One thing is certain in this life (besides death and taxes): eventually we will all get cataracts.  As one the most commonly performed surgeries in the USA, cataract removal is a highly specialized refractive procedure in today's world, restoring vision and also minimizing the reliance on glasses in some cases.  But while scientists have been perfecting artificial lenses (called IOLs), manufacturing a "holy grail" lens that focuses from distance to near like a young person's natural lens has proven extremely difficult. Imagine a world where you didn't have to implant an artificial lens that is limited by the physics of acrylic -- a world where you regrew your own lens that acted just like the 20 year old eye that you remember so fondly, adjusting freely to distance and up close ranges with reckless abandon.  Sound like a pipe dream? Not so fast.

An adult cataract via

Fresh off the presses in last month's Nature, scientists in China successfully regrew natural lenses in infants with congenital cataracts using their own lenticular stem cells. The idea to use stem cells to regrow a lens was a common nuisance following cataract surgery. Sometimes after removing the cataract and replacing it with an IOL, cells will grow across the implant and cause blur and distortion.  It's called posterior capsule opacification.  These cells are easily removed with a quick laser procedure, but where did they come from?  During cataract surgery, ophthalmologists leave the capsular bag of the natural lens behind to help hold and support the implant in its' proper place.  The capsule may have a few 'lens epithelial stem cells" or LECs as the study author refers to them left behind from the lens removal, which begin to divide and grow.  All this time doctors have treated these cells like annoying debris, but Dr. Lin and his team of researchers had a different opinion.  If these stem cells were growing, why wouldn't they keep growing a whole new lens?  They tested their theory in mice and rabbits, and when those studies proved effective they moved forward to the biggest challenge yet, human infants.

In 3 months, Dr. Lin's team reported the presence of a biconvex lens following cataract removal. A small 2 mm scar remained where the incision was made during cataract surgery that would have damaged the stem cells in that area.  Larger incisions would cause larger scars, making the surgery ineffective.  This is one of the reasons that many doctors question whether an adult procedure of this nature is possible; typical adult cataract surgery techniques require incisions 3 times larger than those used by Dr. Lin and his colleagues.

There are very few options for infants born with congenital cataracts; implanting IOLs to correct vision after removing the cataract causes significantly more issues in babies than in adults, and many doctors prefer leaving the child aphakic (without any internal lens) and relying on contact lenses for vision correction to avoid the risks.  Dr. Lin and colleagues conducted their research on a group of 12 infants with bilateral congenital cataracts. Half of the children were left aphakic (normal standard of care) using normal cataract extraction procedures, and the other half were left aphakic with "minimally invasive" cataract surgery that left layers of LECs behind. In 3 months a biconvex lens had regenerated in the eyes with stem cells left behind, and in 8 months that lens was the size and shape of the lens of a normal infant that had not undergone cataract surgery, and also showed accommodative (or focusing) ability. 

Game Changer?  Since we are dealing with infant eyes, we still know very little about how these regenerated lenses will perform visually in the coming years.  Will a cataract return much younger in life than expected? Will vision ever be truly normal? These are questions that only time will answer. The other pressing issue being raised is will this type of procedure potentially work in adults? Could we have a future where an 80 year old having cataract surgery will be able to regrow a brand new lens with all it's previous, youthful focusing ability? Doctors and scientists have raised several doubts:

• When Dr. Lin and his colleagues performed the "minimally invasive" technique required to leave behind enough stem cells to regrow a lens, they made only a small, 2 mm incision into the capsular bag.  In today's adult cataract surgery, a 6 mm incision into the bag is standard. Removing an adult cataract through such a small incision would be extremely challenging with today's technology, so we would need innovations to make this procedure possible in adults. 
• Could adult stem cells have the same capacity to regrow a lens as infant stem cells do?  Would you need to leave behind more of them to get the same result?  We just don't know what an elderly adult's stem cells would be able to accomplish yet.
• Will patients be willing to wait 3-8 months (or longer if adult stem cells work slower as some predict!) to be able to see again after cataract surgery? In today's world of IOL implantation, cataract patients see clearly the very next day.  Waiting for months at extremely high Rx ranges (without a natural lens, your Rx would hover in the +20.00  mark!) would probably be a dealbreaker for patients even considering this type of procedure.

