Course of pattern-reversed visual evoked cortical potentials in 30 eyes after bony orbital decompression in dysthyroid optic neuropathy

Diagnostic methods for dysthyroid optic neuropathy: A systematic review and analysis

Diagnosis of dysthyroid optic neuropathy (DON) typically relies on a set of diagnostic clinical features, including decreased visual acuity, impaired color vision, presence of relative afferent pupillary defect, optic disc swelling and ancillary tests including visual field (VF), pattern visual evoked potential (pVEP), and apical crowding or optic nerve stretching on neuroimaging. We summarize various diagnostic methods to establish or rule out DON. A total of 95 studies (involving 4619 DON eyes) met the inclusion criteria. All of the studies considered clinical features as evidence of DON, while most of the studies confirmed DON diagnosis by combining clinical features with ancillary tests. Forty studies (42.1%) used at least 2 out of the 3 tests (VF, pVEP and neuroimaging) and 13 studies (13.7%) used all 3 tests to diagnose DON. In 64 % of the published studies regarding DON, the diagnostic methods of DON were not specified. It is important to note the limitations of relying solely on clinical features for diagnosing DON. On the other hand, since some eyes with optic neuropathy can be normal in one ancillary test, but abnormal in another, using more than one ancillary test to aid diagnosis is crucial and should be interpreted in correlation with clinical features. We found that the diagnostic methods of DON in most studies involved using a combination of specific clinical features and at least 2 ancillary tests.

Surgical management of dysthyroid optic neuropathy: A systematic review

OBJECTIVE

There is currently no recommendation on the optimal surgical management for dysthyroid optic neuropathy (DON). The aim of this study is to systematically review the surgical management of DON and its outcome on visual acuity (VA).

DATA SOURCES

MEDLINE, Cochrane Library, and clinicaltrials.gov REVIEW METHODS: A systematic review of studies about the surgical management of DON was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Articles were included if preoperative and postoperative VA in logMAR (Logarithm of the Minimum Angle of Resolution) were available.

RESULTS

Fifteen articles were included in the study accounting for 669 orbits. The mean VA improvement was of 0.44 logMAR overall, 0.41 logMAR for 1-wall, 0.41 logMAR for 2-wall, and 0.55 logMAR for 3-wall decompressions. The mean reduction in exophthalmos was 4.9 mm overall, 4.3 mm for 1-wall, 4.54 mm for 2-wall, and 6.02 for 3-wall decompressions. The mean new onset diplopia (NOD) rate was 19.84% overall, 19,12% for 1-wall, 20.75% for 2-wall, and 19.83% for 3-wall decompressions.

CONCLUSION

The results are limited due to the high number of biases in the included studies. It seems that 3-wall decompression offers the best VA improvement and proptosis reduction although also the highest NOD and complications rate. Two-wall balanced decompression or 1-wall inferomedial decompression seems to be effective with less morbidity.

Comparison of surgical effect in active and inactive Dysthyroid Optic Neuropathy after Endoscopic Transnasal Medial Orbital Decompression

PURPOSE

To evaluate and compare the changes in orbital soft tissue volume and visual function after endoscopic transnasal medial orbital decompression in patients with active and inactive dysthyroid optic neuropathy (DON).

METHODS

This prospective, cohort study recruited 112 patients (112 eyes) with DON who were divided into an active and inactive DON group (56 eyes each) by clinical activity scores. All patients underwent endoscopic transnasal medial orbital decompression. The pre- and post-operative orbital soft tissue volumes were measured with high-resolution computed tomography (CT) using Mimics software. Visual function, including best-corrected visual acuity (BCVA), visual field (VF), and visual evoked potential (VEP), was recorded before and after surgery.

RESULTS

Preoperatively, compared with the inactive DON group, the active DON group had greater extraocular muscle volume (EMV) and EMV/orbital volume (OV) ratio, but worse BCVA, VF, and exophthalmos. Postoperatively, although the EMV slightly increased, with the enlarged medial rectus muscle contributing dramatically, the EMV/OV ratio decreased in patients with DON. Besides, visual function including BCVA, VF, VEP and exophthalmos was also improved in both groups after surgery. There were no significant differences in postoperative OV; EMV; EMV/OV ratio; and the BCVA, VF, and VEP parameters between both groups (all P > 0.05).

CONCLUSION

Patients with DON who did not respond well to steroids, regardless of disease activity, may benefit from orbital decompression via the decrease in the proportion of EMV in OV, especially patients with active DON, who showed more improved visual function than patients with inactive DON.

