CATARACT

CATARACT

Our eye is like a camera. A camera has a group of lenses to zoom and focus the image. The same job in human eye is done by a single structure called as “Lens”. This lens is placed behind the iris and helps in focusing and zooming the images.

This lens is a clear structure which is placed in a bag called as “Capsular bag” similar to a toffee being wrapped tightly by a plastic paper. But this capsular bag has no free ends.

In old age due to many bodily changes, this lens slowly starts losing its transparency. This opacification of lens is called as “Cataract”. Since cataract is a disorder of old age, every individual has to face it in old age. Cataracts commonly affect both eyes, but it is not uncommon for cataracts in one eye to advance more rapidly. Typical symptoms may include blurry vision, glare, difficulty with night vision, poor color vision, or frequent changes in eyeglass prescription.

There is no medical treatment for cataract. Surgery is the only treatment available. Cataract surgery is the most commonly performed surgery in the world. It has 98 percent success rate. With the advancements in surgical fields, now, a cataract surgery can be done without injection (needle prick), within a few minutes with Phaco. The patient can resume his duties on the same day of surgery.

Cataract surgery is performed to replace the opaque natural lens (cataract) with an artificial IOL. As said earlier, the lens is placed in capsular bag which has no free openings. To reach the lens, we need to make an opening in the surface of the bag. This is called capsulotomy. Through this opening, the lens is removed, leaving an empty bag. An artificial lens (IOL, IntraOcular Lens) is placed in this bag, which now starts doing the job of original lens. This bag is placed inside the eye ball (imagine the toffee being placed in a sealed box). To reach this we need to make an opening in the eyeball, which is called as “incision ”. Through this incision we reach the capsular bag, make an opening in the bag (capsulotomy), remove the lens and insert an IOL in the bag. Briefly, these are the steps of surgery. Since the structures of eye are very small, a microscope is used to magnify the image. Therefore it’s a microscopic surgery and requires utmost care and skill.

Surgical Techniques

There are many surgical techniques based on the different approaches in either of above mentioned steps. The incision can be placed on sclera or limbus or cornea. Corneal incision is the most preferred as it has least tissue manipulation. The size of incision can vary from a large 12 mm to less than 2 mm size. The lesser the size, the lesser the tissue manipulation and healing time and recovery time. A large incision may need stitches to close it. While smaller ones do not need stitches. Stitches should best be avoided as they cause redness, discomfort and watering. The removal of lens can be done manually which requires a large incision, or it can be done with Phaco with very small incision. Phaco is a technique where in a needle is passed into the lens, which dissolves the lens with ultrasound energy and sucks the lens. Phaco is the best and the most ideal technique of cataract surgery.

Anesthesia

The surgery is usually done under Local anesthesia (Peribulbar or Retrobulbar anesthesia) where an injection is given around the eye. Eye is massaged for the dispersion of injection. This injection has the risk of bleeding, optic nerve injury, globe injury etc. To prevent these complications, the latest preferred mode of anesthesia is Topical Anesthesia, where in ‘Eye drops’ are used instead of injection. It’s always advisable to find a surgeon who can operate without injection.

Intra Ocular Lens (IOL)

There are different types of IOLs available. Rigid IOLs need a large incision for insertion. Foldable IOL needs a small incision. Usually the IOL corrects only far distance. Patient requires glasses for reading. Multifocal IOL corrects both far and near vision which makes the patient less dependant on glasses. UV filter IOL s have the capacity to filter the ultraviolet rays which may be harmful to retina.

Role of anesthetist in cataract surgery:

Though the surgery is done under topical or peribulbar anesthesia, due to old age, there are risks of systemic complications like heart blocks, arrhythmias etc. An anesthetist will take care of such problems, if they arise. Therefore , Its advisable to undergo cataract surgery in a setup where an anesthetist is readily available.

Before the surgery, anesthetist examines the patient and advices him about medications. During surgery , he monitors for any untoward event and tackles it if arises.

Prior to operation:

Few important investigations like blood sugar, ECG etc. are done. Ocular tests like Eye pressure, Syringing are also done. Few tests are done to calculate the power of IOL that has to be placed. Pre anesthetic checkup is done for fitness.

Anesthetist’s orders need to be followed. On the day of surgery patient can have a head bath, as he would be asked not to have head bath for few weeks after surgery. You need to instill eyedrops on the morning of surgery as adviced. You need to change your clothes before being taken into the operation theatre.

During the operation:

Drops will be instilled to numb your eyes ( some surgeons may give an injection around the eye for the same purpose). You may be asked to follow some instructions like : “Staring at a light above”, ‘looking down’, ‘not to squeeze the lids’ etc.. You will be in full conscious , you may feel some sensation in the eye, but not the pain. The actual procedure lasts for about 20 to 30 minutes.

After the operation:

You will be shifted to recovery room, where you can have food after about 10 minutes. You will be asked to take few medications. You will be seen by the surgeon after couple of hours. Depending on the type of surgery done, the eye patch may be removed or will be kept for another day. You will be given the postoperative instructions ( a printed material would be given). You need to wear dark goggles in day time to protect the eye from sunlight and dust. At nights to protect from your own fingers , you should wear a eye shield. For about a month you have to instill eye drops as adviced. Usually two visits are required after the surgery, first after one week and next after a month. Glasses would be prescribed after one month of surgery. Till then, dark goggles should be used. You can resume your regular duties one day after the surgery if phaco is done.

What are potential complications of cataract surgery?

While cataract surgery is one of the safest procedures available with a high rate of success, rare complications can arise. The most common problems arising after surgery are persistent inflammation, changes in eye pressure, infection, or swelling of the retina at the back of the eye, and retinal detachment. If the capsular bag is injured, then the artificial lens may need to be placed in a different location. In very rare cases, the intraocular lens moves or does not function properly and may need to be repositioned, exchanged, or removed. All of these complications are extremely rare but can lead to significant visual loss if left untreated; thus, close follow-up is required after surgery.