Related Articles

Purpose:

To investigate multifocal visual evoked potentials (mfVEP) of the amblyopic and fellow eye in amblyopia due to anisometropia.

Methods:

We recorded mfVEP in both eyes of 15 anisometropic amblyopic patients and 15 normal control subjects. The responses from the central 7.0° arc of the visual field were measured, and changes in latency and amplitude were compared between the amblyopic, fellow, and normal control eyes.

Results:

There was a significant difference in the latency and amplitude of mfVEP between the amblyopic and fellow eyes. The responses in the central region of the visual field (rings 1 and 2) had a longer latency and smaller amplitude in the amblyopic eye. In contrast, there was no difference in mfVEP latency or amplitude between the fellow eye and normal control eyes.

Conclusion:

These results suggest that mfVEP may be used as an alternative objective method for diagnosis and monitoring of anisometropic amblyopia.

The latency of the first (P1) and second (P2) major positive waves of the pattern reversal visual evoked potential (VEP) for small checks (15 minutes of arc) was measured in 68 visually normal children and 32 amblyopic children with mild to moderate visual acuity losses. In the normal children there were no P1 and P2 interocular latency differences. The amblyopic children showed longer P1 latencies and shorter P2 latencies in their amblyopic eye than their normal fellow eye. These findings can be accounted for by a selective loss of the contrast-specific evoked potential mechanisms in amblyopia. The 'shorter' P2 latency obtained from amblyopic eyes for small checks is a reflection of the luminance responses that are normally elicited by larger (60 minute) checks.

OBJECTIVES—Recovery to normal or near normal visual acuity is usual after acute demyelinating optic neuritis, despite the frequent persistence of conduction abnormalities as evidenced by the visual evoked potential (VEP). This raises the possibility that cortical adaptation to a persistently abnormal input contributes to the recovery process. The objective of this study was to investigate the pattern of cerebral response to a simple visual stimulus in recovered patients in comparison to normal subjects.
METHODS—Functional magnetic resonance imaging (fMRI) was used to study the brain activation pattern induced by a periodic monocular 8Hz photic stimulus in seven patients who had recovered from a single episode of acute unilateral optic neuritis, and in seven normal controls. VEPs and structural optic nerve MRI were performed on patients.
RESULTS—Stimulation of either eye in controls activated only the occipital visual cortex. However, in patients, stimulation of the recovered eye also induced extensive activation in other areas including the insula-claustrum, lateral temporal and posterior parietal cortices, and thalamus; stimulation of the clinically unaffected eye activated visual cortex and right insula-claustrum only. The volume of extraoccipital activation in patients was strongly correlated with VEP latency (r=0.71, p=0.005).
CONCLUSIONS—The extraoccipital areas that were activated in patients all have extensive visual connections, and some have been proposed as sites of multimodal sensory integration. The results indicate a functional reorganisation of the cerebral response to simple visual stimuli after optic neuritis that may represent an adaptive response to a persistently abnormal input. Whether this is a necessary part of the recovery process remains to be determined.



Background

Amblyopia is a relatively common condition in which visual acuity through an eye is subnormal despite no overt pathology. Pattern visual evoked potential (PVEP) can detect any defect from optic nerve to occipital cortex and pattern electroretinogram (PERG) can detect retinal defects specially the ganglion layers. This study was performed to evaluate the cortical and retinal activity in strabismic and anisometropic amblyopia.

Methods

PVEP and PERG were recorded simultaneously in 40 amblyopes (20 strabismics and 20 anisometropics) and 20 normal control subjects. Normal subjects were age and sex matched with patients.

Results

The P100 latency in PVEP was increased in both groups of patients but the P100 amplitude was reduced only in anisometropic group. In PERG, the amplitude of P50 was reduced in all patients with no significant change in latency.

Conclusion

Beside reduced PVEP responses in strabismic and anisometropic amblyopia, the activity of retina reduced too. It is likely that retinal impulses can affect the development of visual system.

