Once a human eye has elongated beyond its normal length, reversing that stretch is extremely difficult. The structural changes in the eyeball’s outer wall tend to be permanent in adults. In children, though, recent clinical trials have documented small but real reductions in eye length using treatments like repeated low-level red light therapy, with some studies reporting shortening on the order of a tenth of a millimeter over a year. That may sound trivial, but in an organ where fractions of a millimeter determine whether you can read a street sign, it matters. The fuller picture involves a tangle of biology, timing, and treatment trade-offs that makes the answer far more interesting than a flat “no.”
What “Elongated” Actually Means and Why It’s Hard to Undo
In a normally sighted eye, the distance from the front of the cornea to the retina at the back (called axial length) is roughly 23 to 24 millimeters. In myopia, or nearsightedness, the eyeball grows longer than it should, so light focuses in front of the retina instead of on it. Each additional millimeter of length corresponds to roughly two to three additional diopters of myopia. Most of this excess growth happens during childhood and adolescence, when the eye is still developing.
The elongation is driven by remodeling of the sclera, the tough white shell that gives the eye its shape. Research has shown that this remodeling depends heavily on changes in the scleral extracellular matrix, the structural scaffolding of collagen and other proteins that holds the tissue together.1PubMed Central. Scleral remodeling in myopia development When the eye receives signals that it should grow longer, enzymes break down collagen fibers and thin the sclera, allowing it to stretch. The problem is that once collagen has been degraded and the sclera has thinned, the tissue does not simply bounce back when those signals stop. It’s a bit like stretching a leather belt: you can loosen it gradually, but it won’t snap back to its original length on its own.
Visual cues from the retina drive this process. The retina detects whether images are focused correctly and sends chemical signals through intermediate cell layers all the way to the sclera.2PubMed Central. Candidate pathways for retina to scleral signaling in refractive eye growth Retinal glial cells and the retinal pigment epithelium act as relay stations; when the focus signal is off, they alter their release of chemical messengers, disrupting the normal balance between collagen production and collagen breakdown in the sclera.3PubMed Central. Cellular Biological Basis and Novel Breakthroughs in the Pathogenesis of Myopia – A Narrative Review This cascade is what makes elongation an active biological process rather than a passive mechanical one. It also suggests that, in theory, flipping those signals could slow or even partly reverse the growth. In practice, doing so is much harder than it sounds.
The Most Promising Evidence for Actual Shortening
Repeated low-level red light (RLRL) therapy is the treatment generating the most excitement around genuine axial shortening. The protocol typically involves a child looking into a desktop device that delivers low-intensity 650-nanometer red light for three minutes, twice a day, five or more days a week. Multiple randomized trials have now measured actual decreases in eye length in treated children.
In a trial of children with high myopia, the group receiving RLRL showed an average axial length change of −0.06 mm over 12 months, while the untreated control group grew by 0.34 mm. Over half of the treated children experienced shortening of more than 0.05 mm at the 12-month mark.4PubMed. Repeated Low-Level Red Light Therapy for Myopia Control in High Myopia Children and Adolescents: A Randomized Clinical Trial A separate multicenter trial in highly myopic children found an even larger effect: the RLRL group averaged −0.11 mm of change at 12 months, with 59% of treated children showing shortening greater than 0.05 mm, compared to 0% in the control group.5American Journal of Ophthalmology. Axial Shortening Effects of Repeated Low-level Red-light Therapy in Children With High Myopia: A Multicenter Randomized Controlled Trial
A post hoc analysis of an earlier randomized trial dug deeper into who responds. About 22% of RLRL-treated children showed shortening of more than 0.05 mm at 12 months, and about 6% showed shortening exceeding 0.20 mm. Interestingly, choroidal thickening (the choroid is the blood-vessel-rich layer behind the retina) could only explain about 28% of the observed shortening, suggesting that something beyond simply plumping up the choroid is going on.6PubMed Central. Axial Shortening in Myopic Children after Repeated Low-Level Red-Light Therapy: Post Hoc Analysis of a Randomized Trial The remaining 72% of the shortening remains unexplained, which is both intriguing and a reminder of how early we are in understanding this therapy.
The results are genuinely surprising to many researchers who assumed eye length was a one-way ratchet. But the shortening amounts are small in absolute terms, and the longest follow-up data so far cover only 12 to 24 months. Nobody yet knows whether these gains persist over years, or what happens after treatment stops. RLRL is also not widely available or approved in many countries, and its long-term safety profile in children’s retinas is still being tracked.
