Cataracts can be surgically removed without implanting an artificial lens, and the procedure has been performed for centuries. The resulting condition, called aphakia, leaves the eye without its natural focusing element, which means vision is extremely blurry without thick corrective glasses or contact lenses. In modern practice, nearly all cataract surgeries include an intraocular lens (IOL) implant, but specific clinical situations still call for leaving the eye aphakic, and several lines of research are exploring ways to treat cataracts without surgery at all.
How Cataract Surgery Worked Before Artificial Lenses Existed
For most of human history, removing a cataract meant removing the cloudy lens and leaving the patient to cope without one. The oldest known technique, called couching, involved using a needle to push the opaque lens out of the line of sight and down into the vitreous cavity. It dates back thousands of years and persisted in parts of the world well into the twentieth century. Later, surgeons developed methods to extract the entire lens through an incision. None of these approaches involved replacing what was taken out.
Intraocular lens implantation only became routine in the second half of the twentieth century, following pioneering work in the 1940s and 1950s. The shift from aphakic surgery to IOL implantation was driven by a simple optical reality: the natural lens contributes roughly a third of the eye’s total focusing power. Without it, a patient needs glasses so thick they distort peripheral vision, shrink or magnify the image, and create a narrow usable field of view. Modern foldable IOLs, inserted through a tiny incision, have made lens replacement the default worldwide. But “default” is not “always.”
When Surgeons Still Leave the Eye Without a Lens
The most common scenario where a surgeon deliberately leaves an eye aphakic is infant cataract surgery. When a baby is born with a dense congenital cataract, prompt removal is critical to prevent permanent visual impairment from the brain failing to develop normal connections with the eye. But implanting an IOL in a very young child poses problems that do not apply to adults. The eye is still growing rapidly, so the lens power needed at six months of age will be wrong by age five. The immature visual system is also at heightened risk of complications that would be manageable in an adult.
A landmark randomized trial, the Infant Aphakia Treatment Study, followed children who had unilateral cataracts removed before seven months of age. Half received an IOL at the time of surgery, and half were left aphakic and corrected with a contact lens. At age ten, the visual acuity in the treated eye was essentially the same between the two groups.
What did differ was the complication rate. Children who received an IOL during infancy had significantly more adverse events, additional surgeries, and intraocular complications in the first five years compared with those left aphakic and fitted with contact lenses. The study’s conclusion was direct: leaving babies aphakic is preferable when the family can manage contact lens wear.
Living With Aphakia
An aphakic eye is not blind. It simply cannot focus light on its own, so everything appears as a featureless blur without correction. The degree of farsightedness is extreme, typically around +10 to +14 diopters depending on the eye’s other optical properties. Three options exist for correcting this:
- Aphakic spectacles: Very thick, heavy lenses that restore a central image but cause significant magnification (about 25–30 percent), a ring-shaped blind spot in the periphery, and a “jack-in-the-box” effect where objects pop in and out of view as the wearer turns their head. They work reasonably well when both eyes are aphakic and roughly matched, but they are nearly unusable when only one eye lacks a lens, because the brain cannot fuse two images of such different sizes.
- Contact lenses: A much better optical solution for one-eyed aphakia. Contacts sit closer to the eye, so the magnification drops to about 7–10 percent, and peripheral vision is far more natural. The tradeoff is the daily handling, infection risk, and cost, which are more burdensome for infants and young children whose parents must insert and remove the lens.
- Secondary IOL implantation: If someone is left aphakic initially, an artificial lens can be surgically placed at a later date. This is common in pediatric patients once the eye has grown enough for more accurate lens-power calculations, often around age two or later.
Secondary IOL implantation generally improves visual acuity. A large retrospective study found that corrected distance vision improved significantly after the procedure, though the predictability of the final prescription varied depending on the type of lens fixation used and the reason the patient was aphakic in the first place. In children under 30 months who had secondary implantation, longer follow-up periods were associated with a progressive shift toward nearsightedness, reflecting the continued growth of the eye after the lens power was chosen.
Risks of Remaining Aphakic Long-Term
Beyond the optical inconvenience, aphakia creates anatomical changes inside the eye that carry their own risks. The natural lens acts as a physical barrier between the front and back chambers of the eye. Without it, the vitreous gel can shift forward, and the fluid dynamics of the anterior chamber change. These shifts are associated with a higher likelihood of developing glaucoma. Multiple mechanisms have been proposed, including scar tissue forming between the iris and the cornea, vitreous strands migrating into the front of the eye, and chronic low-grade inflammation. A study of adult aphakic patients after complicated cataract surgery found that nearly half had peripheral anterior synechiae (adhesions between the iris and cornea), and about one in six had vitreous in the anterior chamber.
