What are the most common cataract surgery tools that are used, and their approximate costs? This page is all about the most commonly used tools used by eye surgeons. If you think that the invention of the surgical microscope and the major advances in phaco machines were the only determining factors in the evolution of cataract surgery, well think again, because you are wrong. In fact, the modern “Renaissance” of cataract surgery is based upon several inventions that might seem too small to be of that much importance, but yet they are of supreme importance!
We look at some of these inventions and their role in modern cataract surgery. Before proceeding, please be reminded that:
- First, the eye ball or the globe is a hollow ball that is filled with fluids, meaning that if it is pierced, the fluids will leak outside the ball and the ball walls will collapse over each other. It’s a very delicate, yet complex structure, and it requires complex tools to operate on it.
- Second, as we discussed on another page, the lens is exactly like an M&M’s candy button; the outer colorful layer is the lens capsule, while the inner chocolate resembles the lens material.
- Third, the prices that will be mentioned later are approximate figures that can vary with time and can change from one place to another. They are more like a guide that aims to help you better understand why cataract surgery is expensive.
OVDs (ophthalmic viscosurgical devices)
We just mentioned that on piercing the globe, the inner fluids within the eyeball will leak out, and the globe will collapse, rendering the cataract surgery void. However, with the invention of OVDs, all this has changed.
Viscoelastic materials are truly amazing substances in being able to behave as both a gel and as a liquid when subjected to pressure. This means that all the surgeon has to do is just inject some viscoelastic inside the globe in the anterior chamber (after making an incision in the cornea), and the structure of the eye globe will be preserved without collapse owing to their unique space maintenance ability, making the task of the surgeon a much easier one.
These “miraculous” materials help the surgeon in many of the steps of a cataract surgery, like maintaining the formation and depth of the anterior chamber during capsulorhexis (the removal of a circular part of the anterior lens capsule in order to have access to the lens material), and facilitating the insertion of the IOL. After the surgery is finished, the surgeon aspirates the previously injected viscoelastic agent and the job is done.
Viscoelastic agents are composed of one or more of the following materials: sodium hyaluronate, chondroitine sulphate, and hydroxypropyl methylcellulose. All these materials are transparent in nature, so they won’t affect the view of the surgeon after injection. They can be classified based on their behavior into cohesive agents and dispersive agents.
The cohesive agents have chemical and physical properties that make them behave as globules or droplets, meaning that they tend to adhere and coalesce up on their selves, so when they are injected inside the anterior chamber they maintain its space even if there are multiple incisions done on the cornea and during all the manipulations performed inside the eyeball during cataract surgery.
Examples of cohesive OVDs include:
- Healon and Healon GV produced by Abbott medical optics incorporation (AMO). The price of a 40 ml sterile syringe of the first is about $25, while the price of a 40 ml sterile syringe of Healon GV is about $35. All are approximate figures, bear in mind.
- OcuCoat produced by Baush & Lomb incorporation.
- Provisc produced by Alcon Laboratories. The price of a 40 ml sterile syringe is $25 approximately.
Dispersive agents on the other hand, tend to coat surfaces rather than coalescing upon themselves. When dispersive agents are injected inside the anterior chamber, they coat the inner surface of the cornea thus providing a protective layer guarding this delicate layer from damage from manipulations inside the globe or from excessive exposure to ultrasonic power of the phaco probe used to fragment the cataractous nucleus.
Examples of dispersive agents include:
- Viscoat, produced by Alcon Laboratories. The price of a 40 ml sterile syringe is about $20.
- Vitrax, produced by Abbott medical optics corporation.
The OVD is provided as a box containing one sterile syringe containing the viscoelastic agent. The solution is non-pyrogenic (does not lead to rise in body temperature).
The number of syringes of viscoelastic agents used during a single surgery and the types of viscoelastic agents used varies greatly depending on the condition of the patient’s eye.
There are many factors that are taken into consideration like the presence of concomitant ocular diseases, the patient’s initial anterior chamber depth, the condition of the pupil (whether can be dilated pharmacologically or not), the degree of opacification of the nuclear lens, and the type of surgical technique to be used (whether phacoemulsification or extra capsular cataract expression).
MVR and clear corneal blades
Have you ever considered that the eyeball is a freaky small structure to be operated upon? Have you ever thought about the kind of blades that can be used to make an incision in the eyeball without just slicing this delicate gem into two halves?
This is where the tiny ophthalmic blades come to action. In fact, there are different shapes and sizes of these blades. Our main focus will be on the blades most commonly used in cataract surgeries.
The MVR (micro vitreoretinal blade): This type of blade is used to pierce the cornea to make side ports (during cataract surgery, two types of incisions are made. The main port is for introduction of the IOL. The side ports are much smaller incisions used to help the surgeon to introduce other instruments when needed).
They have two shapes; the straight shape and the 45˚curved shape. The MVR is an incredibly thin instrument with an astonishing diameter starting from 0.912 mm.
The price of a disposable straight MVR is about $8, while the price of a disposable curved MVR is about $10.
The clear corneal blade: This is another type of surgical blade used in ophthalmology. It is a spear shaped instrument having variable diameters starting from 1.3mm. It is used to make the main port incision through which the IOL is introduced inside the eye ball.
The price of a disposable clear corneal blade is roughly $7.
Making large corneal incisions as in cases in which the technique of ECCE (extra capsular cataract expression) is used, necessitates suturing of this incision in order to close the wound.
The suture type used in such cases is Nylon 10-0. Nylon is used in manufacturing these microscopic threads because it is monofilamentous, meaning that the whole thread is composed of a single filament. This is of supreme importance because other types of suturing threads that are composed of multiple filaments rolled over each other are not allowed to be used in suturing the cornea. This is because bacteria might settle in the tiny angle between the filaments, rendering this type of suturing thread inadequate to be used in suturing the cornea (to minimize the incidence of endophthalmitis).
The Nylon 10-0 sutures are extremely thin to the extent that they need to be visualized under the magnification of the surgical microscope in order for the surgeon to be able to properly handle this tiny suturing thread. It has an amazing diameter of 0.02 mm that is one fifth the average diameter of a human hair, yet it is strong enough to keep the corneal incision closed.
The Nylon 10-0 is supplied in a double armed form, meaning that there is a needle attached to each of the two ends of the Nylon thread. There are many companies that manufacture this type of suturing thread like:
- Alcon Laboratories, and the price of a single ampoule is about $13.
- Assut sutures, and the price of a single ampoule is about $11.50.
- FSSB sutures, and the price of a single ampoule is about $12.50.