Cataracts & Pseudoexfoliation



Every  eye has a lens that sits directly behind the pupil. It is made out of a  thick, transparent, viscous fluid, surrounded by an extremely thin  equally transparent capsule. The lens is held in proper position by  microscopic fibers called lens zonules. Normally, the lens of the eye is crystal clear and sharply focuses the light that comes into the eye.  This allows us to see clear and sharp images. In many people, as a  result of the aging process -- usually over the age of 60 to 70 -- the  lens of the eye becomes cloudy, hazy and sometimes dark yellow or brown  in color. This process is called cataract formation. When a cataract  develops, images seen by the eye appear cloudy, distorted and less  bright, as if they are seen through tinted frosted glass instead of a  clear windowpane.

In  eyes with pseudoexfoliation, the tiny, flaky particles of this material  deposit on the front surface of the cataract (lens) known as the  anterior capsule, and on the lens zonules.
When  a cataract worsens to the point where the vision is significantly  reduced and can’t be corrected adequately with glasses or contact  lenses, cataract surgery is an option that can restore the vision.  Modern, state of the art cataract surgery is done through a tiny  incision (1/8 of an inch) in the eye using a procedure known as  phacoemulsification – high frequency ultrasound that dissolves the  cataract and vacuums it out of the eye. During phacoemulsification a  tiny remnant of the cataract is left behind; a transparent membrane known as the posterior capsule. Since cataract surgery removes the  focusing lens of the eye, a new lens must be placed inside the eye where  the cataract used to be. This is called an intraocular lens implant or  IOL. The IOL is made out of a clear, transparent plastic and is very  well tolerated by the eye, often restoring perfect or near perfect  vision if the rest of the eye is normal. The IOL sits inside the  capsular bag and posterior capsule of the original lens (cataract) of  the eye that is left behind during the cataract surgery. The capsular  bag and posterior capsule is like a microscopic pocket or envelope that  keeps the IOL in perfect position and centered behind the pupil, thereby  providing excellent vision.

Cataract  surgery has a very high success rate of nearly 98-99%. As a result,  nearly 4 million cataract operations are done in the USA every year. As  people live longer this number is expected to increase in years to come.

A pseudoexfoliation eye with a cataract is typically much more difficult  to operate on than a routine cataract (see details in paragraphs below).  Therefore, one of the most important things about doing cataract  surgery in a pseudoexfoliation eye is for the surgeon to be prepared for  sudden, unusual circumstances that arise and must be dealt with  immediately by performing various intricate, technically demanding  surgical maneuvers. The diagnosis of pseudoexfoliation must therefore be  made prior to surgery, so that the surgeon is well prepared with  non-routine equipment and surgical steps for any unusual difficulties  that may occur. If the cataract is not examined with a slit lamp through  a DILATED pupil preoperatively, then the surgeon may miss the diagnosis  of pseudoexfoliation and will not be prepared for the sudden, unusual  difficulties that can occur during surgery. This dramatically increases the risks and complications of the surgery and may result in requiring  additional operations and permanent reduction or loss of vision.

The  first step of the cataract surgery is to dilate the pupil with several  different eye drops in order to allow the phacoemulsification instrument  to have easy access to the cataract. In eyes with pseudoexfoliation,  the pupil often does not dilate well because the flaky deposits on the  pupil and iris damage the dilating muscles of the iris, preventing  adequate dilation. Experienced pseudoexfoliation cataract surgeons will  often insert “pupil rings” or “iris hooks” into the eye in order to  fully dilate the pupil. Attempting phacoemulsification without adequate  pupil dilation can result in many sight-threatening complications such  as iris and pupil damage, dislocation of the cataract during surgery and  vitreous fluid compartment disruption with vitreous loss. These  complications can cause cloudy vision, glare, inflammation, retinal  detachments, glaucoma (or worsening of pseudoexfoliation glaucoma) and  other serious complications that may require additional surgeries to  attempt to repair the problems.

