Class switch toward noninflammatory, spike-specific IgG4 antibodies after repeated SARS-CoV-2 mRNA vaccination

RNA vaccines are efficient preventive measures to combat the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. High levels of neutralizing SARS-CoV-2 antibodies are an important component of vaccine-induced immunity. Shortly after the initial two mRNA vaccine doses, the immunoglobulin G (IgG) response mainly consists of the proinflammatory subclasses IgG1 and IgG3. Here, we report that several months after the second vaccination, SARS-CoV-2-specific antibodies were increasingly composed of noninflammatory IgG4, which were further boosted by a third mRNA vaccination and/or SARS-CoV-2 variant breakthrough infections. IgG4 antibodies among all spike-specific IgG antibodies rose, on average, from 0.04% shortly after the second vaccination to 19.27% late after the third vaccination. This induction of IgG4 antibodies was not observed after homologous or heterologous SARS-CoV-2 vaccination with adenoviral vectors. Single-cell sequencing and flow cytometry revealed substantial frequencies of IgG4-switched B cells within the spike-binding memory B cell population [median of 14.4%; interquartile range (IQR) of 6.7 to 18.1%] compared with the overall memory B cell repertoire (median of 1.3%; IQR of 0.9 to 2.2%) after three immunizations. This class switch was associated with a reduced capacity of the spike-specific antibodies to mediate antibody-dependent cellular phagocytosis and complement deposition. Because Fc-mediated effector functions are critical for antiviral immunity, these findings may have consequences for the choice and timing of vaccination regimens using mRNA vaccines, including future booster immunizations against SARS-CoV-2.

Towards universal ambient ionization: direct elemental analysis of solid substrates using microwave plasma ionization

A microwave plasma was used for direct ambient ionization mass spectrometry of solid substrates, rapidly yielding atomic spectra without sample digestion or pre-treatment. Further, molecular spectra for the organic components of the substrate were obtained simultaneously, in an ambient ionization format. Initial characterization of the microwave plasma coupling to an ion trap mass spectrometer was carried out using solution standards and a microwave plasma torch (MPT) configuration. The configuration of the microwave plasma was then optimized for ambient ionization. The atomic and organic composition for samples applicable to nuclear and conventional forensic screening, including explosive/radionuclide mixtures and inorganic/organic gunshot residue component mixtures were successfully determined. The technologies employed are readily fieldable; the feasibility of a multimode ion source that could be coupled with a portable ion trap mass spectrometer for rapid, on-site, elemental, isotopic, and molecular screening of samples is demonstrated.

[Astigmatism after trans-scleral posterior chamber lens implantation in young children]

BACKGROUND

The purpose of this study was to evaluate the postoperative astigmatism after trans-scleral fixation of intraocular lenses in children and to develop a strategy for amblyopia prophylaxis.

PATIENTS AND METHODS

In eight eyes with lentectomy, posterior chamber intraocular lenses were fixed in the ciliary sulcus by trans-scleral sutures. The postoperative astigmatism was measured by retinoscopy every 1 to 2 weeks in the first 2 months, followed by monthly intervals thereafter. Keratometry was performed with an automated hand keratometer.

RESULTS

Postoperative astigmatism was 2.5 to 8.0 D. The astigmatism regressed to 0.75 D in half the eyes within 4 weeks and in five of the eyes within 16 weeks. In one of the eight eyes, the astigmatism decreased to 2.0 D and in two it remained unchanged. The astigmatism did not change any more after 16 weeks postoperatively. Visual acuity was 0.016 to 1.0.

CONCLUSIONS

Our study shows that the postoperative astigmatism regresses soon and does not seriously interfere with amblyopia therapy. If greater than 2 D, half of the astigmatism should be corrected with glasses, even in the early postoperative period. After 16 weeks, full correction is recommended.

[Amiodarone-associated optic neuropathy: an independent syndrome? Three patients with bilateral optic neuropathy]

BACKGROUND

Optic neuropathy has been reported to occur during antiarrhythmic therapy with amiodarone. Whether or not there is a causal relationship has been discussed controversely.

PATIENTS

Three patients presented with a visual impairment three to seven months after starting amiodarone therapy. In all three patients both optic discs were swollen and showed hemorrhages on the margin. After discontinuing amiodarone, the vision improved and the swelling of the optic discs resolved.

CONCLUSION

The bilateral occurrence at the same time, the close time correlation with the amiodarone application and the improvement after discontinuing amiodarone suggest that our three patients suffered from a toxic effect of amiodarone rather than an incidental other disease, as for instance ischemic optic neuropathy.

