Altered globe dimensions of axial myopia as risk factors for penetrating ocular injury during peribulbar anaesthesia.

We measured the range of equatorial horizontal widths (EHW) in axially myopic eyes and identified the sites of staphyloma using B scan echography. One hundred eyes in 50 patients were studied. The axial lengths (ALs) were sorted into five groups of increasing severity of myopia. The group mean AL, group mean EHW and the ratio of EHW/AL was calculated for each range. The results suggest that the increase in the AL in an axially myopic eye is associated with an increase in the EHW. However, this increase in the group mean EHW is relatively small (2.3 mm) compared with the increase mean AL (8.2 mm) across the entire range. The ratio of EHW/AL decreased with an increase in the group mean AL. Therefore, the increase in EHW in an axially myopic eye is unlikely to be a significant risk factor for inadvertent ocular injury for peribulbar injections if a careful single medial canthal approach is used. There was high incidence of staphylomas in eyes with AL > 29 mm, most were inferior to the posterior pole of the globe, and there were none at the equator.

Sorsby's fundus dystrophy: a case report of 24 years follow-up with electrodiagnostic tests and indocyanine green angiography.

PURPOSE: Five families with dominantly inherited macular dystrophy were originally described by Sorsby et al. in 1949. Key features include early bilateral central visual loss secondary to either choroidal neovascularisation or central geographical atrophy and late progressive chorioretinal atrophy. We report a member of one of the original families who has been studied with a series of investigations over a long time, providing important information on differences in the phenotype and natural history of a rare genetically determined macular dystrophy. METHODS: The patient has been followed up for the last 24 years, from asymptomatic to full manifestation of Sorsby's fundus dystrophy. Series of fundus photographs, colour vision, dark adaptation and electrodiagnostic tests were performed. The disease was also studied with fundus fluorescein angiography and indocyanine green angiography. RESULTS: Unlike her other family members, who were reported in other studies as all having rapid loss of vision secondary to disciform macular disease, our patient has a unique clinical course in that she has a progressive bilateral central and generalised chorioretinal atrophy with a well-preserved minute central island of fovea. Nyctalopia was her early and only symptom. There was evidence of central scotoma, tritanopia and mild abnormality in dark adaptation. Rod function was affected earlier and to a larger degree than cone function. CONCLUSIONS: The overall features suggest phenotypic variability within a family in this autosomal dominant macular dystrophy. The findings from indocyanine green angiography and a consecutive series of electrodiagnostic tests in this condition support the theory of partial choroidal hypoperfusion and an interesting progressive rod-cone dystrophy as part of the pathophysiology.

Pigmentary retinal dystrophy and the syndrome of maternally inherited diabetes and deafness caused by the mitochondrial DNA 3243 tRNA(Leu) A to G mutation.

OBJECTIVE: To study the association of retinal disease and the syndrome of maternally inherited diabetes and deafness caused by an A to G mutation in the tRNA leucine gene at base pair 3243 (A3243G) of the mitochondrial genome. DESIGN: Observational study of a genetically defined subject group. PARTICIPANTS: Thirteen subjects with the mitochondrial DNA A3243G mutation from seven different pedigrees with maternally inherited diabetes and deafness. INTERVENTION: Assessment of visual symptoms and visual acuity, dilated indirect ophthalmoscopy, retinal photography, and retinal electrophysiology. MAIN OUTCOME MEASURES: Loss of vision, funduscopic evidence of pigmentary retinal disease or diabetic retinopathy, and electrophysiologic evidence of defective functioning of the retinal pigment epithelium/photoreceptor complex. RESULTS: Funduscopic examination revealed abnormalities of retinal pigmentation in ten subjects (77%). Defects included speckled and patchy hyperpigmentation at the posterior pole of the fundus, particularly in the macular area, and varying degrees of loss of retinal pigmentation. Three subjects (23%) had visual symptoms, which included night blindness, visual loss, and photophobia. Electrophysiologic studies revealed impaired electro-oculogram responses in four of nine subjects with defects of retinal pigmentation (44%), two of whom also had much reduced scotopic and, to a lesser extent, flicker electroretinogram b wave potentials. Two subjects had diabetic retinopathy, including one with retinal depigmentation and impaired electro-oculogram activity. Both subjects with diabetic retinopathy had unilateral reduced electroretinogram responses, especially oscillatory potentials. CONCLUSIONS: Abnormalities of retinal pigmentation are common in subjects with maternally inherited diabetes and deafness caused by the mitochondrial DNA A3243G mutation. Visual symptoms, in particular loss of visual acuity, appear to be infrequent. The combination of deficits in the electro-oculogram and scotopic and flicker electroretinograms suggests that the retinal dystrophy includes defective functioning of retinal pigment epithelial cells and of both rod and cone photoreceptors. The pigmentary retinopathy does not prevent diabetic retinopathy; a single subject had funduscopic and electrophysiologic evidence of both diseases. Current evidence suggests that the mitochondrial DNA A3243G mutation accounts for 0.5% to 2.8% of diabetes. Most ophthalmic and diabetic clinics are therefore likely to contain such patients, who may benefit from identification of the genetic defect causing their disease and from genetic counseling.

