Spinal cord involvement by atrophy and associations with disability are different between multiple sclerosis and neuromyelitis optica spectrum disorder

BACKGROUND AND PURPOSE

The cervical and thoracic cross-sectional spinal cord area (CS-SCA) in multiple sclerosis (MS) correlates with disability, whilst such a correlation remains to be established in neuromyelitis optica spectrum disorder (NMOSD). Our aim was to clarify differences between MS and NMOSD in spinal cord segments where CS-SCA is associated with disability.

METHODS

The CS-SCA at C2/C3, C3/C4, T8/T9 and T9/T10 vertebral disc levels was measured in 140 MS patients (111 with relapsing-remitting MS and 29 with progressive MS) and 42 NMOSD patients with anti-aquaporin-4 immunoglobulin G. Disability was evaluated by Expanded Disability Status Scale (EDSS) scores. Multivariate associations between CS-SCA and disability were assessed by stepwise forward multiple linear regression.

RESULTS

Thoracic CS-SCA was significantly smaller in NMOSD patients than in MS patients even after adjusting for age, sex and disease duration (P = 0.002 at T8/T9), whilst there was no difference in cervical CS-SCA between the two diseases. Cervical and thoracic CS-SCA had a negative correlation with EDSS scores in MS patients (P < 0.0001 at C3/C4 and P = 0.0002 at T8/T9) whereas only thoracic CS-SCA correlated with EDSS scores in NMOSD patients (P = 0.0006 at T8/T9). By multiple regression analyses, predictive factors for disability in MS were smaller cervical CS-SCA, progressive course, older age and a higher number of relapses, whilst those in NMOSD were smaller thoracic CS-SCA and older age.

CONCLUSIONS

Thoracic CS-SCA is a useful predictive marker for disability in patients with NMOSD whilst cervical CS-SCA is associated with disability in patients with MS.

Retinal function determined by flicker ERGs before and soon after intravitreal injection of anti-VEGF agents

Background

To evaluate the retinal function before and soon after an intravitreal injection of an anti-vascular endothelial growth factor (anti-VEGF) agents.

Methods

Seventy-nine eyes of 79 patients that were treated by an intravitreal injection of an anti-VEGF agent for age-related macular degeneration (AMD), diabetic macular edema (DME), or retinal vein occlusion (RVO) with macular edema (ME) were studied. The RETeval® system was used to record 28 Hz flicker electroretinograms (ERGs) from the injected and non-injected eyes before (Phase 1, P1), within 2 h after the injection (P2), and 2 to 24 h after the injection (P3). Patients were grouped by disease or by the injected agent and compared. The significance of the changes in the implicit times and amplitudes was determined by t tests.

Results

The amplitudes were not significantly different at the three phases. The implicit time of the injected eye was 31.2 ± 3.2 msec at P1, and it was not significantly different at P2 (31.7 ± 3.1 msec) but it was significantly longer at P3 (32.2 ± 3.3 msec, P < 0.01, ANOVA for both). The implicit time in the non-injected fellow eye was 30.5 ± 3.3 msec at P1, and it was significantly longer at P2 (31.1 ± 3.2 msec) and phase 3 (31.3 ± 3.4 msec, P < 0.01, ANOVA for both).

Conclusions

The results indicate that an intravitreal anti-VEGF injection will increase the implicit times not only in the injected eye but also in the non-injected eye soon after the intravitreal injection.

Electroretinograms recorded with skin electrodes in silicone oil-filled eyes

Purpose

To assess the physiology of the retina by electroretinography (ERG) with skin electrodes in eyes that had undergone vitrectomy with silicone oil (SO) tamponade.

Design

Retrospective case series.

Method

ERGs were recorded from eleven eyes with complex vitreoretinal disorders and from the normal fellow eyes. The affected eyes underwent pars plana vitrectomy (PPV) with SO tamponade. ERGs were recorded before and after the SO was removed. The amplitudes and implicit times of the a- and b-waves of the affected eyes were compared to those of the normal fellow eyes. In addition, the ratios of the amplitudes of the b-waves of the affected eyes to those of the fellow eyes were compared before and after the SO was removed.

Results

ERGs were recordable from 7 eyes (63.6%) before the SO was removed and 11 eyes (100%) after the SO was removed. The a- and b-wave amplitudes were significantly smaller in the affected eyes than those of the fellow eyes at the baseline. The b-wave amplitude before the removal of the SO was significantly and positively correlated with that after the SO removal. The ratios of the b-waves of the affected/normal fellow eye significantly increased after the SO was removed.