Magnetisation transfer ratio (MTR) can reveal the degree of proton exchange between free water and macromolecules and was suggested to be pathological informative. We aimed to investigate changes in optic nerve MTR over 12 months following acute optic neuritis (ON) and to determine whether MTR measurements can predict clinical and paraclinical outcomes at 6 and 12 months. Thirty-seven patients with acute ON were studied within 2 weeks of presentation and at 1, 3, 6 and 12 months. Assessments included optic nerve MTR, retinal nerve fibre layer (RNFL) thickness, multifocal visual evoked potential (mfVEP) amplitude and latency and high (100%) and low (2.5%) contrast letter acuity. Eleven healthy controls were scanned twice four weeks apart for comparison with patients. Patient unaffected optic nerve MTR did not significantly differ from controls at any time-point. Compared to the unaffected nerve, affected optic nerve MTR was significantly reduced at 3 months (mean percentage interocular difference = −9.24%, p = 0.01), 6 months (mean = −12.48%, p<0.0001) and 12 months (mean = −7.61%, p = 0.003). Greater reduction in MTR at 3 months in patients was associated with subsequent loss of high contrast letter acuity at 6 (ρ = 0.60, p = 0.0003) and 12 (ρ = 0.44, p = 0.009) months, low contrast letter acuity at 6 (ρ = 0.35, p = 0.047) months, and RNFL thinning at 12 (ρ = 0.35, p = 0.044) months. Stratification of individual patient MTR time courses based on flux over 12 months (stable, putative remyelination and putative degeneration) predicted RNFL thinning at 12 months (F2,32 = 3.59, p = 0.02). In conclusion, these findings indicate that MTR flux after acute ON is predictive of axonal degeneration and visual disability outcomes.

Objective:

Diffusion tensor imaging (DTI) quantifies Brownian motion of water within tissue. The goal of this study was to test whether, following a remote episode of optic neuritis (ON), breakdown of myelin and axons within the optic nerve could be detected by alterations in DTI parameters, and whether these alterations would correlate with visual loss.

Methods:

Seventy subjects with a history of ON ≥6 months prior underwent DTI of the optic nerves, assessment of visual acuities (VA) and contrast sensitivities (CS), and laboratory measures of visual evoked potentials (VEP) and optical coherence tomography (OCT).

Results:

Radial diffusivity (RD) correlated with visual acuity (r = −0.61), Pelli-Robson CS (r = −0.60), 5%CS (r = 0.61), OCT (r = −0.78), VEP latency (r = 0.61), and VEP amplitude (r = −0.46). RD differentiated the unaffected fellow nerves from affected nerves in all visual outcome categories. RD also discriminated nerves with recovery to normal from mild visual impairment, and those with mild impairment from profound visual loss. RD differentiated healthy controls from both clinically affected nerves and unaffected fellow nerves after ON. RD differentiated all categories of 5%CS outcomes, and all categories of Pelli-Robson CS with the exception of normal recovery from mildly affected.

Conclusions:

Increased optic nerve radial diffusivity (RD) detected by diffusion tensor imaging (DTI) was associated with a proportional decline in vision after optic neuritis. RD can differentiate healthy control nerves from both affected and unaffected fellow nerves. RD can discriminate among categories of visual recovery within affected eyes. Optic nerve injury as assessed by DTI was corroborated by both optical coherence tomography and visual evoked potentials.

GLOSSARY

= 5% contrast sensitivity;

= confidence interval;

= clinically isolated syndrome;

= contrast sensitivity;

= diffusion tensor imaging;

= fractional anisotropy;

= magnetic resonance;

= multiple sclerosis;

= neuromyelitis optica;

= optical coherence tomography;

= optic neuritis;

= Pelli-Robson contrast sensitivity;

= radial diffusivity;

= retinal nerve fiber layer;

= region of interest;

= visual acuity;

= visual evoked potential.

