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 Dr. Sanjay Dhawan
Cataract & Lens Implant
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What is Phacoemulsification?
What is it done for?
Who is a good candidate?
What are the benefits?
What are the risks?
What tests are required?
What is the anesthesia & discomfort involved?
 
What is Phacoemulsification?
 

Phacoemulsification is the current method of choice for performing cataract surgery. The whole operation is done through a small incision of less then 3 mm a marvel of scientific advancement.

What is it done for?
 

Cataract is the condition where the natural lens of the eye develops opacity that leads to blurring of vision. When the decrease is vision is problematic enough to cause disturbance in routine life activities, the Phacoemulsification surgery can be performed for visual recovery. In some selected case this may also be done for refractive or presbyopic correction. Click here to read more about Cataract Diseases.

Who is a good candidate?
 

Anyone with significant cataract and without any uncontrolled systemic or complicating condition is a suitable candidate. Individuals with systemic conditions like diabetes, high blood pressure or heart disease should first have their systemic disease managed by a concerned specialist before going in for cataract surgery. It is also desirable to get a written clearance and any special instruction from the treating physician.

What are the benefits?
 

Phacoemulsification leads to rapid recovery of vision and early rehabilitation to normal life. It is a comfortable and convenient surgery. In most situations the patient does not need to stay in the hospital for more than a few hours. There are minimal restrictions or precautions after surgery and routine normal activities can be resumed within a day or so.

What are the risks?
 

Phacoemulsification is a relatively safe surgery for cataract, however, like any other surgery complications can occur in unfortunate circumstances. Many a times these circumstances are beyond human control. Some of the common and important complications are:

  • Rupture of posterior capsule

  • Prolapse of vitreous requiring vitrectomy

  • Hemorrhage (including Expulsive Hemorrhage)

  • Dislocation & displacement of lens / nucleus or fragments into vitreous

  • Dislocation & displacement of artificial intra-ocular lens

  • Inadequate support for lens implantation requiring use of an alternative type of lens implantation or postponing or abandoning lens implant

  • Pain & increase the eye pressure or glaucoma post-operatively

  • Infection or endophthalmitis which may require injection of antibiotics into the vitreous or even vitrectomy surgery. Although extremely uncommon (about 0.01 – 0.03 %) it is the most dreaded complication. Most cases of endophthalmitis occur because of infecting organisms from the patient’s own body and infrequently by infecting agents present in the fluids used for surgery. There is no way to predict or completely eliminate the risk of this complication. People with diabetes are at greater risk.

  • Corneal oedema

  • Refractive error and astigmatism

  • Wound leak

  • Inflammation or uveitis

  • TASS or Toxic Anterior segment syndrome

  • After-cataract or opacity of posterior capsule may be pre-existing or may develop a few months to years after cataract surgery. This is not really a complication but effect of natural healing process. It can be very easily & safely treated by YAG Laser Capsulotomuy.

What tests are required?
 

Some of the preliminary tests are:

  • Blood Sugar (Fasting & PP)

  • Urine (Routine & Microscopy)

  • ECG

Other systemic tests may be required depending on the clinical situation or co-existing diseases. Certain special eye tests are required:

  • Detailed eye examination

  • Keratometry (measurement of corneal curvature)

  • Ultrasound (A-scan) of the Eye or Biometry (to calculate the power of the lens to be implanted)

What is the anesthesia & discomfort involved?
 

Most cases are operated under Topical Anesthesia (also called Eye Drops or Surface Anesthesia) where some anesthetic eye drops proparacaine or lignocaine are instilled a few times before the surgery. Some special circumstances or uncooperative patients may require injection or peri-bulbar anesthesia.

Before the surgery it is important to dilate the pupil of the eye with use of various eye drops which may take about 1-2 hours.

The surgery is quite painless, however, the patient may feel some pressure & touch on the eye. Patient needs to stare straight up into the bright light of the microscope through.

What are the alternatives / options?
 

Following are alternatives:

  • Phacoemulsification

  • MICS – Micro-incision Cataract Surgery is just a minor variation of above technique where it is possible to operate through less than 2 mm incision. However, there seems to be no advantage over a temporally placed 3 mm incision and the lenses available till date which can go through less 2 mm incision are very new and not yet reliable.

