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Professor Sun Xinghuai on the relationship between myopia and glaucoma丨WOC 2022

Posting time:2022-10-06 02:14:17

Professor Sun Xinghuai on the relationship between myopia and glaucoma丨WOC 2022

Editor's Note Glaucoma is the second leading cause of blindness in the world after cataract, mainly including primary open angle glaucoma (POAG), normal tension glaucoma (NTG) and primary angle closure disease (PACD). type. Myopia, especially moderate to high myopia, is considered to be one of the high-risk factors for the development of glaucoma. So far, the mechanism by which the two influence each other is not fully understood. The relationship between myopia and glaucoma is complex. At the 2022 World Ophthalmology Congress (WOC 2022), Professor Sun Xinghuai from the Eye and ENT Hospital of Fudan University shared his views on myopia and glaucoma. The close relationship has been confirmed in many studies, but the association between myopia and PACD should not be ignored. Myopia and glaucoma are important public health problems in Asia. As an important cause of irreversible blindness, the prevention and treatment of glaucoma has always been one of the important ophthalmic public health problems worldwide. In Asia, it has caused a huge public health burden. Epidemiological surveys show that in East and Southeast Asia, the number of young people with myopia and high myopia continues to increase, and the rate is rising; the number of glaucoma patients is also increasing, and Asia is expected to have the largest number of glaucoma cases. Myopia is an important risk factor for glaucoma. Domestic and foreign studies have shown that glaucoma and myopia are closely related. The incidence of glaucoma in patients with myopia is high. As myopia deepens, the risk of glaucoma increases. The data showed that the odds ratio (OR) for developing glaucoma in people with low myopia was 2.3, while the odds ratio (OR) for developing glaucoma in people with moderate to high myopia was 3.3. High myopia is more common in glaucoma patients than in non-glaucoma patients. Myopia and glaucoma are closely related to the occurrence of glaucoma. It has been reported in the literature in recent years that some pathological changes of glaucoma have some similarities with the anatomical changes of patients with high myopia, such as the lengthening of the anterior and posterior diameter of the eyeball (axial), etc., which make the occurrence of glaucoma in patients with myopia. Risk is greater. At the same time, myopia, especially high myopia, undergoes remodeling of the scleral structure, resulting in changes in the structure of the chamber angle and weakness of the posterior sclera, especially the cribriform plate, which reduces the tolerance of myopic patients to intraocular pressure. Therefore, myopia is closely related to the occurrence of glaucoma. Both the anterior and posterior segments of myopic patients have factors that increase the susceptibility to glaucoma 1. Anterior segment: The aqueous humor is drained through numerous micropores (filter curtains) at the anterior chamber angle and then reaches the aqueous humor vein. In myopic eyes, these The change of micropores will increase the outflow resistance of aqueous humor, which is prone to glaucoma. 2. Posterior segment of the eye: During the elongation of the eye axis of myopic eyes, the optic disc and optic nerve fibers are twisted and displaced. If the factor of high intraocular pressure is added, it is easy to damage the visual function and cause glaucoma. Changes in the outflow system of the anterior segment in patients with myopia 1. Higher basic intraocular pressure studies have shown that intraocular pressure is positively correlated with the increase in myopia degree. It should be noted that the reduction of eyeball hardness in patients with high myopia will affect the measurement of intraocular pressure. Surveys have shown that glaucoma patients with myopia have higher intraocular pressure than non-myopia patients (16 mmHg for high myopia and 14 mmHg for hyperopia). 2. Peak intraocular pressure after cataract surgery Compared with emmetropic eyes, high myopia is more likely to have peak intraocular pressure after cataract surgery, and the intraocular pressure is higher at different follow-up points (as shown in the figure below). 3. The difference of glucocorticoid response is similar to POAG, myopic eyes have high response to glucocorticoid to increase intraocular pressure. The study found that the trabecular meshwork-inducible glucocorticoid-responsive protein gene (TIGR) was found in 3.9% of the glaucoma population, while only 0.3% in the general population, so it is speculated that such glaucoma-related genes may appear more frequently in the glaucoma population. in people with high myopia. 