TYPES
A subcapsular cataract occurs at the back of the lens. People with diabetes or those taking high doses of steroid medications have a greater risk of developing a subcapsular cataract.
A nuclear cataract forms deep in the central zone (nucleus) of the lens. Nuclear cataracts usually are associated with aging.
A cortical cataract is characterized by white, wedge-like opacities that start in the periphery of the lens and work their way to the center in a spoke-like fashion. This type of cataract occurs in the lens cortex, which is the part of the lens that surrounds the central nucleus.
SYMPTOMS
Adult cataracts develop slowly and painlessly. Vision in the affected eye or eyes slowly gets worse.
Mild clouding of the lens often occurs after age 60, but it may not cause any vision problems.
By age 75, most people have cataracts that affect their vision.
Visual problems may include the following changes:
-Being sensitive to glare
-Cloudy, fuzzy, foggy, or filmy vision
-Difficulty seeing at night or in dim light
-Double vision
-Loss of color intensity
-Problems seeing shapes against a background or the difference between shades of colors
-Seeing halos around lights
Cataracts generally lead to decreased vision, even in daylight. Most people with cataracts have similar changes in both eyes, although one eye may be worse than the other. Many people with this condition have only mild vision changes.
Other symptoms may include:
Frequent changes in eyeglass prescription
Exams and Tests
- Visual acuity test: An eye chart test is
used to measure your reading and distance vision.
- Refraction: Your eye
doctor should determine if glasses would improve your vision.
- Glare testing: Vision may be significantly altered in certain lighting conditions and normal in others; in these circumstances, your doctor may check your glare symptoms with a variety of different potential lighting sources.
- Potential acuity testing: This helps the
ophthalmologist get an idea of what your vision would be like after removal of
the cataract. Think of this as the eye's vision potential if the cataract was
not present.
- Contrast sensitivity testing: This checks for your
ability to differentiate different shades of gray, which is often this limited
by cataracts.
- Tonometry: a standard test to measure fluid pressure inside the eye
(Increased pressure may be a sign of glaucoma.)
- Pupil dilation: The pupil is enlarged with eye drops so that the ophthalmologist can further examine the lens and retina. This is important to determine if there are other conditions which may ultimately limit your vision besides cataracts.
TREATMENT
The following may help people who have an early cataract:
-Better eyeglasses
-Better lighting
-Magnifying lenses
-Sunglasses
As vision gets worse, you may need to make changes around the home to avoid falls and injuries.
*The only treatment for a cataract is surgery to remove it. Surgery is done if you cannot perform normal activities, such as driving, reading, or looking at computer or video screens, even with glasses.
*If a cataract is not bothersome, surgery is usually not necessary. Cataracts usually do not harm your eye, so you can have surgery when it is convenient for you.
*However, some people may have additional eye problems, such as diabetic retinopathy, that cannot be treated without first having cataract surgery.
CLASSIFICATION
Cataracts may be partial or complete, stationary or progressive, or hard or soft. The various types of cataracts are nuclear, cortical, mature, and hypermature. Cataracts are also classified by their location, e.g. posterior (classically due to steroid use) and anterior (common (senile) cataract related to aging).
The following is a classification of the various types of cataracts.
Classified by etiology
Age-related cataract
Cortical senile cataract
Immature senile cataract (IMSC): partially opaque lens, disc view[clarification needed] hazy
Mature senile cataract (MSC): completely opaque lens, no disc view
Hypermature senile cataract (HMSC): liquefied cortical matter: Morgagnian cataract
Senile nuclear cataract
Cataracta brunescens
Cataracta nigra
Cataracta rubra
Congenital cataract
Sutural cataract
Lamellar cataract
Zonular cataract
Total cataract
Secondary cataract
Drug-induced cataract (e.g. corticosteroids)
Traumatic cataract
Blunt trauma (capsule usually intact)
Penetrating trauma (capsular rupture and leakage of lens material—calls for an emergency surgery for extraction of lens and leaked material to minimize further damage)
Classified by opacities,
Cataract can be classified by using Lens Opacities Classification System III (LOCS III: Nuclear NC1-5, Cortical C1-5 and Posterior P1-5. By application planning in procedures of phacoemulsification, LCOS III can be converted in newer cataract grading systems. Gede Pardianto (2009) introduced Optical Biometry Based Cataract Grading System (OBBCGS) that is helpful in cataract grading due to phacoemulsification planning. LOCS III's NC0, C0 and P0 can be converted as OBBCGS' no cataract (NC), LOCS III's NC1-3, C1-3, P1-4 can be converted to OBBCGS' Optical Biometry Examined Cataract (OBEC) and LOCS III's NC4-5, C4-5, P4-5 can be converted to OBBCGS's Optical Biometry Unexamined Cataract (OBUC); that need examination by Applanation Ultrasound Biometry.
