Corneal AstigmatismNCT03841253
Treatment of Vision Disturbances Due to Corneal Irregularities by Trans-epithelial Optical Phototherapeutic Keratectomy (TE-oPTK)
A study testing Trans-epithelial PTK, Trans-epithelial PTK (retrospective data collection) and EpiMaster Application Software in people with Corneal Astigmatism, run by London Vision Clinic at 1 site in United Kingdom.
Trial summary
This study sets out to evaluate the EpiMaster application software for use in predicting the refractive change induced by a trans-epithelial phototherapeutic keratectomy (TE-PTK) procedure in eyes with irregularly irregular astigmatism. Read more about this study
- Who is it for?
- Ages 21 to 70 yearsHealthy volunteers can take part
- Conditions the study is for
- Corneal Astigmatism
- What is being tested?
- Trans-epithelial PTK, Trans-epithelial PTK (retrospective data collection) and EpiMaster Application Software
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 45 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- 1 Aug 2019to 1 Nov 2028
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 21 to 70 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Patient presents with topographic irregularly irregular astigmatism and associated quality of vision issues, where TE-PTK would be a more effective treatment than topography-guided ablation or other therapeutic treatment options.
- Medically suitable for corneal laser refractive surgery.
- Calculated residual stromal thickness ≥250 µm.
- Subjects should be 21 years of age or older.
- Contact lens wearers must stop wearing their contact lenses one week per decade of wear before baseline measurements in case of hard contact lenses and one week before baseline measurements in case of soft contact lenses.
- Patient will be able to understand the patient information and willing to sign an informed consent.
- Patient will be willing to comply with all follow-up visits and the respective examinations.
Who cannot join
- Patient not being able to tolerate local or topical anesthesia
- Autoimmune diseases
- Sicca syndrome, dry eye
- Herpes viral (herpes simplex) infections
- Herpes zoster
- Diabetes
Show all 24Show fewer
- Pregnant or nursing women (or who are planning pregnancy during the study)
- Patients with a weight of > 135 kg
- Any residual, recurrent or acute ocular disease or abnormality of the eye, e.g.
- Cataract
- Suspected glaucoma or an intraocular pressure > 21 mm of Hg
- Corneal disease
- Corneal thinning disorder, e.g. keratoconus,
- Pellucid marginal corneal degeneration
- Dystrophy of the basal membrane
- Corneal oedema
- Exudative macular degeneration
- Infection
- Any residual, recurrent, or active abnormality of the cornea to be treated, e.g.
- Existing corneal implant
- Corneal lesion
- Unstable refraction
- Connective tissue disease
- Dry eye
Trial locations and contacts
1 site in 1 country.
About this study
This study sets out to evaluate the EpiMaster application software for use in predicting the refractive change induced by a trans-epithelial phototherapeutic keratectomy (TE-PTK) procedure in eyes with irregularly irregular astigmatism. If validation criteria are met during the observational phase, the software refractive prediction will be used to plan the refractive correction in TE-PTK treatments.
Read the detailed description
Complications after laser eye surgery can often result in the front surface of the eye (the cornea) becoming irregular, which causes visual symptoms such as halos, glare, starbursts, double vision, and reduced contrast sensitivity. For the past 20 years, corneal irregularities have been treated using wavefront-guided ablation, topography-guided ablation or trans-epithelial phototherapeutic keratectomy (TE-PTK). Topography-guided ablation is the most effective treatment for certain types of irregularity and works by using a laser to remove tissue from the cornea in a pattern derived from a topography scan (a measurement of the shape and curvature of the front of the eye) designed to make the corneal surface more regular.
However, topography-guided ablation is less effective for other types of irregularity. In these cases, the corneal epithelium (the layer of skin on the surface of the cornea) has changed in thickness to partially hide the irregularity on the body of the cornea under the epithelium (the stroma). The epithelium does this by becoming thinner over peaks and thickening over troughs in the stroma. Therefore, the topography measurement can only detect the proportion of the irregularity that has not been hidden by the epithelium, hence reducing its effectiveness. The preferred treatment option is TE-PTK; the laser treatment is applied onto and through the epithelium, breaking through to the stroma where the epithelium is thinnest, thus removing tissue from the peaks on the stroma resulting in a more regular surface.
The main weakness of TE-PTK is that it may unpredictably change the refraction to become more short-sighted or more long-sighted or change the astigmatism. To improve this, we have developed the Epimaster software that simulates a TE-PTK treatment and predicts the change in refraction.
