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The miracle of maintaining eye shape: How do Ophthalmic Viscosurgical Devices work?
Ophthalmic Viscosurgical Devices (OVDs) play an indispensable role in modern ophthalmic surgery. This transparent gel-like material not only maintains the shape and volume of the anterior chamber of the eye, but also protects the intraocular tissue from possible damage during surgery. The mechanism of operation of OVDs and their wide application in various ophthalmic surgeries make this topic worthy of in-depth discussion.
OVDs are derived from the original "viscoelastic material", whose extraordinary shape-holding ability and fluidity are the key to ophthalmic surgery.
OVDs maintain their shape by using a special substance that is introduced into the anterior chamber of the eye at the beginning of surgery and removed at the end of surgery. Its unique lubricity and fluidity allow surgical tools to operate freely within it, while under low shear stress, OVDs can maintain their shape and avoid collapse.
Application scope of OVDs
The primary uses of these devices include protecting the corneal endothelium from mechanical trauma and maintaining the volume and shape of the intraocular space during surgery. During surgery, OVDs are introduced into the anterior chamber of the eye via a syringe through a catheter and are removed by suction after surgery, and the space is filled with an appropriate physiological fluid (eg, buffered saline).
OVDs are commonly used during cataract surgery, corneal surgery, glaucoma treatment, ocular trauma, and vitreoretinal surgery.
Contraindications and side effects of OVDs
Although the use of OVDs may cause some side effects, due to its many advantages in ophthalmic surgery, especially in anterior chamber operations, OVDs have become an indispensable tool in surgery. There are currently no known contraindications to the use of sodium hyaluronan-based OVDs as an adjunct to anterior segment surgery.However, if OVDs remain in the eye after surgery, they may cause excessive intraocular pressure elevation, which usually occurs on the first day after surgery and resolves spontaneously within three days. This phenomenon is believed to be caused by the obstruction of aqueous humor outflow due to the large molecules of OVDs.
Desirable Characteristics of OVDs
An ideal OVD should have several properties, including ease of placement, low viscosity during placement, stability under positive pressure, stable performance during phacoemulsification, and no interference with device use or manual intervention. Placement of crystals, etc.
The physical properties of OVDs, such as viscoelasticity, viscosity, pseudoplasticity, and surface tension, directly affect their clinical characteristics.
In many cases, it is particularly important to choose the appropriate OVD based on the needs of the surgery. For example, pseudoplasticity is the property of a material that changes rapidly from a gel-like state to a liquid when subjected to varying shear stresses. This allows OVDs to flexibly respond to different challenges during surgery.
Manufacturing of OVDs
OVDs are sterile saline solutions composed of one or more viscoelastic compounds and buffers to maintain a pH between 7 and 7.5. Common ingredients include sodium hyaluronate, chondroitin sulfate and hydroxypropyl methylcellulose, etc.
Historical BackgroundSince Meyer and Palmer first isolated hyaluronic acid from the vitreous cortex in 1934, this technology has undergone decades of development. OVDs were first used in surgery in 1972, and a variety of formulations with different physical characteristics were quickly developed. To date, OVDs have become an essential tool in ophthalmic surgery.
ConclusionIn summary, the development of Ophthalmic Viscosurgical Devices has not only changed the way ophthalmic surgery is performed, but also ensured the safety and effectiveness of the surgery. So, have you ever thought about what more efficient technologies will be available in the future to further improve the safety and effectiveness of ophthalmic surgery?