Evaluation of visual evoked potentials in dysthyroid optic neuropathy

PURPOSE

To evaluate the findings of visual evoked potentials (VEP) in patients with dysthyroid optic neuropathy (DON).

METHODS

In this observational, cross-sectional study 40 eyes (22 patients) with a diagnosis of DON were included.

RESULTS

We discovered that in 16 out of 37 eyes with pattern-VEP (p-VEP), the latency of P100 wave was normal in spite of having a diagnosis of DON. The same pattern was also observed in the measurement of the amplitude of P100 wave: in 28 out of 37 eyes with p-VEP the amplitudes were observed as normal. In 3 eyes of 3 patients p-VEP showed no response, therefore a flash-VEP (f-VEP) was performed. Flash-VEPs of those patients indicated a prolonged P100 latency with a reduced amplitude. The sensitivity of abnormal P100 latency was 56.8% (95%CI 39.5-72.9%); and that of reduced P100 amplitude was 24.3% (95%CI 11.8-41.2%). Also, in 40 eyes color vision test by Arden was performed. In 36 eyes (20 patients) the tritan value was pathological (based on a threshold of ≥8%).

CONCLUSION

According our data, VEP seems to have a limited potential especially in patients with a good best-corrected visual acuity (BCVA ≤0.2 LogMAR) for identifying the optic nerve involvement. The fact that P100 latency and amplitude were normal even in cases with an optic nerve swelling makes us question the usefulness of the VEP for diagnosing cases of DON in daily clinical life.

Outcomes of Patients With Dysthyroid Optic Neuropathy Treated With Intravenous Corticosteroids and/or Orbital Decompression Surgery: A Systematic Review and Meta-analysis

CONTEXT

The level of evidence is low for the treatment of patients with dysthyroid optic neuropathy (DON) and there is no consensus on the treatment of DON with intravenous high-dose glucocorticoids (ivGC) or direct surgical decompression.

OBJECTIVE

To compare the efficacy of glucocorticoid treatment and orbital decompression (OD) in DON.

DATA SOURCES

PubMed, EMBASE, and Cochrane Library were searched along with other sources.

STUDY SELECTION

A total of 17 studies met the inclusion criteria.

DATA EXTRACTION

Standard methodological guidance of the Cochrane Handbook was used and data were independently extracted by multiple observers. The primary outcomes were the improvement of best corrected visual acuity (ΔBCVA). Secondary outcomes were proptosis reduction, change in diplopia, visual field defects, and intraocular pressure (IOP).

DATA SYNTHESIS

The ΔBCVA in the ivGC + OD group was improved 0.26 LogMAR more than in the ivGC group (P = .007). The ΔBCVA in the OD group was better than in the ivGC group (P = .008). Posttreatment proptosis in the ivGC + OD and OD groups were improved further by 3.54 mm and 3.00 mm, respectively, than in the ivGC group (P < .01). The mean deviation (MD) in the ivGC + OD group was improved by an additional 5.33 dB than in the ivGC group (P = .002). The IOP in the ivGC + OD group was improved further than in the ivGC group (P = .03).

CONCLUSIONS

Based on the results of the present meta-analysis, OD or ivGC + OD may be more effective in improving BCVA and MD and reducing proptosis compared with ivGC. Compared with ivGC alone, ivGC + OD is more effective in improving IOP than ivGC. Although this study improves the hierarchy of evidence in the treatment of DON, additional randomized controlled trials are needed to confirm this conclusion.

Reduced choroidal peripapillary capillaries in thyroid-associated ophthalmopathy with early stage of dysthyroid optic neuropathy

AIM

To investigate whether the subtle change of choroidal/retinal vessel densities and volumes in thyroid-associated ophthalmopathy (TAO) could be an early sign to detect dysthyroid optic neuropathy (DON).

METHODS

This was a retrospective cross-sectional study, and a total of 98 eyes from 50 subjects were enrolled under certain criteria. Thirty-four eyes of normal controls and 64 eyes of TAO, including 39 eyes of DON and 25 eyes of TAO without DON, underwent optical coherence tomography angiography (OCTA) scanning. All the tested parameters of OCTA scanning including choroid radial peripapillary capillaries (RPC), retinal nerve fiber layer (RNFL), and macular ganglion cell complex (GCC) were compared among groups, and the correlation between OCTA parameters and visual function parameters was also investigated.

RESULTS

Whole choroidal RPC was significantly reduced in DON (48.24%±0.4978%) compared to normal (50.33%±0.3173%) and TAO without DON (49.16%±0.5463%; P=0.0041). The reduction of whole choroidal RPC was also correlated with visual field (VF) defect in DON (r=0.5422, n=39). Although vision acuity and VF were improved in all the patients with DON after being treated with medical and surgical decompression, the reduction of RPC density were not reversed.