Correlation between the orbital and intraocular portions of the optic nerve in glaucomatous and ocular hypertensive eyes.

BACKGROUND/PURPOSE: It has recently been reported that the retrobulbar optic nerve diameter (OND) and cross-sectional area (ONCSA) are reduced in glaucoma. This study was performed to investigate the correlation between the orbital and intraocular portions of the optic nerve. METHODS: One eye of 20 volunteers (16 glaucoma subjects, 4 ocular hypertension subjects) underwent optic disc analysis using Heidelberg retinal tomography, and echographic measurements of the retrobulbar optic nerve. RESULTS: The male-to-female ratio was 6.5:3.5, and the mean age of our sample (+/- SD) was 62.25 +/- 13.7 years. Orbital optic nerve diameter and cross-sectional area correlated significantly and positively with the neuroretinal rim area (Spearman's rank correlation coefficient; OND: rs = 0.488, p = 0.0336; ONCSA: rs = 0.619, p = 0.0079), but not with any other topographical disc data. The retrobulbar optic nerve cross-sectional area-to-disc area ratio (ONCSA/D) was found to have a significant negative correlation with the cup area/disc area ratio (simple regression analysis; r = -3.948, p = 0.046), and a statistically demonstrable positive correlation with the neuroretinal rim area/disc area ratio (r = 0.451, p = 0.046). CONCLUSION: The results of this study indicate that orbital optic nerve dimensions are a reflection of the neuroretinal rim area of the optic disc. Echographic measurements of the retrobulbar nerve may be additive to the traditional triad of raised intraocular pressure, field defects and glaucomatous optic neuropathy that suggests a diagnosis of glaucoma.

Evaluation of optic disc cupping using high-resolution ocular ultrasound.

BACKGROUND/PURPOSE: The new Biovision B-Scan Probe has greater resolution than its predecessors because of its posteriorly placed focus (25 mm inside the eye) and the consequent reduction in size of the sound field. We investigated the accuracy, reproducibility and test-retest variability of two-dimensional optic cup measurements using this new-generation B-scanner. METHODS: One randomly selected eye of 20 patients underwent five repeated measurements of vertical (VOCD) and horizontal optic cup diameters (HOCD), and optic cup depth, using confocal scanning laser tomography (Heidelberg Retinal Tomograph) and high-resolution ultrasound (Biovision, Chiron Vision, UK) on two separate occasions. There was one operator per instrument who was masked to all clinical data and previous measurements. Accuracy of ultrasound readings was quantified by comparing the results with those of Heidelberg Retinal Tomography (HRT). RESULTS: The 95% confidence interval for the bias of echographic vertical and horizontal cup diameter measurements was -95 +/- 48 microns and -19 +/- 72 microns respectively, and -87 +/- 328 microns for cup depth readings. The indices of reproducibility (mean coefficient of repeatability +/- SD) were: VOCD: 177 +/- 105 microns [B-scan] 209 +/- 100 microns [HRT]; HOCD: 179 +/- 61 microns [B-scan], 205 +/- 101 microns [HRT]; cup depth: 206 +/- 63 microns [B-scan], 204 +/- 124 microns [HRT]. Ninety-five per cent limits of agreements between initial and retest values for ultrasound were 18 +/- 136 microns [VOCD], 2 +/- 144 microns [HOCD] and 4 +/- 156 microns [cup depth], compared with 1 +/- 104 microns [VOCD], 20 +/- 102 microns [HOCD] and 3 +/- 168 microns [cup depth] for scanning laser tomography. CONCLUSION: The results demonstrate that measurements of optic cup diameter and depth using ultrasound correlate strongly with corresponding HRT readings. These echographic measurements are reproducible, and not subject to clinically meaningful test-retest variability. This technique of measuring two-dimensional cup parameters does not require expensive specialist equipment and has many potential clinical applications which are discussed.