For decades, parents of children born with congenital cataracts (a cloudiness of the lens that reduces vision from birth) were faced with a difficult choice.  If they did not have the cataract removed early on, the result was permanently reduced vision in the eye even if cataract surgery was performed at an older age because the eye was functionally occluded during it's prime years of visual development. However if they did remove the cataract, there was significant risk of complications with using intraocular lens implants (IOLs) at such a young age, and parents were often left with having to use high powered glasses in the affected eye until the child was older and could have a less risky IOL surgery implantation.  Both choices had major drawbacks -- a risky surgery or a child needing to wear bulky glasses with a high prescription in the affected eye that is left without a lens for several years.  Luckily research has provided us with new options, and the current recommendations from a 2014 study by the American Medical Association point towards contact lens use as being a great alternative in the pediatric aphakic patient until an IOL can be safely implanted.

Congenital cataract via

The research published in the Journal of American Medical Association Ophthalmology compared the visual outcome of infants with unilateral congenital cataracts treated with implantation of an intraocular lens immediately after removal of the cataract, or treatment with contact lenses until a child could more safely have an intraocular lens implanted.  The Infant Aphakia Treatment Study followed 114 infants with congenital cataracts in one eye removed surgically between age 1 and 6 months.  Study participants were enrolled randomly between 2 groups: 57 having immediate IOL implantation, and 57 using contact lenses for vision correction while aphakic (without a lens).

The Results:

At 12 months old, infants in both treatment groups had no statistically significant difference in visual acuity (measured with grating acuity).  The IOL group had more intra- and post-operative complications, higher cost of treatment (by 38%), and higher stress reported by parents or caregivers 3 months after surgery.

At 4.5-5 years old, children were again assessed.

Vision: The average visual acuity between both treatment groups had no statistically significant difference.  50% of children in both groups had "poor visual acuity" out of the treated eye (vision was equal to worse than 20/200 in that eye).  Twice as many children had "good visual acuity" (greater than or equal to 20/32) in the contact lens group compared to the IOL group; 23% of the contact lens group had good acuity versus only 11% of the IOL group.

Ocular Alignment: A high number of patients in both treatment groups had issues with strabismus (an eye turn) in the treated eye.  37% of children in the contact lens group and 43% in the IOL group had strabismus surgery by age 5.

Adverse Effects:  There was a significantly higher complication rate in the IOL group compared to the contact lens wearing group.  56% of contact lens wearing group had had at least 1 adverse event as compared to 81% of children in the IOL group with adverse events.  Glaucoma developed in statistically similar rates between each group.  Contact lens adverse events included corneal abrasion, ulceration, and infections, but none of these events resulted in corneal scars that were considered to impact visual acuity.  Three patients in the contact lens group had IOL implantation before age 5 due to issues with "the day to day contact lens changing and maintenance."

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Additional Surgeries:  At age 5 only 21% of the contact lens wearing group had to have additional intraocular surgery compared with 72% of the IOL group.  The most common surgical procedures were clearing the visual axis of opacity (lens reproliferation, hemorrhage), followed by glaucoma surgery.

Conclusions:
This study did not demonstrate any visual benefit of recommending IOL implantation at the time of infant cataract extraction as compared to leaving the child aphakic and correcting vision with a contact lens.  Due to the significantly higher risk involved with IOL implantation at such a young age, it should only be considered if there is a reason that parents or the child will have extreme difficulty with contact lens insertion, removal, or wear.

This quote from study author Dr. Scott R Lambert, MD sums it up nicely:
"We think that for most infants with unilateral cataract, contact lenses are a better option than an IOL," Dr. Lambert said. "However, in some cases, the parents and their physician may decide that contact lens wear proves to be too challenging, and ultimately not in the child's best interests."

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On a personal, today's post was inspired by a friend of the blog's recent battle with congenital cataracts in her newborn son.  Christina was featured back in 2013 as part of our local blogger sunglasses initiative, and her son, Thomas, has recently had successful bilateral congenital cataract removal.  Just like this study suggests, her doctor has recommended leaving Thomas aphakic and they are about to start with contact lens wear in the coming weeks.  If you want to follow along with Christina and Thomas, just check their blog for regular updates at Carolina Charm. We are wishing them the best in the next step of their journey!