Heterophoria and fixation disparity: a review

Heterophoria does not provide a reliable clue for ordering prisms in an asthenopic patient. The same reservation applies to associated phoria, as determined by prism correction of fixation disparity. Subjective tests for fixation disparity, even those with a fusionable fixation target, do not correctly indicate the vergence position of the eyes under natural viewing conditions. Attempts to measure fixation disparity on the basis of stereo disparity, using the "Measuring and Correction Methods of H.-J. Haase", have failed.

[Can fixation disparity be detected reliably by measurement and correctional techniques according H.J. Haase (MKH)?]

BACKGROUND

The theory of the "Measuring and Correction Methods of H.-J. Haase" (MCH) states that a small misalignment of one eye, called fixation disparity, indicates a difficulty in overcoming a "vergence position of rest" that is different from ortho position. This difficulty, so the theory, can cause asthenopic complaints, such as headaches, and these complaints can be relieved by prisms. The theory further claims that fixation disparity can be ascertained by a series of tests which depend on the subject's perception. The tests most decisive for the diagnosis of a so-called fixation disparity type 2 consist of stereo displays. The magnitude of the prism that allows the subject to see the test configurations in symmetry is thought to be the one that corrects the "vergence position of rest".

METHODS

Nine subjects with healthy eyes in whom a "fixation disparity type 2" had been diagnosed were selected for the study. Misalignment of the eyes was determined according to the principle of the unilateral cover test. Targets identical for both eyes were presented on the screen of the Polatest E. Then, the target was deleted for one eye and the ensuing position change of the other eye was measured, using the search coil technique. This test was performed both with and without the MCH prism.

RESULTS

In all 9 subjects the misalignment was less than 10 minutes of arc, i.e. in the range of normal fixation instability. Averaging across the 9 subjects, the deviation of the eye (misaligned according to MCH) was 0.79 +/- 3.45 minutes of arc in the direction opposed to that predicted by the MCH, a value not significantly different from zero. The MCH prism elicited a fusional vergence movement the magnitude of which corresponded to the magnitude of the MCH prism.

CONCLUSION

Ascertaining fixation disparity with the MCH is unreliable. Accordingly, it appears dubious to correct a "vergence position of rest" on the basis of the MCH.

Bilateral optic neuropathy after bone marrow transplantation and cyclosporin A therapy

BACKGROUND

Cyclosporin A (CsA) is widely used as a prophylactic and therapeutic agent against graft-versus-host disease after bone marrow transplantation. Under this condition optic neuropathy has been found and considered as a possible side effect of cyclosporin A.

CASE REPORT

A 52-year-old man presented with bilateral optic disc swelling and visual loss 6 months after bone marrow transplantation. Cyclosporin A was the only medication with a known neurotoxic side effect. After cessation of cyclosporin A and treatment with oral prednisone, vision improved within 2 months. Optic disc swelling ameliorated within 6 months but partial optic atrophy developed.

DISCUSSION

Cyclosporin A given after bone marrow transplantation may have caused bilateral optic neuropathy in our patient. Microangiopathy of the optic nerve may be the pathogenetic mechanism.

Transscleral suture fixation of posterior chamber intraocular lenses in children under 3 years

BACKGROUND

Children who have undergone lentectomy for congenital or traumatic cataract do not have adequate capsular support for secondary posterior chamber intraocular lens (PC-IOL) implantation and thus will become severely amblyopic if contact lens intolerance occurs. In order to prevent amblyopia we fixed PC-IOLs by transscleral sutures in three children younger than 3 years. Clinical outcome, visual acuity and course of refraction were studied.

METHODS

Four eyes of three children with contact lens intolerance were operated. Posterior chamber lenses (PC-IOL) were sutured in the ciliary sulcus by transscleral sutures. Two children had monocular traumatic cataract and one child underwent surgery on both eyes for congenital cataract. To allow adjustment of refraction in situ without removing the primarily implanted and transsclerally fixed PC-IOL we used the piggyback intraocular lens system for implantation.

RESULTS

Visual acuity improved in all four eyes. The two children with traumatic cataract achieved visual acuity of 0.7 and 1.0, respectively, and stereopsis. No complications related to the technique of transscleral suture fixation of the PC-IOL were observed. Postoperative changes in refractive power were caused by a myopic shift between -1.0 D and -9.0 D. Follow-up was 25-70 months.

