Risks of No-Touch Laser Eye Surgery

Medically reviewed by: Op. Dr. Alim Huseynov · Last updated: 8 September 2026

Risks of no-touch (surface) laser eye surgery

The method marketed as “no-touch” is known in the medical literature as transepithelial photorefractive keratectomy (T-PRK). Together with PRK and LASEK it belongs to the surface ablation family: the laser works from the front surface of the cornea and no flap is created. Flap-related complications therefore do not occur; in return, the epithelium has to grow back, so healing and the risk profile differ from flap-based methods.

This page explains the known risks of surface ablation on the basis of peer-reviewed publications. Each section states which study it relies on, and full citations are listed under References.

What “no-touch” does and does not mean

“No-touch” is not a technology or a separate device; it is a marketing name for a surgical technique. Its medical equivalent is transepithelial PRK, and T-PRK is a version of PRK — performed since 1987 — in which the epithelium is removed by the laser itself. The term describes epithelial removal without a blade or alcohol; it does not mean the eye is never touched during surgery.

Is the eye really never touched?

1. The eyelids are held open with a speculum, which is placed in contact with the eye.
2. The eye is irrigated with a cannula.
3. The surface is dried with a PVA sponge.
4. After the first laser stage the eye may be irrigated and dried again.
5. Mitomycin-C, used to reduce haze, is applied to the surface with a sponge.
6. The eye is irrigated and dried once more to remove the drug completely.
7. A bandage contact lens is placed at the end of the procedure.

So even in a procedure presented as “no-touch”, the eye is touched at least seven times. These contacts are not in themselves a source of risk — the eye is numbed with anaesthetic drops and no pain is felt. What matters is the expectation the term creates in the patient.

Who is surface ablation preferred for?

1. Eyes that do not have enough corneal thickness for a flap.
2. Patients with a history of, or risk factors for, retinal detachment.
3. Occupations and sports with a high chance of blunt eye trauma, where the possibility of flap displacement should be removed entirely.
4. Eyes in which preserving stromal tissue takes priority — thin corneas or mild topographic irregularity.

Known risks of surface ablation

1. Postoperative pain and epithelial healing

Because the epithelium is removed, pain, stinging, watering and light sensitivity are expected until it closes again. A bandage contact lens is placed to reduce pain and is removed once the epithelium has healed.

Randomised comparative trials show that epithelial closure takes a similar time with all three techniques — transepithelial (laser), mechanical (blade) and alcohol-assisted removal: on average 3.6–3.7 days [1]. In another randomised trial the proportion of eyes healed by day three was 89.7% with transepithelial PRK versus 62.1% with alcohol-assisted PRK; however, day-one pain scores were higher in the transepithelial group [2].

2. Haze — corneal clouding

Haze is a loss of corneal clarity that develops in the anterior stroma during wound healing. It usually begins 1–3 months after surgery, peaks between the third and sixth month and fades over time in most eyes; in a minority it affects visual acuity and contrast sensitivity for months [3]. Haze is specific to surface ablation and is not seen in this form after flap-based procedures.

Reported rates vary between studies because patient profiles and mitomycin-C use differ. In a series of 362 eyes below −6.0 D operated without mitomycin-C, clinically significant (grade ≥2) haze occurred in 9 eyes (2.5%) [4]. In another series of 238 eyes, haze of any grade was found in 22 eyes (9.2%) [5]. In a large series of 3,566 eyes, haze was seen in 4.25% of the eyes that did not respond to steroids. In eyes that developed a steroid-induced pressure rise the rate was 16.98% [6].

Factors that increase the risk of haze

• High myopia and the deeper ablation it requires [6]
• Astigmatism: without mitomycin-C, ≥1.25 D was a significant risk factor [4]
• Tear-film and lid disease: short tear break-up time, meibomian gland dropout, contact lens intolerance and low vitamin D [5]
• Ultraviolet exposure, especially in the first months
• Individual predisposition: epithelial samples taken before surgery show a different gene expression profile in eyes that later develop haze [7]

3. Mitomycin-C: lowers haze risk, but has its own cost

Mitomycin-C (MMC) is an antineoplastic agent also used in oncology. In surface ablation it is applied to the stromal bed at very low concentration and for a short time to suppress the myofibroblast response that causes haze. Current reviews describe MMC, together with topical steroids, as a prophylactic agent for preventing haze and its recurrence [3].

MMC also has a cost: it delays epithelial healing, and prolonged or high-concentration use raises concerns about limbal stem cells and the corneal endothelium. Whether it is used, at what concentration and for how long is therefore decided eye by eye; some surgeons prefer not to use it in low-risk cases.

