0.05). The mean improvement in patients who were initially without light perception was 0.85 +/- 0.29 log MAR compared with 1.77 +/- 0.35 in patients who had light perception (p < 0.05). There were no significant differences in improvement of visual acuity when analyzing the effect of patient age and timing of surgery. Patients who sustain penetrating trauma have a worse prognosis than those with blunt trauma. The presence of no light perception and an orbital fracture are poor prognostic factors in visual loss following blunt facial trauma. It seems that clinical judgment on indication and timing of surgery, and not absolute criteria, should be used in the management of traumatic optic neuropathy.

Adolescent↗
PubMed2001

Choroidal infarction, anterior ischemic optic neuropathy, and central retinal artery occlusion from polyarteritis nodosa.

PURPOSE: Ocular ischemia from polyarteritis nodosa (PAN) is rare. The authors present a case of multifocal ocular infarction from PAN. METHODS AND RESULTS: A 70-year-old woman developed hand and foot numbness followed by intermittent blurred vision and binocular horizontal diplopia. Two weeks later, she suddenly lost vision in the right eye from a central retinal artery occlusion and then developed a left anterior ischemic optic neuropathy and bilateral triangular choroidal abnormalities consistent with infarction. Her erythrocyte sedimentation rate and C-reactive protein were elevated. Although giant cell arteritis was suspected, a multiple mononeuropathy was demonstrated by electromyogram and nerve conduction velocity studies. Biopsy specimens from her sural nerve and biceps muscle showed a necrotizing vasculitis with fibrinoid necrosis, consistent with PAN. CONCLUSIONS: Polyarteritis nodosa can produce ischemia of a variety of ocular structures, including the retina, choroid, and optic nerve. In our patient, all three structures were affected. To our knowledge, this is the first reported case of the triangular sign of Amalric in PAN.

Aged↗
PubMed2001

Sepsis after Bartholin's duct abscess marsupialization in a gravida.

BACKGROUND: Little information exists regarding sepsis following marsupialization of a Bartholin's duct abscess. We report a gravida who became septic after marsupialization. CASE: A 30-year-old primigravida at 32 weeks' gestation underwent marsupialization of a Bartholin's gland abscess. Postoperatively, she developed fever with maternal and fetal tachycardia. She was admitted to the hospital and started on broad-spectrum antibiotics. Her temperature increased to 39 degrees C, and she became hypotensive. Blood work demonstrated evidence of disseminated intravascular coagulopathy. The patient was stabilized with aggressive fluid resuscitation, antibiotics, transfusion of blood products and oxygen therapy. Within 24 hours, the fever and coagulopathy resolved. She was discharged on postoperative day 5 and gave birth without complications at 38 weeks' gestation. CONCLUSION: Pregnant women undergoing marsupialization of a Bartholin's gland abscess should be considered at high risk and managed accordingly.

Abscess↗
PubMed2000

Visual function loss from vigabatrin: effect of stopping the drug.

OBJECTIVE: To determine if visual function loss from vigabatrin use recovers after the drug is discontinued. BACKGROUND: Vigabatrin is an effective antiepileptic drug, but it is known to cause a variety of changes in visual function, including reductions in the visual field, visual acuity, color vision, and in electroretinogram (ERG) and electro-oculogram amplitudes. It is not known whether these changes are reversible. METHODS: Measurements of static and kinetic visual fields, visual acuity, color vision, and the ERG were recorded while patients were taking vigabatrin and again in 13 patients who had discontinued the drug because of lack of efficacy or reductions in visual field. Most of the patients had been off the drug for 3 to 6 months, although two patients had been drug-free for almost 1 year. RESULTS: Although ERG cone implicit time improved, most of the patients did not show improvement in either clinical measures of visual function (i.e., visual acuity, color vision, visual fields) or in ERG amplitudes. However, several patients who showed minimal visual field loss while on the drug had substantial recovery of ERG amplitudes. There was no statistical association between recovery of function and either duration of treatment or cumulative dosage. The multifocal ERG showed a diffuse loss of function that was not isolated to the periphery. CONCLUSIONS: Although the visual deficits in patients taking vigabatrin tend to be mild, most patients do not show improvement after they stop taking the drug. Visual field loss resulting from vigabatrin was not reversible. Visual acuity, color vision, and ERG amplitude loss may be reversible in patients with minimal or no field loss.

Adult↗
PubMed2000

A case-control study of tobacco and alcohol consumption in Leber hereditary optic neuropathy.

