Ocular Surface Changes in Patients with Thyroid Eye Disease: An Observational Clinical Study

Dixon MRI-based quantitative parameters of extraocular muscles, intraorbital fat, and lacrimal glands for staging thyroid-associated ophthalmopathy

OBJECTIVE

To investigate the value of Dixon magnetic resonance imaging (MRI)-based quantitative parameters of extraocular muscles (EOMs), intraorbital fat (IF), and lacrimal glands (LGs) in staging patients with thyroid-associated ophthalmopathy (TAO).

METHODS

Two hundred patients with TAO (211 active and 189 inactive eyes) who underwent Dixon MRI for pretreatment evaluation were retrospectively enrolled and divided into training (169 active and 151 inactive eyes) and validation (42 active and 38 inactive eyes) cohorts. The maximum, mean, and minimum values of the signal intensity ratio (SIR), fat fraction (FF), and water fraction (WF) of EOMs, IF, and LGs were measured and compared between the active and inactive groups in the training cohort. Binary logistic regression analysis, receiver operating characteristic curve analysis, and the Delong test were used for further statistical analyses, as appropriate.

RESULTS

Compared with inactive TAOs, active TAOs demonstrated significantly greater EOM-SIRmax, EOM-SIRmean, EOM-SIRmin, IF-SIRmax, IF-SIRmean, LG-SIRmax, LG-SIRmean, EOM-WFmean, EOM-WFmin, IF-WFmax, IF-WFmean, and LG-WFmean and lower EOM-FFmax, EOM-FFmean, IF-FFmean, IF-FFmin, and LG-FFmean values (all p < 0.05). The EOM-SIRmean, LG-SIRmean, and LG-FFmean values were independently associated with active TAO (all p < 0.05). The combination of the EOM-SIRmean, LG-SIRmean, and LG-FFmean values showed better performance than the EOM-SIRmean value alone in staging TAO in both the training (AUC, 0.820 vs 0.793; p = 0.016) and validation (AUC, 0.751 vs 0.733, p = 0.341) cohorts.

CONCLUSION

Dixon MRI-based parameters of EOMs, LGs, and IF are useful for differentiating active from inactive TAO. The integration of multiple parameters can further improve staging performance.

CRITICAL RELEVANCE STATEMENT

In this study, the authors explored the combined value of quantitative parameters of EOMs, IF, and LGs derived from Dixon MRI in staging TAO patients, which can support the establishment of a proper therapeutic plan.

KEY POINTS

The quantitative parameters of EOMs, LGs, and IF are useful for staging TAO. The EOM-SIRmean, LG-SIRmean, and LG-FFmean values were found to independently correlate with active TAO. Joint evaluation of orbital tissue improved the ability to assess TAO activity.

Radiological measurements of lacrimal gland in thyroid eye disease

PURPOSE

Lacrimal gland enlargement is a common feature of thyroid eye disease (TED) and has been positively correlated with the clinical activity score. Although lacrimal gland volume is the preferred measure of lacrimal gland size, its calculation is not clinically translatable due to the expertise, time and advanced software required. The aim of our study is to determine whether the lacrimal gland volume in patients with TED undergoing magnetic resonance imaging (MRI) can be estimated using simpler lacrimal gland linear and area measurements.

METHODS

A retrospective review of 102 orbits (51 patients) with TED who underwent orbital MRI was conducted. The maximum length, width, and area of the lacrimal gland were measured in axial and coronal sections. Lacrimal gland volume was calculated by using a manual segmentation technique on all consecutive axial slices on commercially available software, OsiriX. All quantitative measurements were correlated with the lacrimal gland volume.

RESULTS

Mean age of participants was 59 ± 16 years, and 67% (n = 34) were females. With multivariate analyses, combined lacrimal gland axial and coronal areas strongly correlated with volume (r = 0.843, p < 0.01). Strong univariate predictors of volume included axial area (r = 0.704, p < 0.01) and coronal area (r = 0.722, p < 0.01), while moderate predictors included axial length (r = 0.523, p < 0.01), axial width (r = 0.521, p < 0.01), coronal length (r = 0.450, p < 0.01), and coronal width (r = 0.649, p < 0.01).

CONCLUSION

In patients with thyroid eye disease, lacrimal gland volume can be estimated using axial and coronal areas, which is simpler and more time efficient than calculating volumes.