Fifty-five patients with amblyopia in unilateral high myopia without strabismus were treated. Thirty-two (58%) had a visual improvement by two lines or more on the Snellen chart and 17 (31%) attained a final visual acuity of 6/12 or better. In patients with pretreatment corrected vision of 6/60 or better in the amblyopic eye treatment consisted of full-time occlusion of the good eye, in some cases supplemented by the after-image method of pleoptic exercises in the amblyopic eye. Overall improvement of vision in this group was 72.7%. Occlusion of the good eye combined with pleoptic exercises in the amblyopic eye had no advantage over simple occlusion of the good eye. In patients with pretreatment corrected vision worse than 6/60 in the amblyopic eye occlusion of the amblyopic eye was done and the after-image method of pleoptic exercises was instituted. Improvement of vision in this group was 36.3%. The study showed that it is worth the trouble to treat this disorder even after the age of 14 years and stresses the utility of pleoptic therapy in older patients with severe amblyopia.

Purpose

To compare conventional visual evoked potential (cVEP) and multifocal visual evoked potential (mfVEP) methods in patients with optic neuritis/multiple sclerosis (ON/MS).

Methods

mfVEPs and cVEPs were obtained from eyes of the 19 patients with multiple sclerosis confirmed on MRI scans, and from eyes of 40 normal controls. For the mfVEP, the display was a pattern-reversal dartboard array, 48° in diameter, which contained 60 sectors. Monocular cVEPs were obtained using a checkerboard stimulus with check sizes of 15′ and 60′. For the cVEP, the latency of P100 for both check sizes were measured, while for the mfVEP, the mean latency, percent of locations with abnormal latency, and clusters of contiguous abnormal locations were obtained.

Results

For a specificity of 95%, the mfVEP(interocular cluster criterion) showed the highest sensitivity (89.5%) of the 5 monocular or interocular tests. Similarly, when a combined monocular/interocular criterion was employed, the mfVEP(cluster criterion) had the highest sensitivity (94.7%)/specificity (90%), missing only one patient. The combined monocular/interocular cVEP(60′) test had a sensitivity (84.2%)/specificity (90%), missing 3 patients, 2 more than did the monocular/interocular mfVEP(cluster) test.

Conclusion

As the cVEP is more readily available and currently a shorter test, it should be used to screen patients for ON/MS with mfVEP testing added when the cVEP test is negative and the damage is local.

Purpose

To evaluate orbital blood flow velocities and optic nerve diameter with Doppler and gray-scale sonography in patients with acute unilateral optic neuritis (ON).

Methods

Orbital Doppler and gray-scale sonography was performed in 46 eyes of 23 patients aged 19- to 47-years with acute unilateral ON. ON was diagnosed by an ophthalmologist on the basis of clinical presentation, presence of decreased visual acuity and assessment of visual evoked potentials. The peak systolic velocity (PSV) and end-diastolic velocity (EDV), as well as the resistance index (RI) and pulsatile index (PI) of the ophthalmic artery (OA), central retinal artery (CRA), posterior ciliary arteries (PCAs) and optic nerve diameter were measured in both eyes. We compared results from affected and unaffected eyes using the paired t-test. The area under the receiver operating characteristic (ROC) curves was used to assess the diagnosis of ON based on measured blood flow parameters of the OA, CRA and PCAs and optic nerve diameter.

Results

The mean (standard deviation) optic nerve diameter in eyes with ON was 4.1 (0.8) mm, which was significantly larger than the 3.0 (0.4) mm diameter measured in unaffected control eyes (p < 0.001). There were no differences in average PSV, EDV, RI, or PI of the OA and CRA between affected and unaffected eyes (p > 0.05). The mean RI in the PCAs was slightly lower in the eyes with ON than in the contralateral eyes (0.60 vs. 0.64, p < 0.05). The area under the ROC curves indicated that optic nerve diameter was the best parameter for the diagnosis of ON.

Conclusions

Optic nerve diameter was related to ON, but orbital blood flow parameters were not.