CONCLUSION

Transscleral suture fixation of PC-IOLs did not cause specific complications during follow-up of up to 70 months. This technique offers an important option for the correction of an aphakic refractive error which cannot be corrected otherwise. In future the piggyback intraocular lens system may help to rather atraumatically correct postoperative changes in refractive power.

[Strabismus surgery under subconjunctival anesthesia: technique and evaluation by patient and his surgeon]

BACKGROUND

In adults, eye muscle surgery can be performed under local anesthesia without retrobulbar injection. We wanted to know how patients and surgeons perceive this procedure.

PATIENTS AND METHODS

50 patients and 3 surgeons were interviewed with a questionnaire after operation on one or two straight eye muscles, including revisions in 11 cases. The patients were sedated with benzodiazepines. The conjunctiva was anesthetized with tetracaine eye drops. During the operation, mepivacaine was irrigated under the muscle insertion using a blunt needle.

RESULTS

The patients perceived little or no pain during the operation. This corresponded to the surgeon's judgement. 96% of the patients would prefer local over general anesthesia in case of a second operation.

CONCLUSION

The technique can be recommended for surgery of rectus muscles in adults, even in the case of revision.

Duction ranges in normal probands and patients with Graves' ophthalmopathy, determined using the Goldmann perimeter

BACKGROUND

We examined whether the Goldmann perimeter is suitable for measuring the range of monocular ductions, especially in the follow-up of patients with Graves' ophthalmopathy.

METHODS

Using the Goldmann perimeter, the range of monocular ductions was determined in one eye of 100 normal probands (aged between 21 and 70 years) and of 36 patients (aged between 29 and 66 years) with a motility disturbance due to Graves' ophthalmopathy. Subjects were asked to follow target I/4e which was slowly moved by the examiner in the vertical and the horizontal meridian. The end-point of the pursuit movement observed by the examiner was taken as the duction limit. Subjects were measured twice, in half of the cases by the same, in the other half by two different examiners.

RESULTS

In the 100 normal probands, the mean ranges of ductions were: elevation 37.6 degrees, depression 58.0 degrees, adduction 51.6 degrees, abduction 48.7 degrees. There was a slight age-related decline. The intraobserver and interobserver mean coefficients of variation ranged between 1.5% and 3.8%. In the 36 patients with Graves' ophthalmopathy the coefficients were between 0.7% and 2.3%. In both the normal probands and the Graves' ophthalmopathy patients, the coefficients were smaller for the total vertical and horizontal duction ranges than for adduction, abduction, elevation and depression alone.

CONCLUSIONS

Measurements of the range of monocular ductions with the Goldmann perimeter are highly reproducible and appear to be suitable for follow-up studies in patients with Graves' ophthalmopathy.

Little correlation of the pattern electroretinogram (PERG) and visual field measures in early glaucoma

Pattern-electroretinograms (PERG) to checkerboard reversal at 16/s. 0.8 degrees and 15 degrees check size and visual fields (Octopus G1) were retrospectively analyzed in 40 eyes of 30 patients with early glaucoma. The mean visual field defect was calculated separately for the central 26 degrees x 34 degrees covered by the PERG stimulus (MDc) and the more peripheral area (MDp) surrounding the stimulus. Deeper field loss was correlated with a reduced pattern electroretinogram amplitude (p < 0.01 for both MDp and MDc), indicating that the pattern electroretinogram deteriorates as glaucoma advances. If the analysis was confined to those 18 eyes (16 patients) that had no field defect within the area covered by the PERG stimulus (normal MDc but abnormal MDp), 13 of these had an abnormal PERG amplitude (p < 0.001). The results suggest that the PERG can reveal impairment of ganglion cell function that is not detected by conventional perimetry.

A case of localized retinal damage in thallium poisoning

PURPOSE

To determine the cause of visual impairment and to document the late eye disturbances in a case of thallium poisoning.

PATIENT

A 44-year-old woman presented with a history of repeated attacks of complete alopecia over a period of several months, diffuse pain in both legs, transient gastrointestinal disturbances, abasia with a progressive paraparesis, paresthesia in the fingertips, and polyneuropathy. She complained of slowly progressive visual deterioration in both eyes which began about six months after the first attack of alopecia. The optic discs showed distinct signs of temporal atrophy together with a deep temporal excavation. The Goldmann perimetry revealed an absolute central scotoma. Traces of thallium were found in the urine and in the serum. The district attorney later discovered that her husband had been trying to poison her with thallium.

METHODS

The clinical and electrophysiological examinations included visual evoked potentials (VEP) and electroretinography (flash ERG, multifocal ERG and pattern ERG).

