Preoperative Evaluation for LASIK Surgery
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The preoperative LASIK evaluation is a structured, comprehensive examination performed to determine whether a patient is a suitable candidate for laser in situ keratomileusis and, if so, to plan a treatment that maximizes optical quality while preserving corneal biomechanical integrity. It is among the most detailed ocular examinations in routine practice. Its two overarching objectives are to identify eyes at risk for postoperative ectasia and to identify and correct conditions—most commonly ocular surface disease—that degrade the accuracy of preoperative measurements and the quality of postoperative outcomes.[1][2]
Required Elements of the Evaluation
The American Academy of Ophthalmology Refractive Surgery Preferred Practice Pattern specifies that a comprehensive medical eye evaluation be performed before any refractive surgery procedure, with the following elements in addition to those of the comprehensive adult medical eye evaluation:[1]
Distance and near visual acuity, with and without correction
Manifest and, when appropriate, cycloplegic refraction
Computerized corneal topography/tomography
Central corneal thickness measurement
Evaluation of tear film and ocular surface
Evaluation of ocular motility and alignment
History
Chief Complaint, Goals, and Expectations
The single most important predictor of postoperative satisfaction is whether expectations were met. Understanding why the patient has chosen LASIK clarifies the appropriate target (full distance correction, monovision, blended vision) and surfaces unrealistic goals early.
A patient who is contact lens intolerant and wants functional vision without correction has realistic expectations likely to be met.
A patient who expects vision better than their current best-corrected acuity, or who is unwilling to accept any possibility of residual refractive error, night vision symptoms, or the eventual onset of presbyopia, is a poor candidate.
Unrealistic patient expectations are listed by the AAO as a contraindication to refractive surgery, on equal footing with anatomic contraindications.[1] Informed consent should explicitly review dry eye and eventual presbyopia as common, expected adverse effects rather than complications.[1] Patients should also understand that although more than 90% of appropriately selected patients achieve excellent uncorrected distance vision, many still require spectacles in low-light conditions and with age.[3]
Screening for uncontrolled mental illness, including anxiety and depression, is also recommended, as this is an AAO-listed contraindication.[1] Patients with chronic pain syndromes, somatization, or central sensitization warrant particular caution given the association with post-refractive corneal neuropathic pain.[3]
Refractive Stability
Refraction should have been stable for at least 1 to 2 years, and surgery is typically deferred until after age 21 owing to ongoing refractive change; FDA labeling for each specific laser platform should be consulted.[4][1] Unstable refraction is an absolute contraindication.[1] Old spectacle prescriptions and prior refraction records are the most practical means of verification. There is no upper age limit provided the eye is otherwise normal, though older patients should be counseled that a refractive lens exchange or cataract-based approach may be more appropriate.[4][3]
Contact Lens Discontinuation
Contact lens–induced corneal warpage can produce topographic patterns indistinguishable from early ectasia and can shift refraction by more than 1 D. Lenses must be discontinued and topography documented as stable on two separate visits before final treatment planning:
Soft lenses: typically 3 days to 2 weeks
Soft toric lenses: 2 to 3 weeks
Rigid gas permeable lenses: 3 weeks or longer, occasionally months, with 1 additional week per decade of wear as a common rule of thumb
Orthokeratology: several months, until documented stability
Past Medical and Ocular History
Systemic conditions that impair wound healing or destabilize refraction, and ocular conditions that may reactivate or progress, must be identified:
Autoimmune and collagen vascular disease (rheumatoid arthritis, systemic lupus erythematosus, Sjögren syndrome) — risk of impaired epithelial healing, sterile infiltrates, and corneal melt with perforation. Uncontrolled autoimmune or immune-mediated disease is a contraindication; the safety of surgery in well-controlled disease has not been established by randomized trials and remains controversial.[4][5][1]
Diabetes mellitus — associated with epithelial adhesion abnormalities, delayed healing, and reduced corneal sensation; uncontrolled diabetes should be avoided.[5][1]
Herpes simplex or varicella zoster keratitis — excimer laser and ultraviolet exposure may reactivate latent virus; a history of HSV/VZV keratitis is listed among conditions in which LASIK may not be advisable, and antiviral prophylaxis should be considered if surgery is undertaken.[1][5]
Uveitis and uncontrolled glaucoma — both listed contraindications; glaucoma is of particular concern because the flap alters applanation tonometry and because the suction ring transiently raises intraocular pressure.[1]
Keloid formation — historically cited as a concern for haze after surface ablation; evidence for a true association is weak, but it is worth documenting.
