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Revisiting the Pathogenesis of Diabetic Retinopathy from the Perspectives of ‘Xuanfu’ and ‘Luomai’ (Part II)
Ruo Xiangxia, Wu Chengliang, Zeng Min
Expert Introduction
Ruo Xiangxia, MD, Chief Physician, Doctoral Supervisor, Director of the Research Department at Gansu Provincial Hospital of Traditional Chinese Medicine, Secretary of the Ophthalmology Party Branch, Fourth Batch of National Excellent Clinical Talent in Traditional Chinese Medicine, Sixth Batch of Western Light (Tongren Hospital) Visiting Scholar, Flexible Talent Introduced by Lanzhou First People’s Hospital, Fourth Batch of Gansu Province Traditional Chinese Medicine Mentorship Teacher, Member of the Ophthalmology Branch of the Chinese Association of Traditional Chinese Medicine, Member of the Ophthalmology Branch of the Chinese Association of Integrative Medicine, Executive Member of the Diabetes Branch of the Chinese Association for the Promotion of Traditional Chinese Medicine, Director of the Ophthalmology Branch of the Gansu Ethnic Medicine Association, Deputy Director of the Gansu Provincial Association of Integrative Medicine Ophthalmology, Secretary-General of the Science Association of Gansu Provincial Hospital of Traditional Chinese Medicine, has published over 50 papers, with 3 included in SCI, co-authored 4 textbooks, chief edited 3, holds 1 software copyright, has presided over 2 national-level fund projects, 3 provincial-level, 6 municipal-level, participated in 13 provincial-level and above research projects, and has led and participated in 10 various scientific and technological progress awards, including 1 second prize for scientific and technological progress in Gansu Province for a project he led.
Introduction
Diabetic retinopathy (DR) is a common vascular complication of diabetes and one of the leading causes of irreversible blindness. It is characterized by retinal vascular leakage, neovascularization, and fibrous proliferation. In Traditional Chinese Medicine (TCM), DR falls under the category of “Xiaoke Neizhang” (internal disorders of diabetes), with the disease located in the eyes. The fundamental pathogenesis involves the imbalance of Qi, Blood, Yin, and Yang in the organs, representing a deficiency of the root and excess of the branch, with a mixture of deficiency and excess. TCM diagnosis and treatment of DR have unique characteristics, often believed to be caused by prolonged diabetes leading to Yin deficiency and Qi exhaustion, with blood stasis obstructing the meridians and causing insufficient nourishment. The closure of the ‘Xuanfu’ is the root of all diseases; if the ‘Xuanfu’ is closed and its opening and closing functions are impaired, the circulation of Qi and Blood throughout the body becomes abnormal, leading to stagnation in the meridians. This article aims to explore the pathogenesis of DR from the perspectives of ‘Xuanfu’ and ‘Luomai’, providing a theoretical basis for a deeper understanding of DR from the microscopic structural level of TCM.
“All organs have ‘Xuanfu’”, and ‘Xuanfu’ and ‘Luomai’ are distributed throughout the ocular system. The opening and closing functions of the ‘Xuanfu’ in the eyes ensure the orderly transport of subtle substances within the ocular meridians, while the nourishment of the ‘Xuanfu’ by the essence and blood from the ocular meridians ensures its normal opening and closing. The two functions complement each other and influence each other pathologically. Long-term consumption of rich and fatty foods, excessive emotional stimulation, irregular sexual activity, overexertion, or congenital deficiencies can all lead to dysfunction of the organs, impairing the opening and closing of the ‘Xuanfu’, resulting in the inability to properly distribute and nourish the organs with the essence of food and water, leading to chaotic circulation of Qi and fluids throughout the body, and the accumulation of toxins resulting in diabetes.
