Preliminary Study on the Correlation Between Episcleral Venous Pressure and Intraocular Pressure in TAO Patients and Its Clinical Value.

OBJECTIVE: To study the correlation between episcleral vein pressure (EVP) with intraocular pressure (IOP), exophthalmos, and optic nerve injury in thyroid-associated ophthalmopathy (TAO) patients and to explore the possibility of higher EVP as an intervention indicator in TAO patients.

METHODS: This study was a case-control study, including the TAO group and normal control group. TAO group: 15 patients (30 eyes) were diagnosed with TAO complicated with exophthalmos. Normal control group: 14 cases, 28 eyes. EVP, IOP, exophthalmos, retinal nerve fiber layer thickness, and visual field were measured, respectively in the two groups. Non-parametric test was used to compare the difference between EVP and IOP between the two groups, test the correlation between EVP and IOP or exophthalmos, and analyze the clinical characteristics of optic nerve injury in patients with elevated IOP in the TAO group.

RESULTS: The EVP in the TAO group (15.30±3.48 mmHg) was significantly higher than the normal control group (8.82±1.44 mmHg) (P < .001). The IOP in the TAO group (18.55±8.13 mmHg) was significantly higher than in the normal control group (12.98±2.10 mmHg) (P < .001) (3) There was a positive linear correlation between EVP (X) and IOP (Y) in TAO group: Y = 0.9684x + 3.737 (rs>0, P < .05); There was a positive linear correlation between EVP (Y) and exophthalmos (X) in TAO group: Y = 0.9218x - 2.691 (rs>0, P < .05); Some TAO patients with elevated EVP had the related manifestations of optic nerve function impairment: thinning of retinal nerve fiber layer and loss of visual field. However, there was no clear correlation between EVP and the thickness of the optic nerve fiber layer (P = .4354).

CONCLUSION: The increase of EVP is an important factor leading to elevated IOP in TAO patients, which may be used as an indicator for intervention treatment in TAO patients. EVP can be used to indirectly evaluate orbital pressure. TAO patients can develop secondary glaucoma with irreversible optic nerve damage due to the continuous Elevation of EVP.