Conclusion

The results indicate that ERGs picked up by skin electrode can be used to assess the physiology of the retina in eyes with a SO tamponade. The amplitude of the b-waves of the ERGs in silicone-filled eyes can be used to predict the amplitude after the silicone is removed.

Automated Measurement of the Foveal Avascular Zone in Swept-Source Optical Coherence Tomography Angiography Images

Purpose

The purpose of this study was to evaluate automated measurement of the foveal avascular zone (FAZ) area using the Kanno-Saitama macro (KSM) software in Image J with swept-source optical coherence tomography angiography (SS-OCTA) images.

Methods

In this cross-sectional study, one photographer scanned the macular area (3 × 3 mm) of healthy volunteers twice on the same day, at the same time. The FAZ area was measured from the en face image of the superficial retinal layer by two masked examiners, using the KSM and the Advanced Retina Imaging (ARI)-network method in Carl Zeiss online analysis. Intra- and interscan reproducibility and FAZ area were compared among the methods.

Results

Forty eyes of 22 healthy volunteers were included in the analysis. The mean ± SD age of the subjects was 34.6 ± 12.4 years. Intra- and interscan intraclass coefficients ranged from 0.997 to 1.000 and 0.989 to 0.995, respectively. The mean FAZ area was 0.264 ± 0.08 mm² by the KSM, 0.245 ± 0.08 mm² by the ARI, and 0.281 ± 0.09 mm² by the manual method. The mean difference between the KSM and manual methods was 0.015 mm², which was significantly smaller than the mean difference between the ARI and manual methods (0.034 mm²; P < 0.001).

Conclusions

Automated determination of the FAZ area is feasible and yields results comparable to those obtained by manual measurement. The FAZ area measured with the KSM program is less user dependent and could potentially contribute to our understanding of the pathophysiology of various retinal diseases, particularly underlying vascular diseases.

Translational Relevance

This study demonstrates a novel automated determination of the FAZ area using the Image J macro program in SS-OCTA images. This program was feasible and yields results comparable to those obtained by manual measurement.

Intravitreal Injection of 1.25% Povidone Iodine Followed by Vitrectomy Using 0.025% Povidone Iodine Irrigation for Treating Endophthalmitis

Purpose

To investigate the safety and effectiveness of intravitreal injection (IVI) of 1.25% povidone iodine (PI) followed by vitrectomy using 0.025% PI irrigation for treating endophthalmitis.

Methods

Prospective case series study. Nine eyes of 8 patients with postoperative or endogenous endophthalmitis treated at the Nihon University Hospital between April 2015 and October 2017 were studied. First, IVI of 0.1 mL/1.25%PI was conducted, followed by anterior chamber irrigation and vitrectomy using 0.025%PI irrigation solution. Corneal epithelial damage, anterior chamber inflammation, and vitreous inflammation were assessed and fundus examinations were performed, using a slit-lamp microscope and indirect ophthalmoscopy. A specular microscope, Goldmann perimetry, and electroretinography (ERG) were also used.

Results

In all but case 7, endophthalmitis resolved rapidly and good visual acuity was maintained. No adverse events were noted. Furthermore, the perioperative ERG showed improvements in the oscillatory potentials amplitudes on ERG and flicker ERG, as well as in the implicit time of the a-wave, suggesting functional recovery in the retinal outer and inner layers after therapy.

Conclusions

IVI of PI followed by vitrectomy was thought to be a safe and effective treatment for endophthalmitis.

Translational Relevance

We succeeded in proving the clinical safety of IVI of PI followed by vitrectomy with PI irrigation as well as previous experimental reports. PI is available in world widely, therefore this method will be optimal treatment for endophthalmitis.

Novel mutations in the RS1 gene in Japanese patients with X-linked congenital retinoschisis

X-linked congenital retinoschisis (XLRS) is an inherited retinal disorder characterized by reduced central vision and schisis of the macula and peripheral retina. XLRS is caused by mutations in the RS1 gene. We have identified 37 different mutations in the RS1 gene, including 12 novel mutations, in 67 Japanese patients from 56 XLRS families. We present clinical features of these patients in relation to the associated mutations.

