# CBD Versus Codeine After Laser Eye Surgery: What a 35-Person Trial Found > **Author:** Benjamin Caplan, MD (ABFM Board Certified, MA Lic. #240562, NPI: 1962722637) > **Publisher:** CED Clinic (https://cedclinic.com) > **Canonical URL:** https://cedclinic.com/oral-cbd-versus-codeine-after-laser-eye-surgery/ > **Published:** 2026-07-29T23:17:02-04:00 | **Last Modified / Clinically Audited:** 2026-09-27T22:01:57-04:00 > **Clinical Summary:** Explore the oral CBD versus codeine after laser eye surgery trial showing similar pain control but limited evidence for opioid replacement. --- CED Clinical Relevance #82 Clinical Evidence Update A same-day randomized human trial directly compared oral CBD with an opioid-containing analgesic after laser eye surgery, but the small sequential-eye design and incomplete noninferiority details require restraint. Clinical Insight | CED Clinic Randomized, Controlled Cross-over Comparison of Oral Cannabidiol to Oral Opioid for Postoperative Photorefractive Keratectomy Pain Control. is a recent peer-reviewed paper that deserves more than a headline because it sits directly inside a common clinical question: oral CBD compared with codeine-acetaminophen after photorefractive keratectomy. The useful reading is deliberately balanced. The paper gives CED readers a stronger evidence signal than a news blurb or anecdote, but it also shows why [cannabinoid medicine](https://cedclinic.com/cannabinoids-prostate-cancer-anti-tumor-drugs/) still needs product-specific, dose-specific, and patient-specific interpretation. For patients and clinicians, the point is not to convert the finding into a simple recommendation. The point is to understand what the study investigated, what it appeared to find, and where the evidence still stops short of a treatment rule. CBDAcute PainEye SurgeryRandomized TrialOpioid Comparison Audience Patients, caregivers, clinicians, and cannabis-science readers interested in short-term pain after photorefractive keratectomy Primary Topic oral CBD compared with codeine-acetaminophen after photorefractive keratectomy Source [Read the full source](https://pubmed.ncbi.nlm.nih.gov/42524865/) A randomized crossover trial in 35 adults found no significant difference in reported pain between oral CBD and codeine-acetaminophen after photorefractive keratectomy. Recovery measures were also similar, while mild sensorium changes appeared with first CBD exposure. The result is clinically interesting, but it does not establish broad equivalence or an opioid-sparing standard. What This Study Teaches Us The trial suggests that 50 mg of low-THC oral CBD twice daily produced similar reported pain scores to codeine-acetaminophen in a small, tightly defined laser-eye-surgery setting. It also shows why a nonsignificant difference should not automatically be treated as proof of noninferiority without the prespecified margin and confidence interval. Why This Matters Acute postoperative pain is a common setting for opioid exposure, and patients increasingly ask whether CBD can substitute for conventional analgesics. A direct randomized comparison is valuable, but its clinical meaning depends on the design, comparator schedule, blinding, statistical framework, and narrow surgical population. Study Snapshot Study Type Prospective, randomized, crossover, self-controlled clinical trial Population 35 adults undergoing bilateral sequential photorefractive keratectomy Intervention Low-THC oral CBD, 50 mg twice daily Comparator Codeine-acetaminophen 30 mg/300 mg every 4 hours Sequence Each participant received one regimen for one eye procedure and the other regimen for the contralateral eye in randomized order Primary Outcomes Pain and uncorrected visual acuity at postoperative month 3 Pain Result Mean and maximum pain ratings did not differ significantly; p = 0.538 Vision Result Visual acuity improved by month 3 with no treatment-related difference; p = 0.928 Safety Signal Sensorium scores were higher when CBD was used for the first eye, suggesting a first-exposure effect; p = 0.035 Major Limitation Small single-practice study with sequential procedures; the abstract does not report blinding, a noninferiority margin, or confidence intervals for the pain comparison Journal Journal of Cataract & Refractive Surgery Published Online July 