Background

Optic neuritis is associated with neurodegeneration leading to chronic impairment of visual functions.

Objective

This study investigated whether early treatment with interferon beta (IFN-β) slows retinal nerve fibre layer (RNFL) thinning in clinically isolated optic neuritis.

Methods

Twenty patients with optic neuritis and visual acuity decreased to ≤0.5 (decimal system) were included into this prospective, open-label, parallel group 4-month observation. After methylprednisolone pulse therapy, 10 patients received IFN-β from week 2 onwards. This group was compared to 10 patients free of any disease modifying treatment (DMT). The parameter of interest was change in RNFL thickness assessed at baseline and at weeks 4, 8, and 16. Changes in visual acuity, visual field, and visual evoked potentials (VEPs) served as additional outcome parameters.

Results

RNFL thinning did not differ between the groups with a mean reduction of 9.80±2.80 µm in IFN-β-treated patients (±SD) vs. 12.44±5.79 µm in patients who did not receive DMT (baseline non-affected eye minus affected eye at week 16; p = 0.67, t-test, 95% confidence interval: −15.77 to 10.48). Parameters of visual function did not show any differences between the groups either.

Conclusions

In isolated optic neuritis, early IFN-β treatment did not influence RNFL thinning nor had it any effect on recovery of visual functions.

The disparity between clinical visual function and pattern visual evoked response (VER) was studied in 53 patients who had suffered an attack of optic neuritis (ON) more than six months before. The visual functions tested included Snellen visual acuity, colour vision, visual field, and contrast sensitivity. The effect of pattern presentation, check size, and luminance was tested by recording VERs with several stimulus configurations. VER amplitudes were found to be associated with the outcome of all four clinical tests, independently of check size, luminance, or the presentation method used. On the other hand VER latencies were hardly ever related to the results of any of the four clinical visual tests. These findings support the idea that VER amplitude provides information about visual spatial perception, while VER latency is more related to the extent of demyelination.

Aims

To investigate optic nerve head topography in patients with optic neuritis compared to controls using the Heidelberg retina tomograph‐II (HRT‐II) and to determine if detected changes are related to visual function and electrophysiology.

Methods

25 patients with a previous single episode of unilateral optic neuritis and 15 controls were studied with HRT‐II, visual evoked potentials, and pattern electroretinogram. Patients also had testing of visual acuity, visual field, and colour vision.

Results

In affected eyes compared to fellow eyes, there was reduction of both the mean retinal nerve fibre layer (RNFL) thickness at the disc edge (p = 0.009) and the neuroretinal rim volume (p = 0.04). In affected eyes compared to control eyes, the three dimensional optic cup shape measure was increased (p = 0.01), indicative of an abnormal cup shape. There were no other significant differences in HRT‐II measures. Within patient interocular difference correlation was used to investigate the functional relevance of these changes and demonstrated associations between RNFL thickness change and changes in visual acuity, visual field, and colour vision. Colour vision change was also associated with change in neuroretinal rim volume.

Conclusions

HRT detects functionally relevant changes in RNFL thickness and neuroretinal rim volume between eyes affected by optic neuritis and unaffected fellow eyes.

Conventional MRI sequences do not permit the distinction between the different pathological characteristics (oedema, demyelination, gliosis, axonal loss) of the multiple sclerosis plaque. Magnetisation transfer imaging and transverse magnetisation decay curve (tMDC) analysis may be more specific. These techniques have been applied to the optic nerves in 20 patients with optic neuritis and the results correlated with clinical and visual evoked potential (VEP) findings. tMDC analysis failed to identify separate intracellular and extracellular water compartments within the optic nerve but gave a measure of transverse relaxation time (T2) without the confounding effects of CSF in the nerve sheath. Both T2 and magnetisation transfer ratio (MTR) were abnormal after an episode of optic neuritis. T2 did not correlate with visual function or with VEP latency or amplitude. There was a significant correlation between MTR reduction and prolongation of VEP latency: this increased latency may reflect an effect of myelin loss on MTR. Longer lesions were associated with worse visual outcome, implying that the overall extent of pathological involvement is likely to influence the degree of functional deficit.

