GUIDELINES FOR THE CATARACT PROGRAMS
IN LATIN AMERICA /
INDEX
- INTRODUCTION
- IDENTIFICATION AND SELECTION OF PATIENTS FROM THE SOCIO-ECONOMIC PERSPECTIVE
- MEDICAL DIAGNOSIS
- TREATMENT – SURGICAL PROCEDURE
- INSTRUMENTS
- HUMAN RESOURCES, PHYSICAL SETUP and EQUIPMENT
- INVOLVEMENT OF DIFFERENT CONSTITUENTS IN THE CATARACT PROJECT
- INTRODUCTION
There are estimated 45 million blind people in the world and 135 million more are visually impaired1. Cataractsarethe leading cause of blindness and most are age-related2. Todayalmost 20 million people are blind due to cataracts.If nothing were done this number would double by 20203. Cataract prevalence however, differs from one region to another. In the developing world it is estimated that 50% of blindness is due to cataracts4. There is no known prevention for cataracts, but adequate surgery can restore vision5.
Definition: A cataract is the clouding of the normally clear, natural crystalline lens of the eye. The lens is composed of water and protein. The protein is arranged in a highly organized pattern that allows light to pass through it with minimal distortion. As a result, the lens appears virtually clear. The lens can become cloudy (see Causes of Cataracts), blocking or scattering some light and preventing it from reaching the retina in sharp focus. This causes blurred vision and glare.
Most cataracts progress slowly over a period of years, but their rate of progression isunpredictable and it cannot be currently prevented. They can affect one eye or both eyes. As cataracts become denserthey produce visual symptoms; these typically include blur, glare, halos around lights, and double vision. Colors can become dull, a brown-yellow tint is common, and driving can become dangerous. Nonremoved cataracts can cause blindness.
Researchers continue to study cataracts, but their cause remains uncertain. However, there are certain risk factors associated with cataracts, they include:
- Age. Most people older than 60 years have cataracts.
- Medical conditions. Diabetes and other systemic diseases, glaucoma, and metabolic abnormalities can contribute to the development ofcataracts.
- Physical injuries. Commonly called traumatic cataracts. A blow to the eye, great heat or cold, chemical injury, exposure to radiation (usually associated with radiation therapy for cancer patients), and other injuries can lead to cataract formation.
- Ultraviolet radiation (UVA or UVB). Long-term exposure to sunlight is believed to speed up the development of cataracts.
- Oral steroids and other medications. Oral steroids (such as prednisone), the gout medication allopurinol, the breast cancer drug tamoxifen, the heart medication amiodorone, and the long-term use of aspirin have also been associated with cataracts.
- Smoking. Studies indicate that smokers are twice as likely to develop cataracts as non-smokers and that quitting can reduce the risk for developing cataracts.
With modern medical technology, cataracts are routinely treated safely and effectively using microsurgical techniques. Today, cataract extraction is one of the most successful surgical procedures—about 98 percent of all cataract surgical procedures result in improved vision in the short term.
- IDENTIFICATION AND SELECTION OF PATIENTS FROM THE SOCIO-ECONOMIC PERSPECTIVE
The Latin American area is facing a challenging scenario with respect to healthcare services.In general terms, the majority of the population in the region is covered by health systems financed through public resources. Government institutions are responsible for providing these services;however, the demand has been greater than the level of service provided.
Government institutions face numerous difficulties when they try to expand coverage and maintain a good level of quality in their services. They normally have large bureaucratic organizations that make operations inefficient, and their resource management systems are difficult to control. Their aim of providing services for more people causestheir administrators to constantly seek lower cost supplies and services, with the consequence of acquiring lower quality/lower technology options.
The treatment of cataracts is an example of a condition that has been directly affected by the public segment’s less than efficient management. The vast majority of the cataract procedures performed by the government are done with the outdated manual ECCE (Extra Capsular Cataract Extraction) technique with a rigid intraocular lens (IOL) implantation that consequently generates problems in the near term, such as Posterior Capsule Opacification (PCO), which adversely affects visual function and often requires a second intervention.
Phacoemulsification and a foldable IOL implantation offer a superior option with a smaller incision and the clinical and patient benefits related to it. However this adequate surgical procedure is not used in some cataract programs because of a lack of training of the surgeons, lack of information on the benefits for the patients, or funding issues. Thephacoemulsification technique has been successfully used in cataract projects in Brazil that were funded by the Federal Government and State Health Programs.