29, 2026 PMID 42524865 DOI 10.1097/j.jcrs.0000000000002030 Clinical Bottom Line This small randomized crossover trial found similar reported pain after PRK with oral CBD and codeine-acetaminophen, but it is not enough to establish CBD as broadly equivalent to opioids or as routine postoperative care. What the Trial Compared Thirty-five adults underwent sequential PRK procedures in both eyes. In randomized order, each participant received oral CBD after one eye procedure and codeine-acetaminophen after the other. The CBD regimen was 50 mg twice daily. The comparator was codeine 30 mg with acetaminophen 300 mg every four hours. Participants recorded pain and symptoms, and investigators assessed visual and quality-of-life outcomes. What the Results Showed Pain peaked on postoperative day 2 with both regimens. The abstract reports no statistically significant difference in mean or maximum pain ratings between treatments. Visual acuity improved by month 3 without a treatment-related difference. Other symptoms and patient-reported outcomes were described as equivalent, although the abstract provides limited numerical detail. Why No Significant Difference Is Not Enough A nonsignificant superiority test does not by itself prove that two treatments are noninferior or clinically equivalent. A formal noninferiority conclusion ordinarily requires a prespecified margin and confidence interval showing that the difference stays within that margin. Those details are not reported in the PubMed abstract. Until the full statistical plan is reviewed, the safest description is that this small study detected no significant pain-score difference. The First-Exposure Sensorium Signal Sensorium scores were significantly higher when CBD was used after the first eye procedure, but not when it followed the second procedure. The authors interpreted this as a first-exposure effect. That finding deserves practical attention because even mild subjective changes can matter for driving, work, medication combinations, and postoperative instructions. What an Opioid-Sparing Claim Would Require The trial did not establish that CBD reduces opioid exposure across surgical care, works in other acute-pain settings, or matches non-opioid standards such as acetaminophen and NSAID-based regimens. Larger blinded trials should report rescue medication, adverse events, clinically meaningful pain differences, noninferiority margins, confidence intervals, and patient-level preferences. How Strong Is This Evidence? The randomized sequence and within-person comparison reduce some between-person variability, and the study directly addresses a clinically relevant analgesic comparison. Confidence remains limited by the sample of 35, the sequential-eye design, sparse safety detail, and incomplete reporting of the noninferiority framework in the abstract. Where This Paper Deserves Skepticism Pain after a first procedure may differ from pain after a second because expectations, experience, timing, and learning can change. A crossover sequence helps analyze this problem but does not remove it, especially when treatment effects may be perceptible and blinding is not described in the abstract. What This Paper Does Not Show The trial does not prove that CBD is equivalent to codeine, replace opioids in general, outperform non-opioid multimodal analgesia, work for [chronic pain](https://cedclinic.com/cannabinoids-pain-management-opioid-alternative/), or justify self-directed use of retail CBD after surgery. How This Fits With the Broader Clinical Conversation Postoperative opioid reduction is an important goal, but the relevant comparison is not simply CBD versus an opioid. Modern pain care often uses procedure-specific combinations of local therapy, acetaminophen, anti-inflammatory medication when appropriate, and limited rescue opioids. CBD also varies across products. A studied low-THC oral formulation cannot validate untested retail products with different concentrations, contaminants, absorption, or labeling accuracy. Dr. Caplan’s Take *I find this trial worth attention because it asks a direct clinical question in humans and uses each participant as their own comparator. That is more useful than an anecdote or a mechanistic claim.