Evaluation of Corneal Biomechanical Properties in Patients With Thyroid Eye Disease Using Ocular Response Analyzer

The Changes in Ocular Biomechanical Response Parameters and Intraocular Pressure After Surgical Treatment for Thyroid Eye Disease

Purpose

To investigate changes in ocular biomechanical response parameters and intraocular pressure (IOP) in patients with thyroid eye disease (TED) undergoing orbital decompression or anterior blepharotomy.

Methods

Eighty-three eyes from 46 patients receiving orbital decompression (the orbital decompression group) and 45 eyes from 28 patients receiving anterior blepharotomy (the anterior blepharotomy group) were retrospectively enrolled from a tertiary center. Corvis ST tonometry was used to assess ocular biomechanical response and biomechanically corrected IOP (bIOP) pre- and postoperatively. Non-contact tonometry (IOP-NCT) was also performed.

Results

In the anterior blepharotomy group, the margin reflex distance decreased (P < 0001). The highest concavity radius (P = 0.026) and whole eye movement (P = 0.003) increased. Neither IOP-NCT nor bIOP had a significant change. In the orbital decompression group, the extent of exophthalmos decreased (P < 0.001). The A2 length (P = 0.009) decreased. The bIOP did not show a significant change (16.4 ± 2.7 vs. 16.7 ± 4.5; P = 0.415), but the IOP-NCT decreased significantly (17.5 ± 3.3 vs. 16.0 ± 3.3; P < 0.001). Higher baseline IOP-NCT (β = -0.40, P < 0.001) and greater reduction in stiffness parameter A1 (SP-A1; β = 0.05, P = 0.002) were associated with more significant IOP-NCT reduction after the orbital decompression.

Conclusions

Ocular biomechanical response parameters may change after TED surgery, potentially affecting IOP measurements, particularly in patients receiving orbital decompression.

Evaluation of corneal endothelium and correlation with disease severity in patients with Graves' ophthalmopathy: A specular microscopy-based study

PURPOSE

To investigate the possible corneal endothelial damage in Graves' ophthalmopathy (GO) and its relationship with GO activity.

METHODS

This cross-sectional study included 101 eyes of 55 patients with GO. Each eye was assigned a specific clinical activity score (CAS). Accordingly, they were classified as active (CAS ≥ 3) or inactive (CAS< 3). The corneal endothelium was measured using a non-contact specular microscope (Tomey EM-4000; Tomey Corp.). Endothelial cell density (ECD), average cell area (ACA), standard deviation of cell area (SD), coefficient of variation in cell area (CV), hexagonal cell ratio (HEX), and central corneal thickness (CCT) were recorded.

RESULTS

Among the eyes included in the study, 71 had inactive GO and 30 had active GO. ACA and HEX levels were lower (p<0,001) and CV values were higher (p<0.001) in patients with GO than in healthy subjects. Corneal endothelial cell morphology was altered in active GO compared to inactive GO. The SD (p=0,009) and CV (p<0,001) were significantly higher in active GO than in inactive GO. When the parameters examined were correlated with CAS, a statistically significant positive correlation was observed between proptosis (p=0,036, r=0,385) and CV (p=0,001, r=0,595).

CONCLUSION

Our study confirmed that morphological changes occur in the corneal endothelium of patients with GO. CV and SD values, in conjunction with CAS, can be used as non-invasive and quantitative indices to examine the activity status of GO. The demonstration of endothelial changes even in GO eyes with low CAS may be considered an incentive to include non-contact specular microscopy in the routine clinical evaluation of all patients with GO.

Influence of corneal biomechanical properties on intraocular pressure measurement in different types of Graves’ orbitopathy

BACKGROUND/AIMS

To compare the ocular biomechanical properties of inactive Grave's orbitopathy (GO) patients and healthy subjects and to evaluate the influence of severity and phenotype of GO on these parameters.

METHODS

This was a cross-sectional study. All included inactive GO patients and healthy controls underwent complete ocular examination, including Goldman applanation tonometry (GAT), corneal biomechanical analysis using Ocular Response Analyser (ORA), and corneal epithelial thickness analysis using Optovue. Patients with inactive GO were classified based on the severity and orbital phenotype (predominantly myogenic or lipogenic). Comparison among groups was performed.

