Cataracts:  A Trial Lawyers Guide

 General information and terminology

A cataract is a clouding of the natural lens of the eye. As a rule, we recommend waiting until the vision is degraded to 20/40 or worse. If visually disabling, however, the surgery can be done at an earlier stage.

The lens of the eye is analogous to the camera lens. The retina is the “film;” the iris-pupillary complex the “aperture.”  The cavity behind the lens that fills the posterior 2/3 of the eye is called the vitreous or vitreous gel.  You will hear about this gel later.  Just like nature abhors a vacuum, most cataract surgeons dread the vitreous.

An artificial lens commonly referred to as an implant or IOL replaces the cataract.  An eye with an artificial lens is called pseudophakic. Most commonly, posterior chamber IOL’s are placed. These are behind the pupil, into the “capsular bag” or the “ciliary sulcus.”   Anterior chamber lenses used in 1/100 cases are place in front of the iris.

Cataract can range from soft, the consistency of the grape to hard, like the skin of an olive.  As general rule a very dense cataract is more difficult to remove.  However, the level of vision acuity does not always correlate with lens density.

The cataract is split into several pieces either manually or by a femto laser. Despite advantages of the laser only 5% of cases are being done with femto.   By taking the cataract out in pieces the procedure can be done through a smaller opening.  The 6 mm artificial lens (IOL) folds like a taco and can placed through this small 2.4 mm opening.

Of the 3600 procedures covered by Medicare, cataract surgery ranks 6^th in terms of intensity.  It is not a monolithic procedure as each surgeon has multiple techniques in their toolbox depending upon the cataract type and any factors to the eye that can make the surgery more difficult (small pupil, pseudo-exfoliation, prior eye surgery, shallow anterior chamber and so forth).

SURGICAL COMPLICATIONS

A complication is unplanned occurrence which can affect the outcome of the procedure. The prevention and treatment of complications is the priority for all cataract surgeons. There may be delayed recovery time, a return to the OR, or a referral to an outside specialist. Most surgical mishaps—if properly managed– can still achieve a reasonable outcome.

When the cataract is removed, if the posterior capsule or zonular complex is breached penetration into the vitreous cavity often occurs.

A ruptured or broken posterior capsule occurs in up 5% of all surgeries in large reported series.

The vitreous is no longer separated from the anterior portion of the eye and will move towards the wound. The term vitreous loss is used since some of this jelly like material must be removed (and is lost) from the anterior portion of the eye. The eye replaces the vitreous with clear fluid.

When loss of vitreous loss occurs, there is a need to do a vitrectomy. This is a mechanical removal of the vitreal gel with special instruments. Most serious eye complications have vitreous loss as the common pathway to a later problem.

A dropped nucleus refers to loss of lens material into the vitreal cavity. The management of these problems can be touch and go as the surgeon is working under considerable stress.  If improperly handled, a medical malpractice claim can result.  A procedure called posterior assisted levitation can be a godsend or a nightmare, depending upon the surgeon’s surgical acumen.

Zonular weakness or stripping of the zonules with or without with vitreous loss is another undesirable intraocular event.   It can be managed with capsular hooks or capsular tension rings.  An untreated break in the zonules can lead to decentered placement of the IOL.  This is called a dislocated IOL.  Often a second surgery is required to remove the dislocated implant and replace it with a sutured or glued implant.

INTRAOCULAR LENSES COMPLICATIONS

If vitreous loss occurs a backup IOL may need to be inserted. The backup implant is often placed using specialized techniques such as ciliary sulcus or optic capture positioning. With good judgement and technique, patients typically make good recoveries.

Anterior chamber lens IOL’s in experienced hands can be substituted for the original posterior chamber lens.  However, it must be sized and placed properly, otherwise iritis, glaucoma, or corneal decompensation can ensue.

IOL’s are available in standard monofocal or multifocal version. The monofocal lens has one focal point, either distance or near. The multifocal (and extended depth of focus) versions have two more focal points.

Multifocal versions give the most freedom from glasses but they also cause a loss of contrast sensitivity that can be troublesome for some patients.  There is also a potential for halos or glare around lights referred to as dysphotopsia. These can be positive or negative depending if they are light or dark.   These risks should be highlighted in the informed consent.  The surgeon must be on the ready to exchange the multifocal lens or refer out if after six months the problems persist.

Implants come in different powers chosen to reduce the refractive error.  Great care must be taken to assure the correct power IOL is implanted.  An incorrect power is very hard to defend against.  A system’s error may be invoked but human error occurred somewhere down the chain of command.  This is different from “a refractive surprise” where the implant power turned out to be incorrect due to the vicissitudes of eye anatomy.