What happens to the zonular fibers/ciliary body after lens replacement?

[watermelon master]

MS2 here, doing some autonomic drugs and that got me thinking. When you replace the lens after cataract surgery, does it attach onto the zonular fibers? is that even possible? do they get ripped out when you take out the old lens?

does that mean when you get your lens replaced do you have problems accommodating if the zonular fibers do not reattach?

Asking this purely for the sake of learning, thanks!

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[DrRedstone]

Also an MS2, but worked in ophthalmology for a while. The IOL (intraocular lens) that is inserted sits in the capsule of the old lens. It does not accommodate, so most people still need glasses for reading. Some new multifocal lenses have attempted to address the problem with variable success.

This is probably a good video to watch to see exactly what happens.

 

[sab3156]

The IOL (intraocular lens) that is inserted sits in the capsule of the old lens. It does not accommodate, so most people still need glasses for reading. Some new multifocal lenses have attempted to address the problem with variable success.

Accomodative pseudophakic IOLs have existed for years, though, and are not the same thing as multifocal IOLs. Accomodative IOLs, such as Crystalens (FDA approved in 2010 if I remember correctly, correct me if I'm wrong), may not be technically accomodating in the phakic sense (so it is sometimes referred to as "pseudoaccomodation" in the literature I've seen), but axial position of the IOL does change as it sits in the capsular bag.

Real and Pseudoaccommodation in Accommodative Lenses
Visual performance with accommodating and multifocal intraocular lenses

 

[watermelon master]

Also an MS2, but worked in ophthalmology for a while. The IOL (intraocular lens) that is inserted sits in the capsule of the old lens. It does not accommodate, so most people still need glasses for reading. Some new multifocal lenses have attempted to address the problem with variable success.

This is probably a good video to watch to see exactly what happens.

Well I guess that pretty much answers it. I didn't realize the lens sits inside of a capsule. I presume the zonular fibers are attached to the capsule and not the lens? Why would accomodation be affected after lens removal and replacement with the new lens then? Is it a physical property of the new lens?

 

[sab3156]

Why would accomodation be affected after lens removal then?

Traditional IOLs cannot accomodate because they are not designed in that way. Accomodative IOLs can (not really in the phakic sense, but similar idea). See my post above for information about the AIOL. One of the challenges in developing new AIOLs is to address the problem of fibrosis and atrophy of the capsular bag following cataract surgery, which eventually results in functional loss of the capsular bag in terms of being able to move the AIOL back and forth. Several authors propose putting the AIOL in a different spot (I think this is proposed in the review I cited above) like into the ciliary sulcus so that it can benefit from contractions of the ciliary muscles of the ciliary body.

The lens as a model for fibrotic disease

 

[MstaKing10]

MS2 here, doing some autonomic drugs and that got me thinking. When you replace the lens after cataract surgery, does it attach onto the zonular fibers? is that even possible? do they get ripped out when you take out the old lens?

does that mean when you get your lens replaced do you have problems accommodating if the zonular fibers do not reattach?

Asking this purely for the sake of learning, thanks!

Essentially the capsular bag is unroofed, the natural crystalline lens is removed and the new implant lens is placed inside of the bag. In an uncomplicated Surgery, the zonules are not damaged. The zonules are attached to the capsule (not the lens) and also attached to the ciliary body.

In terms of accommodation, this is a controversial topic. Several theories exist about how accommodation happens and how that function is lost leading to presbyopia. New lenses can account for this to some degree as has been explained above but this seems beyond the scope of your question. Read up about it, truly a fascinating subject.