What is Cataract?
- It is loss of clarity of the natural lens, which prevents light rays from reaching the retina. It might vary from slight grayish discoloration of lens to pearly white or brownish-black colored lens depending on the stage and type of cataract.
- In early cases, a simple change in spectacle power may help. However quality of vision may be affected, and can be noticed easily if the cataract is more in one eye.
- As the cataract progresses, vision drops even with spectacles, till finally
only the perception of light remains.
Ageing is the most common cause of cataract. Every person gets it sooner or later, especially people over 60yrs of age. Occasionally it can start at a younger age and rarely it may be present even at birth. Other causes include diabetes, eye injury, use of certain medications, and secondary to other eye diseases such as uveitis and glaucoma.
Signs and symptoms of cataracts include
Factors that increase your risk of cataracts include:
- Increasing age
- Excessive exposure to sunlight
- High blood pressure
- Previous eye injury or inflammation
- Previous eye surgery
- Prolonged use of corticosteroid medications
- Drinking excessive amounts of alcohol
- The most common symptom blurring of vision, which is painless and gradually worsens.
- Clouded, blurred or dim vision
- Increasing difficulty with vision at night
- Sensitivity to light and glare
- Need for brighter light for reading and other activities
- Seeing “halos” around lights
- Frequent changes in eyeglass or contact lens prescription
- Fading or yellowing of colors
- Double vision in a single eye
- Surgery can be performed manually through 5- 6 mm wound called SICS (Small Inscision Cataract Surgery).
- Phacoemulsification is at present the universally accepted standard-of-care for cataract surgery.Ultrasound energy is used in phacoemulsification to break up the cataract (Emulsify) into microscopic fragments which can be sucked out of the eye.
- The femtosecond laser technology that brought new levels of safety, accuracy and predictability to LASIK surgery is also advancing cataract surgery. In our office, we call the procedure Refractive Laser-Assisted Cataract Surgery (ReLACS), but it also is known generally as laser cataract surgery.
What is MICS?
- The surgical wounds have progressively become smaller and now the latest technique is “Micro-coaxial Phacoemulsification” or MICS.
- MICS is phacoemulsification of the cataract through a wound of 2.2 mm or less, with implantation of an intra-ocular lens through the same wound.
- Wound healing and refractive stabilization is faster in MICS than in traditional phaco.
- Furthermore these lenses are preloaded by the manufacturer into the injector. Thus they can be directly injected into the eye without touching the lens by any instruments.
The majority of the IOLs implanted are mono-focal. They can focus light rays from one particular distance only. Normally distance objects are clear and one needs glasses for reading.
Intra ocular lens can be rigid or foldable. The advantage of foldable lenses is that it can be inserted through a smaller wound.
Monofocal Aspheric IOLs
These IOLs additionally correct ‘higher order aberrations’ (especially spherical aberration), which cannot be otherwise corrected by spectacles. This improves the quality of vision and clarity especially in dim light condition.
Multifocal lenses are specially engineered and have different segments built onto the same lens. These segments focus light from both distant as well as near objects, allowing spectacle freedom for most activities.
Traditionally used monofocal IOLs correct only the spherical refractive error. Patients with preexisting astigmatism will need spectacle correction for distance vision and near. Toric IOLs eliminates the need of glasses for distance.
Recently multifocal IOLs have also been introduced with this option, thus correcting for distance, near and cylindrical error.
A limitation of standard multifocal IOLs is that they provide good distance and near vision but have a somewhat compromised intermediate vision. This is the distance used for working on computers. Trifocal IOLs provide excellent vision not only for near and far, but also for intermediate distances.
Toric Multifocal IOLs
Astigmatism is a refractive error in which the curvature of the cornea is different in different meridia. People with astigmatism were earlier not suitable for multifocal IOLs. Now with the introduction of Toric Multifocal IOLs, it is possible to correct this astigmatism and also provide good near vision to this group of people.
At “The Eye Infirmiry” , we have always been at the forefront of embracing new technologies which increase our accuracy and precision, improve safety, or enhance patient comfort.
Let’s take a closer look at some of the sophisticated equipment in our armamentarium. Once cataract is diagnosed, preoperative tests and evaluation are done to calculate the power as well as determine the appropriate type of the lens to be implanted. This technology of using the appropriate IOL based on individual eye parameters is referred to as Customised Cataract Surgery.
Biometry (IOL power calculation) is done by trained professional and every effort is made to ensure accurate results. It involves measurement of the eyeball length and corneal power.
Pentacam (Oculyzer from Alcon)
This is based on Scheimpflug camera wherein the corneal power is measured at multiple points. These measurements are based on elevation from a reference sphere – a form of elevation-based topography.
The Pentacam can also accurately measure thickness of the cornea at various locations. This helps in assessing the corneal cylinder (astigmatism) accurately for planning toric IOLs as well as for planning limbal relaxing incisions for correction of astigmatism during surgery.
The Pentacam helps us to manage complex cases such as patients coming for cataract surgery after having undergone refractive surgery (for example LASIK or PRK) or those with Keratoconus.
This works on the principle of partial coherence laser interferometry. Here the length of the eye is measured using laser, and hence is extremely accurate for calculating IOL power calculation. All the measurements are taken without touching the patient’s eye. It is an extremely fast machine which
can take hundreds of readings within minutes