Prior strabismus or history of phoria/tropia — an unrecognized minor strabismus controlled by prismatic effect in spectacles may decompensate into symptomatic diplopia after LASIK. This is why ocular motility and alignment testing is a required element of the evaluation.[6][1]
Prior corneal or refractive surgery (RK, PRK, LASIK, corneal transplant) — alters biomechanics, flap creation, and healing.
Avellino (granular type 2) corneal dystrophy — excimer ablation can precipitate dramatic accelerated deposition; a specific contraindication in the review literature.[5]
Medications
Isotretinoin — meibomian gland atrophy and severe evaporative dry eye; a listed contraindication. Typically discontinued 6 to 12 months before surgery.[1][7]
Amiodarone — verticillata and reported healing concerns; a listed contraindication.[1][5]
Sumatriptan (Imitrex) — cited by the AAO among systemic medications representing a relative contraindication because of reported effects on corneal healing.[1]
Colchicine and levonorgestrel implants — also listed by the AAO among medications of concern.[1]
Antihistamines, anticholinergics, diuretics, and antidepressants — all associated with aqueous tear deficiency or meibomian gland dysfunction and will exacerbate postoperative dryness.[7]
Hormonal changes — pregnancy and lactation are contraindications because of transient refractive shift and dry eye.[4][1]
Social and Occupational History
Occupation and avocation determine both candidacy and procedure choice.
Significant occupational or recreational risk of corneal trauma (military service, law enforcement, martial arts, contact sports) is specifically identified by the AAO as a reason to consider PRK, another surface ablation, or SMILE instead of LASIK, because of the lifelong risk of flap dislocation.[1]
Occupations requiring critical night vision (commercial driving, aviation) warrant additional counseling regarding glare and halo.[6]
Tobacco and heavy alcohol use may impair epithelial healing.
Family History
A family history of keratoconus or corneal transplantation should heighten suspicion for subclinical ectatic disease and lower the threshold for advanced tomographic, epithelial, and biomechanical screening, even when Placido topography appears normal.
Physical Examination
Visual Acuity and Refraction
Uncorrected and corrected distance acuity are recorded, along with near acuity, which is required by the PPP and is essential for presbyopia counseling and monovision planning.[1]
A careful manifest refraction with fogging to avoid over-minusing is checked against a cycloplegic refraction. Cycloplegia is essential to uncover latent hyperopia, which is more common than appreciated and is a frequent cause of unexpected hyperopic outcomes when the manifest refraction alone is treated.[6] Discrepancy of more than 0.50 D between manifest and cycloplegic values warrants repeat measurement and consideration of accommodative spasm.
Loss of best-corrected acuity or an unexplained decrement in corrected acuity is a red flag for early ectasia, cataract, or macular pathology and must be explained before proceeding.
External and Adnexal Examination
Periocular anatomy directly affects the ability to create a flap.[6] The AAO lists orbital, eyelid, or ocular anatomy that precludes proper function of the mechanical or femtosecond microkeratome among special considerations that may favor an alternative procedure.[1] Assess for:
Deep-set eyes, narrow palpebral fissure, or prominent brow — may prevent adequate suction ring placement or docking
Small palpebral aperture requiring lateral canthotomy
Prominent globes with poor lid closure
Chalazion or lid lesion — may itself induce refractive astigmatism and should be treated first[6]
Eyelid Margin and Meibomian Glands
Blepharitis and meibomian gland dysfunction must be identified and treated before surgery. Uncontrolled external disease—including blepharitis, dry eye syndrome, and atopy/allergy—is a listed contraindication.[1] Evaluate lid margin telangiectasia, gland capping, expressibility and quality of meibum, Demodex collarettes, and floppy eyelid signs.
Cornea and Anterior Segment
Epithelial basement membrane dystrophy / poor epithelial adherence / recurrent erosion syndrome — explicitly identified by the AAO as a special consideration favoring surface ablation over LASIK, given the risk of intraoperative epithelial sloughing, subsequent epithelial ingrowth, and diffuse lamellar keratitis.[1][6]
Corneal scarring or vascularization — may indicate prior herpetic or other infectious keratitis; extensive vascularization is a contraindication and also raises limbal bleeding risk during flap creation.[1]
Guttae / endothelial dystrophy — Fuchs endothelial dystrophy has been associated with poor flap adhesion and corneal decompensation; visually significant stromal or endothelial dystrophies are contraindications.[6][1]
Anterior chamber and iris — posterior synechiae, iris atrophy, or transillumination defects suggest prior uveitis or herpetic disease.