  • SICS – Small Incision Cataract Surgery is an alternative to conventional surgery. The incision is large 5-7 mm and the nucleus of the cataract is removed in-toto. This technique is useful in cases with extremely hard brown or black cataract or for mass application for community service. Non-foldable lens is implanted, however, no suture / stitch is required

What are the steps of surgery? (see Video)
  This surgery is performed through a small incision of less than 3 mm that does not require any sutures / stitches. The capsule of the natural lens / cataract is opened with a needle by a process called rhexis. The hard core or nucleus is converted into a soft pulp or emulsified with the help of high frequency sound waves / ultra-sound delivered through the Phacoemulsification probe. This pulp is sucked out of the eye while a fluid is being irrigated into the eye. The soft cortex around the nucleus is simply aspirated out clearing the space for implantation of artificial intra-ocular lens. A foldable intra-ocular lens is loaded on a special injector and injected / implanted into the eye through the 3 mm incision.
 

What are the implants & material used?
 

Foldable lenses are made of two types of material – hydrophilic and hydrophobic acrylic – the latter being better in terms of long term results and least possibility of posterior capsule opacity.

In terms of optical design the intraocular lenses are of two main types:

Unifocal – The lens is single focal length which is usually aimed to focus at mid or far distance. As a consequence the person needs to wear glasses for reading near print and sometime for far. However, the quality of vision & contrast achieved with this lens is far better.

Multifocal – The lens has two focal lengths – one to focus the far objects and one to focus near objects. The need for wearing spectacles is minimized, however, at the cost of loss of some contrast sensitivity, glare and image quality. Moreover, these lenses are expensive and need a period of adjustment after both eyes are implanted with the same type of lens.

What technology is used?
  The technology that works at the heart of this surgery uses high frequency sound waves with frequencies 40,000-60,000 Hz (Ultrasound). These waves are generated by piezoelectric crystals houses in Phacoemulsification hand-piece and controlled by the surgeon through a computerized panel. The machine also uses fluidics whereby special fluid is constantly irrigated into and aspirated out of the eye. All good phacomachines work on the same principles and deliver the same end-result, the difference being only of different level of comfort they provide to the surgeon in terms of ease of use.
  How much is the time taken for surgery, in hospital and for recovery?
  Phacoemulsification surgery takes about 5-20 minutes (in most cases about 15 minutes) except in special or difficult circumstance where it may take longer. However, the preparation may take anything between 1-2 hours. It is advisable to observe the patient for about 2 hours after the surgery. So total time spent in the hospital is about 4-6 hours.
  What are the precautions & care before & after the surgery?
  Before
The patient needs to instill some antibiotic eye drops about 4 times a day in both eyes for about 3-5 days before the surgery. Some oral medicines as pre-medication may be required. The eye surgeon decides the type of medicines & dosage. The treatment for any other systemic diseases is to be continued even on the day of surgery except that anti-coagulant or blood thinning medicines may have to be discontinued a few days prior to operation.

After
Avoid head bath for a few days to 1 week
Avoid rubbing, pressing, massaging, heat, dust, dirt and bright sun for 1 month (use sunglasses outdoors)
Avoid heavy weights and strenuous physical activity for 1 month
Avoid swimming and splashing of water on eyes for 1 month
Continue other treatments advised by other doctors’ e.g. for Diabetes, High Blood Pressure, Asthma, etc.
Patient can resume most of the normal life activities from the next day
  What are the complications?
  The complications have already been detailed above in the risks.
  What is the long-term outlook?
  Cataract surgery has excellent long-term results. The lens implanted in the eye lasts lifetime (there is no expiry of this lens and it does not need to be replaced except in rare circumstances of any problem).
However, some patients may develop thickening / opacity of posterior capsule (a thin membrane on which the lens is placed) that may interfere with vision – this is called After-cataract. This can be easily treated by a short procedure called Nd-YAG Laser Capsulotomy.
  What are the advantages of getting it done by you / your hospital?
  The author has more than 20 years of experience of doing Cataract Surgery and more than 10 years experience of Phacoemulsification Surgery. The author has expertise in use of topical anesthesia (surface or eye drops anesthesia) in more than 99 % of his cases and an extremely low rate of complications. The emphasis is more on quality & finesse an not on irrationally trying out new lenses / products which are constantly being pushed into market by various companies. The author is conservative in his approach and pays great respect to human eyes & visual needs of the patient.

Driven by the quest for quality the author has always worked in institutions that offer facilities of high standards. The current hospitals where the author operates have the best of facility, technology & material for use in eye surgery.
  Discussion
 

Which Intraocular Lens (IOL) is most suitable for my eyes?