4. Structural differences of OCT Under normal circumstances, patients with high myopia have larger Schlemm's canal (SC) and thinner trabecular meshwork (TM) thickness, and SC area is negatively correlated with intraocular pressure; while after cataract surgery, intraocular pressure A decrease in SC area and vertical diameter, as well as a decrease in TM thickness and width, was observed in the elevated eyes. 5. Other changes include the subclinical inflammatory internal microenvironment of high myopia and the increased relative ratio of liquefied vitreous to gel vitreous in myopic eyes. Changes in the posterior segment of the eye in patients with myopia Characteristic changes in the scleral cribriform plate, retinal nerve fiber layer (RNFL) thickness near the optic disc, and retinal microvasculature in highly myopic eyes contribute to glaucoma susceptibility, both in terms of mechanical stress and microcirculation increase. Because the subjective symptoms of myopic patients with glaucoma are not warning, the fundus changes and visual field defects are complicated, and the influence of pseudo-low intraocular pressure makes the early diagnosis of glaucoma and the timely detection of glaucoma progression often difficult. 1. Optic head (ONH) changes Enlargement of the posterior segment of the optic disc and thinning of the cribriform plate in myopic eyes; decreased color contrast between the pink neural retinal rim and the pale optic cup and flattened cup fovea. In addition, the rotational distortion of the optic disc in myopic eyes and the morphological changes of the parapapillary atrophy spots including α, β, γ, and δ regions make it difficult to identify glaucomatous optic disc changes. 2. RNFL changes It is also difficult to accurately assess RNFL using ophthalmoscopy or fundus photographs. Quantitative detection of RNFL by OCT shows that with the increase of myopia, the average RNFL thickness decreases, and both the superior and inferior temporal RNFL peaks shift to the temporal side. . In addition, it should be noted that the normal OCT database currently used is less than 26 mm in axial length. Using the OCT of this database to detect high myopia will cause the false appearance of RNFL thinning. This artifact can be avoided if detected by OCT from a database of normal eyes with a long axis ≥26 mm. 3. Retinal microvascular changes Compared with emmetropic eyes, retinal perfusion around the optic disc in highly myopic eyes is reduced. The study found that the retinal perfusion changes in myopia are similar to the microvascular changes next to the optic disc in POAG. Whether there is a relationship between the two deserves further study and exploration. OCTA detection showed that the retinal perfusion around the optic disc was relatively decreased in patients with leopard-skin fundus. 4. The study of abnormal visual field found that after comparing the visual field damage of POAG patients with different degrees of refraction, the visual field changes were not typical in glaucoma patients with myopia. The deterioration of visual acuity is often attributed to the deepening of myopia, and high myopia may have glaucoma-like visual field damage, but it is relatively stable and non-progressive. Myopia and PACD Axial myopia is generally considered to be a protective factor for PACD: Professor Sun Xinghuai's team found that 3.6% (5/138) of myopic eyes with an axial axis ≥25 mm were PACD patients. Chakravartiet et al found that PACD was 1.9% (6/322) in myopic patients ≤ -5.0 D or axial > 25 mm; while Yong et al found the prevalence of myopia ≤ -0.50 D in glaucoma was 22% (94/427) ), with a PACD of 2.6% (11/427). Biological parameters of PACD in myopic eyes These myopic eyes have a relatively small anterior segment, a more anterior lens position, and a longer vitreous cavity. Of note, the causes of angle closure in PACD vary, and gonioscopy should be performed in every patient. Future research considers that the optimization of early diagnostic parameters, the use of genomics and metabolomics to discover new biomarkers, and the development of functional neuroimaging methods such as fMRI, can better distinguish between myopia and glaucoma changes. landmark. SUMMARY Myopia, a known risk factor for glaucoma, is closely associated with both the anterior segment (outflow system) and the posterior segment of the eye (optic nerve), but it is unclear how it develops into glaucoma. Previous studies have shown that myopia is associated with both POAG and NTG, however, the relationship between myopia and PACD should not be ignored. Professor Sun analyzed the relationship between myopia and glaucoma from the anterior and posterior segments of the eye, and finally looked forward to the future hotspots for distinguishing myopia and glaucoma, in order to carry out early diagnosis and early treatment of such patients, preserve their residual vision, and improve the quality of life of patients.

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