A pathological indicator for dysthyroid optic neuropathy: tritan color vision deficiency

[Interdisciplinary Management of Orbital Diseases]

Diagnosis and therapy of orbital diseases is an interdisciplinary challenge, in which i.e. otorhinolaryngologists, ophthalmologists, radiologists, radiation therapists, maxillo-facial surgeons, endocrinologists, and pediatricians are involved. This review article describes frequent diseases which both, otolaryngologists and ophthalmologists are concerned with in interdisciplinary settings. In particular the inflammatory diseases of the orbit including orbital complications, autoimmunological diseases of the orbit including Grave´s orbitopathy, and primary and secondary tumors of the orbit are discussed. Beside describing the clinical characteristics and diagnostic steps the article focusses on the interdisciplinary therapy. The review is completed by the presentation of most important surgical approaches to the orbit, their indications and possible complications. The authors tried to highlight the relevant facts despite the shortness of the text.

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.

Current Therapeutic Approaches for Graves' Orbitopathy - are Targeted Therapies the Future?

Graves' orbitopathy is an autoimmune disease of the orbit that most frequently occurs with Graves' hyperthyroidism. The occurrence of autoantibodies directed against the TSH receptor (TRAb) is of central importance for the diagnosis and pathogenesis. These autoantibodies are mostly stimulating, and induce uncontrolled hyperthyroidism and tissue remodelling in the orbit and more or less pronounced inflammation. Consequently, patients suffer to a variable extent from periocular swelling, exophthalmos, and fibrosis of the eye muscles and thus restrictive motility impairment with double vision. In recent decades, therapeutic approaches have mainly comprised immunosuppressive treatments and antithyroid drug therapy for hyperthyroidism to inhibit thyroid hormone production. With the recognition that TRAb also activates an important growth factor receptor, IGF1R (insulin-like growth factor 1 receptor), biological agents have been developed. Teprotumumab (an inhibitory IGF1R antibody) has already been approved in the USA and the therapeutic effects are enormous, especially with regard to the reduction of exophthalmos. Side effects are to be considered, especially hyperglycaemia and hearing loss. It is not yet clear whether the autoimmune reaction (development of the TRAb/attraction of immunocompetent cells) is also influenced by anti-IGF1R inhibiting agents. Recurrences after therapy show that the inhibition of antibody development must be included in the therapeutic concept, especially in severe cases.

The prevalence of red-green color vision deficiency and its related factors in an elderly population above 60 years of age

AIM

To determine the prevalence of red-green (RG) color vision deficiency (CVD) in an elderly population and its related factors.

METHODS

This report is a part of the Tehran Geriatric Eye Study: a cross-sectional population-based study that was conducted on the elderly population (≥60y) of Tehran, Iran using multi-stage stratified random cluster sampling. All study participants underwent complete ocular examination, including the measurement of uncorrected and best-corrected visual acuity, objective and subjective refraction, and slit-lamp biomicroscopy. The color vision was tested using Ishihara plates with the near optical correction in place.

RESULTS

Of the 3791 invitees, 3310 participated in the study. The data of 2164 individuals were analyzed after applying the exclusion criteria. The prevalence of R-G CVD was 3.73% (95%CI: 2.37%-5.09%) in the whole sample; the prevalence of protanomaly, protanopia, and deuteranopia was 1.51%, 1.76%, and 0.45%, respectively. The prevalence of R-G CVD was significantly higher in males than in females. The prevalence of RG CVD increased with advancing age from 2.91% in the age group 60-64y to 5.8% in the age group ≥80y (P=0.070). According to the multiple logistic regression model, male sex, and glaucoma were significantly related to RG CVD. Older age and hypertension also had a marginally significant relationship with RG CVD.

CONCLUSION

Changes in color vision occur in the elderly due to the aging process and some physiological and pathological factors. Since the change in visual perception may affect the person's performance, this aspect of the visual system's function should also be taken into consideration in the examinations of the elderly.

A diagnostic model based on color vision examination for dysthyroid optic neuropathy using Hardy-Rand-Rittler color plates

PURPOSE

To investigate color vision deficiency and the value of Hardy-Rand-Rittler (HRR) color plates in monitoring dysthyroid optic neuropathy (DON) to improve the diagnosis of DON.

METHODS

The participants were divided into DON and non-DON (mild and moderate-to-severe) groups. All the subjects underwent HRR color examination and comprehensive ophthalmic examinations. The random forest and decision tree models based on the HRR score were constructed by R software. The ROC curve and accuracy of different models in diagnosing DON were calculated and compared.

RESULTS

Thirty DON patients (57 eyes) and sixty non-DON patients (120 eyes) were enrolled. The HRR score was lower in DON patients than in non-DON patients (12.1 ± 6.2 versus 18.7 ± 1.8, p < 0.001). The major color deficiency was red-green deficiency in DON using HRR test. The HRR score, CAS, RNFL, and AP100 were found to be important factors in predicting DON from random forest and selected by decision tree to construct the multifactor model. The sensitivity, specificity, and the area under the curve (AUC) of the HRR score were 86%, 72%, and 0.87, respectively. The HRR score decision tree had a sensitivity, specificity, and AUC of 93%, 57%, and 0.75, respectively, with an accuracy of 82%. The data of the multifactor decision tree were 90%, 89%, and 0.93 for sensitivity, specificity, and AUC, respectively, with an accuracy of 91%.

CONCLUSION

The HRR test was valid as screening method for DON. The multifactor decision tree based on the HRR test improved the diagnostic efficacy for DON. An HRR score of less than 12 and red-green deficiency may be characteristic of DON.

[Thyroid Eye Disease-Compressive Optic Neuropathy]

BACKGROUND

The aim of this study was to evaluate the functional outcomes in terms of best-corrected visual acuity (BCVA) and visual field (VF) defects in optic nerve compression (thyroid eye disease-compressive optic neuropathy, TED-CON) patients after treatment.