The aim of the study is to validate the refractive prediction produced by the Epimaster software by comparing this to the achieved result in the patients treated. The treatment received by the patient will be the same as has been used routinely for the past 20 years.
- Conditions
- Corneal Astigmatism
- Being tested
- Trans-epithelial PTK, Trans-epithelial PTK (retrospective data collection), EpiMaster Application Software
- Keywords
- Trans-epithelial phototherapeutic keratectomy, PTK, TE-PTK, Corneal epithelium, Excimer laser
- Medical subject headings
- Astigmatism
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Trans-epithelial PTKProcedure or surgery
The MEL 90 excimer laser will be used to ablate the corneal epithelium and stroma to a pre-defined depth, using the epithelium as a natural masking agent to smooth the stromal surface.
Trans-epithelial PTK (retrospective data collection)Procedure or surgery
The MEL 90 excimer laser will be used to ablate the corneal epithelium and stroma to a pre-defined depth, using the epithelium as a natural masking agent to smooth the stromal surface.
EpiMaster Application SoftwareProcedure or surgery
The EpiMaster Application Software imports epithelial thickness data and corneal front surface topography data, and uses this to calculate the refractive change that would be induced by a trans-epithelial PTK treatment.
| Study group | Role | What they receive |
|---|---|---|
| Observational Phase 1 | Other | A trans-epithelial PTK procedure will be performed using the MEL 90 excimer laser. The refractive outcome will be compared to the refractive change predicted by the EpiMaster application software. Data is collected prospectively. Receives: Procedure: Trans-epithelial PTK |
| Observational Phase 1b | Other | A trans-epithelial PTK procedure will be performed using the MEL 90 excimer laser. The refractive outcome will be compared to the refractive change predicted by the EpiMaster application software. Data is collected retrospectively. Receives: Procedure: Trans-epithelial PTK (retrospective data collection) |
| Treatment Phase 2 | Experimental | If the transition criteria are met during the observational phase, the treatment phase will be initiated. A trans-epithelial PTK procedure will be performed using the MEL 90 excimer laser, including a refractive component according to the values determined using the EpiMaster application software. Receives: Procedure: EpiMaster Application Software |
What is being measured
The primary outcome is the main question the study is designed to answer.
The tendency of manifest sphere, cylinder and axis
The correct tendency of manifest sphere, cylinder and axis should be achieved in 90% of cases, where tendency refers to:
- The sign of the predicted and the post-operative sphere is equal for predicted sphere values greater than absolute value 0.50 D (confidence limit)
- The sign of the predicted and the post-operative cylinder is equal (same cylinder format setting like e.g. plus cylinder format) for predicted cylinder values greater than absolute value 0.50 D (confidence limit)
- The cylinder axis of the predicted and the post-operative cylinder do not deviate by more than ±45° for predicted cylinder values greater than absolute value 0.50 D (confidence limit)
- In none of the cases the prediction in sphere and cylinder is more than absolute value 2.00 D off the post-operative values.
Measured: 3-12 months
Standard deviation of SEpostop-SEpredicted
Standard deviation of SEpostop-SEpredicted at each follow-up time point (represents the scatter of the refractive outcome), where SEpredicted is the refractive outcome predicted by the EpiMaster application software.
Measured: 12 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted15 Feb 2019
- Study start1 Aug 2019
- Primary completion1 Mar 2028 (estimated)
- Study completion1 Nov 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (5)Papers the sponsor has linked to this study.
- Other trials for Corneal AstigmatismStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Model description
- Phase 1 will be observational comparing the software predicted refractive change to the observed refractive change. Data will be collected prospectively. Phase 1b will be observational comparing the software predicted refractive change to the observed refractive change. Data will be collected retrospectively. Phase 2 will use the software predicted refractive change to plan the refractive component of the treatment.
- Masking
- None (open label)
- Enrolment
- 45 participants (estimated)
Sponsor and investigators
- Lead sponsor
- London Vision Clinic
- Sponsor type
- University, hospital or other
- Collaborators
- Optana GmbH
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03841253
- Sponsor's protocol ID
- LO007
- Status last verified
- Feb 2026
- First submitted
- 12 Feb 2019
- Last updated
- 12 Feb 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Participant data will not be shared with other researchers.
Publications
Reinstein DZ, Archer TJ, Gobbe M. Refractive and topographic errors in topography-guided ablation produced by epithelial compensation predicted by 3D Artemis VHF digital ultrasound stromal and epithelial thickness mapping. J Refract Surg. 2012 Sep;28(9):657-63. doi: 10.3928/1081597X-20120815-02.
