The ultimate goal of oculoplastic surgery is to preserve visual function, and with this in mind, to achieve cosmetic improvement by striving for integrity and bilateral symmetry of the eyelid, orbit, and other ocular appendages. The conjunctiva is lined on the inner surface of the eyelid and the surface of the eye and consists of the lid conjunctiva, bulbar conjunctiva, and fornix conjunctiva, forming an open, sac-like structure. The conjunctiva is relatively lax and ductile, and can repair itself with mild injury. If the injury is severe, it can affect the appearance and movement of the eye and cause visual dysfunction, so repair and reconstruction of conjunctival defects is an important task in oculoplastic surgery. Common conjunctival injuries include lid bulb adhesions, foveal stenosis, and lid conjunctival layer defects of the eyelid, which are discussed in this article. Treatment of traumatic lid adhesions Lid adhesions occur most often as a result of chemical (acid, alkaline) burns, thermal burns, blast injuries, conjunctival scarring, and as a sequel to conjunctival surgery. Severe lid adhesions can limit eyelid rotation and even lead to strabismus, diplopia, entropion, impingement, and canthal deformity. Depending on the extent of the adhesions, they can be divided into partial, extensive, total and atretic lid bulb adhesions. Clinical symptoms include shortening or even complete loss of the conjunctival fornix, especially in the lower fornix, conjunctival epithelialization on the corneal surface, neovascularization, limited rotation of the eye in all directions in severe cases, and varying degrees of static corneal lesions, such as corneal leukoplakia or even ocular atrophy. Conjunctival chemical injuries resulting in lid adhesions are the most common clinically, with alkali burns usually causing serious complications and very difficult clinical management. Alkali burns are often a complex and lengthy pathological process, with reference to Hughes’ staging method and relevant domestic materials are divided into 3 stages: 1. Acute stage: seconds-24h after the burn, manifested as corneal, conjunctival epithelial necrosis, detachment, conjunctival edema ischemia, corneal stromal layer edema clouding, corneal edge and nearby blood vessels extensive thrombosis, hemorrhage severe alkali burns, the cornea is porcelain white, unable to peer into the eye The tissue situation, due to ischemic necrosis of the iris and ciliary body, atrial fluid secretion is reduced and intraocular pressure is significantly reduced. 2, repair period: roughly 5-7 days to 2 weeks after the injury corneal epithelium begins to regenerate, new blood vessels gradually invade the cornea, iritis tends to be static. 3, complication period: 2-3 weeks after the burn into the complication period, there are often repeated and persistent aseptic corneal ulcers, which can lead to corneal perforation, scar healing from the detachment of necrotic tissue of the lid bulb conjunctiva, shortening or disappearance of the fornix, adhesion of the lid bulb or formation of corneal white spots, and even the occurrence of eyelid atresia. During the acute and repair periods, lid bulb adhesions are actively prevented in addition to supportive treatment and counteracting alkaline substances that seep into the eye; during the complication period, corneal perforation is actively prevented and all types of complications are treated symptomatically. Treatment of lid bulb adhesions should be determined by the extent of adhesions and the degree of scar formation and is commonly used as follows: 1. Mild lid bulb adhesions: strip scar adhesions and fan-shaped scar adhesions are common. The Z-shaped scar adhesions can be corrected with a Z-plasty, in which two triangular conjunctival flaps are designed in opposite directions with the cords as the longitudinal axis and sutured in place of each other. Fan-shaped scar adhesions can be corrected with a v-Y angioplasty, in which a “V” shaped incision is made in the area of adhesions, the scar is released, the “V” shaped flap is advanced, and the wound is sutured into a “Y” shape; or a narrower or the narrower adhesions can be cut horizontally and sutured longitudinally; or the lid bulb adhesions can be repaired by combining the V-Y principle with a locally advanced flap. 2. Partial lid bulb adhesions: small conjunctival defects after separation of adhesions can be treated with lid conjunctival flap advancement, which generally has a large number of folds in the conjunctiva of the upper vault of the upper lid and is loose enough to cover the wound after correction of the lower lid lid bulb adhesions are released; it can also be done with a free transplantation of the lid conjunctiva of the contralateral vault of the same eye or the vault of the healthy eye. 3. Severe lid bulb adhesions: the lid bulb is lost, the eyelid adheres to the cornea in a large area, and the lid margin and eyelid are often partially defective. The lid margin and eyelid defect will be corrected as appropriate after the lid