RESULTS

The VEP showed a reduction in amplitude and a prolonged latency indicating a conduction block. The pattern ERG was initially normal. At a follow-up examination 6 years later, a slight amplitude reduction in the pattern ERG was found. The multifocal ERG showed a diminished amplitude in the center of the retina (up to +/- 10 degrees visual angle).

CONCLUSIONS

The electrophysiological investigations in our patient--who had an optic atrophy--indicated a conduction block of the retinal nerve fibers (VEP) and an additional lesion at or before the retinal bipolar cells (multifocal ERG), localized in the central +/- 10 degrees. These findings suggest that thallium poisoning can lead to a combined lesion of the retinal nerve fibers and the neural retina.

Diameter of the optic nerve in idiopathic optic neuritis and in anterior ischemic optic neuropathy

PURPOSE

There is considerable overlap in the clinical profile of patients with idiopathic optic neuritis (ON) and anterior ischemic optic neuropathy (AION). We tested the hypothesis that the retrobulbar diameter of the optic nerve may be a criterion for the differential diagnosis between ON and AION.

METHODS

The diameter of the optic nerve was measured by B-scan ultrasonography with the eye in an abducted position. Only patients with a unilateral optic neuropathy were included, 16 ON patients (mean age 24 years, 5 with and 11 without disc swelling) and 9 patients with AION (mean age 72 years). As controls for the ON patients 10 young normal subjects (mean age 25 years) and as controls for the AION patients 10 elderly subjects with eye problems not related to the optic nerve (mean age 76 years) were examined.

RESULTS

In the ON patients with disc swelling the diameter of the optic nerve was 5.4 +/- 0.5 mm in the affected and 3.0 +/- 0.3 mm in the unaffected side. This difference was significant (Wilcoxon-test, p = 0.043). In the ON patients without disc swelling the diameter of the optic nerve was 4.4 +/- 0.4 mm in the affected and 3.0 +/- 0.3 mm in the unaffected side. This difference was significant (Wilcoxon-test, p = 0.003). In the AION patients the diameter of the optic nerve was 3.0 +/- 0.3 mm on the affected and 2.8 +/- 0.4 mm on the unaffected side. This difference was not significant (Wilcoxon-test, p = 0.093). Comparing the optic nerves with ON and AION to those of the controls, the diameter was significantly enlarged in the nerves with ON and normal in the nerves with AION (one factor repeated ANOVA).

CONCLUSION

The diameter of the optic nerve is increased in ON without disc swelling and even more so in ON with disc swelling. The enlargement is probably due to edema of the nerve itself, not the surrounding subarachnoidal space. In AION, the diameter of the optic nerve is normal. Measuring the diameter of the optic nerve by B-scan ultrasonography is particularly useful in the differential diagnosis between ON with disc swelling and AION.

[Fixation disparity with the Pola pointing test: not representative for eye position under natural viewing conditions]

BACKGROUND

According to certain findings obtained with the Zeiss Polatest, H.J. Haase defined a "Fixation Disparity Type One". In this diagnosis, the "Zeigertest" is particularly important. The Zeigertest consists of a central ring presented to both eyes for fixation, a vertical clock hand presented to the right eye and two markings at the six and twelve o'clock positions presented to the left eye. All parts are surrounded by a binocularly visible frame. Subjects with a "Fixation Disparity Type One" see a misalignment between the clock hand and the peripheral markings. We investigated (1) whether the perceived misalignment correlated with an objective deviation of the eyes from orthovergence and (2) whether subjects with a "Fixation Disparity Type One" had a deviation of the eyes from orthovergence when looking at a natural, i.e., fully fusionable object.

SUBJECTS AND METHODS

Out of 303 medical students, 10 subjects with a "Fixation Disparity Type One" were selected and asked to indicate the perceived alignment or misalignment in the Zeigertest with a laser pointer. Two subjects without fixation disparity served as controls. The position of both eyes was recorded using the search coil technique. One of the 10 subjects with "Fixation Disparity Type One" had to be excluded due to excessive blinking. Experiment 1: In the beginning all parts of the Zeigertest were presented to both eyes (natural viewing condition). Then, the object for one of the eyes was switched off leaving the frame as the only fusional stimulus. The outcome variable was a refixation movement of the other eye. This experiment is similar to the unilateral cover test. Experiment 2: In the beginning all parts of the Zeigertest were presented to both eyes (natural viewing condition). Then, the original Zeigertest was switched on (clock hand presented only to the right eye, peripheral markings only to the left eye). The outcome variable was a change of vergence.