People suffering from cataract and planning for cataract surgery are faced with this difficult question & a frustrating list of choices. I will attempt to make it simple, let me start by explaining a few characteristics of the Intraocular Lenses (IOL):

What is Intraocular Lens (IOL)?
In cataract surgery the natural lens of the eye is removed. This leads a significant decrease in the optical convergence power of the eye or hypermetropia. Intraocular lenses are small lenses made of polymers and implanted into the eye in place of natural lens to help focus the light on to retina.

Foldable vs. Non-foldable Lenses
In conventional cataract surgery & in SICS a large cut / incision is made in the eye to remove the cataract. This is followed by insertion of a rigid 6.0/6.5 mm lens through the incision into the eye. These lenses are rarely used these days.
In phacoemulsification the entire operation done through a small hole of 3.0 mm or less. It is not possible to implant a rigid lens. This difficulty is overcome by use of very flexible lenses which can be folded and loaded in special injectors aninserted through the small hole into the eye. These are currently the preferred lens to be used.

Lens Material (Silicone, Hydrophillic & Hydrophobic Acrylic)
Foldable Intraocular Lenses are commonly made of silicone or acrylic polymer (hydrophobic or hydrophillic).
Silicone was used in older lenses & gave good optical results in the immediate post-operative period. But these lenses were somewhat bulky and lead to severe thickening of anterior & posterior capsules (membrane covering of natural lens which is left behind to provide support for artificial intraocular lens). This lead to deterioration of vision and required treatment by YAG Laser Capsulotomy.
Hydrophillic Acrylic lenses are highly flexible and slim, therefore, can be introduced through extremely small incisions. They have good immediate visual results but suffer from tendency to cause thickening of posterior lens capsule.
Hydrophobic Acrylic lenses are slightly less flexible and somewhat thicker than their hydrophillic counterparts. But they are extremely inert and do not lead to lens capsule thickening. Due to these properties they are ideal for use in children, young adults and the eyes predisposed to inflammation. Being hydrophobic in nature it is possible to incorporate a color tint to avoid blue chromatopsia after surgery.

Spheric vs. Aspheric IOL
Spheric are the conventional lenses where both surfaces of the lens are uniformly curved or are part of a sphere. These lenses have inherent problem of spherical aberrations caused by excessive bending of light at the edges.
Aspheric or advanced optics lenses have their curvatures flattening out towards the periphery or edge, thereby, minimizing spehrical aberrations.
Aspheric lenses give much sharper vision and better contrast but due to decreases depth of focus, the need for reading glasses becomes more urgent. On the other hand spheric lenses, though lack the sharpness & contrast to some extent but have better depth of focus leading to slightly better near vision. However, almost all lens manufacturers are replacing their spherical lenses with aspheric.

Monofocal vs. Multifocal IOL
Monofocal lenses have a single focal length and unlike the natural lens do not possess the ability to change the focus. Therefore the patient needs to wear reading glasses in order to focus at near fine print. But these lenses provide much better contrast and image clarity.
Multifocal lenses have 2 foci - a distance and a near focus. This is achieved by having multiple optical zones fashioned in the lens in the form of alternating rings for distance and near. This leads to splitting of light into distance and near foci. As a result both the distant and near objects can be focussed in the eye at the same time. However, the contrast and sharpness of the vision is reduced significantly. There lenses are also prone to more glare and haloes of light during driving at night time.
So for patients who need sharp vision and better contrast and do not hesitate in wearing reading glasses, monofocal lenses are most suitable. Whereas, those who do not want dependence on reading glasses but are willing to compormise on contrast and sharpness of vision, can opt for multifocal lenses.
Please note that both eyes should have the same type of lens - monofocal OR multifocal.

Toric vs. Non-toric
Toric lenses, besides having spherical power, also have cylindrical power which corrects astigmatism present in the eye. Non-toric lenses do not have any cylindrical power. Eyes with no or negligible astigmatism require non-toric lens and the eyes with significant astigmatism would benefit from toric lenses. Toric lenses are especially useful in patients with high degree of against the rule corneal astigmatism which is not amenable to correction but incision placement.

My preferred lens
Currently I prefer to use Foldable Hydrophobic Acrylic Aspheric Monofocal Lens with a natural color tint and toric where required. Multifocal is preferred where cosmetic requirements is more important and there are no critical visual needs.

 
Author: Dr. Sanjay Dhawan
Last Updated on: 1 March, 2014
   

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