Echographic measurements of the retrobulbar optic nerve in normal and glaucomatous eyes.

AIM: A study was designed to investigate whether measurements of the optic nerve diameter (OND) and cross sectional area (ONCSA), as measured by B-scan ultrasonography, are altered in glaucoma. The reproducibility and test-retest variability of echographic estimates of retrobulbar optic nerve dimensions was also tested. METHODS: One eye of 49 glaucoma patients and 90 control subjects underwent five repeated echographic measurements of the maximal interpial diameter and cross sectional area of the orbital optic nerve on two separate occasions. All measurements were taken by one experienced ultrasonographer. RESULTS: Mean optic nerve diameter (SD) for the control group was 2.86 (0.46) mm, and was independent of height (multiple regression analysis: p = 0.21), axial length (p = 0.74), spherical equivalent (p = 0.97), sex (ANOVA: p = 0.36), or race (p = 0.14), but was inversely related to age (p = 0.01). Reproducibility of OND readings in control subjects was 0.149 mm (coefficient of repeatability). Test-retest variability of interpial diameter was -0.02 (0.29) mm. Mean interpial diameter of the optic nerve was significantly smaller among glaucomatous eyes (2.58 (0.501) mm) than controls (Mann-Whitney U test: p < 0.0001). Glaucomatous optic nerves also had a significantly smaller cross sectional area (6.68 (2.58) mm2) than those of healthy volunteers (8.25 (1.67) mm2) (p = 0.004). CONCLUSION: Echographic measurements of the orbital optic nerve are highly reproducible and not subject to clinically meaningful test-retest variability. Optic nerve interpial diameter and cross sectional area are reduced in glaucomatous eyes, reflecting nerve fibre loss. This technique may be useful in distinguishing between normal and glaucomatous eyes where optic disc morphometry is inconclusive or impossible as a result of opaque media.

Carbon monoxide poisoning causes optic neuropathy.

PURPOSE: To describe the electrophysiological and psychophysical effects of carbon monoxide (CO) poisoning on visual function. METHODS: Three patients are presented who suffered CO poisoning, two due to suicide attempts and one in the course of a road traffic accident. After a full ocular examination, Goldmann visual fields, flash and pattern visual evoked potentials (VEPs) and flash and pattern electroretinograms (ERGs) were tested. RESULTS: Electrophysiology showed reduced or absent N95 components of the pattern ERG and delayed, reduced VEPs. A positive-negative-positive (PNP) VEP waveform was seen in two cases. In one case, where presentation occurred at an early stage, visual and electrophysiological function was improved with hydroxycobalamine. CONCLUSIONS: The combination of ERG and VEP findings suggest that CO poisoning can cause a toxic optic neuropathy that may have a similar aetiological mechanism to that in tobacco amblyopia. Early treatment with hydroxycobalamine may be of some benefit.

Electrophysiological findings in Stargardt's-fundus flavimaculatus disease.

PURPOSE: To determine the incidence of electrophysiological abnormalities in patients with Stargardt's-fundus flavimaculatus (STGD/FFM) disease. METHODS: A retrospective review was carried out of the hospital records of 46 patients who had undergone a scotopic, single flash photopic and 30 Hz electroretinogram (ERG), pattern ERG (PERG) and electro-oculogram (EOG). RESULTS: Patients were classified in two groups: those with flecks (n = 26) and those without flecks (n = 20). The incidence of abnormalities (amplitude and/or latency) for the two groups was: PERG, 90% and 98%; 30 Hz ERG, 55.8% and 50%; scotopic ERG, 38.5% and 27.5%; and single flash photopic ERG, 26% and 16%, respectively. EOG abnormalities occurred significantly more frequently in the group with flecks compared with the group without flecks: 69% and 42.5% respectively (p < 0.025). Furthermore, in the group with flecks the group mean scotopic ERG b-wave, 30 Hz ERG b-wave and PERG (P50) amplitude were significantly lower than in the group without flecks (p < 0.01). CONCLUSIONS: The most consistent electrophysiological abnormality in STGD/ FFM is the reduction of the PERG. However, EOG, 30 Hz ERG, scotopic and photopic ERG abnormalities can also frequently occur. ERG and EOG abnormalities occur more often in the presence of flecks.