RESULTS

Experiment 1: A significant refixation movement did not occur in any of the subjects. Experiment 2. In all 9 subjects with "Fixation Disparity Type One" the vergence changed significantly between 2.4 and 14.9 arcmin. The change of vergence correlated significantly with the angle of the perceived misalignment between clock hand and peripheral markings.

CONCLUSION

A fixation disparity ascertained at the Zeigertest does not indicate a fixation disparity under natural viewing conditions.

[Etiology of contact lens failure in pediatric aphakia. Indications for intraocular lenses?]

Due to the low rate of complications, lentectomy and contact lens fitting is the standard treatment for congenital cataract. However, contact lens fitting is not possible in all children. The authors report the main reasons for discontinuation of contact lenses in their patients.

METHOD

In 134 consecutive lentectomies of 90 children, the underlying eye diseases and general diseases, the age at operation, compliance of parents and children, and social background were analyzed.

RESULTS

Twenty of the 90 children had to discontinue contact lens wearing. Twelve of these children were operated on one eye and 8 on both eyes. Only 2 children showed signs of contact lens complications. In 2 children treatment was stopped because of the poor visual prognosis and in 10 children the parents discontinued contact lens treatment because of a severe handicap of the child (n = 2) or due to misunderstanding and parental noncompliance (n = 8). Six children refused contact lenses without obvious reasons. Among the latter, children 2-4 years of age were at the greatest risk. Children with additional systemic abnormalities frequently developed contact lens intolerance.

CONCLUSION

In children with systemic abnormalities and in the case of parental communication and compliance problems, discontinuation of contact lenses has to be expected in up to 30% of cases. In these children and in children who object to contact lenses at the age of 2-4 years, intraocular lens implantation should be considered, especially in unilateral cataract, if successful contact lens treatment is not achievable within 8-12 weeks.

[Orbital sarcoidosis--a case with an unusual course]

BACKGROUND

Most cases of orbital sarcoidosis are associated with a systemic sarcoidosis.

PATIENTS AND METHODS

A 67-year-old woman suffered from an orbital mass on the right side, which led to disturbance of the ocular motility. Slight improvement was achieved by the administration of systemic steroids.

RESULTS

Histologically a chronic granulomatous inflammation was revealed in the biopsy of the orbital mass. The suspected diagnosis was sarcoidosis, but three conventional chest X-rays within 10 months and the serum angiotensin-converting-enzyme were normal. Suprisingly a computertomography of the chest showed mediastinal lymphomas.

CONCLUSION

Granulomatous orbital inflammation without any local cause or other systemic granulomatous disease strongly suggests a systemic sarcoidosis. In case of missing lymph node enlargement in conventional chest X-ray computertomography should be performed.

Visual field defects in optic neuritis and anterior ischemic optic neuropathy: distinctive features

BACKGROUND

We analyzed the value of visual-field defects in the differential diagnosis of optic neuritis (ON) and non-arteritic anterior ischemic optic neuropathy (AION).

METHODS

Ninety-nine consecutive patients with acute-onset optic neuropathy formed the basis for this study. Compressive and vasculitic neuropathies were excluded. Eighty-six patients fulfilled the criteria for either ON (50 patients): < or = 35 years, normal disk, recovery of visual function, or AION (36 patients): > or = 60 years, swelling of the disk, no recovery of visual function. Without knowledge of other clinical data, visual fields obtained by Gold-mann perimetry were classified into five types of defects (forced choice). With the correct diagnosis at hand, fields were reviewed for characteristic features.

RESULTS

Forced-choice classification into defect types [%]: Central scotoma ON 68, AION 18; superior altitudinal defect ON 13 AION 7; inferior altitudinal defect ON 8, AION 52; peripheral defect ON 1, AION 5; diffuse defect ON 10, AION 18. Search for pathognomonic defects: a scotoma centered on the fixation point with a sloping border occurred exclusively in ON (25 of 50 patients). An inferior altitudinal defect with a sharp border along the horizontal meridian, particularly in the nasal periphery, occurred only in AION (10 of 36 patients). A steep centrocecal scotoma occurred in 3 of the 36 AION cases and not at all in the ON cases. Scotomas in the center breaking through to the periphery, superior altitudinal defects (with a sloping border along the horizontal meridian) and diffuse depressions verging on blindness occurred in both ON and AION.