Images

Background

In multiple sclerosis relapses refractory to intravenous corticosteroid therapy, plasma exchange is recommended. Immunoadsorption (IA) is regarded as an alternative therapy, but its efficacy and putative mechanism of action still needs to be established.

Methods

We prospectively treated 11 patients with multiple sclerosis who had optical neuritis and fulfilled the indications for apheresis therapy (Trial registration DE/CA25/00007080-00). In total, five IA treatments were performed using tryptophan-IA. Clinical activity (visual acuity, Expanded Disability Status Scale, Incapacity Status Scale), laboratory values and visual evoked potentials were measured before, during and after IA, with a follow-up of six months. Moreover, proteomic analyses were performed to analyze column-bound proteins as well as corresponding changes in patients’ sera.

Results

After the third IA, we detected an improvement of vision in eight of eleven patients, whom we termed responders. Amongst these, the mean visual acuity improved from 0.15 ± 0.12 at baseline to 0.47 ± 0.32 after the third IA (P = 0.0252) up to 0.89 ± 0.15 (P < 0.0001) at day 180 ± 10 after IA. Soluble interleukin-2 receptor decreased in responders (P = 0.03), whereas in non-responders it did not. Proteomic analyses of proteins adsorbed to IA columns revealed that several significant immunological proteins as well as central nervous system protein fragments, including myelin basic protein, had been removed by IA.

Conclusions

IA was effective in the treatment of corticosteroid-refractory optic neuritis. IA influenced the humoral immune response. Strikingly, however, we found strong evidence that demyelination products and immunological mediators were also cleared from plasma by IA.

In a single-blind controlled clinical trial patients with optic neuritis caused by demyelination were given a single retrobulbar injection of triamcinolone. Though the treated group showed a trend towards more rapid recovery of vision than the controls, there was no significant difference in visual acuity, colour vision, or visual fields during the first six months after treatment. We conclude that routine use of corticosteroids is not justified in unilateral optic neuritis when vision in the other eye is good. Shortening the period of visual disability in bilateral disease or unilateral disease when vision in the other eye is poor, however, may be justifiable.

Aim: To evaluate if functionally relevant deficits in reading performance exist in children with essential microstrabismic amblyopia by comparing the monocular and binocular reading performance with the reading performance of normal sighted children with full visual acuity in both eyes.

Methods: The reading performance of 40 children (mean age 11.6 (SD 1.4) years) was evaluated monocularly and binocularly in randomised order, using standardised reading charts for the simultaneous determination of reading acuity and speed. 20 of the tested children were under treatment for unilateral microstrabismic amblyopia (visual acuity in the amblyopic eyes: logMAR 0.19 (0.15); fellow eyes −0.1 (0.07)); the others were normal sighted controls (visual acuity in the right eyes −0.04 (0.15); left eyes −0.08 (0.07)).

Results: In respect of the binocular maximum reading speed (MRS), significant differences were found between the children with microstrabismic amblyopia and the normal controls (p = 0.03): whereas the controls achieved a binocular MRS of 200.4 (11) wpm (words per minute), the children with unilateral amblyopia achieved only a binocular MRS of 172.9 (43.9) wpm. No significant differences between the two groups were found in respect of the binocular logMAR visual acuity and reading acuity (p>0.05). For the monocular reading performance, significant impairment was found in the amblyopic eyes, whereas no significant differences were found between the sound fellow eyes of the amblyopic children and the control group.

Conclusion: In binocular MRS, significant differences could be found between children with microstrabismic amblyopia and normal controls. This result indicates the presence of a functionally relevant reading impairment, even though the binocular visual acuity and reading acuity were both comparable with the control group.

Aim: To offer a critique of current methods of defining amblyopia treatment outcome and to examine alternative approaches.

