Development of Minimally Invasive Vitrectomy The field of vitreoretinal surgery has advanced rapidly since Dr. Machemer in the United States began to apply transciliary vitrectomy in the early 1970s. Machemer initially used a 17G (1.5 mm tip diameter) transciliary vitrectomy multifunctional instrument. This instrument required a fiberoptic cuff and a scleral incision of 2.3 mm. In 1974, O’Malley and Heitz designed a smaller glass cutter head with a diameter of 0.9 mm (20G), and this less invasive, three-channel, 20G vitrectomy system is still in use today. In 1996, Dr. Chen of McGill University in Canada adopted vitrectomy through a scleral self-closing tunnel incision, which is an exploration of reducing surgical injury and shortening the surgical time. This method avoids the insertion and removal of scleral plugs, prevents outflow of intraocularly irrigated fluid or the escape of gases, and maintains intraocular pressure, and the surgical scleral incision is self-closing after the removal of the instrument, without the need for stitches. can be closed by cauterization. This method has been adopted and improved by many scholars, but the surgery still needs to do the incision of the surface tissue of the white eyeball, the damage is still larger, the operation is also more time-consuming, and it has not reached the real minimally invasive. In 2001, Dr. Fujii and his colleagues at the University of Southern California designed a 25G (0.5mm diameter glass cutter head) microsurgical system, i.e., the transconjunctival suture-free vitrectomy system (25G TVS) and a series of matching surgical instruments, which was firstly reported in the American Journal of Ophthalmology in October 2002 for the first time. In October 2002, the American Journal of Ophthalmology reported for the first time on their initial success with the system, which marked a breakthrough in vitrectomy surgery. It made vitrectomy minimally invasive and minimally invasive vitrectomy was born. The 25G microsurgical system has a higher cutting frequency and suction power compared to conventional vitrectomy systems. Unlike traditional irrigation tubes, the 25G Microcatheter System consists of three trocars (introduced by puncture with a trocar needle), an irrigation tube, a scleral plug forceps, and three tube plugs. The trocars are polyethyleneimine tubes that are 3.6 mm long with internal and external diameters of 0.57 mm and 0.62 mm, respectively, and have a small loop on the outer portion of the eye that allows the trocars to be manipulated with forceps grasps.The 25G perfusion tube is a metal tube that is 5 mm long with internal and external diameters of 0.37 and 0.56 mm, respectively. The tube is inserted into the eye through the trocar and does not require sutures for fixation.The 25G system is accompanied by a series of vitreoretinal microsurgical instruments, including a glass cutting head, light-conducting fibers, internal ocular microscopic forceps, and intraocular coagulators, which are much more sophisticated than those used for traditional vitrectomy surgery. So far, there are not many hospitals abroad that can carry out this kind of surgery, and there are only a few large hospitals in China that can carry out this kind of surgery. The main advantages of minimally invasive vitrectomy Traditional vitrectomy surgery generally involves making a ring-sized (40-45 mm) incision in the surface layer of the white eyeball, traction on the four rectus muscles, suturing and fixation of the corneal contact lens fixation ring, and making three 1-mm-long puncture holes in the inner layer of the eyeball in order to enter the vitreous cavity located in the middle of the eyeball and to cut the vitreous humor that has a lesion. Because the incisions are large, sutures are needed to close the incisions after the vitrectomy is done. Minimally invasive vitrectomy uses a cannula needle to puncture the bulbar conjunctiva and sclera directly into the vitreous cavity, which quickly establishes the three channels needed for the surgery and places temporary cannulas over the channels to keep the puncture openings in the conjunctiva and sclera in the same line. The irrigation tubes and surgical instruments enter and exit the eye through the cannula, which avoids damage to the eyeball caused by repeated entry and exit of the surgical instruments. Because the diameter of the cannula needle and surgical instruments are very small, only a small hole needs to be passed through the conjunctiva and sclera, and the conjunctival and scleral wounds can be closed on their own after the cannula is removed, so the purpose of suture-free is achieved, and the postoperative inflammation is light and the recovery is fast. All these improvements not only reduce the trauma caused by surgery, but also simplify the surgical operation and save the operation time. Minimally invasive vitrectomy, when combined with the use of a non-contact wide-angle microsurgical system, makes the procedure even simpler and less invasive, and also saves surgical time because it eliminates the need to suture the fixation ring that holds the corneal contact lens in place. Because minimally invasive vitrectomy does not require an incision in the bulbar conjunctiva, it has unique advantages for patients who need to protect their bulbar conjunctiva, such as those with glaucoma. Who is a good candidate for minimally invasive vitrectomy? Minimally invasive vitrectomy is suitable for the following patients: 1. Vitreous clouding that affects vision significantly; 2. Non-absorbable vitreous hemorrhage; 3. Anterior retina; 4. Anterior macula; 5. Macular lentigines; 6. Vitreous tissue biopsy; 7. Retinal detachment of foramen ovale without proliferative vitreoretinopathy (PVR); 8. Those who need to undergo sheath incision of the retinal vasculature; 9. Those who need to undergo removal of the remaining lens cortex; and 11. Those who need to undergo removal of the lens cortex. The person who needs to do the residual lens cortex removal; 10, vitreomacular pulling syndrome; 11, traction retinal detachment; 12, endophthalmitis. The main shortcomings and problems to be solved in minimally invasive vitrectomy The main shortcomings of minimally invasive vitrectomy: 1. The flow rate of thick blood and proliferative film is slower than that of 20G system, and the glass cutting head is easy to be clogged; 2. The efficiency of intraocular operation is not as high as that of traditional vitrectomy, and it is difficult to carry out complex intraocular operation; 3. Some supporting instruments are not yet perfect, and the indications for the operation are somewhat limited; 4. Some of the supporting instruments are not perfect, so the indications for the surgery are limited; 4. There are some cases of incision leakage after the surgery, mostly in patients with thin scleral wall in high myopia or scleral scar in secondary surgery, and the incision of these patients is not easy to be closed by themselves, so it is necessary to be cautious to do minimally invasive vitrectomy surgery. Problems to be solved: 1, can dissolve or liquefy the vitreous and vitreous blood so that it is easy to cut and suction of the chemical drugs to be studied and developed; 2, supporting the surgical instruments need to be improved and perfected; 3, surgical operation skills need to be further improved; 4, postoperative incision leakage prevention and disposal. Prospect of minimally invasive vitrectomy Minimally invasive vitrectomy has the advantages of small damage, light postoperative reaction, fast recovery, fewer complications, and is suitable for some special patients, which makes vitreous surgery enter a new stage. In order to expand the indications of minimally invasive vitrectomy so that more patients can receive this surgery, some scholars are now working on the research of chemical drugs that can dissolve or liquefy vitreous and vitreous blood. These drugs dissolve the vitreous and thick vitreous blood, making it easy to cut and aspirate. Among them, the application of hyaluronidase and hemofibrinolytic enzyme is the hotspot of the current research and has achieved preliminary results in the clinic, which is a very strong support for the development of minimally invasive vitrectomy. With the development of science and technology, especially the continuous improvement of instruments and the development of enzyme-assisted technology, minimally invasive vitrectomy will become more and more mature.