adhesions have been adequately corrected. In patients with severe combined burns, the body is still hypersensitive despite the fact that it has been one year since the burns were sustained, and if there are drug or food allergies, it is not advisable to perform any surgery for lid bulb adhesions at this time, otherwise not only will the surgery fail but the lesion will be aggravated, and the surgery should only be performed after the allergies have gradually subsided over time. Second, reconstruction of the inner eyelid layer of a full eyelid defect The eyelid is anatomically divided into two parts, called the upper and lower lids. Histologically, the eyelid can be divided into seven layers from anterior to posterior, namely: 1) the skin layer; 2) the subcutaneous tissue layer; 3) the orbicularis oculi muscle layer (transverse muscle); 4) the submuscular tissue layer; 5) the fibrous layer (lid plate); 6) the Müller muscle layer (smooth muscle); and 7) the conjunctival layer (lid conjunctiva). In clinical practice, we divide the eyelid into anterior and posterior layers using the gray line as a boundary. The anterior layer includes the skin, subcutaneous tissue, orbicularis oculi muscle, and submuscular tissue and is called the cutaneous muscle layer; the posterior layer includes the lid, Müller muscle, and lid conjunctiva and is called the lid conjunctiva layer. This concept of stratification is extremely important in guiding reconstructive surgery of the eyelid. The main causes of eyelid defects are: tumor resection-induced defects, congenital eyelid defects, and traumatic eyelid defects. With the development of modern industry and transportation, the number of eyelid defects due to trauma is increasing every year. Regardless of the cause of the eyelid defect, the treatment of the eyelid defect must include the repair and reconstruction of the anterior and posterior components of the eyelid in accordance with the correct eyelid anatomy. In the repair and reconstruction of eyelid defects, the anterior and posterior layers (or at least one layer) must have their own blood supply in order to provide an adequate blood supply to the repairing graft on the basis of its own survival needs. It is unlikely that a tissue graft or lid substitute can be successfully transplanted on tissue that does not have a blood supply. The basic procedures for upper and lower posterior eyelid reconstruction include free lid implants, external orbital rim periosteal flaps, gliding lid conjunctival flaps, and transposed lid flaps. A variety of lid substitutes are also used to repair posterior lamina defects, including nasal septum cartilage, auricular cartilage, oculoscleral, hard palate mucosa, radiolucent lid, radiolucent aorta, and composite eyelid tissue flaps taken from the contralateral eye, depending on the extent of the defect and the blood supply to the implant bed. Mild inner lid defect repair can be done by sharing the normal eyelid lid conjunctival tissue, by sliding a tissue flap from the still preserved upper or lower lid, or by taking a lid conjunctival composite graft piece from the contralateral upper lid. It is important to note that when using a lid conjunctival composite graft from the contralateral upper lid, the size of the graft is limited by the amount of the contralateral upper lid that can be excised and whether the donor defect can be sutured directly in one stage. Moderate medial lid defects can be repaired using a vertical gliding lid conjunctival flap from either the upper or lower lid to reconstruct the medial lid layer of the defect area. Since the arterial arch of the lid margin is approximately 3 mm from the lid margin, at least 3 mm of tissue from the width of the lid margin should be preserved on the side where the lid conjunctival flap is taken to ensure blood supply and tissue tone in the donor area. Severe medial lid defects require a lid conjunctival substitute, most commonly a hard palate mucosal graft. The dense collagen fiber structure and density of the hard palpebral mucosa is similar to that of the lid, providing better stability and resistance to deformation. The graft not only repairs the inner lid layer, but also has scaffolding properties that allow it to adhere well to the surface of the eye and conform to the curvature of the eye. The hard palpebral mucosa graft is often used to repair lower lid defects, but because it is slightly harder than the lid, it tends to abrade the corneal epithelium when repairing upper lid defects, so the graft often requires the patient to wear contact lenses temporarily after surgery to prevent corneal damage. The normal conjunctival sac is a sac-like cavity consisting of the lid conjunctiva attached behind the lid plate, the fornix conjunctiva, and the bulbar conjunctiva covering the surface of the eye. If the conjunctival sac becomes shallow or small for various reasons and a prosthetic eye cannot be placed, it is called conjunctival sac stenosis, and in severe cases, the conjunctival sac is completely or nearly completely