Method: Literature appraisal and descriptive case presentations.

Results: Currently, the outcome of amblyopia treatment is expressed as the number of acuity chart lines gained or, alternatively, achievement of an arbitrarily adopted level of visual acuity. As binocular vision is optimised with equal visual input from each eye the authors propose that the optimum outcome of amblyopia therapy is to achieve a visual acuity in the amblyopic eye equal to that of its fellow. In addition, improvement should be graded as the proportion of change in visual acuity with respect to the absolute potential for improvement (that is, that pertaining in the fellow eye at end of treatment).

Conclusions: There are two methods of appropriately describing the outcome of amblyopia treatment: firstly, by the difference in final visual acuity of amblyopic and fellow eye (residual amblyopia); secondly, the proportion of the deficit corrected.

OBJECTIVES—To compare the degree of visual evoked potential (VEP) delay to stimulation of central, nasal, and temporal regions of the macula in optic neuritis, to determine whether the differential involvement of parvocellular and magnocellular fibre types suggested by other studies is governed by retinotopic factors.
METHODS—VEPs were recorded to reversal of 40' checks in the central (4° radius) and the left and right surrounding regions of the visual field (as far as 10° vertical and 14° horizontal) in 30patients recently recovered from the acute stage of optic neuritis, and in 17 age matched controls.
RESULTS—In the control group, VEP latencies were similar to stimulation of the central and temporal regions of the macula, marginally shorter from the nasal region. In the patients with optic neuritis, VEPs were significantly more delayed from the central region, on average by about twice as much as from the nasal and temporal regions. Delays seen in some of the VEPs from the patients' fellow eyes tended to be more uniformly distributed.
CONCLUSIONS—Although the central region of the macula is where the density of parvocellular innervation is greatest, there is no reason to suppose that the VEPs to stimulation of the nasal and temporal regions (almost all P100 activity arising from within the central 10°) are mediated by fibres of another type. Consequently it is suggested that the central fibres were most affected by demyelination, not on account of their belonging to the parvocellular type but because of their particular situation in the optic nerve. Centrally located fibres may experience greater exposure to factors causing demyelination, or fibres located closer to the edge of the plaque may undergo more effective remyelination in the first few weeks after the acute episode.



The perception of contrast was measured in patients with acute unilateral optic neuritis by a technique of subjective suprathreshold contrast matching, and was compared with contrast sensitivity as defined by threshold measurements. The suprathreshold apparent contrast and threshold contrast sensitivity was repeatedly assessed during the recovery phase. Generally, an attenuation of suprathreshold apparent contrast was found for high and intermediate spatial frequencies in the eye with optic neuritis. At a low spatial frequency, however, the suprathreshold contrast vision was spared. The threshold contrast sensitivity was not however, spared at low spatial frequencies. During recovery this frequency-specific loss in suprathreshold apparent contrast diminished and finally a "normal" suprathreshold contrast vision was observed in all affected eyes reaching a visual acuity of 1.0 or better. In these cases also subjectively normal vision was reported in site of a persisting abnormality in threshold contrast sensitivity.

Objectives:

Determine the utility of optical coherence tomography (OCT) to detect clinical and subclinical remote optic neuritis (ON), its relationship to clinical characteristics of ON and visual function, and whether the retinal nerve fiber layer (RNFL) thickness functions as a surrogate marker of global disease severity.

Methods:

Cross-sectional study of 65 subjects with at least 1 clinical ON episode at least 6 months prior. Measures included clinical characteristics, visual acuity (VA), contrast sensitivity (CS), OCT, and visual evoked potentials (VEP).