Reproducibility of Macular Vessel Density Calculations Via Imaging With Two Different Swept-Source Optical Coherence Tomography Angiography Systems

Purpose

To evaluate the reproducibility of vessel density calculations using different binarization methods obtained via two commercially available swept-source optical coherence tomography angiography (SS-OCTA) systems.

Methods

Healthy volunteers were imaged using two swept-source optical coherence tomography angiography (SS-OCTA) devices, PLEXElite and Triton. SS-OCTA examinations were performed using a 3 × 3-mm volume scan pattern centered on the fovea. A total of six methods were used for binarization in ImageJ, two global thresholding and four local adaptive thresholding methods. Resultant vessel density values were compared between the instruments and binarization methods. Images for 60 eyes from 30 healthy subjects were assessed by two reviewers who were blinded to the scanning system used.

Results

Twenty-two eyes were excluded due to poor image quality (17 eyes from Triton, 4 eyes from PLEXElite, and 1 eye from both instruments, P = 0.003). A final 38 eyes from 23 subjects were eligible for analysis. Each binarization method and instrument led to different median values. The coefficients of variation for vessel density measurements ranged from 0.3% to 2.3% and 0.6% to 4.7% for the PLEXElite and Triton, respectively. Local adaptive thresholding methods revealed higher reproducibility than did global thresholding methods for both devices.

Conclusions

Macular scans with both SS-OCTA instruments showed good reproducibility for vessel density measurements. PLEXElite recorded fewer poor images and had higher reproducibility than did Triton. These findings will inform the selection of proper binarization methods for the clinical detection of vascular diseases affecting the central retina.

Translational Relevance

The reproducibility for macular vessel measurements with SS-OCTA instruments was good. PLEXElite recorded fewer poor images and had higher reproducibility than did Triton.

Clinical Features of Japanese Patients With Anti-α-enolase Antibody-Positive Autoimmune Retinopathy: Novel Subtype of Multiple Drusen

PURPOSE

To evaluate clinical features of Japanese patients with anti-α-enolase antibody-positive autoimmune retinopathy (anti-enolase AIR).

DESIGN

Multicenter retrospective observational case series.

METHODS

Forty-nine eyes of 25 Japanese anti-enolase AIR patients (16 female and 9 male; mean age at first visit, 60.8 years) were included. Fundus characteristics, perimetry, spectral-domain optical coherence tomography (SD-OCT), electroretinography (ERG), best-corrected visual acuity (BCVA), and complicating systemic tumors were assessed. Protein localization of α-enolase was examined by immunohistochemistry in an enucleated eye of 1 patient.

RESULTS

Patients were classified into 3 groups: multiple drusen (48%), retinal degeneration (36%), and normal fundus (16%). Drusen varied in size from small deposits to vitelliform-like lesions. Images on SD-OCT revealed dome-shaped hyperreflectivity beneath the retinal pigment epithelium (RPE), corresponding to drusen. Perimetry showed that ring scotoma was the most frequent (39%). Rod-system and/or single-flash cone responses revealed decreased responses in 81% of the eyes. Combined rod and cone system responses demonstrated significantly lower a-wave amplitudes in the degeneration group than in the drusen group (P = .005). BCVA was improved or maintained in 80% of the eyes during follow-up. Malignant or benign tumors were detected in 30% of patients. The RPE and photoreceptor layers were immunopositive for α-enolase.

CONCLUSIONS

The drusen subtype, scarcely described in the literature, is suggested to characterize Japanese patients with anti-enolase AIR. The different funduscopic features with different functional severities may have resulted from antibody-mediated damage to RPE as well as photoreceptor cells.

Evaluation of microvascular changes in the macular area of eyes with rhegmatogenous retinal detachment without macular involvement using swept-source optical coherence tomography angiography

Purpose

To evaluate microvascular changes in the macular area of eyes with rhegmatogenous retinal detachment (RRD) without macular involvement (macula-on RRD) using swept-source optical coherence tomography angiography (SS-OCTA).

Patients and methods

Five patients with macula-on RRD were eligible for analysis. All patients underwent SS-OCTA examination (Triton) for the macular area. The healthy fellow eyes were included as controls. The vessel density (VD) was calculated using binarization, and the foveal avascular zone (FAZ) was measured. The VD and FAZ area were compared between the eyes with RRD and the fellow eyes using the Wilcoxon signed rank test.