PubMed 22947295Reinstein DZ, Archer TJ, Gobbe M. Improved effectiveness of transepithelial PTK versus topography-guided ablation for stromal irregularities masked by epithelial compensation. J Refract Surg. 2013 Aug;29(8):526-33. doi: 10.3928/1081597X-20130719-02.
PubMed 23909779Reinstein DZ, Archer TJ, Dickeson ZI, Gobbe M. Transepithelial phototherapeutic keratectomy protocol for treating irregular astigmatism based on population epithelial thickness measurements by artemis very high-frequency digital ultrasound. J Refract Surg. 2014 Jun;30(6):380-7. doi: 10.3928/1081597X-20140508-01.
PubMed 24972404Guglielmetti S, Kirton A, Reinstein DZ, Carp GI, Archer TJ. Repair of Irregularly Irregular Astigmatism by Transepithelial Phototherapeutic Keratectomy. J Refract Surg. 2017 Oct 1;33(10):714-719. doi: 10.3928/1081597X-20170721-04.
PubMed 28991341Reinstein DZ, Archer T. Combined Artemis very high-frequency digital ultrasound-assisted transepithelial phototherapeutic keratectomy and wavefront-guided treatment following multiple corneal refractive procedures. J Cataract Refract Surg. 2006 Nov;32(11):1870-6. doi: 10.1016/j.jcrs.2006.07.016.
PubMed 17081871
Study at a glance
From the registry record, last updated by the sponsor on 12 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Treatment of Vision Disturbances Due to Corneal Irregularities by Trans-epithelial Optical Phototherapeutic Keratectomy (TE-oPTK)
- ClinicalTrials.gov ID
- NCT03841253
- Acronym / sponsor ID
- LO007
- Conditions
- Corneal Astigmatism
- Keywords
- Trans-epithelial phototherapeutic keratectomy, PTK, TE-PTK, Corneal epithelium, Excimer laser
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 45 participants (estimated)
- Lead sponsor
- London Vision ClinicUniversity, hospital or other
- Collaborators
- Optana GmbH
- Study start
- 1 Aug 2019 (actual)
- Primary completion
- 1 Mar 2028 (estimated)
- Study completion
- 1 Nov 2028 (estimated)
- First posted
- 15 Feb 2019 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study sets out to evaluate the EpiMaster application software for use in predicting the refractive change induced by a trans-epithelial phototherapeutic keratectomy (TE-PTK) procedure in eyes with irregularly irregular astigmatism. If validation criteria are met during the observational phase, the software refractive prediction will be used to plan the refractive correction in TE-PTK treatments.
Detailed description
Complications after laser eye surgery can often result in the front surface of the eye (the cornea) becoming irregular, which causes visual symptoms such as halos, glare, starbursts, double vision, and reduced contrast sensitivity. For the past 20 years, corneal irregularities have been treated using wavefront-guided ablation, topography-guided ablation or trans-epithelial phototherapeutic keratectomy (TE-PTK). Topography-guided ablation is the most effective treatment for certain types of irregularity and works by using a laser to remove tissue from the cornea in a pattern derived from a topography scan (a measurement of the shape and curvature of the front of the eye) designed to make the corneal surface more regular.
However, topography-guided ablation is less effective for other types of irregularity. In these cases, the corneal epithelium (the layer of skin on the surface of the cornea) has changed in thickness to partially hide the irregularity on the body of the cornea under the epithelium (the stroma). The epithelium does this by becoming thinner over peaks and thickening over troughs in the stroma. Therefore, the topography measurement can only detect the proportion of the irregularity that has not been hidden by the epithelium, hence reducing its effectiveness. The preferred treatment option is TE-PTK; the laser treatment is applied onto and through the epithelium, breaking through to the stroma where the epithelium is thinnest, thus removing tissue from the peaks on the stroma resulting in a more regular surface.
The main weakness of TE-PTK is that it may unpredictably change the refraction to become more short-sighted or more long-sighted or change the astigmatism. To improve this, we have developed the Epimaster software that simulates a TE-PTK treatment and predicts the change in refraction.
The aim of the study is to validate the refractive prediction produced by the Epimaster software by comparing this to the achieved result in the patients treated. The treatment received by the patient will be the same as has been used routinely for the past 20 years.