Effects of supplemental oxygen on forearm vasodilation in humans.

Supplemental O2 reduces cardiac output and raises systemic vascular resistance in congestive heart failure. In this study, 100% O2 was given to normal subjects and peak forearm flow was measured. In experiment 1, 100% O2 reduced blood flow and increased resistance after 10 min of forearm ischemia (flow 56.7 +/- 7.9 vs. 47.8 +/- 6.7 ml.min-1.100 ml-1; P < 0.02; vascular resistance 1.7 +/- 0.2 vs. 2.4 +/- 0.4 mmHg.min.100 ml.ml-1; P < 0.03). In experiment 2, lower body negative pressure (LBNP; -30 mmHg) and venous congestion (VC) simulated the high sympathetic tone and edema of congestive heart failure. Postischemic forearm flow and resistance were measured under four conditions: room air breathing (RA); LBNP+RA; RA+LBNP+VC; and 100% O2+LBNP+VC. LBNP and VC did not lower peak flow. However, O2 raised minimal resistance (2.3 +/- 0.4 RA; 2.8 +/- 0.5 O2+LBNP+VC, P < 0.04). When O2 alone (experiment 1) was compared with O2+LBNP+VC (experiment 2), no effect of LBNP+VC on peak flow or minimum resistance was noted, although the return rate of flow and resistance toward baseline was increased. O2 reduces peak forearm flow even in the presence of LBNP and VC.

Electroretinographic findings in Fuchs' heterochromic cyclitis.

PURPOSE: Fuchs' heterochromic cyclitis (FHC) is an inflammatory disease of unknown aetiology. Although anterior segment signs and vitreous changes are well recognised, retinal features are unusual. To assess the extent of retinal involvement, we performed electrophysiological testing in a group of FHC patients. METHODS: Retinal function was assessed by means of flash electroretinogram (ERG) using a Ganzfeld stimulus, and pattern electroretinogram (PERG) using a checkerboard stimulus of spatial frequency 0.5 and 1.0 cycle per degree reversing at 6 Hz. A total of 21 patients with unilateral, normotensive FHC with visual acuities of 6/5 to 6/9 were studied. RESULTS: In the flash ERG, selective scotopic b-wave abnormalities occurred in 9 (43%) of 21 FHC eyes. Despite clear media and no history of ocular surgery, 7 patients showed abnormalities of the PERG. CONCLUSIONS: These electrophysiological findings suggest subclinical damage to the inner retinal layers, but not involving the photoreceptors, in eyes with FHC.

Optic atrophy in Wolfram (DIDMOAD) syndrome.

Wolfram syndrome is the association of diabetes mellitus and optic atrophy, also called DIDMOAD (diabetes insipidus, diabetes mellitus, optic atrophy and deafness). Incomplete characterisation has caused diagnostic confusion; we therefore undertook a nation-wide cross-sectional case finding study. We identified 45 patients with Wolfram syndrome, median age 29 years. All patients fulfilled the ascertainment criteria (juvenile onset diabetes mellitus and optic atrophy). Optic atrophy presented in 38 patients with reduced visual acuity and colour vision defect (median age 11 years), progressing to visual acuity of 6/60 or less in 35 patients (median time 8 years, range 1-25 years). Visual field examinations recorded before acuity deteriorated showed central scotomas with peripheral constriction. Blind patients had absent pupillary reflexes. Horizontal nystagmus was seen in patients with other signs of cerebellar degeneration. There was no pigmentary retinal dystrophy; only 3 patients had background diabetic retinopathy, despite a median duration of diabetes of 24 years. Electroretinography was normal in 3 patients and showed reduced amplitude in 3 patients; visual evoked responses were abnormal (10/10 patients: reduced amplitude to both flash and pattern stimulation). Magnetic resonance imaging showed generalised brain atrophy with reduced signal from the optic nerves and chiasm. A postmortem brain specimen from one patient revealed atrophy of the optic nerves, chiasm, cerebellum and brainstem. We found no evidence of mitochondrial genome defects or rearrangements. This primary neurogenerative disorder presents with diabetes mellitus and progressive optic atrophy, probably due to pathology in the optic nerve.