RESULTS

60 eyes from 30 inactive GO patients and 30 healthy eyes were examined. Corneal hysteresis (CH) was significantly lower in inactive GO patients (9.6 [p25 8.1; p75 11.2]) compared to controls (10.4 [9.8; 11.5]) (p = 0.012). In GO patients, cornea compensated intraocular pressure (IOPcc) was significantly higher than Goldman applanation tonometry IOP (IOP-GAT) (p = 0.001). A total of 13.3% GO patients were initially classified as having ocular hypertension (OHT; defined as IOP > 21 mmHg with no signs of glaucomatous optic neuropathy) based on IOP-GAT measurement. According to IOPcc, 27.8% of GO patients were classified as OHT. In GO patients, no differences were found in corneal bimechanical properties according to the disease severity or orbital phenotype.

CONCLUSIONS

CH is significantly lower in inactive GO patients compared to healthy subjects. ORA corrected IOP was significantly higher in GO patients compared to IOP-GAT. No differences in corneal biomechanical properties between mild and moderate-to-severe GO disease and between myogenic and lipogenic orbitopathy were found.

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.

Corneal Tonometric and Morphological Changes in Patients with Acromegaly

(1) Purpose: This study aimed to investigate the changes in Reichert Ocular Response Analyzer (ORA) parameters, corneal endothelium parameters, central corneal thickness (CCT), and intraocular pressure (IOP) before and after the transsphenoidal resection of pituitary adenoma in patients with acromegaly. (2) Methods: This was a single-center, prospective, interventional study. Twenty patients with newly diagnosed acromegaly were examined before and 19 ± 9 months after transsphenoidal resection. The participants underwent a comprehensive ophthalmological examination including pneumatic IOP (IOP air puff), Goldmann applanation tonometry (IOP GAT), CCT measured using the iPac pachymeter (CCT_UP), IOP value corrected for CCT_UP using the Ehlers formula (IOPc) ORA measurements included corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated IOP (IOPcc), and Goldmann-correlated IOP (IOPg). CCT from non-contact specular microscopy (CCT_NSM), the number of endothelial cells (CD) per mm2, and average cell size (AVG) were determined with non-contact specular microscopy. (3) Results: A statistically significant decrease was observed in CCT_UP (p = 0.007), and IOP air puff (p = 0.012) after surgery. Moreover, we noted a statistically significant increase in CD (p = 0.001), and a statistically significant decrease in AVG (p = 0.009) and CCT_NSM (p = 0.004) after surgery. A statistically significant decrease was also observed in IOPg (p = 0.011), CH (p = 0.016), and CRF (p = 0.001) after surgery. The mean value of IOP GAT and IOPc was lower after the surgery. However, the difference was not statistically significant. (4) Conclusions: Our study revealed significant changes in biomechanics, corneal endothelium, CCT and IOP after pituitary adenoma resection in patients with acromegaly. It proves that the eye might be sensitive to long-term overexposure to growth hormone (GH) and insulin-like growth factor-1 (IGF-1). We suggest that disease activity be taken into consideration on ophthalmological examination.

Clinical Characteristics of Idiopathic Orbital Inflammation Syndrome in Relation to Intraocular Pressure

Purpose

To investigate the clinical characteristics of idiopathic orbital inflammation and changes in intraocular pressure (IOP) before and after its treatment.

Patients and Methods

We retrospectively studied 20 eyes from the medical records of 19 patients who were diagnosed with idiopathic orbital inflammation between April 1, 2004, and April 30, 2019, at Toyama University Hospital. The inflammation site (type of disease), treatment provided, IOP before and after treatment, and the symptoms (proptosis, decreased ocular movements or diplopia, periorbital edema, and ocular pain) were analyzed.

Results

The types of idiopathic orbital inflammation were dacryoadenitis in 14, myositis in 7, diffuse-type in 3, and posterior periscleritis in 1 case. The mean IOP after treatment was 15.4±3.9 mm Hg, which was significantly lower than the mean pretreatment IOP of 19.0±5.3 mm Hg (p = 0.009). Before treatment, all cases with the diffuse-type had high IOPs of 21 mm Hg or more. Ocular pain and eye movement disorders were present in 86% and 100% of subjects in the group with an IOP of 21 mm Hg or higher, but 38% and 31% in the group with an IOP of 20 mm Hg or lower, respectively.

Conclusion

Diffuse-type of idiopathic orbital inflammation is prone to develop high IOP. Patients with idiopathic orbital inflammation and high IOP exhibit many symptoms such as decreased ocular movements, diplopia, and ocular pain.

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.