Results

The patients’ clinical characteristics were as follows: age, 49.0 years (21.0, 54.0) (median [25, 75th percentile]); preoperative best-corrected visual acuity, −0.08 (−0.08, 0.11) for RRD and −0.08 (−0.08, −0.03) for the fellow eye (P=0.50); and axial length, 27.0 (25.1, 28.7) mm for RRD and 27.4 (25.6, 28.5) mm for the fellow eye (P=0.31). The parafoveal VD was not significantly different between the eyes with RRD and the fellow eyes (P=1.00 for the superficial retina and P=0.44 for the whole retina). The FAZ area was also similar for the eyes with RRD and the fellow eyes (P=0.31 for the superficial retina and P=0.13 for the whole retina).

Conclusion

The findings of this study suggest that the macular microvasculature remains intact in eyes with macula-on RRD.

Optic disc vessel density in nonglaucomatous and glaucomatous eyes: an enhanced-depth imaging optical coherence tomography angiography study

Purpose

To evaluate the ability of enhanced-depth imaging (EDI) optical coherence tomography angiography (OCTA) to detect vascular signals inside the glaucomatous optic disc.

Patients and methods

Ten glaucomatous eyes of 8 subjects and 11 nonglaucomatous eyes of 7 subjects underwent EDI and conventional OCTA for optic disc analysis. The optic disc vessel density (VD) at maximum scan depth (2 mm) was compared between the 2 methods and between glaucomatous and nonglaucomatous eyes. Regression analysis was used to determine the factors affecting disc VD.

Results

The median (25th, 75th percentile) of the visual field mean deviation was −20.5 (−25.1, −13.5) dB in glaucoma. The disc VD measured with the EDI method was significantly greater than that measured with the conventional method in glaucoma and nonglaucoma. The disc VD was also significantly lower in glaucoma than in nonglaucoma. The disc VD and mean deviation were significantly and positively correlated in both methods (conventional: R²=0.27, EDI: R²=0.22).

Conclusion

The correlation between disc VD and glaucoma severity was comparable between conventional and EDI measurements. Images obtained with EDI-OCTA have the additional benefit of revealing more vascular signals in deeper layers. The disc VD, as determined by both conventional and EDI-OCTA methods, may be an indicator of glaucoma severity.

Visual prognosis better in eyes with less severe reduction of visual acuity one year after onset of Leber hereditary optic neuropathy caused by the 11,778 mutation

Background

Patients with Leber hereditary optic neuropathy (LHON) have a progressive decrease of their visual acuity which can deteriorate to <0.1. Some patients can have a partial recovery of their vision in one or both eyes. One prognostic factor associated with a recovery of vision is an early-age onset. The purpose of this study was to determine other clinical factors that are predictive of a good visual recovery.

Methods

Sixty-one Japanese LHON patients, with the 11,778 mutation and a mean age of 23.1 ± 12.1 years at the onset, were studied. All patients were initially examined at an acute stage of LHON and were followed for 3 to 10 years. At 1 year after the onset, the lowest visual acuity was <0.1 in all eyes. We studied the following parameters of patients with/without a final visual acuity of ≥ 0.2: sex; heavy consumption of cigarettes and alcohol; taking idebenone; mean age at onset; mean lowest visual acuity; and distribution of the lowest and the final visual acuity.

Results

Fifteen (24.6%) of the 61 patients or 25 (20.5%) of the 122 eyes had a recovery of their visual acuity to ≥ 0.2. The mean age at onset of these 15 patients with visual recovery to ≥ 0.2 was 17.5 ± 7.7 years, and that of the 46 patients without visual recovery to ≥ 0.2 was 25.0 ± 12.8 years (P = 0.02, Mann-Whitney U test). The mean lowest visual acuity of the 25 eyes with visual recovery ≥ 0.2 was 0.04, and that of the 97 eyes without visual recovery to ≥ 0.2 was 0.015 (P < 0.001, Mann-Whitney U test). Fifty percent (15/30) of the eyes whose lowest visual acuity was ≥ 0.04 during 1 year after the onset had a visual recovery to ≥ 0.2, while 11% (10/92) of the eyes whose the lowest visual acuity was ≤ 0.03 had a visual recovery to ≥ 0.2 (P < 0.001, χ² test). There were no significant differences in the other clinical factors.

Conclusion

A final visual acuity of ≥ 0.2 was associated with a less severe reduction of the visual acuity at 1 year after the onset. Our findings can be used to predict the visual prognosis in LHON patients.