ERG and EOG abnormalities in carriers of X-linked retinitis pigmentosa.

The diagnosis of X-linked retinitis pigmentosa (XL-RP) relies on the identification of the female carriers, in whom fundal abnormalities are often minimal and variable. The electroretinogram (ERG) has been reported as abnormal in 54-96% of heterozygote females. This study examines the combined use of electro-oculogram (EOG) and standardised ERG in 31 obligate and 33 non-obligate carriers of XL-RP. In the obligate carrier group, the EOG was abnormal in 13 carriers (41%), the ERG abnormal in 21 carriers (68%) and a combined EOG and ERG abnormality occurred in 24 carriers (77%). An EOG abnormality alone occurred in 2 carriers (6.5%). Fourteen obligate carriers (45%) showed a peak to peak delay of the ERG scotopic b wave, this being a previously unreported phenomenon. Similarly, in the non-obligate carrier group, the EOG was abnormal in 11 carriers (44%) and the ERG abnormal in 19 carriers (73%). The results of this study suggest that the use of both tests, including measurement of the scotopic b wave latency, may increase the carrier detection rate.

Imaging of optic disc drusen: a comparative study.

The choice of imaging technique to identify the presence of optic disc drusen has not been well established. We performed computed tomography (CT), magnetic resonance imaging (MRI), fundus fluorescein angiography and B-mode ultrasonography (B-USG) on four patients with optic disc drusen as the sole identifiable pathological process. CT, MRI and examination for autofluorescence demonstrated the presence of drusen in only one case each. B-USG showed characteristic features of optic disc drusen in all cases. We suggest that B-USG, a non-invasive and inexpensive technique, may be the imaging method of choice in identifying the presence of disc drusen.

Neurologic investigations of childhood abdominal migraine: a combined electrophysiologic approach to diagnosis.

Neurologic studies of childhood migraine, including imaging techniques and electrophysiology, have identified a number of abnormalities, but none of high specificity. Therefore, a diagnostic marker for childhood migraine and its equivalents remains elusive. In this study a combined electrophysiologic approach is assessed, using measurements of visually provoked beta-activity, high-frequency photic following responses, and visually stimulated event-related potentials. Eighteen children younger than 10 years of age with abdominal migraine and/or cyclic vomiting syndrome were investigated with these techniques. They were compared with the responses from a number of control groups, including a group diagnosed as childhood migraine with or without aura. Individually, each investigation yielded high sensitivities but low specificities ( < 50%). However, when these techniques were used in combination the specificity for migraine rose to > 90%. There was no significant difference between abdominal migraineurs and those with migraine with or without aura in any of the parameters studied. This combined approach is potentially useful in the diagnosis of abdominal migraine and supports the view that abdominal migraine can be classed as a true childhood migraine equivalent.

1044 women with migraine: the effect of environmental stimuli.

This study initiated by a self-help migraine group investigated disability caused by visual environmental stimuli, e.g. glare, flicker, pattern and color. One thousand forty-four women with migraine completed the self-report questionnaire on visual environmental stimuli reported in earlier studies to precipitate or aggravate migraine. One hundred twenty-one female controls were obtained from general practice and hospital out-patients. The responses of the classical, common and non-migraine groups were compared. Women with classical migraine expressed greater disability than those with common migraine or controls both in respect of number of visual sensitivities reported (P < 0.0001) and severity of consequences of such stimuli (P < 0.0001). This study indicated differences between classical and common migraine outside of the attack phase apart from aura. Reported range of sensitivities for the migraineurs peaked between the ages of 46-60 years. A high level of unrealized disability caused by visual environmental stimuli was thus identified in hitherto unexplored self-help groups.

Flash and pattern visual evoked potentials in the diagnosis and monitoring of dysthyroid optic neuropathy.