Angle assessment — hyperopic candidates are on average older and more likely to have anatomically narrow angles.[6]
Lens — a visually significant cataract is a contraindication; in such patients lens-based surgery is the appropriate alternative.[1] Early nuclear sclerosis producing a myopic shift also violates the requirement for refractive stability.
Tonometry and Optic Nerve
Baseline intraocular pressure and optic nerve appearance must be documented, because post-LASIK applanation readings underestimate true IOP and this baseline is essential for lifelong glaucoma surveillance. Patients should be given a record listing their diagnosis, preoperative keratometry and refraction, and postoperative refraction, for use in future eye care including cataract surgery — a specific AAO recommendation.[1]
Dilated Fundus Examination
A complete dilated fundus examination is required. In high myopes, careful scleral-depressed peripheral examination is performed to detect lattice degeneration, retinal holes, and tears, which should be treated by a retina specialist before surgery. Note that published evidence has not established that LASIK increases the risk of retinal detachment; the rationale for peripheral examination is the baseline prevalence of peripheral pathology in myopic eyes, not a procedure-specific risk.
Ancillary Testing
Corneal Topography, Tomography, and Ectasia Screening
Abnormal corneal topography/tomography is the single most significant identifiable risk factor for post-LASIK ectasia and is an absolute contraindication when it indicates keratoconus or other ectatic disease.[1][8]
Topography versus tomography
Topography (from topos, place, and graphein, to write) is imaging of the anterior corneal surface — classically Placido-based computerized videokeratography. Tomography (from tomos, a section) mathematically reconstructs the cornea in three dimensions, combining anterior and posterior elevation with a full pachymetric map. Available technologies include horizontal slit scanning, rotating Scheimpflug imaging, very-high-frequency ultrasound arc scanning, and anterior segment OCT.
Screening must go beyond front-surface curvature and a single central pachymetry value; a tomographic approach is essential. Critically, the goal of screening is not only to detect subclinical keratoconus and pellucid marginal degeneration, but also to assess the susceptibility of a relatively normal cornea to biomechanical failure.[8]
Key tomographic parameters and indices
Belin-Ambrósio Enhanced Ectasia Display (BAD-D) — a composite deviation index combining elevation and pachymetric progression; explicitly cited by the AAO as useful for identifying eyes at risk.[1] In a series of post-LASIK ectasia eyes, total deviation (BAD-D) exceeded 1.6 in 50% preoperatively.[9]
Ambrósio Relational Thickness (ART-Max) — pachymetric progression relative to thinnest point; ART-Max below 340 in 45.8% of ectasia cases.[9]
Pentacam Random Forest Index (PRFI) — an artificial intelligence–derived index; in the same series PRFI exceeded 0.125 in 87.5% of eyes that went on to develop ectasia, the highest yield of any single preoperative parameter examined.[9]
Posterior elevation and posterior radius of curvature — posterior elevation is among the parameters that best discriminate ectatic from normal post-LASIK corneas, and elevated posterior elevation is detectable even in the clinically normal fellow eye of unilateral ectasia patients (AUC 0.745; 73.9% sensitivity, 68.8% specificity at a cutoff of 3).[10]
Importantly, current risk criteria remain imperfect. In one post-LASIK ectasia series, 8% of eyes had no identifiable preoperative risk factor by any conventional metric, leading the authors to conclude that biomechanical assessment, epithelial thickness mapping, and AI-derived indices are needed to improve characterization of ectasia susceptibility.[9]
Pachymetry, Residual Stromal Bed, and Percent Tissue Altered
Normal central corneal thickness ranges from approximately 490 to 650 μm.[4] Central corneal thickness measurement is a required element of the preoperative evaluation.[1]
Residual stromal bed (RSB)
For LASIK, a minimum residual stromal bed of 250 μm is suggested as safe, but no absolute value guarantees that ectasia will not occur, because the posterior stroma has weaker tensile strength than the anterior stroma.[1] Some authors prefer a more conservative threshold of 300 μm.[11] In a post-LASIK ectasia case-control series, RSB ≤ 300 μm carried an odds ratio of 74.[12]
Percent tissue altered (PTA)