Corneal biomechanical properties in hyperthyroidism and thyroid eye disease

PURPOSE:

The purpose of this study is to compare the corneal biomechanical properties of hyperthyroids without ophthalmopathy (HWO), thyroid eye disease (TED), and euthyroid participants.

METHODS:

In this prospective comparative study, one eye per patient included in the analysis and according to exclusion criteria, 38 eyes of 40 HWO patients, 31 eyes of 40 TED patients, and 150 eyes of 160 age- and sex-matched euthyroid participants were enrolled. All participants were evaluated by an endocrinologist and oculoplastic surgeon for evaluation of thyroid function and orbitopathy, respectively. Measurements of corneal biomechanical properties were performed using ocular response analyzer and Corvis ST tonometers.

RESULTS:

In the HWO group, applanation-1 length (A1 L), applanation-2 velocity (A2V) (P < 0.001), and corneal resistant factor (P = 0.043) were higher than the control group and corneal hysteresis (CH) was lower (P = 0.018). In the TED group, A1 L, A2V (P < 0.001), and highest concavity radius (HCR) (P = 0.027) were higher than the control group, and the CH (P = 0.007) and highest concavity deformation amplitude (HCDA) (P = 0.001) were lower. Furthermore, the level HCDA in the TED group was lower than HWO group (P = 0.011). The level of upper scleral show and palpebral fissure had a negative correlation with CH and HCDA. The amount of exophthalmos level had a positive correlation with HCR.

CONCLUSION:

Corneal biomechanical properties in the HWO and TED groups were different from the normal euthyroid individuals and may be taken into account in managing situation like glaucoma and refractive surgeries.

Corneal Tomographic Analysis Among Patients With Thyroid Gland Dysfunction

PURPOSE

To analyze the corneal tomographic parameters of patients with thyroid gland dysfunction.

METHODS

This case-control study included 100 eyes of 50 patients with thyroid gland dysfunction and 100 eyes of 50 healthy controls. All eyes were examined by Pentacam (Oculus Optikgeräte GmbH). Pentacam parameters were compared between patients with thyroid gland dysfunction and controls. Spearman's correlation coefficient between different Pentacam parameters and the serum level of free thyroxin (T4) and thyroid-stimulating hormone (TSH) was calculated.

RESULTS

Patients with hypothyroidism had significantly higher median values of steep and maximum simulated keratometric readings, central corneal thickness (CCT), and thinnest pachymetry (CTmin) than both patients with hyperthyroidism and controls (P⩽ .05). The median values of the average and maximum pachymetric progression index (PPI), posterior elevation, and back difference elevation were significantly higher in patients with hyperthyroidism than in patients with hypothyroidism and controls (P ⩽ .05). The Ambrósio Relational Thickness (ARTmax) was significantly reduced in patients with hyperthyroidism (P ⩽ .001). Both CCT and CTmin showed a moderately positive correlation with serum TSH level and a moderately negative correlation with serum free T4 level. Patients with non-autoimmune thyroid gland dysfunction had significantly thinner CCT, CTmin, and inferior vertical deviation than the autoimmune group (P ⩽ .05).

CONCLUSIONS

Thyroid gland dysfunction is associated with significant corneal tomographic changes. Patients with hyperthyroidism tend to have thinner corneas and more abnormal tomographic parameters correlating with keratoconus. No significant tomographic changes were found in association with autoimmune thyroid gland dysfunction. The authors recommend screening and regular follow-up of patients with thyroid gland dysfunction for early detection and management of keratoconus. [J Refract Surg. 2021;37(3):192-197.].

Ocular surface changes in Graves' ophthalmopathy

Many patients with Graves' ophthalmopathy (GO) suffer from dry eye syndrome (DES), and this is one of the most common reasons of eye discomfort in patients with GO. The prevalence of DES in patients with GO is significantly higher than normal subjects. The ocular surface changes involving changes in tears, cornea, conjunctiva and glands occur in GO patients. However, the mechanism of how DES occurs in GO still remains unclear. In this review, the ocular surface changes were illustrated and analyzed the reasons for high prevalence of DES in GO patients.

Changes in ocular biomechanics after treatment for active Graves' orbitopathy

PURPOSE

To evaluate the changes in ocular biomechanical properties in active moderate-to-severe Graves' orbitopathy (GO) after intravenous glucocorticoids (IVGCs), and to clarify correlations between clinical findings and ocular biomechanical properties.