Flash and pattern visual evoked potentials were recorded in 8 patients (13 eyes) with dysthyroid optic neuropathy (DON), diagnosed using the American Thyroid Association classification. All were treated with systemic steroids, but 4 patients (6 eyes) also required orbital decompression. Flash VEP (P2) and pattern VEP (P100) were recorded prior to and 2 weeks after commencing steroid treatment or decompression. Fifteen patients with Graves orbitopathy but without DON, and 20 healthy subjects, acted as controls. Before treatment visual acuity was reduced in 10 eyes and visual fields were abnormal in 5, but the VEP was abnormal in all 13, with the group mean amplitude of P2 and P100 significantly less than controls, and the group mean P100 latency significantly greater than controls. After treatment with high-dose steroids or surgical decompression there were significant improvements in the group mean amplitude of P2 and P100, and significant reductions in P2 and P100 latency; however, individually, improvements in amplitude were more significant than improvements in latency. We conclude that the VEP to flash and pattern stimuli provides a useful diagnostic and monitoring tool in patients with DON, combining objectivity with quantitative analysis.

Does a history of maternal migraine or depression predispose children to headache and stomach-ache?

The incidence of the life time history of both maternal migraine and depression were assessed in children with headache, migraine, recurrent abdominal pain and abdominal migraine. An epidemiological survey of 1,104 children registered with a general practice was undertaken. The incidence of maternal migraine and depression agreed with previous estimates. Children with migraine had a greater proportion of mothers with a history of migraine than those who experienced headache alone compared with controls. The survey showed that mothers with depression predisposed their children to headache but not specifically migraine. A history of maternal depression and migraine was significantly more common and proportionately higher in children with abdominal migraine and recurrent abdominal pain.

Visual evoked cortical responses and electroretinograms following implantation of human fetal mesencephalon to the right caudate nucleus in Parkinson's disease.

Pattern electroretinograms and visual evoked cortical responses following flash and checkerboard pattern reversal stimulation were performed in 7 patients with advanced Parkinson's disease before and after implantation of human fetal ventral mesencephalon to the head of the right caudate nucleus. Six to nine months following surgery there was bilateral enhancement of flash-evoked response amplitudes. Electroretinogram measurements were unchanged. Individual increases in amplitude and decreases in latency were seen following pattern stimulation which were not statistically significant. A relationship between change in dyskinesia, and change in checkerboard pattern stimulation amplitude at 2.4 cycles per degree suggests that amplitude effects at this stimulus frequency are mediated via altered dopaminergic receptor status in the grafted hemisphere. This may be relevant to the mechanisms leading to generalised clinical improvements following this grafting technique.

The use of tinted glasses in childhood migraine.

20 children with clinically diagnosed migraine were asked to wear either a rose coloured tint or density matched blue tint for a period of 4 months. The frequency, duration and intensity of migraine attacks were recorded, together with the amount of visually provoked beta activity in the EEG. After one month's wear all the children in the study revealed an initial improvement in headache frequency. However, only those children wearing rose tints sustained this improvement up to 4 months, when the mean headache frequency had improved from 6.2 per month to 1.6 per month. The headache frequency of those children wearing blue tints revealed no overall improvement after 4 months. The improvements in headache frequency in children wearing rose tints correlated with a reduction in visually provoked beta activity.

The VER as a diagnostic marker for childhood abdominal migraine.

Abdominal migraine is a common childhood migraine equivalent, for which diagnostic criteria have not been defined. As in other children with migraine equivalents this leads to difficulties in diagnosis and determination of prevalence. By recording the fast wave activity (beta rhythmn) in the visual evoked response (VER) to red and white flash, the pattern stimulation, 27 out of 28 children with clinically diagnosed abdominal migraine revealed significant differences compared with normal controls, outside the attack phase. Comparisons with children diagnosed as migraine with or without aura revealed, from the VER findings of higher amplitude fast wave activity and the presence of paroxysmal sharp wave activity, that abdominal migraine appears to be a specific form of childhood migraine. We found that both clinically and electrophysiologically, abdominal migraine changes with age; older children exhibiting a shorter duration of abdominal pain during attacks, and less evidence of sharp wave activity in the VER.