CONCLUSION

A sctoma centered on the fixation point with a sloping border is highly characteristic of ON, while an inferior altitudinal defect with a sharp border along the horizontal meridian, particularly in the nasal periphery, is highly characteristic of AION. To identify these diagnostic criteria, it can be necessary to examine full fields. With restriction of perimetry to 30 degrees a large central scotoma can be mistaken for a diffuse defect and the border in the nasal periphery can be missed.

MRI of lymphomas of the orbits and the paranasal sinuses

PURPOSE

The purpose of this study was to point out MR characteristics of non-Hodgkin lymphomas of the orbits and the paranasal sinuses and the benefit of fat-suppressed contrast-enhanced sequences.

METHOD

The MR images of 16 patients with lymphoma of the orbits and the paranasal sinuses were retrospectively analyzed for signal intensity, contrast enhancement, bone destruction, and mass effect. The findings were confirmed by means of biopsy (Stage IE disease) or follow-up imaging after chemotherapy (Stage IV disease).

RESULTS

MRI clearly delineated the extension of the lymphomas. On the T1-weighted images, the signal intensity of the lymphoma was hypointense compared with the gray matter of the brain in 12 cases and intermediate in 4 cases. The T2-weighted fast SE images showed a hyperintense signal in 12 cases, intermediate in 3 cases, and even hypointensity in 1 case. All lesions enhanced after intravenous Gd-DTPA administration, reliably visible in the T1-weighted fat-suppressed sequences but not visible in three cases in the T1-weighted SE sequences. Bony wall destruction was evident in cases with paranasal but never in isolated orbital lymphoma.

CONCLUSION

While extension of lymphoma can be accurately described by MRI, a specific diagnosis is not achievable on the basis of signal intensities and enhancement patterns alone. Therefore, at least in cases of suspected Stages IE and IIE, biopsy proof is needed. Fat-suppressed contrast-enhanced sequences possess the highest detection rate and should therefore always be applied.

Shift of equiluminance in congenital color vision deficiencies: pattern-ERG, VEP and psychophysical findings

We compared electrophysiological responses [pattern-ERG (PERG) and VEP] and psychophysical measures to color stimuli to separate different forms of anomalous color vision. PERG and VEP were recorded from seven normals and 14 subjects with congenital color vision deficiencies. Stimuli were color checkerboards with 0.5 deg check size, phase reversing at 34 rev/sec. The luminances of the red and green parts were varied in opposite direction from 0 to 30 cd/m2, while the hue of individual squares and space-averaged luminance were held constant. This allowed for one equiluminance condition where flicker appeared fused. In the seven normals, the subjective equiluminance was reached at a luminance ratio red/(red + green) = 0.50-0.53. At that point, the PERG amplitude was moderately, and the VEP amplitude sharply reduced. In 14 color anomalous subjects both the PERG and VEP were sharply reduced at equiluminance. These dips were shifted compared to normals and the dip position corresponded to the predicted luminance ratios obtained by calculations from L- and M-cone activation using the Smith-Pokorny transformation. As we found a close correlation of the VEP-dip position and the anomalous quotient, these electrophysiological measures may allow objective assessment of color vision deficiencies.

Midline granuloma presenting as orbital cellulitis

BACKGROUND

Lethal midline granuloma usually presents with rhinorrhoea and redness of the skin above the nose. Early ocular symptoms are very rare. We here describe a patient who presented with acute orbital cellulitis.

PATIENT

A 73-year-old woman had a 24-h history of severe pain around her left eye. We saw the typical clinical picture of orbital cellulitis. A CT scan revealed a diffuse infiltration of the left upper and lower lid, the anterior orbit and the ethmoidal sinuses.

RESULT

On surgical exploration we found a granular, partly necrotic tumour. Histological examination revealed an angiocentric nasal T-cell lymphoma (midline granuloma).

CONCLUSION

Midline granuloma should be included in the differential diagnosis of acute orbital cellulitis.

Pattern, flicker, and flash electroretinography in human immunodeficiency virus infection: a longitudinal study

To study electroretinographic (ERG) changes in the course of human immunodeficiency virus (HIV) disease, 42 eyes without retinitis were examined twice or more. During 9.6 months of mean observation time the visual acuity did not change. We found progressive functional impairment for the first, second, and third neurons of the visual pathway: the pattern-ERG amplitude (retinal ganglion-cell function) decreased by 11%, the b-wave amplitude (bipolars mediated by Müller cells) decreased by 13%, and the a-wave amplitude (dominated by rods) diminished by 21%. The flicker amplitude (dominated by cones) decreased by 20%. All of the latter four changes were significant (P < 0.02). Damage to the retina in HIV infection cannot solely be explained by visible changes in HIV retinopathy.