Results:

Ninety-six clinically affected optic nerves were studied. The sensitivity of OCT RNFL after ON was 60%, decreasing further with mild onset and good recovery. VEP sensitivity was superior at 81% (p = 0.002). Subclinical ON in the unaffected eye was present in 32%. VEP identified 75% of all subclinically affected eyes, and OCT identified <20%. RNFL thickness demonstrated linear correlations with VA (r = 0.65) and CS (r = 0.72) but was unable to distinguish visual categories <20/50. RNFL was thinner with severe onset and disease recurrence but was unaffected by IV glucocorticoids. OCT measurements were not related to overall disability, ethnicity, sex, or age at onset. The greatest predictor for RNFL in the unaffected eye was the RNFL in the fellow affected eye.

Conclusions:

Visual evoked potentials (VEP) remains the preferred test for detecting clinical and subclinical optic neuritis. Optical coherence tomography (OCT) measures were unrelated to disability and demographic features predicting a worse prognosis in multiple sclerosis. OCT may provide complementary information to VEP in select cases, and remains a valuable research tool for studying optic nerve disease in populations.

GLOSSARY

= analysis of variance;

= clinically isolated syndrome;

= contrast sensitivity;

= Expanded Disability Status Score;

= logarithm of the minimum angle of resolution;

= multiple sclerosis;

= Multiple Sclerosis Severity Score;

= National Center for Research Resources;

= neuromyelitis optica;

= not significant;

= optical coherence tomography;

= optic neuritis;

= retinal nerve fiber layer;

= visual acuity;

= visual evoked potentials.

Objective:

To determine the potential of directional diffusivities from diffusion tensor imaging (DTI) to predict clinical outcome of optic neuritis (ON), and correlate with vision, optical coherence tomography (OCT), and visual evoked potentials (VEP).

Methods:

Twelve cases of acute and isolated ON were imaged within 30 days of onset and followed prospectively. Twenty-eight subjects with a remote clinical history of ON were studied cross-sectionally. Twelve healthy controls were imaged for comparison. DTI data were acquired at 3T with a surface coil and 1.3 × 1.3 × 1.3 mm3 isotropic voxels.

Results:

Normal DTI parameters (mean ± SD, μm2/ms) were axial diffusivity = 1.66 ± 0.18, radial diffusivity = 0.81 ± 0.26, apparent diffusion coefficient (ADC) = 1.09 ± 0.21, and fractional anisotropy (FA) = 0.43 ± 0.15. Axial diffusivity decreased up to 2.5 SD in acute ON. The decrease in axial diffusivity at onset correlated with visual contrast sensitivity 1 month (r = 0.59) and 3 months later (r = 0.65). In three subjects followed from the acute through the remote stage, radial diffusivity subsequently increased to >2.5 SD above normal, as did axial diffusivity and ADC. In remote ON, radial diffusivity correlated with OCT (r = 0.81), contrast sensitivity (r = 0.68), visual acuity (r = 0.56), and VEP (r = 0.54).

Conclusion:

In acute and isolated demyelination, axial diffusivity merits further investigation as a predictor of future clinical outcome. Diffusion parameters are dynamic in acute and isolated optic neuritis, with an initial acute decrease in axial diffusivity. In remote disease, radial diffusivity correlates with functional, structural, and physiologic tests of vision.

GLOSSARY

= apparent diffusion coefficient;

= confidence interval;

= contrast sensitivity;

= diffusion tensor imaging;

= experimental autoimmune encephalitis;

= fractional anisotropy;

= mean diffusivity;

= multiple sclerosis;

= normal-appearing white matter;

= optical coherence tomography;

= optic neuritis;

= relative anisotropy;

= reduced field of view;

= retinal nerve fiber layer;

= region of interest;

= standard deviation;

= signal-to-noise ratio;

= visual acuity;

= visual evoked potentials.

Transient visually evoked potentials (VEPs) to sinusoidal gratings over a range of spatial frequencies have been recorded in cases of optic neuritis. The use of the response to pattern onset in addition to the response to pattern reversal extended the range to higher spatial frequencies by up to two octaves. There was an increase in VEP delay and a greater degree of discrimination from a control group at higher spatial frequencies. This finding is discussed in the light of previous reports of luminance and checkerboard VEPs in demyelinating optic nerve disease. An attempt is made to relate amplitude changes in various VEP components to contrast sensitivity measurements in this group of patients.