Novel RP1L1 Variants and Genotype-Photoreceptor Microstructural Phenotype Associations in Cohort of Japanese Patients With Occult Macular Dystrophy

PURPOSE

To determine the clinical and genetic characteristics of Japanese patients with occult macular dystrophy (OMD) in a nationwide multicenter study.

METHODS

Twenty-three patients from 21 families with clinically diagnosed OMD were studied at 10 institutions throughout Japan. Ophthalmologic examinations including spectral-domain optic coherence tomography were performed. Patients were classified into two phenotype groups: a classical group having both blurred ellipsoid zone and absence of interdigitation zone of the photoreceptors, and a nonclassical group lacking at least one of these two features. Whole-exome sequencing, direct sequencing, and in silico molecular analysis were performed to detect the pathogenic RP1L1 variants. Statistical associations between the phenotype and genotypes based on the presence of pathogenic RP1L1 variants were investigated.

RESULTS

There were 12 families with the classical findings and 9 families with the nonclassical findings. Nine pathogenic RP1L1 missense variants were identified in 12 families (57%) including three reported variants, namely, p.R45W, p.S1199C, and p.G1200A, and six novel variants, p.G221R, p.T1194M, p.T1196I, p.G1200D, p.G1200V, and p.V1201G. The pathogenic missense variants in seven families (33%) were located between amino acid numbers 1196 and 1201. A significant association was found between the photoreceptor microstructural phenotypes and molecular genotypes.

CONCLUSIONS

The spectrum of the morphologic phenotypes and pathogenic RP1L1 variants was documented in a well-characterized Japanese cohort with OMD. A unique motif including six amino acids (1196-1201) downstream of the doublecortin domain could be a hot spot for RP1L1 pathogenic variants. The significant association of the morphologic phenotypes and genotypes indicates that there are two types of pathophysiology underlying the occult macular dysfunction syndrome: a hereditary OMD with the classical phenotype (Miyake's disease), and a nonhereditary OMD-like syndrome with progressive occult maculopathy.

In vivo crystalline lens measurements with novel swept-source optical coherent tomography: an investigation on variability of measurement

Objective

To evaluate the reproducibility of in vivo crystalline lens measurements obtained by novel commercially available swept-source (SS) optical coherence tomography (OCT) specifically designed for anterior segment imaging.

Methods and analysis

One eye from each of 30 healthy subjects was randomly selected using the CASIA2 (Tomey, Nagoya, Japan) in two separate visits within a week. Each eye was imaged twice. After image scanning, the anterior and posterior lens curvatures and lens thickness were calculated automatically by the CASIA2 built-in program at 0 dioptre (D) (static), -1 D, -3 D and -5 D accommodative stress. The intraobserver and intervisit reproducibility coefficient (RC) and intraclass correlation coefficient (ICC) were calculated.

Results

The intraobserver and intervisit RCs ranged from 0.824 to 1.254 mm and 0.789 to 0.911 mm for anterior lens curvature, from 0.276 to 0.299 mm and 0.221 to 0.270 mm for posterior lens curvature and from 0.065 to 0.094 mm and 0.054 to 0.132 mm for lens thickness, respectively. The intraobserver and intervisit ICCs ranged from 0.831 to 0.865 and 0.828 to 0.914 for anterior lens curvature, from 0.832 to 0.898 and 0.840 to 0.933 for posterior lens curvature and from 0.980 to 0.992 and 0.942 to 0.995 for lens thickness. High ICC values were observed for each measurement regardless of accommodative stress. RCs in younger subjects tended to be larger than those in older subjects.

Conclusions

This novel anterior segment SS-OCT instrument produced reliable in vivo crystalline lens measurement with good repeatability and reproducibility regardless of accommodation stress.

Clinical and Genetic Findings of Autosomal Recessive Bestrophinopathy in Japanese Cohort

PURPOSE

To report the clinical and genetic findings of 9 Japanese patients with autosomal recessive bestrophinopathy (ARB).

DESIGN

Retrospective, multicenter observational case series.

METHODS

Nine ARB patients from 7 unrelated Japanese families that were examined in 3 institutions in Japan were studied. A series of ophthalmic examinations including fundus photography, spectral-domain optical coherence tomography, fundus autofluorescence, electrooculography (EOG), electroretinography, and the results of genetic analysis were reviewed.