The other segment that offers services is the private sector; this segment is basically divided into private, private insurance and private assistance medicine. In the Latin America region, the population with access to pure private medicine is limited;the cost to access this level of service is higher than the others and many people cannot afford these types of services.
The Private Assistance medicine sector consists of all the non-profit associations or non-governmental organizations (NGO) that offer health services funded by charitable donations and contributions. Some of them are entirely self-funded, and some charge part of the costs of their services to the end users.
This challenging situation faced bythe Health System in the region results in a large number of patients with no health coverage who require treatment of curable diseases such as cataracts.
Due to this lack health coverage, organizations are identifying the different regions and populations that need support, and a considerable number of cataract programs or “Campaigns” are organized in the area with the best intentions to help people with no financial means affected by cataract to recover their sight.
It is critical that patients selected for cataract programs are filtered and classified according to their financial income level by the adequate institutions (government, churches, etc.). Cataract programs should be used to help people that will not be able to resolve their cataract problem within the private medical sector.
- MEDICAL DIAGNOSIS
Medical criteria to select patients who need a cataract surgical procedure and who have a reasonable probability of a successful outcome will determine the flow for the surgical procedures.
Typical Cataract eye examinations may include the following:
- Refraction. This test determines the eyeglass prescription that will give the best possible vision without surgery. It is performed by asking the patient to look through sample lenses that are held within a device called a refractor.
Visual acuity is not the only factor that determines the need for cataract surgery. Other factors like glare and difficulty seeing in dim light may prevent normal activities under certain lighting conditions that are not duplicated in the ophthalmologist's office. Visual impairment in the presence of bright lights (glare) and difficulty seeing even large objects in dim light (decreased contrast sensitivity) are common in patients with cataracts, even when they can read small letters under standard testing conditions in an ophthalmologist's office.
The effect of visual impairment on lifestyle must also be evaluated when cataract surgery is contemplated. Someone who sees nearly 20/20 in the ophthalmologist's office may experience so much glare that he or she cannot drive safely. On the other hand, someone who can read fewer letters in the office may not notice any limitations because his or her normal daily activities are less visually demanding.
A surgeon's decision to perform cataract surgery is made after a discussion of visual symptoms. Tests for glare disability and decreased contrast sensitivity may be indicated when visual impairment seems to be out of proportion to the visual acuity that is measured with standard techniques.
In the case of Cataract Programs, the surgeons must also understand the activities and environments of the cataract surgery candidatesin order to minimize the potential for post-surgical infections and dependency on additional treatments that might not be available after the surgeons or the patients leave the area where the procedure was performed.
- Slit lamp and Tonometer. This examination enables assessment of many conditions of the external parts of the eye as well as the cornea, pupil, and lens. It is the principal tool used to assess the severity of a cataract and eye pressure.
- Dilated fundus examination. This examination enables assessment of the back of the eye, including the retina and the optic nerve. The pupil must be dilated with drops to allow a good view of structures inside of the eye. Eye droppers must be kept closed in clean places to avoid contamination.
- Keratometry. This examination measures the curvature of the cornea - the clear, outermost part of the eye. The corneal curvature is used to calculate the proper power of the intraocular lens that should be implanted in the eye.
- A-scan. This instrument measures the length of the eye with ultrasound. This measurement, along with the corneal curvature, is used to select the proper power of the intraocular lens to be implanted in the eye.
- B-scan. This instrument evaluates the posterior pole anatomy when it is not possible to examine it directly due to a dense cataract.
The importance of the ophthalmic examination as the means to determine the cause of visual disability and to determine if it is due mainly to cataract cannot be overemphasized.
- Treatment – Surgical Procedure
Today, surgery is the only treatment for cataracts, and is typically performed in an ambulatory surgery center or the outpatient surgery center of a hospital. It does not require a hospital stay, and patients usually go home about an hour after the procedure is completed. Cataract surgery is performed under local anesthesia (an injection of anesthetic around the eye) or topical anesthesia (numbing drops in the eye). In either case, sedatives are routinely given intravenously to keep the patient relaxed during the procedure. Cataract surgery is not painful. Some conditions may require that general anesthesia be administered. In many cases the use of a phaco technique with small incision only requires topical anesthesia. This facilitates patient management and lowers surgical risks in environments where local or general anesthetics or adequate technical assistance are not available.