Retinal detachment is another concern. Aphakic eyes have a higher rate of retinal detachment than eyes with an IOL in place, partly because removing the lens allows the vitreous to move more freely and exert traction on the retina. One older study found that aphakic eyes also had a notably higher rate of cystoid macular edema, a swelling condition that can blur central vision, compared with eyes that still had their natural lens.
These risks are part of why modern surgeons strongly prefer to implant an IOL whenever feasible. In adults, the situations where a lens is deliberately not implanted are rare and usually involve severe trauma, active infection inside the eye, or anatomical conditions that make safe lens fixation impossible. Even in those cases, the goal is typically to place a secondary IOL once the eye has healed.
Could Eye Drops Ever Replace Surgery?
The idea of dissolving a cataract with eye drops instead of cutting into the eye has enormous appeal, especially in low-resource settings where surgical access is limited. The most publicized candidate has been lanosterol, a naturally occurring sterol in the lens. A 2015 study published in Nature reported that lanosterol treatment reduced cataract severity and increased lens transparency in rabbit lenses in vitro and in dogs in vivo, pointing to it as a potential nonsurgical therapy.
The excitement was tempered by follow-up work. A later study specifically tested whether lanosterol and a related compound, 25-hydroxycholesterol, could dissolve the insoluble protein aggregates found in cataractous lenses. The results were negative: neither compound reduced insoluble protein levels, and binding studies suggested the molecules do not adequately attach to the crystallin proteins responsible for lens opacity. The researchers concluded that these oxysterols failed to restore lens clarity.
The story is not entirely closed, though. A 2025 study took a different approach: instead of applying lanosterol directly, researchers delivered mRNA encoding lanosterol synthase (the enzyme that produces lanosterol) packaged in lipid nanoparticles. When applied topically to the eyes of rats with cataracts, this treatment increased lanosterol levels within the lens and produced a measurable improvement in cataract symptoms. The strategy is still in early animal testing, but it suggests the problem with earlier lanosterol studies may have been delivery rather than the molecule itself.
Getting any drug to the lens is inherently difficult. The eye has multiple anatomical barriers, including the tear film, the corneal epithelium, and the aqueous humor turnover that washes drugs away. Traditional eye drops lose most of their active ingredient before it reaches the lens. Nanomedicine-based delivery systems, including nanoparticle formulations designed to improve corneal penetration and provide sustained drug release, are being developed to address exactly this bottleneck.
N-Acetylcarnosine Drops and the Supplement Market
If you have searched for cataract eye drops online, you have almost certainly encountered N-acetylcarnosine (NAC) drops, sold under brand names like Can-C. The biochemical logic sounds reasonable: L-carnosine is an antioxidant that, once inside the eye, could theoretically counteract the oxidative damage that drives lens protein aggregation. N-acetylcarnosine is a prodrug form that can penetrate the cornea and then convert to L-carnosine in the aqueous humor.
A small clinical trial reported that after six months, 90 percent of eyes treated with NAC drops showed improvement in best-corrected visual acuity, and the benefits appeared to persist over 24 months. However, a Cochrane systematic review assessed this evidence and highlighted that the studies were small, conducted by a single research group with commercial ties to the product, and had not been independently replicated. The review did not find sufficient evidence to recommend NAC drops for cataract treatment.
This is a pattern worth being aware of: a handful of small positive studies, a plausible mechanism, and aggressive marketing that outpaces the actual evidence. NAC drops are sold as supplements, not approved pharmaceuticals, so they have not undergone the rigorous phase III trials required for a drug claim. They will not hurt your eyes, but there is no strong independent evidence that they will clear an established cataract. If you are considering them, be honest with yourself about the quality of evidence behind the claims, and do not delay a surgical evaluation on the basis of supplement marketing.
Regenerating the Lens From the Eye’s Own Cells
Perhaps the most striking recent development is not about avoiding lens replacement but about getting the eye to grow a new lens on its own. Researchers identified that the lens capsule contains epithelial stem/progenitor cells capable of regenerating lens tissue. In conventional cataract surgery, most of these cells are destroyed or removed along with the cataract. A team in China designed an alternative surgical approach, sometimes called minimally invasive lens-content removal surgery, that clears the opaque lens material through a small opening while deliberately preserving the lens capsule, the resident stem cells, and their surrounding microenvironment.