RESULTS

Genetic analyses identified 7 pathogenic variants in BEST1 including 2 novel variants, c.478G>C (p.A160P) and c.948+1delG. Homozygous variants were found in 4 families and compound heterozygous variants were found in 3 families. Two patients were diagnosed as ARB only after the whole exome sequencing analyses. The Arden ratio of the EOG was less than 1.5 in all 7 patients tested. Vitelliform lesions typical for Best vitelliform macular dystrophy were not seen in any of the patients. Seven patients shared some of the previously described features of ARB: subretinal deposits, extensive subretinal fluid, and cystoid macular edema (CME). However, the other 2 patients with severe retinal degeneration lacked these features. Focal choroidal excavations were present bilaterally in 2 patients. One case had a marked reduction of the CME and expansion of subretinal deposits over an 8-year of follow-up period.

CONCLUSIONS

Japanese ARB patients had some but not all of the previously described features. Genetic analyses are essential to diagnose ARB correctly in consequence of considerable phenotypic variations.

Detailed analysis of family with autosomal recessive bestrophinopathy associated with new BEST1 mutation

Purpose

To describe the clinical and genetic findings in a patient with autosomal recessive bestrophinopathy (ARB) and his healthy parents.

Methods

The patient and his healthy non-consanguineous parents underwent detailed ophthalmic evaluations including electro-oculography (EOG), spectral-domain optical coherence tomography (SD-OCT), and fundus autofluorescence (FAF) imaging. Mutation analysis of the BEST1 gene was performed by Sanger sequencing.

Results

The FAF images showed multiple spots of increased autofluorescence, and the sites of these spots corresponded to the yellowish deposits detected by ophthalmoscopy. SD-OCT showed cystoid macular changes and a shallow serous macular detachment. The Arden ratio of the EOG was markedly reduced to 1.1 in both eyes. Genetic analysis of the proband detected two sequence variants of the BEST1 gene in the heterozygous state: a novel variant c.717delG, p.V239VfsX2 and an already described c.763C>T, p.R255W variant associated with Best vitelliform macular dystrophy and ARB. The proband’s father carried the c.717delG, p.V239VfsX2 variant in the heterozygous state, and the mother carried the c.763C>T, p.R255W variant in the heterozygous state. The parents who were heterozygous for the BEST1 variants had normal visual acuity, EOG, SD-OCT, and FAF images.

Conclusions

In a truncating BEST1 mutation, the phenotype associated with ARB is most likely due to a marked decrease in the expression of BEST1 promoted by the nonsense-mediated decay surveillance mechanism, and it may depend on the position of the premature termination of the codon created.

Assessment of Macular Function during Vitrectomy: New Approach Using Intraoperative Focal Macular Electroretinograms

Purpose

To describe a new technique to record focal macular electroretinograms (FMERGs) during vitrectomy to assess macular function.

Methods

Intraoperative FMERGs (iFMERGs) were recorded in ten patients (10 eyes) who undergo vitrectomy. iFMERGs were elicited by focal macular stimulation. The stimulus light was directed to the macular area through a 25 gauge (25G) glass fiber optic bundle. Background light was delivered through a dual chandelier-type light fiber probe. Focal macular responses elicited with combinations of stimulus and background luminances were analyzed.

Results

A stimulus luminance that was approximately 1.75 log units brighter than the background light was able to elicit focal macular responses that were not contaminated by stray light responses. Thus, a stimulus luminance of 160 cd/m² delivered on a background of 3 cd/m² elicited iFMEGs from only the stimulated area. This combination of stimulus and background luminances did not elicit a response when the stimulus was projected onto the optic nerve head. The iFMERGs elicited by a 10° stimulus with a duration of 100 ms and an interstimulus interval of 150 ms consisted of an a-, b-, and d-waves, the oscillatory potentials, and the photopic negative response (PhNR).

Conclusions

Focal ERGs with all components can be recorded from the macula and other retinal areas during vitreous surgery. This new technique will allow surgeons to assess the function of focal areas of the retina intraoperatively.

Structural and magnetic properties of mixed Co–Ln (Ln = Nd, Sm, Eu, Gd and Ho) diethyleneglycolate complexes

Co–Ln diethyleneglycolates consisting of 1D-chains of [(Ln₂Co₂)(Cl)₂(deg)₄] tetramers were produced in degH₂. In the tetramers 5 and 7 Co²⁺ and Ln³⁺ coordinated cations are antiferromagnetically weakly interacting.