4. Steroid-induced rise in intraocular pressure

Steroid drops are continued for weeks after surface ablation to suppress haze. In a series of 3,566 eyes, steroid-induced ocular hypertension occurred in 2.97%. The risk was higher with male sex, thicker corneas, flatter keratometry, high myopia, the presence of haze and the use of stronger steroids such as dexamethasone [6].

5. Infectious keratitis

While the epithelium is open and a bandage lens is in place, the cornea is exposed to micro-organisms for longer than after flap-based surgery. Infectious keratitis is rare but sight-threatening.

In a multicentre series covering 25,337 PRK procedures, infectious keratitis was reported in 5 eyes — roughly 1 in 5,000 procedures (0.02%). Every case presented between the second and seventh postoperative day, and the organisms cultured were predominantly Staphylococcus, including two methicillin-resistant S. aureus. The same series identified 26 eyes with sterile infiltrates in the first week, which resolved after the bandage lens was removed and antibiotic cover increased [8].

6. Loss of Bowman’s layer and what it means

The cornea has five main layers:

1. Epithelium: a 5–6 cell thick, non-keratinised stratified squamous layer. It renews itself.
2. Bowman’s layer: an acellular layer of irregularly arranged collagen fibres. The epithelium anchors firmly to it; it gives the cornea structural support and forms the plane through which nerve fibres pass towards the epithelium. Once removed, it does not regenerate.
3. Stroma: about 90% of corneal thickness. Injury here can heal with loss of clarity and/or a change in curvature.
4. Descemet’s membrane: the basement membrane secreted by the endothelium.
5. Endothelium: a single cell layer that maintains corneal hydration; damage leads to oedema and loss of vision.

In surface ablation Bowman’s layer is ablated together with the epithelium; in flap-based procedures it is cut but largely remains in place centrally [9]. Because it does not regenerate, this loss is permanent.

7. Dry eye and corneal sensation

Corneal nerves are affected by both surface and flap-based methods; what differs is the shape of the cut. In surface ablation the nerve endings are removed centrally by the ablation; in flap-based surgery they are cut along the flap edge. In both, a temporary reduction in tear production and corneal sensation is expected in the early months, and artificial tears are standard treatment during this period [9].

Untreated moderate to severe dry eye before surgery is more than a comfort issue: tear-film disease also increases the risk of haze [5]. Dry eye should therefore be treated before surgery is planned.

8. Night vision, glare and halos

Halos around lights, glare and reduced night vision may occur in the first weeks and settle in most patients. A large scotopic pupil and a high amount of correction can make these symptoms more noticeable, which is why the optical zone is planned together with pupil diameter.

9. Residual refractive error and retreatment

Laser correction targets the refraction on the day of surgery. Particularly with high corrections, some residual error or regression over time is possible, and retreatment may be considered if the eye is suitable. Retreatment requires refractive stability across at least two measurements and sufficient corneal thickness.

No surgeon can guarantee that an eye will never change again. Laser surgery is a corrective procedure; ageing, diabetes, hypertension and kidney disease can affect vision in later years. For this reason a lifetime guarantee cannot be given in refractive surgery.

10. Sun and UV protection

In the months after surface ablation, ultraviolet light is one of the factors that increase haze risk. UV-blocking sunglasses are therefore recommended outdoors, especially where reflection is high — sea, snow and altitude. This is firm advice for the early months; for the longer term your surgeon will set the duration according to your own risk profile.

Is there a real difference in risk between T-PRK (“no-touch”) and conventional PRK?

Published randomised comparisons show no meaningful difference between the two techniques in safety or efficacy.

• In a one-year, double-masked, contralateral-eye study, visual acuity, accuracy of astigmatic correction, contrast sensitivity and haze at 12 months were comparable; day-one pain was higher in the transepithelial group [2].
• In a randomised trial comparing all three techniques (transepithelial, mechanical, alcohol-assisted), no difference was found in safety, efficacy, refractive accuracy or haze, and epithelial closure times were similar [1].

After surgery: what to expect and when

• End of surgery: a soft protective contact lens is placed and removed once the epithelium has closed (usually 3–5 days).
• First 3–4 days: moderate to severe pain, watering, stinging and light sensitivity are expected.
• Week 1: vision becomes usable; most patients cannot return to work or drive before this.
• Months 1–3: vision settles gradually towards the target; fluctuation during this period is normal.
• 2 weeks: no eye make-up. 3–4 weeks: no swimming pool, sea or heavy sweating sport.

Four factors that lower the risk

Patient factor — correct patient selection

From a surgical point of view, the single most important risk factor is the wrong patient selection. Age, refractive stability, corneal thickness and topography, tear-film status and systemic disease determine the method. This assessment is made by examination and measurement; opinions on suitability given over the internet should not be relied upon.

