Lattice degeneration is most closely associated with retinal detachment. The resulting retinal fissures account for 40% of eyes with foraminogenic detachment, and lattice-like degeneration is present in approximately 7% of normal eyes. Most often seen between the equatorial portion of the temporal or superior temporal quadrant and the serrated edge, it is pyknotic or striated, with the long axis parallel to the serrated edge. The retina within the lesion thins and has many white lines that are interlaced and arranged in a lattice pattern. These lines are actually occluded or terminal vessels with white sheaths. Pigment clusters are sometimes seen within the lesion, originating from the retinal pigment epithelium. There is a relationship with the condition of the retina itself, the condition of the vitreous and the eye itself and even genetic factors. 1.Retinal degeneration and fissure formation Because of the complex structure of retina and unique blood supply, it is easy to cause degeneration for various reasons. The peripheral part and macula are the good parts of degeneration. Retinal degeneration is the basis for the formation of retinal fissures. The following changes are common before the occurrence of lacunae (1) Lattice degeneration: Lattice degeneration is most closely related to retinal detachment. The resulting lacunae account for 40% of eyes with lacunar detachment. It is also seen in about 7% of normal eyes. Lattice degeneration has no racial or gender differences in its onset, invades both eyes, and is often symmetrical in its formation and location. The lesions are mostly seen in the lateral or superior temporal quadrant between the equatorial portion and the serrated edge, and are pyknotic and striated, with well-defined island-like lesions with the long axis parallel to the serrated edge. The lesions vary greatly in size, ranging from 1DD to more than 1/2 circumference in the long right and from 0.5DD to 2DD in width. The retina of the lesion was thin. There are many white lines that are interlaced to form a grid facade. Such lines are connected to the retinal vessels outside the lesion, which are actually occluded or terminal vessels with tubular white sheaths. White pigment clumps can also sometimes be seen distributed within the lesion, called pigmented character-like degeneration, with pigment originating from the retinal pigment epithelium. (2) Cystoid degeneration: It is usually found in the macula and near the serrated edge of the inferior temporal side, with clear, round or round-like edges and dark red color. Small cavities may fuse into large cystic cavities, so the size varies greatly. Reticular cystic degeneration occurs in the peripheral part of the fundus, becoming clustered and slightly elevated red dots, with fibrous or granular clouding of the vitreous body nearby. Cystoid degeneration in the macula initially appears as a small foveal cavity, which is particularly obvious on examination without rays. The small cystic cavities in the peripheral part or macula gradually fuse with each other to form large cystic cavities. The anterior wall often ruptures due to vitreous traction, but only when there is rupture of the anterior and posterior walls does it become a true fissure and cause retinal detachment. Cystic degeneration is a change in the retina caused by a variety of causes (such as age-related changes, inflammation, trauma, high myopia, etc.) that affect the retinal nutrient metabolism and cause the breakdown of its neural components, resulting in the formation of cavities in its inner plexiform layer or inner and outer nuclear layers. The cavity is filled with fluid containing mucopolysaccharide components. (3) Frost-like degeneration: mostly occurs near the equator and serrated edge, and some areas covered by tiny white or slightly yellow shiny particles can be seen on the retinal surface. The thickness is uneven, as if the retina is covered with a frost. This degeneration may appear alone. It can also coexist with checkered degeneration and cystic degeneration. Frost-like degeneration near the equator and fused into a band is also called snail track-like degeneration. (4) Pavement stone-like degeneration: It is usually seen in myopic patients over 40 years of age. It is common in both eyes. It appears as yellowish round or round-like, well-defined, multiple atrophic lesions with pigmented margins, with large and small lesions arranged in a patchwork. The lesions are pavement-like. The choroidal capillary network in the central part of the lesion is atrophied, exposing the large choroidal vessels or even the pale sclera. If the degenerative area is subjected to vitreous traction, it leads to the formation of retinal fissures. (5) Retinal pressure whitening and non-pressure whitening: The elevated part of the