CONCLUSION

There is a notable reduction in choroidal RPC in DON, which is correlated with VF defect. The reduction of RPC density could not be reversed immediately by medical and surgical decompression even when vision and VF were improved. These findings suggest that choroidal RPC could be a useful parameter to diagnose and monitor early stage of DON.

Multi-Parametric Diffusion Tensor Imaging of The Optic Nerve for Detection of Dysthyroid Optic Neuropathy in Patients With Thyroid-Associated Ophthalmopathy

Objective

To evaluate the microstructural changes of the orbital optic nerve in thyroid-associated ophthalmopathy (TAO) patients with or without dysthyroid optic neuropathy (DON) using diffusion tensor imaging (DTI) and investigate whether DTI can be used to detect DON.

Materials and Methods

59 bilateral TAO patients with (n= 23) and without DON (non-DON, n= 36) who underwent pretreatment DTI were included and 118 orbits were analyzed. The clinical features of all patients were collected. DTI parameters, including mean, axial, and radial diffusivity (MD, AD, and RD, respectively) and fractional anisotropy (FA) of the intra-orbital optic nerve for each orbit were calculated and compared between the DON and non-DON groups. ROC curves were generated to evaluate the diagnostic performance of single or combined DTI parameters. Correlations between DTI parameters and ophthalmological characteristics were analyzed using correlation analysis.

Results

Compared with non-DON, the DON group showed decreased FA and increased MD, RD, and AD (P < 0.01). In the differentiation of DON from non-DON, the MD was optimal individually, and the combination of the four parameters had the best diagnostic performance. There were significant correlations between the optic nerve's four DTI metrics and the visual acuity and clinical active score (P < 0.05). In addition, optic nerve FA was significantly associated with the amplitude of visual evoked potentials (P = 0.022).

Conclusions

DTI is a promising technique in assessing microstructural changes of optic nerve in patients with DON, and it facilitates differentiation of DON from non-DON eyes in patients with TAO.

Clinical electrophysiology of the optic nerve and retinal ganglion cells

Clinical electrophysiological assessment of optic nerve and retinal ganglion cell function can be performed using the Pattern Electroretinogram (PERG), Visual Evoked Potential (VEP) and the Photopic Negative Response (PhNR) amongst other more specialised techniques. In this review, we describe these electrophysiological techniques and their application in diseases affecting the optic nerve and retinal ganglion cells with the exception of glaucoma. The disease groups discussed include hereditary, compressive, toxic/nutritional, traumatic, vascular, inflammatory and intracranial causes for optic nerve or retinal ganglion cell dysfunction. The benefits of objective, electrophysiological measurement of the retinal ganglion cells and optic nerve are discussed, as are their applications in clinical diagnosis of disease, determining prognosis, monitoring progression and response to novel therapies.

Retinal nerve fiber layer thickness measured by optical coherence tomography predicts visual recovery after orbital decompression for dysthyroid optic neuropathy

PURPOSE

To determine the prognostic value of optical coherence tomography (OCT) measurement of the peripapillary retinal nerve fiber layer (RNFL) thickness in visual recovery after orbital decompression of patients with dysthyroid optic neuropathy (DON).

METHODS

A total of 52 eyes of 37 patients who underwent orbital decompression for DON between 2013 and 2019 were retrospectively reviewed. We examined peripapillary RNFL thickness, best-corrected visual acuity (BCVA), visual field (VF) for mean deviation (MD) and pattern standard deviation (PSD), and pattern-reversed visual evoked potential (PVEP) for P100 latency and amplitude before and after surgery. Black and white checkerboard square sizes of PVEP were 15 and 60 arcmin (arcminute and minute of angle). Changes in RNFL overall thickness and by quadrant and interocular differences were evaluated and studied regarding changes in BCVA, VF and PVEP.

RESULTS

There was a significant improvement in BCVA, VF, and PVEP, whereas a dramatic reduction in RNFL thickness of all DON patients in global average, temporal, superior, and inferior quadrants (P = 0.005, P = 0.024, P = 0.016, and P = 0.001, respectively) after decompression surgery, except for nasal quadrant (P = 0.057). The preoperative RNFL thickness in each quadrant was negatively correlated with postoperative changes of BCVA and PSD and positively correlated with changes of MD and P100 amplitude at 60 arcmin (all P < 0.05). Except for temporal quadrant (P = 0.125), the preoperative RNFL thickness in other quadrants was positively correlated with postoperative changes of P100 amplitude at 15 arcmin (all P < 0.05). The nasal RNFL thickness was an excellent predictor for improvement in BCVA by 20/25 or better and in MD by 10 dB or more after surgery, whose cutoff value was 73.50 μm, while the inferior and superior RNFL thickness could act as a predictor for improvement in P100 amplitude by 5 μV or more at 60 arcmin and at 15 arcmin, respectively, whose cutoff value was, respectively, 143.00 μm and 130.50 μm (all P < 0.05).