Phacoemulsification
The most common and advanced cataract surgery technique is phacoemulsification or "phaco." The surgeon first makes a small incision at the edge of the cornea and then creates an opening in the membrane that surrounds the cataract lens. This thin membrane is called the capsule. Next, a small ultrasonic probe is inserted through the opening in the cornea and capsule. The probe's vibrating tip breaks up or "emulsifies" the cloudy lens into tiny fragments that are suctioned out of the capsule by an attachment on the probe tip. After the lens is completely removed, the probe is withdrawn leaving only the clear (now empty) bag-like capsule, which will act as support for the intraocular lens (IOL).
Phacoemulsification allows cataract surgery to be performed through a very small incision in the cornea. Stitches are seldom needed to close this tiny entry, which means that there is less discomfort and quicker recovery of vision than with other surgical techniques. Small incisions and the absence of stitches do not change the curvature of the cornea like larger ones that are required with older surgical techniques. This allows for a more rapid rehabilitation of vision and possibly less post-operative dependence on glasses for good distance vision.
In order to take maximum advantage of the phaco procedure and a small incision, it is advisable to implant a foldable IOL after the removal of the cataract-damaged lens. There are different kinds of materials used in these foldable IOLs, with different properties and effects on the posterior capsule. So far clinical studies have shown the most biocompatible material with the human eye today is the acrylic IOL with hydrophobic properties,which hasa lower incidence posterior capsule opacification (PCO).
During the entire procedure an OVD (ophthalmic visco surgical device), commonly known as viscoelastic, needs to be used to protect the corneal endothelial cells. Thisinternal layer of the cornea (endothelium) contains a certain number of cells that do not regenerate if they suffer any damage. Thusduring the cataract procedure, these cells must be protected for a better surgical outcome. The ability of a viscoelastic to coat the endothelial cells and adequately maintain anterior chamber space is considered critical for endothelial protection during the phaco process. The performance of this material will generate better post-operative visual acuity, less endothelial cell loss and reduced incidence of IOP increase. It is reasonable to assume that low income patients operated on in Cataract Programs have not have easy access to post-surgical care and that any complication could put their recovered sight at risk.
There are different OVD products which differ in the kind of substance and properties that deliver. If the procedure is done with products with hydroxy-propyl-methyl- cellulose (HPMC), the surgeon should use more volume of this material to provide an adequate protection of the endothelium, as the HPMC is easily removed from the eye during the phaco procedure.
Extracapsular Cataract Extraction
A less common method of cataract surgery is the manual extracapsular cataract extraction (ECCE). This procedure, which was developed before phaco, is often used for removal of very advanced cataracts that may be too hard to break up using phaco or in patients who have multiple eye conditions that render phaco a less desirable surgical option.
ECCE requires a larger incision than phaco, perhaps 10 to 12 millimeters long, at the side of the cornea so the cataract can be removed in a single piece. Visual recovery may be slower after ECCE than phaco and there may be more discomfort because of the larger incision and sutures that are required to close it.
Once the cataract is removed, an IOL is implanted in the eye. Given that a larger incision has been made to remove the cataract-damaged natural lens, the surgeon has the option of inserting a non foldable IOL made from a medical-grade Plexiglas-like PMMA material or a foldable material as discussed above. This procedure requires placing sutures to close the wound.
This kind of procedures hasa higher risk of endoophthalmitis and PCO, which normally is treated but will affect the overall clinical outcome of the procedure.
The capsule that is intentionally left in the eye to support the IOL may become cloudy as part of the normal healing process after cataract surgery. This condition is called "posterior capsule opacification" (PCO) or "after-cataract," and it can reduce vision if it becomes dense enough.
When vision declinesbecause of posterior capsule opacification, a small opening can be made in the capsule behind the IOL with a YAG laser, which is named for the material used to generate the laser energy (yttrium-aluminum-garnet).
It is very reasonable to assume that low income patients operated in Cataract Programs have no easy access to post-surgical care and PCO or other complications could put their recovered sight at risk.
- INSTRUMENTS
Sterilization process and instrument cleansing must be performed in the appropriate centers or selected facilities to ensure sanitization and optimal outcomes.
The different methods that can be used must be in compliance with local regulations and with manufacturers’ instructions of equipment and instruments.In addition, they must be overseen by professionals on the team with the adequate knowledge and experience.
Handling of ophthalmic instruments
Theophthalmic instruments and microsurgical devices need special treatment and handling to remain in optimal condition. Some activities will need to be performed on a recurrent basis to guarantee the surgical outcome and safety for the patient.
The nursing staff is crucial to this task, and must be trained to know the correct handling and maintenance of the instruments.Some training must be performed if the staff is not aware of ophthalmic procedures to avoid waste and instrument damage.
- Maintenance
Cleansing
Drying