[Short-term effect of megadose steroid therapy in optic neuritis]

15 patients with unilateral optic neuritis and 2 patients with bilateral optic neuritis were treated with 1000 mg methylprednisolone i.v. per day for 5 days. In the cases of unilateral optic neuritis, visual acuity was reduced to < or = 0.1, in those with bilateral optic neuritis to < or = 0.6 in the better eye. The treatment was started one to 70 days after the onset of the neuritis. We examined whether vision recovered rapidly during the treatment. As a rapid recovery we defined a fourfold improvement on a logarithmic scale during the 5 days of methylprednisolone medication. Such a rapid recovery was found in 11 of the 15 patients with unilateral and in 1 of the 2 patients with bilateral optic neuritis. A similar recovery was not found before and after the treatment interval. Although we did not have a control group, the correlation in time between the therapy and the rapid recovery suggests that the megadose steroids were effective in our patients. This interpretation is compatible with the results of the randomized controlled multicenter trial of Beck et al. (New Engl. J. Med. 326:81, 1992): However, the beneficial effect was seen up to 6 months only; one year after treatment, visual functions did no longer differ between the megadose and the placebo groups. Low-dose oral steroids did not improve visual function at any time and carried a higher risk for new episodes of neuritis, compared to placebo. Therefore, the "traditional" low-dose steroid therapy for optic neuritis has become obsolete.

Sezolamide: additivity to timolol twice daily

Sezolamide, a potent topical carbonic anhydrase inhibitor previously known as MK-417, was studied to determine its ocular hypotensive activity in patients with elevated intraocular pressure while on continuing therapy with topical timolol. This was a three-centre, double-masked, randomised, placebo-controlled, parallel study in 36 patients with bilateral primary open angle glaucoma or ocular hypertension on therapy receiving 0.5% timolol twice daily, with a morning intraocular pressure greater than or equal to 22 mmHg in both eyes 2-4 hours following an 8 a.m. dose of timolol. Sezolamide 1.8% or placebo twice daily was added to treatment with timolol on the evening of day 1 and continued for 2 weeks. Twelve-hour diurnal curves were performed before the study on day 1 (timolol alone) and on day 15. Intraocular pressure measurements were also taken on days 2 and 8 at 8 a.m. and 9 a.m. Patients who received timolol and sezolamide showed additional intraocular pressure reductions from day 1 (timolol alone) of 8.0 to 15.5%, which were significant at all times. At hours 1, 2, 4 and 8 the reductions in intraocular pressure observed in the group receiving sezolamide and timolol were significantly greater than those in the group receiving timolol and placebo.

Retinal and cortical activity in human subjects during color flicker fusion

Pattern electroretinograms (PERG) and cortical visually evoked potentials (VEP) were simultaneously recorded from 7 visually normal and 1 protanopic subjects. Stimuli were color checkerboards (0.5 degrees check size), phase-reversing at 17 Hz (i.e. 34 reversals/sec). Using a stepwise sweep procedure, the luminance of the red (lambda peak = 550 nm) and green (lambda peak = 630 nm) checks varied in 11 steps in opposite directions from 0 to 30 cd/m2, embracing the subjective equiluminance point. For normal subjects at subjective equiluminance, the VEP amplitude dropped sharply down to 13 +/- 2% of the value at pure luminance contrast. The PERG, however, was only reduced to 56 +/- 10% at this point, an attenuation 4 times less than that of the VEP. In contrast to normal subjects, in the protanopic subject the PERG was sharply reduced at equiluminance, parallel to the VEP. This would be expected when L-cones are missing. Assuming that the PERG reflects the activity of the retinal ganglion cells, our findings suggest that human retinal ganglion cells respond well under the condition of equiluminant flicker fusion, which is in agreement with recent single-cell studies in the monkey. Consequently, the temporal low-pass filter, which mediates color-flicker fusion, would seem to lie central to the retinal ganglion cells.

Changes of slow cortical negative DC-potentials during the acquisition of a complex finger motor task

To study whether electrophysiological correlates of increasing motor skill can be demonstrated in man, we recorded cortical negative DC-potentials during the acquisition of a complex finger movement in 21 subjects. The movement consisted in moving a matchstick to and fro between the index finger (II) and the little finger (V). Cortical negative DC-potentials were recorded at Fz, Cz, C1, C2 and Pz. As a control a simple finger movement was performed during the same session by 7 of the Ss. Both tasks were repeated 60-80 times and averages of the first and the last 15 artifact-free single runs were compared. Whereas only a slight, inconstant decrease in surface electronegativity during the simple motor task was observed, a significant reduction in potential size occurred during the complex task at Cz (maximum), C1, C2 and Pz but not at Fz. In addition, a significant difference in the decrease of surface electronegativity between various electrode positions was observed. We suggest that these changes in potential size during the process of motor learning may reflect an altered cortical organisation of movement control during the acquisition of a complex motor task.