PTA is now regarded as the most robust single predictor of ectasia in eyes with normal preoperative topography:
- PTA = (FT + AD) / CCT
where FT = flap thickness, AD = ablation depth, and CCT = preoperative central corneal thickness.[1][12]
In the defining case-control study of 30 ectasia eyes with normal preoperative Placido topography versus 174 uncomplicated controls with ≥3 years of follow-up:
| Risk factor | Prevalence in ectasia eyes | Odds ratio |
|---|---|---|
| PTA ≥ 40% | 97% | 223 |
| Age < 30 years | 63% | — |
| RSB ≤ 300 μm | 57% | 74 |
| Ectasia Risk Score ≥ 3 | 43% | — |
| Ectasia Risk Score ≥ 4 | — | 8 |
Data from Santhiago et al.[12]
Stepwise logistic regression identified PTA ≥ 40% as the single most significant independent variable (P < .0001).[12] The AAO endorses PTA ≥ 40% as associated with higher ectasia risk in the setting of normal preoperative topography.[1]
PTA is conceptually superior to RSB or CCT alone because it is individualized — it expresses the relationship between total tissue altered and the original corneal thickness rather than an absolute value applied uniformly across corneas of differing thickness.[8]
Note that PTA thresholds derived for LASIK do not transfer directly to surface ablation. In 408 eyes undergoing transepithelial PRK with mean RSB of 336 μm (range 310–348 μm) and mean PTA of 30.9%, the posterior corneal surface remained stable at 2 years with no sign of iatrogenic ectasia, and no linear relationship was found between PTA or age and posterior surface change.[13]
Other recognized risk factors
Thin preoperative CCT, young age (a frequently overlooked but important factor — 79% of eyes in one ectasia series were under 25), high attempted correction, microkeratome flap creation, and low RSB.[8][9]
Epithelial Thickness Mapping
Epithelial thickness mapping has emerged as a valuable adjunct that detects ectatic disease masked by compensatory epithelial remodeling — the epithelium thins over a developing cone and thickens over adjacent flatter areas, which can normalize the anterior curvature map and conceal early disease from Placido topography.
The characteristic pattern in keratoconus is focal thinning over the cone with concentric surrounding thickening, typically inferior or inferotemporal, with increased standard deviation of epithelial thickness across zones.[14][15]
Critically, epithelial thickness and distribution are altered in forme fruste keratoconus eyes that have normal topography.[14]
A two-step OCT decision tree using pachymetric and epithelial map parameters plus pattern recognition achieved 100% specificity with 97.8% sensitivity for manifest keratoconus, 100% for subclinical keratoconus, and 73.7% for forme fruste keratoconus.[16] A comparable algorithm on a different OCT platform reached 100% specificity, 100% sensitivity in manifest KC, and 90.4% sensitivity in subclinical KC, with high agreement against the Belin-Ambrósio display.[17]
Measurements are highly reproducible (ICC ≥ 0.95 across all regions), and a model combining epithelial thickness standard deviation with the superior-to-inferior thickness ratio achieved an AUC of 0.955 (92.1% sensitivity, 100% specificity) for early keratoconus.[15]
Bowman's layer vertical thickness profiles add further discriminative power; a discriminant function combining maximum ectasia indices for epithelium and Bowman's layer reached AUC 0.970 for subclinical keratoconus.[18]
Epithelial mapping is best used in conjunction with, not in place of, tomography.[16]
Corneal Biomechanics
Because ectasia is fundamentally a biomechanical failure, direct biomechanical assessment complements geometric screening. Dynamic Scheimpflug analysis provides indices such as the Corvis Biomechanical Index and the CBI-LVC (laser vision correction–specific variant), the latter being among the parameters that best discriminate post-LASIK ectatic eyes from normal post-LASIK controls.[10] Combined tomographic-biomechanical indices (e.g., the Tomographic and Biomechanical Index) are increasingly used, and the ectasia literature explicitly calls for biomechanical assessment to close the diagnostic gap left by tomography alone.[9][8]
Ocular Surface and Dry Eye Assessment
Ocular surface disease degrades both the accuracy of preoperative measurements (keratometry, topography, aberrometry, biometry) and the quality of postoperative outcomes, and refractive surgery can itself induce or worsen it. The ASCRS Cornea Clinical Committee developed a consensus preoperative OSD algorithm specifically because most surveyed surgeons were not using modern diagnostic tests despite recognizing the importance of the problem; treating OSD preoperatively significantly improves postoperative visual outcomes and satisfaction.[2]