Orthokeratology and the Choroid Question
Orthokeratology (ortho-k) uses specially designed rigid contact lenses worn overnight to temporarily reshape the cornea. The primary goal is correcting vision so children can go without glasses during the day, but ortho-k also slows myopia progression. Some studies have observed short-term axial shortening in the first weeks to months of wear. In one study, children who wore ortho-k lenses showed an initial shortening of about 0.08 mm after one month. However, the eye gradually returned to its baseline length by around month seven, and continued growing from there. By 20 months, the initial shorteners had still gained length, though less than children who didn’t experience that early shortening.7PubMed Central. Axial length shortening after orthokeratology and its relationship with myopic control
A key piece of this puzzle is the choroid. When ortho-k changes the way light focuses on the peripheral retina, the choroid thickens, which temporarily nudges the retina forward and reduces the measured axial length. A study in myopic adolescents found a strong negative correlation between changes in choroidal thickness and changes in axial length during ortho-k: when the choroid got thicker, axial length measurements went down, and vice versa.8PubMed Central. Axial Length Control Is Associated With A Choroidal Thickness Increase in Myopic Adolescents After Orthokeratology This means much of the apparent “shortening” from ortho-k is really choroidal thickening creating the optical equivalent of moving the retina forward a sliver, rather than the scleral shell actually shrinking. It’s a meaningful distinction, because the scleral stretch itself hasn’t been undone.
Over longer periods, ortho-k’s main benefit is slowing further elongation. A three-year comparison of different ortho-k lens designs found that all designs slowed growth relative to what would be expected without treatment, though the amount varied by design. Children wearing lenses with one design grew by about 0.59 mm over three years, while those wearing another grew by about 0.73 mm.9PubMed Central. Effects of different orthokeratology lens designs on slowing axial length elongation in children with myopia Slowing matters enormously, especially in children at risk for high myopia, but it is not reversal.
Atropine Eye Drops and the Dose Debate
Atropine, a drug originally derived from the belladonna plant, has been used for decades to slow myopia progression in children. It works by blocking certain receptors in the eye, though the exact mechanism behind its anti-myopia effect is still debated (it’s probably not just about relaxing the focusing muscle, since even very low doses that don’t fully dilate the pupil still seem to work). The LAMP study found that 0.05% atropine eye drops reduced axial elongation to an average of 0.20 mm per year, compared to 0.41 mm per year with placebo, following a clear dose-response relationship.10PubMed. Low-Concentration Atropine for Myopia Progression (LAMP) Study: A Randomized, Double-Blinded, Placebo-Controlled Trial of 0.05%, 0.025%, and 0.01% Atropine Eye Drops in Myopia Control
The dose question gets complicated, though. A separate trial testing the very lowest concentration, 0.01% atropine, found essentially no benefit: axial elongation over two years was nearly identical between the atropine and placebo groups.11JAMA Ophthalmology. Low-Dose 0.01% Atropine Eye Drops vs Placebo for Myopia Control: A Randomized Clinical Trial The implication is that the concentrations showing clear benefit (0.025% to 0.05%) come with more side effects like light sensitivity and blurred near vision, while the gentlest dose may do nothing meaningful. Atropine slows elongation but does not reverse it. No study has shown atropine-treated eyes actually getting shorter.
Specialty Spectacles and Soft Contact Lenses
Several spectacle lens designs aim to slow myopia by manipulating how light focuses on the peripheral retina. Defocus incorporated multiple segments (DIMS) lenses, for instance, have hundreds of tiny lenslets that create a zone of altered focus around the central correction. A three-year follow-up in children found that DIMS wearers progressed significantly less than those wearing conventional single-vision lenses, with the slowing effect being more pronounced in children over 10.12PubMed Central. Effectiveness of Defocus Incorporated Multiple Segments in Slowing Myopia Progression in Pediatric Patients as a Function of Age: Three-Year Follow-Up Multifocal soft contact lenses operate on a similar principle and also slow progression. Like atropine and ortho-k, though, the story here is about slowing the rate of elongation, not shortening what has already grown.
What Happens When Treatment Stops
A practical concern with any myopia control treatment is what happens after you stop using it. The evidence suggests that at least some of the benefit can be lost. A systematic review of optical interventions found that discontinuing treatment often led to a rebound effect: the eye grew faster for a period after stopping than it would have during treatment. Ortho-k showed the strongest rebound, multifocal soft contact lenses a milder one, and peripheral-defocus spectacle lenses a variable one.13PubMed Central. Systematic Review of Myopia Progression after Cessation of Optical Interventions for Myopia Control A separate systematic review estimated the average rebound in axial length across all treatment types at about 0.10 mm after roughly 10 months off treatment.14PubMed. Assessing the rebound phenomenon in different myopia control treatments: A systematic review
The rebound is thought to be linked to the gradual reversal of choroidal thickening and the loss of the altered peripheral focus that the treatments produce. When those signals go away, the eye goes back to its prior growth trajectory, sometimes accelerating temporarily. This is why many clinicians recommend continuing myopia control treatment until the late teenage years, when the eye’s growth naturally plateaus.
Atropine may be an exception. A Japanese study found that children treated with 0.01% atropine for two years, then observed for 12 months after stopping, did not show a significant rebound compared to controls.15PubMed. Assessment of myopic rebound effect after discontinuation of treatment with 0.01% atropine eye drops in Japanese school-age children That said, this was the same low concentration that another trial found ineffective in the first place, so the absence of rebound may partly reflect the absence of much initial effect. Higher-concentration atropine studies have shown some rebound after cessation in other settings.