CONCLUSION

RNFL thickness measured by OCT was correlated with visual function recovery after decompression surgery in patients with DON, which could also act as a predictor for better visual prognosis.

Comparison of 2-wall versus 3-wall orbital decompression against dysthyroid optic neuropathy in visual function: A retrospective study in a Chinese population

To compare visual function of 2-wall (medial and lateral) versus 3-wall (medial, lateral, and inferior) orbital decompression in patients with dysthyroid optic neuropathy (DON).A total of 52 eyes of 37 patients underwent orbital decompression for DON between 2013 and 2019 were retrospectively reviewed. Two- or 3-wall decompression was performed in 31 eyes of 23 patients and 21 eyes of 14 patients, respectively. We examined best-corrected visual acuity (BCVA), visual field mean deviation (MD) and pattern standard deviation (PSD), pattern-reversed visual evoked potential (PVEP) for P100 latency and amplitude at 60 and 15 arcmin stimulation checkerboard size, as well as proptosis using Hertel exophthalmometry.Whether 2-wall or 3-wall decompression, all parameters of visual function were improved after surgery (all P < .05). The improvement in BCVA, MD, and PSD was not statistically significant between groups (all P > .05). Proptosis reduction was higher after 3-wall decompression (P = .011). Mean increase in P100 amplitude after 3-wall decompression was statistically higher than that of after 2-wall decompression at 60 and 15 arcmin (P = .045 and .020, respectively), while the mean decrease in P100 latency was similar between the groups (P = .821 and .655, respectively). Six patients (66.67%) had persistent postoperative diplopia and 1 patient (20%) had new-onset diplopia in 3-wall decompression group, which were higher than in 2-wall decompression group (46.15% persistent postoperative diplopia and no new-onset diplopia).Both 2-wall and 3-wall decompression can effectively improve visual function of patients with DON. Three-wall decompression provides better improvement in P100 amplitude and proptosis, however new-onset diplopia is more common with this surgical technique.

Orbital decompression surgery for the treatment of Graves' ophthalmopathy: comparison of different techniques and long-term results

AIM

To evaluate the long-term results of different orbital decompression techniques performed in patients with Graves' ophthalmopathy (GO).

METHODS

Totally 170 cases with GO underwent orbital decompression between 1994 and 2014. Patients were divided into 4 groups as medial-inferior, medial-lateral (balanced), medial-lateral-inferior, and lateral only according to the applied surgical technique. Surgical indications, regression degrees on Hertel exophthalmometer, new-onset diplopia in the primary gaze and new-onset gaze-evoked diplopia after surgery and visual acuity in cases with dysthyroid optic neuropathy (DON) were compared between different surgical techniques.

RESULTS

The study included 248 eyes of 149 patients. The mean age for surgery was 42.3±13.2y. DON was the surgical indication in 36.6% of cases, and three-wall decompression was the most preferred technique in these cases. All types of surgery significantly decrease the Hertel values (P<0.005). Balanced medial-lateral, and only lateral wall decompression caused the lowest rate of postoperative new-onset diplopia in primary gaze. The improvement of visual acuity in patients with DON did not significantly differ between the groups (P=0.181).

CONCLUSION

The study show that orbital decompression surgery has safe and effective long term results for functional and cosmetic rehabilitation of GO. It significantly reduces Hertel measurements in disfiguring proptosis and improves visual functions especially in DON cases.

Electrophysiological Studies in Thyroid Associated Orbitopathy: A Systematic Review

Dysthyroid optic neuropathy (DON) is the commonest cause of blindness in thyroid associated orbitopathy (TAO). While diagnosis remains clinical, objective tests for eyes with early or equivocal findings are lacking. Various electrophysiological studies (EPS) have been reported, yet the types and parameters useful for DON remain inconclusive. We performed a systematic literature search in MEDLINE, EMBASE and the Cochrane databases via the OVID platform up to August 20, 2017. 437 records were identified for screening and 16 original studies (1327 eyes, 787 patients) were eligible for review. Pattern visual evoked potential (pVEP) was the most frequently studied EPS. Eyes of TAO patients with DON showed delayed P100 latencies, decreased P100 amplitudes or delayed N75 latencies during pVEP, compared to those without or healthy controls. Due to study heterogeneity, no quantitative analysis was possible. This review highlights the most common type (pVEP) and useful parameters (P100 latency and amplitude) of EPS, and supports further research on them using standardized testing conditions.