Classified by location of opacity within lens structure (however, mixed morphology is quite commonly seen, e.g. PSC with nuclear changes and cortical spokes of cataract)
-Anterior cortical cataract
-Anterior polar cataract
-Anterior subcapsular cataract
-Nuclear cataract (affecting the lens nucleus) — grading correlates with hardness and difficulty of surgical removal
1: Grey
2: Yellow
3: Amber
4: Brown/black (Note: "black cataract" translated in some languages (like Hindi) refers to glaucoma, not the color of the lens nucleus)
-Posterior cortical cataract
-Posterior polar cataract (importance lies in higher risk of complication—posterior capsular tears during surgery)
-Posterior subcapsular cataract (PSC) (clinically common)
-After-cataract: posterior capsular opacification (PCO) subsequent to a successful extracapsular cataract surgery (usually within three months to two years) with or without IOL implantation. Requires a quick and painless office procedure with Nd:YAG laser capsulotomy to restore optical clarity.
TREATMENT
Surgery
The standard cataract surgical procedure is typically performed in either a hospital or in an ambulatory surgery center. The most common form of cataract surgery today is a process called phacoemulsification. With the use of an operating microscope, your surgeon will make a very small incision in the surface of the eye in or near the cornea. A thin ultrasound probe is inserted into the eye that uses ultrasonic vibrations to dissolve (phacoemulsify) the clouded lens. These tiny fragmented pieces are then suctioned out through the same ultrasound probe. Once the cataract is removed, an artificial lens is placed into the same thin capsular bag that the cataract occupied. This intraocular lens is essential to help your eye focus after surgery.
There are three basic techniques for cataract surgery:
- Phacoemulsification: This is the most common form of
cataract removal as explained above. In this most modern method, cataract
surgery can usually be performed in less than 30 minutes and usually requires
only minimal sedation and numbing drops, no stitches to close the wound, and
no eye patch after surgery.NO VISIBLE OR NOTICEABLE CUT.
- Extracapsular cataract surgery: This procedure is used
mainly for very advanced cataracts where the lens is too dense to dissolve
into fragments (phacoemulsify) or in facilities that do not have
phacoemulsification technology. This technique requires a larger incision so
that the cataract can be removed in one piece without being fragmented inside
the eye. An artificial lens is placed in the same capsular bag as with the
phacoemulsification technique. This surgical technique requires a various
number of sutures to close the larger wound, and visual recovery is often
slower. Extracapsular cataract extraction usually requires an injection of
numbing medication around the eye and an eye patch after surgery.
- Intracapsular cataract surgery: This surgical technique requires an even larger wound than extracapsular surgery, and the surgeon removes the entire lens and the surrounding capsule together. This technique requires the intraocular lens to be placed in a different location, in front of the iris. This method is rarely used today but can be still be useful in cases of significant trauma.
Complications are possible after cataract surgery, including endophthalmitis, posterior capsular opacification and retinal detachment.
**Laser surgery involves cutting away a small circle-shaped area of the lens capsule, enough to allow light to pass directly through the eye to the retina. There are, as always, some risks, but serious side effects are very rare.As of 2012 research into the use of extremely-short-pulse (femtosecond) lasers for cataract surgery was being carried out.High frequency ultrasound is also used for cataract surgery.
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