A practical sequence
Symptom questionnaire. TFOS DEWS III recommends the OSDI-6 with a cutoff score ≥ 4 as the screening instrument.[19] The DEQ-5 (> 5) and full OSDI (> 12) are also validated.[7] Non-invasive breakup time (NIBUT). A positive symptom score plus NIBUT < 10 s establishes a diagnosis of dry eye under DEWS III.[19] Fluorescein breakup time under 10 s is likewise abnormal.[7] Tear osmolarity. Alternatively diagnostic when ≥ 308 mOsm/L in the higher eye, or an interocular difference > 8 mOsm/L.[19] Vital dye staining. Positive symptoms together with > 5 corneal fluorescein spots, and/or > 9 conjunctival lissamine green spots, and/or lid margin lissamine staining ≥ 2 mm in length and ≥ 25% in width also establishes the diagnosis.[19] Point-of-care MMP-9. A result > 40 ng/mL suggests benefit from topical anti-inflammatory therapy such as cyclosporine.[7] Schirmer testing. Provides a quantitative estimate of aqueous production but has low sensitivity (40%–50%) and poor reproducibility, and should not be used as a sole screening test.[7][11] Meibography and lipid layer interferometry (e.g., Oculus Keratograph 5M, LipiView) to subclassify evaporative disease and quantify gland dropout.[19] Subclassification and management
DEWS III subclassifies dry eye into tear film components (lipid, aqueous, mucin/glycocalyx) and ocular surface and adnexal components (anatomical misalignment, blink/lid closure abnormality, lid margin disease, neural dysfunction, ocular surface cell damage, primary inflammation/oxidative stress), with the express purpose of directing etiology-specific therapy.[19] This matters preoperatively because an incomplete blink or lagophthalmos requires a different intervention than aqueous deficiency.
Treatment is initiated and the patient re-evaluated with repeat topography until the surface is optimized, because measurements taken on a compromised surface will propagate error into the treatment plan.[2] Options include lid hygiene and warm compresses, preservative-free artificial tears, punctal occlusion, omega-3 supplementation, topical cyclosporine, lifitegrast, short-course topical corticosteroid, oral tetracyclines for meibomian gland dysfunction, and intense pulsed light or thermal pulsation.
Inadequately controlled dry eye is a contraindication.[1] Significant dry eye is also specifically listed as a condition favoring PRK, another surface ablation, or SMILE over LASIK, on the understanding that these mitigate but do not eliminate risk.[1] When tear production is extremely low, as in Sjögren syndrome, and symptoms do not improve with treatment, deferring surgery entirely is appropriate.[11] Patients with suspected Sjögren syndrome should undergo serologic evaluation.[7]
Postoperative dry eye should be presented at consent as an expected effect: it usually resolves over 6 to 12 months but persists in up to 20% of patients, and may in part represent a corneal neuropathy.[3]
Pupillometry
Scotopic pupil size is conventionally measured with an infrared pupillometer, and documentation of scotopic pupil diameter has traditionally been considered mandatory on the premise that larger pupils predispose to postoperative glare and halo.[6]
This premise is no longer well supported. The AAO Refractive Surgery PPP states that published studies have failed to demonstrate a relationship between pupil size and the quality of postoperative vision, minimizing the importance of pupillometry in the preoperative workup.[1] Pupil size may still be recorded for documentation and consent purposes, but should not by itself disqualify a candidate, and the relationship between pupil diameter and dysphotopsia should be presented to patients as controversial rather than established.[1]
Wavefront Aberrometry
Wavefront analysis quantifies higher-order aberrations that are not captured by sphere and cylinder and that may degrade quality of vision. Eyes with substantial preexisting higher-order aberrations—particularly coma, which may itself be a marker of subclinical ectasia or of a decentered prior ablation—are poor candidates for conventional treatment, since standard profiles will not correct and may amplify them.
Wavefront-guided ablation uses total ocular aberrometry and is best suited to eyes in which aberrations are predominantly internal/lenticular or arise from a previously decentered or irregular ablation.