In a study involving human infants with congenital cataracts, this technique led to functional lens regeneration in the operated eyes, with visual outcomes that surpassed those of traditional surgery. The same approach was validated in rabbits and macaques before the human trial. The regenerated lens was transparent and contributed to the eye’s focusing ability.
This work is still early-stage and has significant limitations. It has only been demonstrated in very young eyes, where the regenerative capacity of lens epithelial cells is at its peak. Whether adult eyes, where the stem cell population is older and less active, can achieve the same regeneration is an open question. The technique also requires surgeons to work through a much smaller capsular opening, which is technically more demanding. And even in the infant study, the regenerated lenses were smaller than natural lenses and did not provide perfect optics. Still, the concept represents a fundamentally different philosophy: rather than replacing a biological structure with a synthetic one, help the body rebuild what was lost.
Why the Lens Clouds in the First Place
Understanding why cataracts form helps put all these approaches in context. The lens is composed largely of crystallin proteins, which are arranged with extraordinary precision to maintain transparency. Unlike most tissues, the lens has no blood supply and almost no protein turnover. The crystallins you are born with are largely the same ones you carry at age 80. Over decades, these proteins accumulate damage from ultraviolet radiation, oxidation, and various chemical modifications. The damaged proteins begin to unfold, expose sticky surfaces, and clump together into insoluble aggregates that scatter light.
This process is, to some extent, inevitable. By age 75, roughly half of all people either have a cataract or have had one removed. The aggregation follows multiple pathways and produces varied types of clumps depending on which crystallin is involved and what kind of damage triggered the unfolding. Alpha-crystallins normally act as molecular chaperones, binding to partially unfolded proteins and preventing them from aggregating. But alpha-crystallins themselves eventually become overwhelmed and damaged, losing their protective function. At that point, aggregation accelerates.
This complexity is part of why a simple eye-drop cure has been so elusive. The aggregated proteins are not a single target. They are a heterogeneous mix of damaged molecules held together by various interactions, and reversing that process is chemically far more difficult than preventing it. Surgery sidesteps the chemistry entirely by physically removing the problem, which is why it remains the only proven treatment for established cataracts.
What About Preventing Cataracts From Forming?
If reversing aggregation is hard, could you slow it down enough to matter? Epidemiological studies have identified several modifiable risk factors for cataracts: smoking, diabetes, prolonged corticosteroid use, heavy alcohol consumption, and cumulative UV exposure. Wearing UV-blocking sunglasses and quitting smoking are the two interventions with the strongest observational support for reducing cataract risk, though no randomized trial has proven that either prevents cataracts outright.
Antioxidant supplementation has been studied extensively, on the logic that oxidative damage is a key driver of crystallin aggregation. Large trials of vitamins C, E, and beta-carotene have generally been disappointing, showing no meaningful reduction in cataract incidence. A few studies have suggested a modest benefit from long-term multivitamin use, but the effect sizes are small and inconsistent. The American Academy of Ophthalmology does not recommend any supplement specifically for cataract prevention.
Dietary patterns rich in fruits and vegetables are associated with lower cataract risk in observational data, but it is difficult to disentangle diet from other lifestyle factors. The honest summary is that there is no proven way to prevent age-related cataracts entirely. You can reduce your exposure to known accelerants, but the underlying process of protein damage over a lifetime is probably not fully avoidable.
How Secondary Lens Implantation Works
For someone already living with aphakia who wants to reduce dependence on thick glasses or contacts, a secondary IOL can be implanted in a separate surgery. The approach depends on what anatomical support structures remain. If the capsular bag that once held the natural lens is intact, a standard posterior-chamber lens can be placed inside it. If the capsule has been damaged or removed, surgeons have several alternatives: suturing a lens to the iris, clipping a lens onto the front of the iris, or suturing a lens to the sclera (the white wall of the eye).
Each fixation method has different tradeoffs in terms of accuracy, complication profile, and long-term stability. Iris-clip lenses, for example, showed the lowest prediction error in one large study, but were associated with more bleeding inside the eye after surgery. Scleral-fixated lenses are versatile but technically complex. The decision depends on the individual anatomy of the eye and the surgeon’s experience.
In children, the timing of secondary implantation matters. Placing a lens too early means the eye will outgrow the prescription quickly, leading to progressive nearsightedness. A study of children implanted before 30 months of age found a significant myopic shift over time, with longer follow-up correlating with greater nearsightedness. Waiting longer allows for a more stable prescription, but it also means the child must cope with contact lenses or glasses in the interim, which has its own challenges for development and compliance.