Epstein-Barr virus (EBV) is a DNA virus that mainly causes infectious mononucleosis. Ocular manifestations are rare and typically mild. Only a few cases of EBV involving the retina or the optic nerve have been reported. Herein, we report the case of a 67-year-old man with bilateral chorioretinitis and optic neuritis due to EBV. The patient had no previous ocular history and presented with decreased vision in both eyes. His past medical history included EBV encephalopathy, which was confirmed serologically, a few months before. Ophthalmological examination revealed bilateral chorioretinitis and optic neuritis, confirmed by fluorescein angiography as well as electrophysiological tests (visual evoked potentials and electroretinogram). It is very important to include EBV in the differential diagnosis of chorioretinal atrophic lesions. Clinicians should be aware of ocular manifestations of EBV, in order to suggest ophthalmological examination and start treatment promptly before irreversible damage to the optic nerve or retina occurs.

AIMS--The study aimed to assess the effect of initial visual acuity and type of amblyopia on the long term results of successfully treated amblyopia. METHODS--The visual acuity of 94 patients, who had been successfully treated for unilateral amblyopia by occlusion of the good eye and followed up to the age of 9 years, was examined 6.4 years, on average, after cessation of treatment. Patients were divided into two groups according to the depth of amblyopia before occlusion therapy was started: those with visual acuity between 20/60 and 20/100 and those with visual acuity of 20/100 or worse. RESULTS--Deterioration of visual acuity was observed in 42% of patients in the first group and in 63% of patients in the second group. Their average deterioration, as measured by the Snellen chart, was 0.58 and 1.54 lines, respectively. The results were also assessed by the division of patients into three groups according to the type of amblyopia: strabismic, strabismic anisometropic, and anisometropic. Deterioration of visual acuity occurred in 46%, 79%, and 36% of patients in these three groups, with an average deterioration on the Snellen chart of 0.70, 2.04, and 0.64 lines, respectively. CONCLUSION--It is concluded that low initial visual acuity and strabismic anisometropic amblyopia are risk factors for deterioration of visual acuity in the long term, following the successful earlier treatment of eyes with amblyopia.

Objective

To determine visual acuity improvement in children with strabismic and combined strabismic-anisometropic (combined-mechanism) amblyopia treated with optical correction alone and to explore factors associated with improvement.

Design

Prospective multi-center cohort study

Participants

146 children 3 to <7 years old with previously untreated strabismic amblyopia (N=52) or combined-mechanism amblyopia (N=94).

Methods

Optical treatment was provided as spectacles (prescription based on a cycloplegic refraction) that were worn for the first time at the baseline visit. Visual acuity with spectacles was measured using the Amblyopia Treatment Study HOTV© visual acuity protocol at baseline and every 9 weeks thereafter until no further improvement in visual acuity. Ocular alignment was assessed at each visit.

Main outcome measure

Visual acuity 18 weeks after baseline.

Results

Overall, amblyopic eye visual acuity improved a mean of 2.6 lines (95% confidence interval: 2.3 to 3.0), with 75% of children improving ≥2 lines and 54% improving ≥3 lines. Resolution of amblyopia occurred in 32% (95% confidence interval: 24% to 41%) of the children. The treatment effect was greater for strabismic amblyopia than for combined-mechanism amblyopia (3.2 versus 2.3 lines, adjusted P=0.003). Visual acuity improved regardless of whether eye alignment improved.

Conclusions

Optical treatment alone of strabismic and combined-mechanism amblyopia results in clinically meaningful improvement in amblyopic eye visual acuity for most 3 to <7-year-old children, resolving in at least one quarter without the need for additional treatment. Consideration should be given to prescribing refractive correction as the sole initial treatment for children with strabismic or combined-mechanism amblyopia before initiating other therapies.