Why Age Is the Biggest Factor
The reason nearly all reversal evidence comes from children is simple: young eyes are still actively growing and remodeling. The scleral tissue is more biologically active, with higher rates of collagen turnover, meaning it can potentially be nudged in either direction. As growth slows in the late teens and early twenties, the sclera becomes more rigid and less responsive to these signals. By adulthood, the elongation is effectively locked in.
Research following a cohort of children aged 8 to 11 found that the eye’s structural changes accelerate once axial length crosses certain thresholds. Damage to the tissue surrounding the optic nerve showed a sharp acceleration around 24 mm, suggesting that keeping children below that length threshold during their growth years could prevent a cascade of structural harm.16PubMed Central. Defining the critical axial length threshold for transition from physiological growth to pathological fundus structural remodeling in adolescent myopia This is why the urgency around myopia control is focused on childhood: the window for intervention, including any possibility of shortening, closes as the eye matures.
Why LASIK Doesn’t Count
A common misconception is that refractive surgery like LASIK or PRK “fixes” the elongated eye. These procedures reshape the cornea so that light focuses correctly on the retina, but they do nothing to the eye’s length. The sclera remains stretched, the retina remains thinner than normal, and the risks associated with a longer eye persist. Complications of high myopia, including retinal detachment, macular degeneration, glaucoma, and cataracts, continue to develop even after successful refractive surgery.17PubMed Central. Complications of high myopia: An update from clinical manifestations to underlying mechanisms A person who had LASIK at 25 may see perfectly without glasses but still faces the long-term structural risks of a 27-millimeter eye. The surgery corrects the optical error but not the anatomy.
Experimental Frontiers
One idea that hasn’t yet made it to large-scale human trials is scleral collagen cross-linking. The concept borrows from corneal cross-linking, an established treatment for keratoconus (a condition where the cornea thins and bulges). By applying a photosensitizer to the sclera and then activating it with light, researchers hope to create new chemical bonds between collagen fibers, stiffening the scleral shell and preventing further stretching. In theory, this could halt elongation at its source. The proposed advantage over other surgical approaches, like posterior scleral reinforcement (where donor tissue is grafted onto the back of the eye), is that cross-linking requires no transplanted material, reducing cost and surgical risk.18PubMed Central. Shaping Eyeballs by Scleral Collagen Cross-Linking: A Hypothesis for Myopia Treatment The research is still at the hypothesis and early animal stage. Whether it will ever work safely in living human eyes, where the sclera sits next to the retina and optic nerve, is an open question.
The Role of Outdoor Time and Screen Habits
Prevention is not reversal, but given how hard reversal is, keeping the eye from elongating in the first place deserves attention. The protective effect of outdoor time against myopia development is one of the most consistently replicated findings in the field. The mechanism appears to involve brighter light stimulating the release of dopamine in the retina, which in turn slows axial elongation.19PubMed Central. Time outdoors and the prevention of myopia: School-based implementation works Animal studies have confirmed this causal pathway: dopamine and drugs that mimic dopamine reliably slow eye growth in experimental models.20PubMed Central. Protective effects of increased outdoor time against myopia: a review
On the other side of the equation, screen time has been linked to higher odds of myopia. A dose-response meta-analysis of 45 studies found that each additional hour of daily screen time was associated with roughly 21% higher odds of myopia, with the odds nearly doubling at four hours per day compared to none.21PubMed Central. Digital Screen Time and Myopia: A Systematic Review and Dose-Response Meta-Analysis The relationship followed a sigmoidal curve, with the sharpest increase between one and four hours. Genetics play a large role in who becomes myopic, but the dramatic rise in myopia rates over a few decades, far too fast for genetic change, points to environmental drivers like education intensity and near-work habits as the dominant force behind the current epidemic.22Ophthalmology. Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050
Measuring Tiny Changes in a Shifting Eye
One complication in all of this research is that the eye’s length isn’t perfectly stable even over the course of a single day. Studies using high-precision optical instruments have found that axial length naturally fluctuates by about 15 to 40 micrometers (0.015 to 0.040 mm) throughout the day in healthy eyes.23Investigative Ophthalmology & Visual Science. Diurnal Axial Length Fluctuations in Human Eyes These fluctuations are too small to be detected by standard ultrasound and require laser-based measurements to capture. When the shortening effects being studied are on the order of 0.05 to 0.15 mm, daily biological noise of up to 0.04 mm means researchers need to be extremely careful about measurement timing and technique. Studies that don’t control for time of day or use less precise instruments may report changes that are partly artifacts. The best trials standardize the measurement time and use optical biometry, but this is worth keeping in mind when evaluating any single study’s shortening claims.
This measurement challenge also matters for individual patients tracking their own progress. A child’s axial length reading at a Tuesday morning appointment may differ from a reading taken Thursday afternoon for purely biological reasons, having nothing to do with whether a treatment is working. Clinicians generally look at trends across multiple measurements over months rather than reading too much into any single visit.