* *The responsible conclusion is still narrower than the abstract’s strongest language. Similar observed pain scores in 35 people are a signal for a larger trial, not a new postoperative standard.* What a Careful Reader Should Take Away A careful reader should see a promising opioid-comparison signal in one specific surgery, paired with enough statistical and design uncertainty to require replication before routine use. Evidence Interpretation Guide Table of Contents - [How to Interpret This Oral Cbd Compared With Codeine-Acetaminophen After Photorefractive Keratectomy Evidence Without Overstating It](#How_to_Interpret_This_Oral_Cbd_Compared_With_Codeine-Acetaminophen_After_Photorefractive_Keratectomy_Evidence_Without_Overstating_It)[A Four-Step Reading Frame](#A_Four-Step_Reading_Frame) - [The Same Study Can Mean Different Things Depending on the Question Being Asked](#The_Same_Study_Can_Mean_Different_Things_Depending_on_the_Question_Being_Asked)[A Signal Worth Discussing, Not Self-Prescribing](#A_Signal_Worth_Discussing_Not_Self-Prescribing) - [Useful Evidence With Practical Gaps](#Useful_Evidence_With_Practical_Gaps) - [Small Evidence Bases Can Look Larger in Review Form](#Small_Evidence_Bases_Can_Look_Larger_in_Review_Form) - [Outcome Measures Do Not Answer Every Bedside Question](#Outcome_Measures_Do_Not_Answer_Every_Bedside_Question) - [A Step Forward, Not the Final Word](#A_Step_Forward_Not_the_Final_Word) - [Monitoring Matters](#Monitoring_Matters) - [What Better Evidence Would Need](#What_Better_Evidence_Would_Need) - [Access Should Not Outrun Evidence Quality](#Access_Should_Not_Outrun_Evidence_Quality) - [Frequently Asked Questions](#Frequently_Asked_Questions)[Related](#Related) ## How to Interpret This Oral Cbd Compared With Codeine-Acetaminophen After Photorefractive Keratectomy Evidence Without Overstating It A useful evidence report should let the signal breathe without inflating it. The right question is not whether the paper is positive or negative, but what kind of decision it can responsibly support. ### A Four-Step Reading Frame **Evidence type**Start by identifying whether the paper is a randomized trial, review, meta-analysis, observational study, or protocol. **Population**Ask whether the studied population matches the patient or clinical scenario involving short-term pain after photorefractive keratectomy. **Outcome meaning**Look at what actually changed, how it was measured, and whether the change would matter in daily life. **Safety and uncertainty**Read limitations and adverse effects as part of the result, not as a footnote. The Research Question What does the current evidence suggest about oral CBD compared with codeine-acetaminophen after photorefractive keratectomy? The Patient Question Does this mean I should use cannabinoids for short-term pain after photorefractive keratectomy? The Bottom Line The evidence can inform a careful conversation, but it does not replace individualized clinical care. CED Perspective Lens ## The Same Study Can Mean Different Things Depending on the Question Being Asked Scientific papers rarely answer a single question. Patients, clinicians, researchers, policymakers, and critics often read the same data differently. The perspectives below explore how this study looks through several evidence-based lenses. Lens Overview This paper can be read through several lenses. The most useful readings keep oral CBD compared with codeine-acetaminophen after photorefractive keratectomy clinically relevant without treating the evidence as more settled than it is. #### A Signal Worth Discussing, Not Self-Prescribing For patients interested in oral CBD compared with codeine-acetaminophen after photorefractive keratectomy, the paper creates a reasonable conversation starter but not a do-it-yourself treatment plan. In this case, the key is to keep short-term pain after photorefractive keratectomy in view while avoiding claims the study did not test. Lens takeaway Bring the evidence to a clinician; do not turn it into self-directed dosing. #### Useful Evidence With Practical Gaps Clinicians can use the paper to discuss short-term pain after photorefractive keratectomy, but the evidence still leaves product, dose, monitoring, and patient-selection questions open. In this case, the key is to keep short-term pain after photorefractive keratectomy in view while avoiding claims