Dysthyroid optic neuropathy: update on pathogenesis, diagnosis, and management

INTRODUCTION

Dysthyroid optic neuropathy (DON) is a severe manifestation of thyroid eye disease (TED) that can result in permanent vision loss. Management is complex, multidisciplinary, and involves medical and/or surgical therapies. This review describes current concepts in the epidemiology, pathophysiology, diagnosis, and treatment of DON.

AREAS COVERED

An extensive review of the literature was performed to detail current concepts on the diagnosis and management of DON. This includes utilization of various medical and surgical modalities for disease management.

EXPERT COMMENTARY

DON can result in permanent blindness and often requires the use of corticosteroids and surgical decompression. We favor the use of intravenous corticosteroids and a transcaruncular approach when surgical decompression is indicated. The use of orbital radiation for DON is often reserved for patients that are poor surgical candidates and/or patients with refractory disease.

Thyroid-stimulating immunoglobulins indicate the onset of dysthyroid optic neuropathy

PURPOSE

Recognition of dysthyroid optic neuropathy (DON) requires sensitive diagnostic tools. Clinical assessment may fail to reliably evaluate the acuteness of DON especially if signs for inflammation are missing. Aim of this cross-sectional study was to assess the relationship between thyroid-stimulating immunoglobulins (TSI) and onset of DON.

METHODS

At a multidisciplinary orbital center, serum TSI levels were measured in 180 consecutive patients with thyroid eye disease (TED) and 302 healthy controls with a FDA-cleared cell-based bioassay using a chimeric TSH receptor and a CRE-dependent luciferase.

RESULTS

Thirty of 180 (16.7 %) patients with TED had DON of recent onset or a past history of DON (post-DON). Optic disk swelling was present and visual-evoked potentials were pathologic in all eyes with DON of recent onset, but in one of 13 (7.7 %) with post-DON, only (p = 0.005). 19/20 (96 %) patients with DON of recent onset were TSI-positive. TSI was associated with DON of recent onset (OR: 20.96; 95 % CI 1.064-412.85, p = 0.045). All controls were TSI negative. TSI correlated with the clinical activity score (R = 0.70, p < 0.001) and higher TSI-levels were noted in active vs. inactive TED (485.1 ± 132.3 vs. 277.7 ± 143.7 %, cut-off < 140 %; p < 0.001). Six of seven (85.7 %) patients with inactive TED with recent onset DON versus one of four (25 %) with active post-DON were TSI-positive (p = 0.006). A discriminatory cut-point of 377 SRR % for TSI was determined based on a ROC analysis (sensitivity: 0.95, specificity: 0.8).

CONCLUSIONS

Serum TSI levels identify patients with DON of recent onset requiring urgent therapy.

Role for rapid surgical intervention in uveal effusion syndrome with associated optic neuropathy

Uveal effusion syndrome (UES) can be associated with nanophthalmos and rarely can present with concomitant optic neuropathy. This case report describes nanophthalmic UES and optic neuropathy treated with early sclerectomies. One month postoperatively, the patient experienced significant improvement in choroidal effusions and optic neuropathy, with increases in visual acuity and visual fields. Early scleral windows surgery for UES with associated optic neuropathy can provide prompt improvement of choroidal swelling, optic nerve edema, and vision, although the relapsing course of this disease presents a challenge to long-term visual prognosis.

Surgical treatment of Graves' ophthalmopathy

The aims of surgical treatment in Graves's orbitopathy (GO) are improvement of function and appearance. Since antiinflammatory treatment of GO rarely results in a complete resolution of symptoms, surgical treatment is very important for patients well being. Rehabilitative surgery includes orbital decompression, squint correction, lid lengthening and blepharoplasty and these procedures have to be performed in centres of expertise. Various techniques have been developed for orbital decompression which allow now a graded approach to proptosis reduction and optic nerve decompression in emergency situations. Extraocular muscle recessions can be successfully performed to treat most of the patients with diplopia. Only large or complex squint angles are difficult to treat and step by step procedures are recommended in these patients. Lid lengthening procedures are performed most often in GO patients and should be performed under local anaesthesia to get a good result. Serious complications are rare.