Wavefront-optimized ablation applies additional peripheral pulses to compensate for the spherical aberration induced by a purely spherocylindrical profile, without measuring the individual eye's higher-order aberrations.
Topography-guided ablation is driven by corneal surface data and is preferred when the aberration source is clearly corneal and irregular.
Wavefront-guided LASIK is safe and effective, but in eyes with unremarkable baseline aberrometry it has not been shown to produce outcomes superior to conventional or wavefront-optimized treatment. A pragmatic approach is to reserve customized profiles for eyes with higher-order RMS above approximately 0.3–0.35 μm at a 6 mm pupil, recognizing that aberrometric measurement is itself degraded by an unstable tear film — reinforcing the requirement to optimize the ocular surface before capturing wavefront data.[2]
Ocular Motility, Alignment, and Binocular Function
Evaluation of ocular motility and alignment is a required element of the preoperative evaluation.[1] Cover/uncover and alternate cover testing at distance and near, with and without correction, should be performed on every candidate.
A decompensating phoria controlled by the prismatic effect of spectacles may become symptomatic once spectacles are removed.
Anisometropic patients with long-standing spectacle-induced aniseikonia may experience a change in binocular function once the anisometropia is eliminated.
Monovision should be trialed with contact lenses before surgery. Patients with reduced stereopsis, an existing phoria, or occupational demands for fine stereoacuity are poor monovision candidates.
Prior strabismus surgery raises the possibility of recurrence or decompensation and warrants a preoperative sensorimotor evaluation.[6]
Contrast Sensitivity
Contrast sensitivity testing (Hamilton-Veale, Mars Letter, Pelli-Robson) characterizes functional vision beyond the high-contrast Snellen chart and is useful for documentation and for counseling patients whose occupations demand good mesopic performance. It is not a required element of the evaluation.[1]
Summary of Contraindications and Alternative-Procedure Triggers
| Category | Contraindications to LASIK |
|---|---|
| Refractive | Unstable refraction; refractive error outside the FDA-approved range for the platform[1] |
| Corneal | Keratoconus, pellucid marginal degeneration, or other abnormal topography/tomography; inadequate corneal thickness or projected PTA ≥ 40% / RSB < 250–300 μm; visually significant corneal dystrophy; extensive corneal vascularization[1][12] |
| Ocular surface | Uncontrolled blepharitis, dry eye, or atopy/allergy[1] |
| Other ocular | Uncontrolled glaucoma; uveitis; visually significant cataract; orbital, eyelid, or ocular anatomy precluding microkeratome or femtosecond docking[1] |
| Systemic | Uncontrolled autoimmune or immune-mediated disease; uncontrolled diabetes; pregnancy or lactation; isotretinoin, amiodarone, and other listed medications (sumatriptan, colchicine, levonorgestrel implants)[1][5] |
| Psychosocial | Unrealistic expectations; uncontrolled mental illness including anxiety and depression[1] |
Conditions that should prompt consideration of surface ablation or SMILE instead of LASIK, rather than outright exclusion, include epithelial basement membrane dystrophy or recurrent erosion, significant but controlled dry eye, borderline corneal thickness, and occupational or recreational exposure to ocular trauma.[1]
Documentation and Informed Consent
Informed consent should be obtained by the operating surgeon and should specifically address the expected occurrence of dry eye, the inevitable onset of presbyopia and consequent need for reading correction, the possibility of residual refractive error requiring enhancement or continued spectacle wear, night vision symptoms, flap-related risks including lifelong dislocation risk after trauma, infection, and the rare but sight-threatening risk of ectasia.[1][3]
At the conclusion of care, patients should be provided with a written record of their diagnosis, preoperative keratometry and refraction, and postoperative refraction, as this information materially affects future intraocular lens calculations and glaucoma management.[1]
Additional Resources
American Academy of Ophthalmology. Refractive Errors & Refractive Surgery Preferred Practice Pattern.
Boyd K, Huffman JM. LASIK. American Academy of Ophthalmology. EyeSmart/Eye health.
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29 1.30 1.31 1.32 1.33 1.34 1.35 1.36 1.37 1.38 1.39 1.40 1.41 1.42 1.43 1.44 1.45 1.46 Jacobs DS, Lee JK, Shen TT, et al. Refractive Errors and Refractive Surgery Preferred Practice Pattern. Ophthalmology. 2023;130(3):P1-P84.
