Cataract: The Disease and The Treatment

         1. What is cataract?
                     Inside the eye, there is a lens which helps us to focus on what we see. With the normal aging process, this transparent lens can slowly become cloudy. This cloudiness of the lens is what we call cataract. This cloudiness can become severe enough to decrease vision.
 
                                  

         2. Who gets cataract?
                     Most of the people having cataract are older than 60 years. In this category of patients, cataract develops due to age, i.e senile cataract. Cataract however can develop due to other causes, like diabetes, chronic intake of steroids, severe eye trauma, and hereditary causes, and hence can develop in all ages.  

         3. What do I feel if I have cataract?
                      Visually significant cataract can make things look blurry, with possible glare seen especially at night with bright lights on, such as when looking at the oncoming headlights of a car.

        4. How to treat cataract?
                      There is no medical treatment for cataract. In addition, unlike what most people think, cataract cannot be removed with a laser.  Cataracts are treated by microscopic surgery, where a tiny incision (less than 3mm) is made in the eye (Figure 1) and the cloudy lens is chattered by a pen-like probe using ultrasonic vibrations (Figure 2), then aspirated through the same probe. A clear, foldable plastic lens is then inserted in the eye through the tiny incision to replace the cloudy lens (Figures 3, 4, and 5). The incision does not need any stitching, but some surgeons do prefer putting one stitch, which they remove one week after surgery. In certain situations, when the lens is very hard, a larger incision is performed and the lens is taken out as is. The foldable implant can be a one-piece or a three-piece design (Figure 6).

             
                   Figure 1.                                                          Figure 2

                   Figure 3.                                                           Figure 4.                                                   Figure 5.

                  Figure 6.

5. What are the risks associated with cataract surgery?
In the vast majority of cases, approximately 95-98% of the time, the surgery is uncomplicated, with excellent visual improvement and patient satisfaction. Cataract surgery should however never be trivialized. In a small percentage of patients, often unpredictable events can occur which can lead to less than ideal results, even if the surgery is performed by experienced surgery. Some of the most common risks are listed and explained below:

                       -Ocular infection (Endophthalmitis): can be serious, and might cause total loss of sight. Fortunately, it is very rare,
                       occuring in one in several thousands of cases.
                       -Swelling of the retina (cystoid macular edema): can develop after cataract surgery from excess inflammation, and can
                       decrease vision. Treatment includes topical steroid eye drops or non-steroidal anti-inflammatory eye drops.  Sometimes
                       steroids injection behind the eye, or intra-ocular vitrectomy surgery can be useful in improving the vision.
                       -Retinal detachment: moderate to high myopes are at a higher risk to develop retinal detachment after cataract surgery.
                        Symptoms include a curtain blocking the vision, flashes of light like lightening streaks, or new floating spots in your vision.
                       -Posteriorly dislocated lens material: rarely, some lens material can fall into the back cavity of the eye (vitreous cavity).
                        When large, the ophthalmologist may recommend a second surgery, a vitrectomy, to remove the dislocated material, to
                         prevent the development of unnecessary inflammation with resultant retinal swelling (macular edema), among others.
                       -Choroidal hemorrhage: rare and unpredictable, happens during cataract surgery, with sudden bleeding in the vascular layer
                        nourishing the retina (called choroid). In some severe cases of choroidal hemorrhage, significant visual loss may ensue.
                       -Corneal decompensation and edema (swelling): can lead to a significant decrease in vision. Some might improve spontaneously,
                         while others might require a corneal transplantation.

   6. Types of implanted artificial lenses

             There are several types of intraocular lens implants.
                   -Conventional (spherical), non-foldable: used in certain selected cases. Some are meant to be placed behind the iris,
                     while others are designed to be inserted in front of the iris.
                   -Conventional (spherical), foldable lenses.
                   -Conventional (spherical), blue light-filtering (yellow-tinted), foldable lenses.
                         -Believed to filter light wavelengths which are harmful to the retina. Their potential benefit is long-term.
                   -Aspheric, foldable lenses, some of which are blue-light filtering:
                         -Designed to decrease optical aberrations (spherical aberration) in the eye that result from the implanted lens.
                         -Examples include Acrysof IQ lens (Alcon, Fort Worth, Texas)
                   -Toric foldable lenses:
                         -Conventional lenses don't compensate for astigmatism. Toric lenses are new technology lenses that have
                          proven effective in correcting pre-existing ocular astigmatism.
                   -Multifocal foldable lenses
                         -Help in improving near-vision. Work best when they are implanted in both eyes.
                         -Examples include Restor intraocular lenses (Alcon, Fort Worth, Texas).

               Non-foldable implants are made of PMMA (polymethyl methacrylate) material, while foldable ones can be made of silicone or acrylic. The latter is the most popular, and it can be hydrophobic or hydrophilic.
 

         7. What to expect during cataract surgery
               -Vision usually improves markedly by the first day, but sometimes takes longer.
               -Patient need to be examined the first day, within a week, and then a month and 3 months later.
               -Avoid direct water exposure to the operated eye for the first week.
               -Avoid rubbing the eye, bending over, or lifting heavy objects for the first week.
               -In some cases, a membrane might form behind the lens implants, decreasing vision. This phenomenon, called posterior capsule
                opacification, or "after-cataract" in the lay-man term, can happen even years after surgery. It is successfully treated by
                "zapping" the opaque capsule using an office-based laser (YAG laser).
               -The eye, devoid of the natural crystalline lens, cannot accommodate after cataract surgery. Luckily, most of the cataract patients
                are in the presbyopic age and might not be bothered to use reading glasses. New implants, however, have shown to be effective
                in providing some acceptable near vision while maintaining a good far vision.
               -The power of intraocular lenses can be calculated in a way to correct pre-existing refractive error. Newer generation,
                toric implants, are now available to correct pre-existing astigmatism as well.