The  second step of cataract surgery, capsulorhexis, requires making a round  incision into the front part (anterior capsule) of the cataract. In  eyes with pseudoexfoliation this incision has to be performed extremely  carefully and gently since any excess tugging, pulling or pushing of the  anterior lens capsule can cause an imperfect capsulorhexis incision,  making the rest of the surgery more difficult, hazardous and  complicated. Experienced pseudoexfoliation cataract surgeons have  experience with delicately creating an appropriately sized and shaped  capsulorhexis incision in order to avoid problems with the remainder of  the surgery.

The  third step of cataract surgery is hydrodissection. This requires  injecting a specially formulated saline solution (BSS) into the cataract  in order to separate the bulk of the cataract from the posterior  capsule and capsular bag. In eyes with pseudoexfoliation, the lens  capsule is more fragile and prone to tears or ruptures caused by  excessive pressure from injection of the BSS. Experienced  pseudoexfoliation cataract surgeons can carefully gauge how much BSS  injection pressure to exert to prevent a tear or rupture of the capsule and its subsequent complications.

The fourth major step of cataract surgery is removal of the bulk of the  cataract using the phacoemulsification probe that is inserted into the  eye through the tiny incision. In eyes with pseudoexfoliation, this part  of the surgery has the highest risk of problems and serious complications. Pseudoexfoliation flakes damage and weaken the  microscopic lens zonules that hold the cataract in position during the  surgery. Excessive pressure, pulling or pushing of the lens zonules  during the phacoemulsification step of cataract surgery may result in  the cataract falling into the back of the eye on the retina or optic  nerve. This serious problem significantly increases the risk of multiple  complications occurring after the surgery, and almost always requires a  second operation to retrieve the fallen, dislocated cataract. Experienced pseudoexfoliation cataract surgeons can often modify their  phacoemulsification surgical techniques and maneuvers on the fly to  avoid this serious complication.

The  fifth step of cataract surgery is to place the IOL inside the  cataract’s residual capsular bag, directly in front of the posterior  capsule and centered behind the pupil. This requires very delicate  surgical maneuvers inside the eye, which experienced pseudoexfoliation cataract surgeons have mastered. Any miss-steps in this part of the  cataract surgery can cause the intraocular lens implant to rip the lens  capsule and fall into the back of the eye on the retina and optic nerve.  This can cause numerous serious postoperative complications and  problems, and most likely will require an additional operation to remove  the dislocated IOL and replace it with a different one that will no  longer be positioned in an ideal location inside the eye.

It should be noted that pseudoexfoliation eyes can have IOL dislocations  even years after successful cataract surgery because of progressive  weakening of the lens zonules. If this occurs, then surgery is usually  needed to retrieve the dislocated IOL and either suture it into the eye  or replace it with another IOL positioned in another part of the eye.

Many  pseudoexfoliation eyes that undergo cataract surgery also have  pseudoexfoliation glaucoma preoperatively. Any complication from the  cataract surgery carries a high risk of aggravating and worsening the  glaucoma.Additionally,  timing of the cataract surgery in a pseudoexfoliation eye is critical.  The surgery should not be done on a “mild” cataract since it’s not wise  to take on significant risk with minimal gain in an eye that has only  mild blurring caused by the cataract. However, it is also not advisable  to delay surgery in a pseudoexfoliation eye till the cataract is very  advanced, since the worse the cataract gets the more difficult it is to  remove without complications. An experienced phacoemulsification cataract surgeon can determine the opportune time to perform the  cataract surgery in order to minimize the risks and reduce surgical  complexity, thereby improving the prognosis and results.

Clearly, cataract surgery in an eye with pseudoexfoliation is significantly more  hazardous and risky than in an eye with a routine cataract. Although  pseudoexfoliation complications can occur in even the most experienced  surgeon’s hands, in general, the more pseudoexfoliation cases a surgeon  has done the less chance there will be complications, and if they occur,  the more likely the surgeon will be able to deal with them and reduce  their severity and threat to vision.