- ↑ 2.0 2.1 2.2 2.3 Starr CE, Gupta PK, Farid M, et al. An algorithm for the preoperative diagnosis and treatment of ocular surface disorders. J Cataract Refract Surg. 2019;45(5):669-684.
- ↑ 3.0 3.1 3.2 3.3 3.4 Wilkinson JM, Cozine EW, Kahn AR. Refractive eye surgery: helping patients make informed decisions about LASIK. Am Fam Physician. 2017;95(10):637-644.
- ↑ 4.0 4.1 4.2 4.3 4.4 Wilson SE. Clinical practice. Use of lasers for vision correction of nearsightedness and farsightedness. N Engl J Med. 2004;351(5):470-475.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Bower KS, Woreta F. Update on contraindications for laser-assisted in situ keratomileusis and photorefractive keratectomy. Curr Opin Ophthalmol. 2014;25(4):251-257.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 Varley GA, Huang D, Rapuano CJ, et al. LASIK for hyperopia, hyperopic astigmatism, and mixed astigmatism: a report by the American Academy of Ophthalmology. Ophthalmology. 2004;111(8):1604-1617.
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 Hakim FE, Farooq AV. Dry eye disease: an update in 2022. JAMA. 2022;327(5):478-479.
- ↑ 8.0 8.1 8.2 8.3 8.4 Santhiago MR, Giacomin NT, Smadja D, Bechara SJ. Ectasia risk factors in refractive surgery. Clin Ophthalmol. 2016;10:713-720.
- ↑ 9.0 9.1 9.2 9.3 9.4 9.5 El-Naggar MT, Elkitkat RS, Ziada HE, Esporcatte LPG, Ambrósio R. Assessment of preoperative risk factors for post-LASIK ectasia development. Clin Ophthalmol. 2023;17:3705-3713.
- ↑ 10.0 10.1 Yang K, Fan Q, Xu L, et al. Accuracy of tomographic and biomechanical parameters in detecting unilateral post-LASIK keratectasia and fellow eyes. Front Bioeng Biotechnol. 2023;11:1163223.
- ↑ 11.0 11.1 11.2 Sakimoto T, Rosenblatt MI, Azar DT. Laser eye surgery for refractive errors. Lancet. 2006;367(9520):1432-1447.
- ↑ 12.0 12.1 12.2 12.3 12.4 Santhiago MR, Smadja D, Gomes BF, et al. Association between the percent tissue altered and post-laser in situ keratomileusis ectasia in eyes with normal preoperative topography. Am J Ophthalmol. 2014;158(1):87-95.
- ↑ Li H, Zhang J, Shao T, et al. Two-year stability of posterior corneal surface after transepithelial photorefractive keratectomy with a residual stromal thickness less than 350 μm. Graefes Arch Clin Exp Ophthalmol. 2023;261(3):797-804.
- ↑ 14.0 14.1 Sukhee N, Namba H, Ikeda M, et al. Corneal epithelium is altered in keratoconus and forme fruste keratoconus. Sci Rep. 2025;15:21384.
- ↑ 15.0 15.1 Oshika T, Sawaki A, Nishida T, Nakamura T, Kojima T. Reproducibility and screening capability of corneal epithelial thickness measurement for keratoconus using anterior segment optical coherence tomography. Clin Ophthalmol. 2025;19:1113-1121.
- ↑ 16.0 16.1 Yang Y, Pavlatos E, Chamberlain W, Huang D, Li Y. Keratoconus detection using OCT corneal and epithelial thickness map parameters and patterns. J Cataract Refract Surg. 2021;47(6):759-766.
- ↑ Yücekul B, Dick HB, Taneri S. Systematic detection of keratoconus in OCT: corneal and epithelial thickness maps. J Cataract Refract Surg. 2022;48(12):1360-1365.
- ↑ Xu Z, Jiang J, Yang C, et al. Value of corneal epithelial and Bowman's layer vertical thickness profiles generated by UHR-OCT for sub-clinical keratoconus diagnosis. Sci Rep. 2016;6:31550.
- ↑ 19.0 19.1 19.2 19.3 19.4 19.5 Wolffsohn JS, Benítez-Del-Castillo J, Loya-Garcia D, et al. TFOS DEWS III diagnostic methodology. Am J Ophthalmol. 2025.