the study did not test. Lens takeaway The clinical value is in structured discussion, not automatic recommendation. #### Small Evidence Bases Can Look Larger in Review Form Systematic reviews can make a field feel mature even when the underlying trials remain few, short, or heterogeneous. In this case, the key is to keep short-term pain after photorefractive keratectomy in view while avoiding claims the study did not test. Lens takeaway Review-level evidence still depends on the quality of the studies underneath it. #### Outcome Measures Do Not Answer Every Bedside Question The paper reports measurable outcomes, but patients also need information about durability, adverse effects, interactions, and real-world use. In this case, the key is to keep short-term pain after photorefractive keratectomy in view while avoiding claims the study did not test. Lens takeaway Statistical improvement is not the same as a complete care plan. #### A Step Forward, Not the Final Word This paper advances the conversation by gathering available evidence, but it also highlights how much [cannabinoid research](https://cedclinic.com/cannabinoids-in-reward-processing-pain-perception/) still depends on small or uneven studies. In this case, the key is to keep short-term pain after photorefractive keratectomy in view while avoiding claims the study did not test. Lens takeaway The field is moving, but the foundation is still being built. #### Monitoring Matters If cannabinoids are considered clinically, monitoring should include symptom response, [side effects](https://cedclinic.com/cannabis-intoxication-memory-disruption/), sedation or impairment, medication interactions, and patient goals. In this case, the key is to keep short-term pain after photorefractive keratectomy in view while avoiding claims the study did not test. Lens takeaway The practical layer determines whether a signal becomes useful care. #### What Better Evidence Would Need Stronger trials should define formulation, dose, comparator, duration, responder profiles, and safety monitoring before broad claims are made. In this case, the key is to keep short-term pain after photorefractive keratectomy in view while avoiding claims the study did not test. Lens takeaway Better evidence needs specificity, not just bigger sample size. #### Access Should Not Outrun Evidence Quality Patients deserve access to careful information, but public messaging should not make early evidence sound settled. In this case, the key is to keep short-term pain after photorefractive keratectomy in view while avoiding claims the study did not test. Lens takeaway Honest uncertainty protects both patients and the credibility of [cannabis medicine](https://cedclinic.com/essential-oils-industrial-hemp-antimicrobial-benefits/). Join the Conversation Have a question about how this applies to your situation? [Ask Dr. Caplan](https://benjamincaplan.com/ask-dr-caplan) Want to discuss this topic with other patients and caregivers? [Join the forum discussion](https://cedclinic.com/interact/discussion-forums/forum/cannabis-industry/) [https://cedclinic.com/contact/](https://cedclinic.com/contact/) Physician-Led, Whole-Person Care A doctor who takes the time to truly understand you. Personal care that starts with listening and is guided by experience and ingenuity. Health, Longevity, Wellness One-on-One Cannabis Guidance Metabolic Balance [Leave a Message](https://cedclinic.com/contact/) [Metabolic Care](https://cedclinic.com/metabolic/metabolic-how-it-works/) [Medical Consulting](https://cedclinic.com/book/) [Cannabis Care](https://cedclinic.com/book/) [https://cedclinic.com/contact/](https://cedclinic.com/contact/) Share this Evidence Watch [X](https://twitter.com/intent/tweet?text=CBD+Versus+Codeine+After+Laser+Eye+Surgery%3A+What+a+35-Person+Trial+Found&url=https%3A%2F%2Fcedclinic.com%2Fcbd-codeine-laser-eye-surgery-pain-trial%2F) [LinkedIn](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fcedclinic.com%2Fcbd-codeine-laser-eye-surgery-pain-trial%2F) [BlueSky](https://bsky.app/intent/compose?text=CBD+Versus+Codeine+After+Laser+Eye+Surgery%3A+What+a+35-Person+Trial+Found%20https%3A%2F%2Fcedclinic.com%2Fcbd-codeine-laser-eye-surgery-pain-trial%2F) [Instagram](https://www.instagram.com/drcaplan/) [Substack](https://doctorapprovedcannabis.substack.com/) [RSS](https://cedclinic.com/feed/) Source: [Randomized, Controlled Cross-over Comparison of Oral Cannabidiol to Oral Opioid for Postoperative Photorefractive Keratectomy Pain Control.](https://pubmed.ncbi.nlm.nih.gov/42524865/) Related Reading at CED Clinic Continue exploring the evidence [Insights from a Full-Spectrum CBD Oil Study on Burning Mouth Syndrome](https://cedclinic.com/full-spectrum-cbd-oil-burning-mouth-syndrome-study/) A separate controlled CBD pain study that illustrates how condition, formulation, and trial design shape interpretation. [Compare oral pain evidence](https://cedclinic.com/full-spectrum-cbd-oil-burning-mouth-syndrome-study/) [Does Low-Dose CBD Cause Psychoactive Effects? Findings from a Dose-Dependent Trial](https://cedclinic.com/dose-dependent-side-effects-cannabinoids-cbd-trial/) Randomized human evidence on subjective effects across low oral CBD doses, relevant to the sensorium finding. [Review dose effects](https://cedclinic.com/dose-dependent-side-effects-cannabinoids-cbd-trial/) [Pain Suzetrigine Data Reveal Reduced Postoperative Opioids](https://cedclinic.com/pain-suzetrigine-data-reveal-reduced-postoperative-opioids/) Broader postoperative analgesia context for interpreting opioid-sparing claims and procedure-specific evidence. [Read postoperative context](https://cedclinic.com/pain-suzetrigine-data-reveal-reduced-postoperative-opioids/) ## Frequently Asked Questions Does this study prove that oral CBD compared with codeine-acetaminophen after photorefractive keratectomy works? No. It supports a clinically interesting signal, but proof requires larger, better-controlled, and more specific trials. Is this enough evidence to change treatment on its own? No. It can inform a clinical conversation, but it should not replace individualized medical judgment or established care. Why does study design matter here? Design affects how confidently readers can separate a true treatment effect from bias, placebo response, measurement choices, and patient selection. What is the biggest limitation? The biggest limitation is that the available studies are relatively small, heterogeneous, and not long enough to answer every practical safety question. Does this apply to every cannabis or CBD product? No. Products differ by cannabinoid content, dose, route, purity, and testing standards, so one paper cannot validate every product. What should patients ask their clinician? Patients should ask how the evidence relates to their own short-term pain after photorefractive keratectomy, medication list, risks, goals, and monitoring plan. Are [side effects](https://cedclinic.com/cannabis-intoxication-memory-disruption/) still important if the findings are positive? Yes. Benefit and risk have to be interpreted together, especially for sedation, impairment, interactions, and vulnerable populations. Why include this as a full CED report? The paper is recent, clinically relevant, and evidence-based enough to deserve careful standalone interpretation rather than a short mention. What would stronger research add? Stronger research would clarify formulation, dose, duration, responder profiles, active comparators, long-term outcomes, and safety monitoring. What is the practical takeaway? The practical takeaway is cautious interest: the signal is worth knowing, but the clinical decision still has to be individualized. ### Related --- ### Verification & Medical Governance - **Lead Clinical Author:** Benjamin Caplan, MD - **Credentials:** Board Certified in Family Medicine (ABFM), Founder & CMO CED Clinic & CED Foundation, Author of *The Doctor-Approved Cannabis Handbook* (Penguin Random House). - **Clinical Scale:** 350,000+ lifetime evaluations overseen; 81,008-patient Real-World Evidence Registry (`~/.ced_rwe_vault.db`); 125,000+ peer-reviewed study literature observatory (`http://localhost:8768/api/explorer/terminal`). - **License Verification:** Commonwealth of Massachusetts License #240562 (https://checkahealthlicense.mass.gov/). - **NPI Registry:** 1962722637 (https://npiregistry.cms.hhs.gov/provider-view/1962722637). - **Ethics & Data Privacy:** Clinical registry observations adhere strictly to HIPAA Safe Harbor de-identification (45 CFR § 164.514(b)) and criteria for secondary research exemption under 45 CFR § 46.104(d)(4).