gone, which is called conjunctival sac atresia. In order to achieve a satisfactory fitting of a prosthetic eye, the conjunctival sac is often surgically corrected to restore the conjunctival sac cavity so that a prosthetic eye can be placed. These procedures are collectively known as conjunctival capsuloplasty, or narrowing eye socket reconstruction. Conjunctival sac stenosis is often combined with other deformities such as eyelid defects, sulcus, orbital hypoplasia, orbital fractures, and internal and external canthus deformities, so the choice of treatment options is important and the selection of the correct surgical sequence is critical. In cases of combined orbital depression, intraorbital filler implantation should be performed first. Currently, intraorbital implantation of coral intraocular hydroxyapatite eye socket is mostly used to correct orbital depression, and after 6 months of postoperative vascularization of the eye socket, free mucosal slice grafting or free skin slice grafting conjunctival capsuloplasty should be performed. In patients with combined orbital fractures, orbital bone defects, and orbital hypoplasia, orbital deformities should be corrected first; in patients with combined larger eyelid defects and internal and external canthal deformities, surgical correction should be performed first, and in patients with smaller lid margin defects and ptosis, surgical treatment should be considered after conjunctival capsuloplasty and prosthetic eye fitting. Mild conjunctival sac stenosis means that there is no defect in the conjunctiva, the conjunctival and subconjunctival scarring is not obvious, the conjunctival sac shape and the upper and lower fornix exist, and the phenomenon is manifested as simple conjunctival sac contraction and stenosis; treatment can be done by eye mold expansion method and fornixoplasty. Partial conjunctival capsuloplasty is suitable for those who have chemical injury, thermal burn or other causes of conjunctival capsular stenosis but still have part of healthy conjunctiva, and conjunctival capsuloplasty is usually performed by free grafting of the orofacial mucosa. Total conjunctival capsuloplasty, also known as total eye socket reconstruction, is indicated in cases where the conjunctival capsule is completely or nearly completely absent or atretic for some reason. Due to the limited area of the lacrimal mucosa, medium-thickness skin grafts are usually used, which are simple and more likely to be successful. However, it is also possible to perform total conjunctival capsuloplasty with the combined application of the labial and buccal mucosa. In addition, the clinical treatment of patients with conjunctival sac stenosis and prosthetic eye cannot be placed, there are still several matters needing attention: 1, due to trauma, thermal burns, chemical injury caused by the conjunctival sac stenosis, atresia, surgery should be performed at least 6 months to 1 year after the injury. However, the decision should not be based solely on the length of time, but mainly on the principle of whether the local scar tissue is softened or not. When the local scar tissue is still hard, it is not suitable for surgery, otherwise the surgery will be difficult to succeed. In cases of conjunctival sac stenosis with obvious eyelid defect or abnormal position, eyelid defect repair should be done first or at the same time. 3, With orbital bone defect or deformity, if it affects the performance of conjunctival sacculoplasty, it should be treated appropriately first to facilitate the conjunctival sac formation. 4.If the prosthetic eye is not easily kept in the conjunctival sac because of lower lid laxity or drop, correction of lower lid laxity should be done first or at the same time. If the entire conjunctival sac does not shrink significantly, but only the inferior fornix becomes shallow or the superior fornix tilts posteriorly, this can be corrected by placing a different shaped eye mold or by deepening the inferior fornix with several pairs of mattress sutures. 6.If there is conjunctiva left, that is, when doing partial conjunctival capsuloplasty, it is better to use mucosa (labial mucosa or buccal mucosa) free transplantation, and there are also medium-thick skin pieces for transplantation repair. 7.When full conjunctival capsuloplasty cannot be adequately corrected by using the mucosa of the mouth and lips, a medium-thickness skin slice free graft can be used for full conjunctival capsular reconstruction. 8.Conjunctival sac stenosis combined with orbital area depression should be corrected first, such as intraorbital HA eye seat implantation, and conjunctival sacplasty should be performed after 3-6 months of eye seat vascularization. A superficial temporal fasciocutaneous flap with superficial temporal artery or a retroauricular fasciocutaneous flap with intraorbital transfer and HA seat implantation should be used to repair orbital depression, which is especially suitable for cases of retinoblastoma (RB) with orbital content atrophy after eye removal and radiotherapy.