As one of the major microvascular complications of diabetes, DR can lead to blindness in severe cases. The essence of ‘Xiaoke Neizhang’ lies in the organ damage caused by prolonged diabetes, leading to an imbalance of Qi, Blood, Yin, and Yang. ‘Xiaoke Neizhang’ is an ocular disease that arises on the basis of the progression of diabetes, closely linked to the evolution of the pathogenesis of diabetes. When the ‘Xuanfu’ of the spleen is impaired, the accumulation of sugar toxins occurs, and the essence and subtle substances cannot be normally distributed throughout the body. The ‘Xuanfu’ in the eyes may lose nourishment due to a lack of subtle substances or may be burned by Yin deficiency and dryness, failing to maintain its normal “gateway” function, leading to impaired opening and closing. Abnormal opening and closing of the ‘Xuanfu’ in the eyes further prevents Qi, Blood, and fluids from passing normally through the ‘Xuanfu’ into the ocular meridians, resulting in deficiency of Qi and Blood, leading to stagnation and eventually causing the ocular meridians to lose nourishment, resulting in diminished vision. As diabetes progresses, it affects the liver and kidneys, leading to insufficient water to nourish fire, insufficient Yin fluids, and excessive virtual fire in the ocular meridians, burning the ocular meridians; or insufficient water to nourish wood, leading to insufficient essence and blood, exacerbating the impaired opening and closing of the ‘Xuanfu’, preventing the ocular meridians from nourishing the visual organs, resulting in blurred vision and even the formation of new blood vessels. Prolonged Yin deficiency inevitably damages Yang, leading to both Yin and Yang deficiency, with Qi, Blood, and fluids lacking the source for transformation and circulation, severely impairing the opening and closing function of the ‘Xuanfu’, leaving the ocular meridians deficient in Qi and Blood, unable to nourish the visual organs, ultimately leading to unclear vision and diminished visual acuity. Throughout the pathogenesis of ‘Xiaoke Neizhang’, the internal factors of Qi, Blood, Yin, and Yang deficiency are the underlying causes, while the impaired opening and closing of the ‘Xuanfu’ and the loss of nourishment in the ocular meridians are the fundamental pathogenesis, which runs through the entire disease process.
The occurrence of diabetes can be attributed to the abnormal opening and closing of the ‘Xuanfu’, leading to the accumulation of sugar toxins and poor distribution of Qi, Blood, and fluids throughout the body. The author believes that the ‘Luomai’ is not only a microscopic channel for the circulation of Qi, Blood, and fluids but also the most important channel for detoxification and waste elimination in the body. If the opening and closing function of the ‘Xuanfu’ is impaired, the turbid toxins generated from the subtle substances circulate throughout the body via the network of ‘Luomai’, stagnating in the meridians, which can lead to the symptoms of toxin damage to the meridians, as Ye Tianshi stated, “prolonged illness enters the meridians.” Prolonged diabetes leads to dysfunction of the opening and closing of the ‘Xuanfu’, preventing the normal circulation and distribution of Qi, Blood, and fluids, which stagnate outside the ‘gateway’ of the ‘Xuanfu’, accumulating in the ‘Luomai’, transforming from clear to turbid over time, leading to the internal generation of toxic evils, producing pathological products such as blood stasis, phlegm-dampness, and turbid toxins. These pathological products combine with sugar toxins in the body, circulating through the Qi and Blood to the ocular meridians, further exacerbating the impaired opening and closing of the ‘Xuanfu’ in the eyes, blocking the toxins and damaging the ocular meridians.
The meaning of stasis includes both poor blood circulation and blood that has deviated from its normal path. In the state of impaired opening and closing of the ‘Xuanfu’, blood cannot flow smoothly in the ocular meridians, leading to stagnation and even obstruction; or if the Qi in the meridians does not contain blood, blood may deviate from its normal path and overflow outside the meridians, both of which can lead to stasis. In the early stage of ‘Xiaoke Neizhang’, specifically the non-proliferative stage, changes in the fundus such as microaneurysms and hard exudates are manifestations of poor blood circulation and stagnation in the ocular meridians; as the stasis of blood remains in the meridians for an extended period, the obstruction of the ocular meridians worsens, leading to soft exudates and microvascular abnormalities, indicating the progression to the pre-proliferative stage; in the proliferative stage, the continuous decline of organ function and impaired opening and closing of the ‘Xuanfu’ exacerbate the Qi deficiency and blood stasis in the ocular meridians, leading to Qi not containing blood, blood deviating from its normal path, and overflowing into the visual organs and the visual essence. Due to long-term lack of nourishment, new meridians may even form. Phlegm-dampness arises from metabolic disorders of body fluids; it is both a pathological product and a pathogenic factor. Phlegm-dampness can obstruct the circulation of Qi and Blood, affecting fluid metabolism, and is closely related to the occurrence and development of ‘Xiaoke Neizhang’. Patients