PATIENTS AND METHODS

In this observational, retrospective study, the medical charts of 51 patients (96 eyes) with a diagnosis of definitive TED-CON between 2010-2020 were included.

RESULTS

After the diagnosis of TED-CON, 16 patients (27 eyes) received steroid-pulse (medical) treatment alone, 67 eyes received an additional surgical orbital decompression, whereas 1 patient (2 eyes) refused both treatment methods. In 74 eyes (77.1%) we detected an improvement of the BCVA ≥ 2 lines after the treatment over a mean time interval of 31.7 weeks (with no significant difference between treatment methods). In 22 eyes (27.2%) out of the 81 that underwent a posttreatment VF examination, we observed a complete resolution of the defects over a mean time interval of 39.9 weeks. When we limited analysis to patients with a minimum follow-up of 6 months at last visit, we found 33 eyes (61.1%) out of 54 eyes still had a VF defect.

CONCLUSION

In our data, more than half of the TED-CON cases (61.5%) had a good prognosis with a final BCVA ≥ 0.8  at the last visit; however, only 22 eyes (27.2%) showed a complete resolution of VF defects, while 33 eyes (61.1%) had residual defects measured after a minimum follow-up of 6 months. These results suggest that while the BCVA recovers relatively well, the VF of patients is likely to remain marked by optic nerve compression.

Selective deficits of S-cone in thyroid-associated ophthalmopathy patients without clinical signs of dysthyroid optic neuropathy

Purpose

We explored whether thyroid-associated ophthalmopathy (TAO) patients without clinical signs of dysthyroid optic neuropathy (DON) would have a selective deficit mediated by S-cone.

Methods

Thirty-two TAO patients without clinical signs of DON (non-DON, 42.03 ± 9.59 years old) and 27 healthy controls (41.46 ± 6.72 years old) participated in this prospective, cross-sectional study. All observers were tested psychophysically after passing color screening tests and a comprehensive ocular examination. Isolated L-, M-, and S-cone contrast thresholds were measured at 0.5 cyc/deg using Gabor patches. We calculated the area under the receiver operating characteristic (ROC) curve to quantify the ability of chromatic contrast sensitivity to detect the early visual function changes in non-DON patients.

Results

S-cone contrast sensitivity in non-DON patients was found to be lower than that of healthy controls (P < 0.001), whereas the sensitivities to L- and M-cone Gabor patches were similar between these two groups (P = 0.297, 0.666, respectively). Our analysis of the ROC curve revealed that the sensitivity to S-cone had the highest index to discriminate non-DON patients from healthy controls (AUC = 0.846, P < 0.001). The deficit of S-cone was significantly correlated with muscle index in non-DON patients (R = 0.576, P = 0.001).

Conclusion

There is a selective S-cone deficit in the early stage of TAO. S-cone contrast sensitivity could serve as a sensitive measure of visual impairments associated with early DON in patients with TAO.

Insights into Current Management Strategies for Dysthyroid Optic Neuropathy: A Review

Dysthyroid optic neuropathy (DON) is a potentially sight-threatening eye disease associated with Graves’ orbitopathy (GO). DON is not common in GO patients, reportedly occurring in only about 5% of patients. The pathogenesis of severe DON is considered to involve both muscular nerve strangulation and impaired blood flow. There is some objective grading of physical examination findings and the severity of GO, including a clinical activity score (CAS) and EUropean Group On Graves’ Orbitopathy (EUGOGO), but no specialized protocol completely characterizes DON. Most clinicians have decided that the combination of clinical activity findings, including visual acuity, color vision, and central critical fusion frequency, and radiological findings, including magnetic resonance imaging (MRI), can be used to diagnose DON. MRI has the most useful findings, with T2-weighted and fat-suppressed images using short-tau inversion recovery (STIR) sequences enabling detection of extraocular changes including muscle and/orbital fat tissue swelling and inflammation and, therefore, disease activity. The first-choice treatment for DON is intravenous administration of steroids, with or without radiotherapy. Unfortunately, refractoriness to this medical treatment may indicate the need for immediate orbital decompression within 2 weeks. Especially in the acute phase of DON, thyroid function is often unstable, and the surgeon must always assume the risk of general anesthesia and intra- and post-operative management. In addition, there are currently many possible therapeutic options, including molecular-targeted drugs. The early introduction and combination of these immunomodulators, including Janus kinase inhibitors and insulin-like growth factor-1 receptor antibody (teprotumumab), may be effective for GO with DON. However, this is still under investigation, and the number of case reports is small. It is possible that these options could reduce systemic adverse events due to unfocused glucocorticoid administration. The pathophysiology of DON is not yet fully understood, and further studies of its treatment and long-term visual function prognosis are needed.

RAPD as a clinical alert for early evidence of dysthyroid optic neuropathy

Dysthyroid optic neuropathy (DON) is a serious manifestation of thyroid eye disease (TED) resulting in permanent visual loss. There is controversy regarding the diagnostic features of DON. Relative afferent pupil defect (RAPD) in TED is highly specific for DON. Our first patient, a 42-year-old male presented with proptosis and intermittent blurring of vision with best corrected visual acuity of 6/6 in both eyes and right RAPD as an early sign of DON. Our second patient, a 54-year-old female presented with proptosis and clinical activity score <3 at the time of presentation. She developed intermittent blurring of vision with left RAPD on her second presentation as clue of bilateral asymmetric DON in her eyes, though BCVA was 6/6 both eyes. Both cases of bilateral asymmetric DON had RAPD as early specific sign of DON, which prompted us to do detailed radio-imaging to confirm DON, hence highlighting the importance of RAPD.