Comparative tolerability of topical carbonic anhydrase inhibitor MK-927 and its S-enantiomer MK-417

A single-dose, randomised, double-masked, placebo-controlled, five-period cross-over comparative ocular tolerance study was undertaken with the topical carbonic anhydrase inhibitor (CAI) MK-927 (1% and 2% concentrations) and its S-enantiomer MK-417 (1% and 1.8% concentrations) in 20 healthy, normal volunteers. Subjects received one drop of placebo (common vehicle) or CAI in each eye on five different days that were separated by washout intervals of 1 week. The incidence of burning increased significantly after treatment with 2% MK-927 (P less than 0.01) and 1.8% MK-417 (P less than 0.05) as compared with placebo. The mean duration of burning following placebo was 16.8 s, somewhat less than that following CAI application (23-37.1 s). The duration of tearing following CAI treatment was also significantly prolonged (P less than 0.05). Pupil size was not changed by CAIs. No other side effects were observed. At 3 h after instillation, intraocular pressure (IOP) was found to be decreased following all four CAI treatments, significantly so with 1% and 1.8% MK-417. The reasonable single-dose tolerability of MK-927 and MK-417 in this sensitive normal-volunteer model supports their potential as topical glaucoma medications. This study suggests that MK-417 may possess greater IOP-lowering activity than MK-927 in man.

Patterns of task-related slow brain potentials in dyslexia

Six dyslexic youths who met the Hughes and Denckla criteria of "dyslexia pure" and 10 normal control subjects were investigated with DC recordings of task-related cortical negativity using 10 leads over the right and left hemispheres. Potentials were recorded during the following tasks: reading, orthographic error detection, letter series, word assembly, word fluency, finding of antonyms, and viewing of Necker cubes. Both groups exhibited greater right hemisphere negativity during the Necker cube task. Whereas controls revealed greater left hemisphere negativity during linguistic tasks, the reverse was found with dyslexics. The right shift was pronounced with the reading, orthographic error detection, and antonym conditions. Differences between the two groups were also found for the pattern of cortical distribution. We conclude that dyslexia is associated with changes in the lateral distribution of cortical activity during certain types of language processing.

Spatial-frequency discrimination of drifting gratings

Spatial-frequency discrimination thresholds were measured for briefly (300 msec) presented sinewave gratings having a contrast one logarithmic unit above detection threshold. The gratings were drifted at rates varying from 1.1 to 40 Hz. In a two-interval forced-choice paradigm thresholds were determined for vertically and obliquely oriented gratings. Three reference spatial frequencies (1, 4, 12 c/deg) were tested. For the 1 c/deg reference spatial frequency, spatial-frequency discrimination thresholds were constant over the wide range of drift rates used. For 4 and 12 c/deg reference gratings, discrimination thresholds were constant for drift frequencies up to 14 Hz. For drift frequencies beyond 14 Hz, spatial-frequency discrimination thresholds increased abruptly, rising from approx. 6% at 14 Hz to 25% at 40 Hz drift rate. Measurements with obliquely oriented gratings yielded comparable results. The increase in the spatial-frequency discrimination threshold for medium-high spatial frequencies and high temporal frequencies might reflect an increase in the spatial frequency bandwidth of the mechanisms sensitive to these stimulus frequencies.

Duration of visual afterimages on modulated backgrounds: postreceptoral processes

A foveal afterimage produced by a small photoflash increases in duration when the luminance of a 5.8 degrees diameter background on which it is seen is temporally modulated. At a modulation frequency of 1 Hz and a depth of modulation of 52%, the duration of the afterimage is prolonged by 335% compared to the duration obtained on a steady background. This increase has been attributed to the functional border resulting from the difference in excitability between bleached and unbleached photoreceptors. Afterimage duration is also prolonged, although only by 20%, when the luminance of the background is kept constant, while the luminance of an annular surround is modulated. This finding suggests a weak effect of neural lateral interaction (via area contrast). If the background luminance is modulated only in the contralateral eye (dichoptic presentation), afterimage duration increases by as much as 54% compared to the unmodulated state. This result indicates that afterimages, in part, are sustained by processes mediated by the visual cortex.