METHODS

A prospective study. A total of 20 consecutive GO patients and 20 age- and sex-matched healthy control subjects were included. GO was diagnosed on the basis of the recommendation by the European Group on Graves' Orbitopathy (EUGOGO), and disease activity was assessed by the clinical activity score (CAS). Patients were assigned to receive once weekly IVGCs (0.5 g, then 0.25 g, 6 weeks each). All participants received a full ophthalmic examination and biomechanical evaluation was performed with dynamic Scheimpflug analyzer (Corvis ST) at baseline and 12th weeks after therapy.

RESULTS

The biomechanically corrected intraocular pressure (bIOP) in GO patients was significantly higher than that in healthy subjects. In contrast, the whole eye movement (WEM) in GO patients was significantly lower than in healthy subjects after adjusting for bIOP. The CAS, NOSPECS score, and exophthalmos were significantly positively correlated with the bIOP and negatively correlated with the WEM after adjusting for bIOP, CCT and age. The WEM significantly increased, whereas bIOP significantly decreased after IVGCs (P < 0.001, P = 0.001 respectively). The overall response rate at the 12th week was 85% (17 of 20).

CONCLUSIONS

The changes of ocular biomechanical properties measured by Corvis ST were an objective indicator of inflammatory activity and severity of GO. Combining CAS and ocular biomechanical properties could better evaluate the therapeutic outcome of active moderate-to-severe GO.

Evaluation of corneal biomechanical properties on ocular response analyzer and their correlation with the clinical profile of the patients with thyroid-associated ophthalmopathy

Purpose: The study evaluates the corneal biomechanical properties on Ocular Response Analyzer (ORA) and aims to establish their correlation with the clinical profile of patients with TAO.Methods: A tertiary care centre-based cross-sectional observational study was conducted. Eighty patients with stage I and II TAO (EUGOGO classification), categorized as group A, were age and sex matched with 85 controls constituting group B. The disease activity was assessed using clinical activity score (CAS). The thyroid hormonal profile of within one-week duration was recorded for each patient of group A. Mean IOP-GAT (IOP using Goldmann applanation tonometer), IOPg (Goldmann-correlated IOP value), IOPcc (cornea-compensated IOP value), CRF (corneal resistance factor), and mean corneal hysteresis (CH) of group A and B were compared. The variation of CH with disease severity, activity, and thyroid status in group A was evaluated.Results: Mean GAT, IOPg, and IOPcc of group A were significantly higher than that of group B (p < .001). Mean CH of group A i.e the visco-elastic dampening ability of cornea was significantly lower than that of group B (p < .001). In group A, mean CH of patients with stage 1 disease severity and CAS<3 was significantly higher than that of patients with stage 2 severity and CAS≥3 (p < .001). CH of hyperthyroid patients was significantly lower than CH of hypothyroid patients (p < .01).Conclusion: TAO affects the biomechanical properties of the globe as reflected by the corneal biomechanics on ORA. The disease severity, activity, and hyperthyroid status are negatively correlated with the CH.

Complementary Keratoconus Indices Based on Topographical Interpretation of Biomechanical Waveform Parameters: A Supplement to Established Keratoconus Indices

Purpose. To build new models with the Ocular Response Analyzer (ORA) waveform parameters to create new indices analogous to established topographic keratoconus indices. Method. Biomechanical, tomographic, and topographic measurements of 505 eyes from the Homburger Keratoconus Centre were included. Thirty-seven waveform parameters (WF) were derived from the biomechanical measurement with the ORA. Area under curve (ROC, receiver operating characteristic) was used to quantify the screening performance. A logistic regression analysis was used to create two new keratoconus prediction models based on these waveform parameters to resample the clinically established keratoconus indices from Pentacam and TMS-5. Results. ROC curves show the best results for the waveform parameters p1area, p2area, h1, h2, dive1, mslew1, aspect1, aplhf, and dslope1. The new keratoconus prediction model to resample the Pentacam topographic keratoconus index (TKC) was WF_TKC = -4.068 + 0.002 × p2area - 0.005 × dive1 - 0.01 × h1 - 2.501 × aplhf, which achieves a sensitivity of 90.3% and specificity of 89.4%; to resample the TMS-5 keratoconus classification index (KCI) it was WF_KCI = -3.606 + 0.002 × p2area, which achieves a sensitivity of 75.4% and a specificity of 81.8%. Conclusion. In addition to the biomechanically provided Keratoconus Index two new indices which were based on the topographic gold standards (either Pentacam or TMS-5) were created. Of course, these do not replace the original topographic measurement.