fundus after scleral indentation becomes opaque gray-white, called pressure whitening. When the lesion is further aggravated, it becomes grayish white even without pressure, which is called non-pressure whitening, and sometimes a clear ridge is formed at its posterior edge. It is mostly seen in the peripheral part of the superior fundus and is considered an indication of vitreous traction. If the posterior vitreous detachment extends, this posterior edge may be torn open and a fissure may form. (6) Dry retinal longitudinal folds: The folds extend from the interdental margin of the serrated rim toward the equator. It is a fold of overgrown retinal tissue. Generally no treatment is needed, but there is also the possibility of objective vitreous traction and fissure at the posterior end of the fold. 2, vitreous degeneration is another key factor causing retinal detachment. Under normal circumstances, the vitreous body is a transparent gel-like structure, filling the cavity in the posterior 4/5 of the eye, which has a supporting role for the retinal neuroepithelium adhering to the pigment epithelium. Except for the ciliary flattening to the serrated edge and the adhesions to the retina around the optic disc, the other parts of the retina are only tightly attached to the inner retinal membrane, but there are no adhesions. Before retinal detachment occurs, common vitreous degeneration changes include: interconnected vitreous detachment, liquefaction, clouding, membrane formation, and condensation. (1) vitreous detachment (detachmentofvitreousbody): vitreous detachment refers to the appearance of a gap between the critical surface of the vitreous and the tissue in close contact with it. Most commonly seen in highly myopic and elderly patients, all parts of the external surface of the vitreous can be detached, posterior vitreous detachment, superior detachment is common, and the relationship with retinal detachment is also relatively close. The main reason for vitreous detachment is the dehydration of the hyaluronic acid in the vitreous body, forming one or more small liquefied cavities within the vitreous body and fusing with each other to form a larger cavity. If the liquid in the cavity breaks through the outer surface of the vitreous into the retina before the separation between the vitreous and retinal inner boundary membrane occurs. If there is some kind of pathological adhesion between the detachment and the retina, retinal fissure may occur due to traction. (2) vitreous liquefaction (fluidityofvitreousbody): vitreous fluid is the change of vitreous body from gel state to dissolved state, which is the disruption of colloid balance caused by vitreous metabolism disorder. It is also common in highly myopic and elderly patients. Liquefaction generally begins in the center of the vitreous, where an optical space appears and gradually expands, or multiple smaller liquefaction cavities may fuse to form a larger one. There are translucent grayish-white filamentous or flocculent material floating and moving in the liquefaction chamber. (3) Vitreous opacitiesandconcentration: There are many causes of vitreous opacities, but those related to primary retinal detachment are caused by the destruction of the vitreous scaffold structure, so they often coexist with vitreous detachment and liquefaction. The clouded fiber bundles have the potential to lead to retinal fissures. The so-called vitreous concentration, which is also a kind of vitreous turbidity, is an opaque body formed by dehydration and degeneration of the scaffold structure when the vitreous is highly liquid, so it can be called atrophic concentration (atrophicconcentration). Compared with the outer surface of the vitreous detachment, the outer surface of the vitreous detachment, and the vitreous liquefaction cavity of the filament-like or flocculent turbidity, there is not much difference in nature, only and degree of more serious, the risk of causing retinal detachment is also more intense. (4) Vitreous membrane formation: also known as massiveperietinalproliferativemembrane, the mechanism of formation is very complex and not yet fully understood. It may involve glial cells, free pigment epithelial cells and their transformation into macrophages and fibroblasts. The proliferating membrane grows along the anterior or posterior retinal interface or the external surface of the vitreous, and when contracted, it can pull the retina to wrinkle, forming some fixed adhesive folds or star-shaped folds. It may even cause the entire posterior retina to crumple together to form a closed funnel shape. This type of proliferative membrane is seen in patients with pre-detachment, mid-detachment, and old detachment of the retina. It occurs in the pre-detachment and is also an important cause of retinal detachment.