PURPOSE: To determine if tobacco or alcohol consumption is associated with vision loss among sibships harboring pathogenic mitochondrial mutations associated with Leber hereditary optic neuropathy. METHODS: Retrospective case-control study with questionnaires obtained from both affected and unaffected siblings from 80 sibships with Leber hereditary optic neuropathy. Sibships harbored molecularly confirmed mitochondrial DNA mutations at nucleotide positions 11778 (63), 14484 (10), and 3460 (7). Exposure in affected individuals was calculated based on reported consumption before vision loss. RESULTS: For male probands (67 sibships), the recurrence risk within a sibship was 10.3% (eight of 78) for males and 3.1% (three of 98) for females. For female probands (13 sibships), the recurrence risk within a sibship was 17.6% (three of 17) for males and 0% (zero of 22) for females. Greater risk of vision loss was associated with male sex (odds ratio [OR] = 6.63; 95% confidence interval [CI] = 2.96 to 14.84; P =.00001) and harboring a 3460 or 14484 in comparison with the 11778 mutation (OR = 2.071; 95% CI = 1.19 to 3.58; P =.0095). No significant association of maximal intensity of smoking or cumulative smoking, whether light or heavy, with vision loss was observed. Light (OR = 0. 31; 95% CI = 0.17 to 0.56; P =.0001) and heavy alcohol consumers (OR = 0.25; 95% CI = 0.11 to 0.58; P =.0011) were less likely to be affected than individuals who did not consume alcohol after adjusting for age, sex, and mutation. In a categorical analysis of sibships with the 3460 or 14484 mutation, no relationship of vision loss with tobacco or alcohol consumption was observed. CONCLUSION: Unlike previous studies, the present study calculated exposure based on self-reported consumption of tobacco or alcohol before vision loss. No significant deleterious association between tobacco or alcohol consumption and vision loss among individuals harboring Leber hereditary optic neuropathy mutations was observed. Tobacco and alcohol do not appear to promote vision loss in Leber hereditary optic neuropathy.

Adolescent↗
PubMed2000

Optic neuropathy occurring after bee and wasp sting.

OBJECTIVE: To inform ophthalmologists about bee and wasp sting-related optic neuropathy. DESIGN: Two case reports and literature review. METHODS: Review of two cases, clinical history, laboratory testing, and follow-up. RESULTS: Two cases of bee and wasp sting optic neuritis are described and five additional cases of optic neuritis occurring after Hymenoptera sting are reviewed from the English language literature. These cases share certain characteristics, including acute to subacute onset of symptoms; moderate to severe visual loss followed by significant visual recovery; edematous and hemorrhagic optic discs; and central or cecocentral scotomas. CONCLUSIONS: Acute optic neuropathy may follow Hymenoptera sting to the face.

Adult↗
PubMed2000

Optic neuropathy associated with laser in situ keratomileusis.

PURPOSE: To report 4 cases of optic neuropathy following laser in situ keratomileusis (LASIK). SETTING: Tertiary Care ophthalmic practices. METHODS: In this retrospective observational case series, 4 patients who developed acute visual loss following LASIK are reported. All had clinical evidence of optic neuropathy. Two had optic disc edema and 2 had normal appearing optic discs initially. None of the patients experienced significant visual recovery, and all developed optic atrophy in the affected eye. RESULTS: All patients had evaluations for alternative etiologies of their optic neuropathy, with negative results. All patients were therefore presumed to have experienced an ischemic optic neuropathy following LASIK. CONCLUSIONS: Patients who have LASIK may experience an acute anterior or retrobulbar optic neuropathy. The etiology is unknown but may be related to the marked increase in intraocular pressure that occurs during a portion of the procedure.

Adult↗
PubMed2000

Thresholds for visual detection of Young's modulus contrast in simulated ultrasound image movies.

Elasticity imaging (EI) is being developed to allow the evaluation of the mechanical properties of soft tissue, but these properties are already assessed in routine ultrasound breast examination using a method that involves the subjective interpretation of tissue motion seen in real-time B-mode image movies during palpation. We refer to this method as relative motion assessment (RMA). The purpose of this study was to begin a process of learning about the usefulness and limitations of RMA relative to the emerging method of elasticity imaging. Perception experiments were performed to measure Young's modulus contrast thresholds for positive contrast lesions under controlled conditions that could subsequently be repeated to evaluate elasticity imaging for the same task. Observer ability to grade relative lesion contrast using RMA was also assessed. Simulated sequences of B-scans of tissue moving in response to an applied force were generated and used in a two-alternative forced-choice (2-AFC) experiment to measure contrast thresholds for the detection of disc-shaped elastic lesions by RMA in the absence of ultrasound echo contrast. Results were obtained for four observers at a lesion area of about 77 speckle cells and for five observers at lesion areas of about 42 and 139 speckle cells. Young's modulus contrast thresholds were found to decrease with increasing lesion size and were well within the range of contrast values that have been measured for breast tumours in vitro. It was also found that observers were quite skilled at using RMA to grade the relative strain contrast of lesions. The nonlinear relationship between the object contrast (Young's modulus contrast) and the image contrast (strain contrast) prevented observers from detecting very small lesions with 100% accuracy, no matter how high the object contrast. A preliminary comparison of the results for RMA with published thresholds for elastography indicated that elastography is likely to offer great benefit in reducing modulus contrast thresholds, but further study is required to confirm this.

Algorithms↗
PubMed2000

Anomalous optic disc elevation associated with ultrasonographic evidence of increased subarachnoid fluid.

The presence of increased subarachnoid fluid around the optic nerve as measured by ultrasound has been shown to be associated with elevated intracranial pressure, as well as a number of other conditions. This finding has proved useful for distinguishing optic disc elevation secondary to papilledema from disc elevation attributable to other causes. This report describes a patient with anomalous optic disc elevation and increased subarachnoid fluid around the optic nerve.

Adult↗