The Association between Autoimmune Thyroid Disease and Ocular Surface Damage: A Retrospective Population-Based Cohort Study

Autoimmune thyroid diseases (ATDs) are potentially connected to lacrimal gland dysfunction and ocular surface disruption. This study aimed to evaluate the relationships between ATD, dry eye disease (DED), and corneal surface damage. In a matched nationwide cohort study, we used Taiwan's National Health Insurance research database to compare the incidences of DED and corneal surface damage between subjects with and without ATD. Multivariable Cox proportional hazards regression models were used to estimate the adjusted hazard ratio (aHR) and 95% confidence interval (CI) for the ophthalmological outcomes. A total of 50,251 matched pairs with 748,961 person-years of follow-up were included for analysis. The incidence of DED was 16.37 and 8.36 per 1000 person-years in the ATD and non-ATD groups, respectively. ATDs were significantly associated with increased DED (aHR: 1.81, 95% CI: 1.73-1.89, p < 0.0001). This association was generally consistent across the subgroups of age, sex, different comorbidity levels, and use of systemic corticosteroids or not. Furthermore, patients with ATD had a higher risk of corneal surface damage compared with non-ATD subjects (aHR: 1.31, 95% CI: 1.19-1.44, p < 0.0001), including recurrent corneal erosions (aHR: 2.00, 95% CI: 1.66-2.41, p < 0.0001) and corneal scars (aHR: 1.26, 95% CI: 1.01-1.59, p = 0.0432). Other independent factors for corneal surface damage were age, sex, diabetes mellitus, Charlson Comorbidity Index scores, and use of systemic corticosteroids. Our results suggested that ATDs were associated with higher risks of DED and corneal surface damage. Considering the high prevalence of ATD, prophylactic and therapeutic strategies should be further developed to prevent irreversible vision loss in this susceptible population.

Association between Thyroid Function and Ocular Parameters

During development, thyroid hormones play an important role in eye development, while in adults, some pathological thyroid conditions can affect the normal functioning of the eyes. Thyroid eye disease is the most well-known eye pathology caused by a pathological thyroid condition. Few studies have investigated the association between ocular parameters and thyroid function. Thus, in this study, we aimed to examine whether thyroid activity affects ocular parameters. This cross-sectional study included 4633 healthy adults recruited within the 10,001 Dalmatians project of the Croatian Biobank. The plasma levels of thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), thyroglobulin (Tg), thyroglobulin antibodies (TgAb), and thyroid peroxidase antibodies (TPOAb) were measured by an immunoassay. We determined 20 ocular parameters for each participant (10 for each eye, including corneal radius, corneal thickness, anterior chamber depth, anterior chamber angle, lens thickness, posterior chamber length, axial length, intraocular lens power (IOL), spherical power, and cylinder power). Patients with hyperthyroidism had thicker corneas compared to euthyroid individuals. Corneal thickness was also negatively associated with plasma TSH levels. Intra-ocular lens power was higher in patients with clinical hypothyroidism, while spherical power was higher in euthyroid individuals with positive antibodies compared to euthyroid individuals. Intra-ocular lens power negatively correlated with fT4 levels, while spherical power positively correlated with TgAb, TPOAb, and Tg levels and negatively correlated with TSH levels. The anterior chamber angle was positively associated with plasma TSH levels and TPOAb levels and negatively associated with plasma fT4 levels. These findings suggest an interesting interplay between ophthalmic measures and thyroid status, detectable even in the general adult population.

Changes in Dry Eye Status after Steroid Pulse and Orbital Radiation Therapies in Active Thyroid Eye Disease

This prospective, observational study examined changes in dry eye status after steroid pulse and orbital radiation therapies in 16 patients (32 eyes) with active thyroid eye disease (TED). TED status was evaluated through clinical activity score (CAS), margin reflex distance (MRD)-1 and 2, presence or absence of Graefe’s sign/lid lag, and Hertel exophthalmometric value. Dry eye status was quantified through presence or absence of superior limbic keratoconjunctivitis, corneal fluorescein staining (AD score), tear break-up time, Schirmer test I results, tear meniscus height, and dry eye-related quality of life score. Meibomian gland dysfunction (MGD) was evaluated through Marx line score, eyelid abnormalities (MGD score), meibum expression score, and meibomian gland loss score. Those items were measured before and 6 months after treatment, and the results were statistically compared. Consequently, CAS significantly improved, and MRD-1 significantly decreased after treatment (p < 0.050). Although a part of MGD status improved (p < 0.050), all items regarding dry eye status did not change significantly after treatment (p > 0.050). Steroid pulse and orbital radiation therapies did not largely alter most items regarding dry eye and MGD status.

Ocular surface disease in thyroid eye disease: A narrative review

Ocular surface disease (OSD) in the setting of thyroid eye disease (TED) is traditionally thought of as a natural consequence of anatomical changes such as proptosis and corneal exposure. However, a growing body of research suggests that ocular surface inflammation and multi-factorial changes to the homeostasis of the ocular surface contribute substantially to the OSD seen in TED patients. In this paper we review the existing literature which highlights the work and existing theories underlying this new paradigm shift.