with diabetes often have weak spleen and stomach, unable to transform and transport, easily generating phlegm turbidity, which obscures the ‘Xuanfu’ in the eyes, causing closure of the ‘Xuanfu’, leading to poor circulation of Qi and Blood and fluid metabolism, where blood stasis in the ocular meridians combines with phlegm turbidity, developing into phlegm-stasis. Furthermore, the “Blood Evidence Theory” states: “Blood stasis that has persisted for a long time can also transform into phlegm-water,” indicating that long-term blood stasis can transform into phlegm. The mutual obstruction of phlegm and stasis further exacerbates the blockage in the ocular meridians, leading to changes in the fundus such as microaneurysms, dot hemorrhages, exudates, and neovascularization. Therefore, the TCM pathogenesis of ‘Xiaoke Neizhang’ is closely related to phlegm-dampness, with phlegm-dampness and blood stasis interacting, forming the characteristic pathogenesis of “phlegm-stasis mutual obstruction.” In patients with diabetes, dysfunction of the middle jiao leads to internal heat, generating sugar toxins, and as diabetes persists, the functions of the five organs are severely impaired, leading to the accumulation of pathological products such as blood stasis and phlegm-dampness, forming turbid toxins such as stasis toxins and phlegm toxins. These turbid toxins are fierce and sticky, and as the newly generated Qi, Blood, and fluids circulate in the meridians, over time they inevitably damage the entire meridian system, affecting the ocular meridians and the clarity of vision. Additionally, the accumulation of turbid toxins further affects the opening and closing of the ‘Xuanfu’ in the eyes, making it difficult to expel the toxic evils from the ocular meridians, exacerbating the stagnation and damage to the ocular meridians.
Thus, it can be seen that ‘Xiaoke Neizhang’ arises from prolonged diabetes, with impaired opening and closing of the ‘Xuanfu’, leading to obstruction of the ocular meridians, resulting in loss of nourishment in the ocular meridians. This disease is often characterized by a mixture of deficiency and excess, with deficiency of Qi, Blood, Yin, and Yang as the root cause, while the accumulation of pathological products transforming into toxic evils obstructs and damages the ocular meridians as the branch. Therefore, the impaired opening and closing of the ‘Xuanfu’, leading to the internal generation of toxic evils over time, damaging the ocular meridians, is the key to the progression of DR, determining the severity and prognosis of the disease.
‘Xuanfu’ and ‘Luomai’ are both fine structures distributed throughout the internal and external organs of the body. They complement each other structurally, functionally, and pathologically, jointly regulating the circulation and distribution of essence, Qi, Blood, and fluids, which supplements the holistic view and syndrome differentiation treatment system of TCM. In recent years, the theories of ‘Xuanfu’ and ‘Luomai’ have become very important parts of the foundational theories of TCM, widely applied in the theoretical research and clinical treatment of TCM ophthalmology, increasingly gaining the attention of ophthalmologists. For instance, in related research and applications of DR, Zhang Shizhong proposed that the basic pathogenesis of DR is the obstruction and damage of the ‘Xuanfu’ based on the theory of ‘Xuanfu’, and guided by this theory, he applied TCM syndrome differentiation treatment for DR, achieving satisfactory results. Zhang Minglian, based on the theory of ‘Luomai’, innovated the ocular meridian theory to guide the clinical differentiation and treatment of DR, combining modern medical treatment methods, achieving significant therapeutic effects.
DR is one of the microvascular complications of diabetes, reflecting endocrine and blood system disorders in the retina caused by diabetes. Its occurrence and development are closely related to diabetes, with the nature of DR being a mixture of deficiency and excess, and the occurrence and development of DR is a dynamic evolutionary process. Therefore, exploring the pathogenesis of DR from the combined perspectives of ‘Xuanfu’ and ‘Luomai’, based on the nature of DR as a mixture of deficiency and excess, posits that “impaired opening and closing of the ‘Xuanfu’ and loss of nourishment in the ocular meridians” is the fundamental pathogenesis of DR, which runs through the entire disease process; “internal generation of toxic evils over time and damage to the ocular meridians” is the key to the progression of the disease, allowing for a deeper understanding of the occurrence and development of DR from the microscopic structural level of TCM. In recent years, the effectiveness of TCM in preventing and treating DR has increasingly been recognized, showing good results in early prevention and improving prognosis. Therefore, further exploration of the theories of ‘Xuanfu’ and ‘Luomai’ in the eyes, analyzing the pathogenesis patterns of DR in terms of ‘Xuanfu’ and ‘Luomai’, and applying this to guide the clinical differentiation and treatment of DR is a direction worthy of further research.
END
References
See details in the “Expert Forum” of the Chinese Journal of Traditional Chinese Medicine Ophthalmology, 2022, Volume 32, Issue 12
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