When laser eye surgery is not appropriate

• Keratoconus or signs of corneal thinning (ectasia) — an absolute contraindication
• Active ocular infection or inflammation
• Pregnancy and breastfeeding
• Corneal thickness below accepted limits
• Cataract affecting vision (laser would not help)
• A history of ocular herpes — requires separate assessment and prophylaxis
• Uncontrolled diabetes
• Active rheumatic or autoimmune disease and untreated severe dry eye
• Genetic corneal dystrophies
• Retinal disease that permanently limits vision

Laser surgery does not cure amblyopia (lazy eye). It may, however, improve day-to-day visual comfort in amblyopic patients who cannot tolerate glasses or contact lenses.

Surgeon factor

Experience, training, academic background, experience in managing complications and communication all matter. A good outcome depends on the surgeon and on the clinical team working with them.

Technology factor

A surgeon works within the limits of the technology available. Pulse frequency, eye-tracker speed, ablation profile and pulse-distribution techniques that reduce thermal load all affect the result. In our centres planning is additionally checked with the RLES AI® clinical decision support software, which verifies tissue safety floors, the postoperative keratometry window and device nomograms. The final clinical decision rests with the surgeon.

Hospital factor

Laser procedures are performed under semi-sterile operating-room conditions. In full-service hospitals, infection control committees apply sterilisation rules without exception. Given that infectious keratitis is a rare but serious complication [8], these conditions work in the patient’s favour.

The hidden cost of a cheap price

The items that set the price — the generation of the laser, the depth of the pre-operative work-up, operating-room conditions, the experience of the team and the follow-up programme — are the same items that set the outcome. When comparing prices, ask what is included: tests, post-operative medication, follow-up visits and, if needed, retreatment.

References

The figures on this page are taken from the peer-reviewed publications below. Citations were verified through PubMed.

1. Hashemi H, Alvani A, Aghamirsalim M, Miraftab M, Asgari S. Comparison of transepithelial and conventional photorefractive keratectomy in myopic and myopic astigmatism patients: a randomized contralateral trial. BMC Ophthalmol. 2022;22(1):68. DOI: 10.1186/s12886-022-02293-2 · PMID: 35148689
2. Gharieb HM, Awad-Allah MAA, Ahmed AA, Othman IS. Transepithelial laser versus alcohol assisted photorefractive keratectomy safety and efficacy: 1-year follow-up of a contralateral eye study. Korean J Ophthalmol. 2021;35(2):142–152. DOI: 10.3341/kjo.2020.0105 · PMID: 33596623
3. Moshirfar M, Wang Q, Theis J, et al. Management of corneal haze after photorefractive keratectomy. Ophthalmol Ther. 2023;12(6):2841–2862. DOI: 10.1007/s40123-023-00782-1 · PMID: 37603162
4. Thomas KE, Brunstetter T, Rogers S, Sheridan MV. Astigmatism: risk factor for postoperative corneal haze in conventional myopic photorefractive keratectomy. J Cataract Refract Surg. 2008;34(12):2068–2072. DOI: 10.1016/j.jcrs.2008.08.026 · PMID: 19027561
5. Kundu G, D’Souza S, Lalgudi VG, et al. Photorefractive keratectomy (PRK) PERFECT protocol — a new algorithmic approach for managing post PRK haze. Indian J Ophthalmol. 2020;68(12):2950–2955. DOI: 10.4103/ijo.IJO_2623_20 · PMID: 33229676
6. Busool Y, Mimouni M, Vainer I, et al. Risk factors predicting steroid-induced ocular hypertension after photorefractive keratectomy. J Cataract Refract Surg. 2017;43(3):389–393. DOI: 10.1016/j.jcrs.2016.12.030 · PMID: 28410723
7. Kumar NR, Khamar P, Shetty R, et al. Identification of novel predictive factors for post surgical corneal haze. Sci Rep. 2019;9:16980. DOI: 10.1038/s41598-019-53123-3 · PMID: 31740714
8. Wroblewski KJ, Pasternak JF, Bower KS, et al. Infectious keratitis after photorefractive keratectomy in the United States army and navy. Ophthalmology. 2006;113(4):520–525. DOI: 10.1016/j.ophtha.2005.09.038 · PMID: 16488012
9. Ganesh S, Brar S, Arra RR. Refractive lenticule extraction small incision lenticule extraction: a new refractive surgery paradigm. Indian J Ophthalmol. 2018;66(1):10–19. DOI: 10.4103/ijo.IJO_761_17 · PMID: 29283117

Last reviewed: 8 September 2026. This page is reviewed regularly in the light of new publications and clinical guideline updates.

Useful links: No-Touch T-PRK Laser Eye Surgery, PRK Laser Eye Surgery, LASEK Laser Eye Surgery, LASIK Laser Eye Surgery, All laser eye treatments.