Study design
- Primary purpose
- Treatment
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 3
- Model description
- Phase 1 will be observational comparing the software predicted refractive change to the observed refractive change. Data will be collected prospectively. Phase 1b will be observational comparing the software predicted refractive change to the observed refractive change. Data will be collected retrospectively. Phase 2 will use the software predicted refractive change to plan the refractive component of the treatment.
| Arm | Type | Receives |
|---|---|---|
| Observational Phase 1 | Other | Procedure: Trans-epithelial PTKA trans-epithelial PTK procedure will be performed using the MEL 90 excimer laser. The refractive outcome will be compared to the refractive change predicted by the EpiMaster application software. Data is collected prospectively. |
| Observational Phase 1b | Other | Procedure: Trans-epithelial PTK (retrospective data collection)A trans-epithelial PTK procedure will be performed using the MEL 90 excimer laser. The refractive outcome will be compared to the refractive change predicted by the EpiMaster application software. Data is collected retrospectively. |
| Treatment Phase 2 | Experimental | Procedure: EpiMaster Application SoftwareIf the transition criteria are met during the observational phase, the treatment phase will be initiated. A trans-epithelial PTK procedure will be performed using the MEL 90 excimer laser, including a refractive component according to the values determined using the EpiMaster application software. |
Who may qualify
- Ages
- 21 to 70 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (7 listed)
- Patient presents with topographic irregularly irregular astigmatism and associated quality of vision issues, where TE-PTK would be a more effective treatment than topography-guided ablation or other therapeutic treatment options.
- Medically suitable for corneal laser refractive surgery.
- Calculated residual stromal thickness ≥250 µm.
- Subjects should be 21 years of age or older.
- Contact lens wearers must stop wearing their contact lenses one week per decade of wear before baseline measurements in case of hard contact lenses and one week before baseline measurements in case of soft contact lenses.
Key exclusion criteria (24 listed)
- Patient not being able to tolerate local or topical anesthesia
- Autoimmune diseases
- Sicca syndrome, dry eye
- Herpes viral (herpes simplex) infections
- Herpes zoster
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Trans-epithelial PTKThe MEL 90 excimer laser will be used to ablate the corneal epithelium and stroma to a pre-defined depth, using the epithelium as a natural masking agent to smooth the stromal surface. | Procedure or surgery | Observational Phase 1 |
| Trans-epithelial PTK (retrospective data collection)The MEL 90 excimer laser will be used to ablate the corneal epithelium and stroma to a pre-defined depth, using the epithelium as a natural masking agent to smooth the stromal surface. | Procedure or surgery | Observational Phase 1b |
| EpiMaster Application SoftwareThe EpiMaster Application Software imports epithelial thickness data and corneal front surface topography data, and uses this to calculate the refractive change that would be induced by a trans-epithelial PTK treatment. | Procedure or surgery | Treatment Phase 2 |
Primary outcome
The tendency of manifest sphere, cylinder and axis
Time frame: 3-12 months
The correct tendency of manifest sphere, cylinder and axis should be achieved in 90% of cases, where tendency refers to: 1. The sign of the predicted and the post-operative sphere is equal for predicted sphere values greater than absolute value 0.50 D (confidence limit) 2. The sign of the predicted and the post-operative cylinder is equal (same cylinder format setting like e.g. plus cylinder format) for predicted cylinder values greater than absolute value 0.50 D (confidence limit) 3. The cylinder axis of the predicted and the post-operative cylinder do not deviate by more than ±45° for predicted cylinder values greater than absolute value 0.50 D (confidence limit) 4. In none of the cases the prediction in sphere and cylinder is more than absolute value 2.00 D off the post-operative values.
Standard deviation of SEpostop-SEpredicted
Time frame: 12 months
Standard deviation of SEpostop-SEpredicted at each follow-up time point (represents the scatter of the refractive outcome), where SEpredicted is the refractive outcome predicted by the EpiMaster application software.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 12 Feb 2026.
- Background: PubMed 22947295Reinstein DZ, Archer TJ, Gobbe M. Refractive and topographic errors in topography-guided ablation produced by epithelial compensation predicted by 3D Artemis VHF digital ultrasound stromal and epithelial thickness mapping. J Refract Surg. 2012 Sep;28(9):657-63. doi: 10.3928/1081597X-20120815-02.
- Background: PubMed 23909779Reinstein DZ, Archer TJ, Gobbe M. Improved effectiveness of transepithelial PTK versus topography-guided ablation for stromal irregularities masked by epithelial compensation. J Refract Surg. 2013 Aug;29(8):526-33. doi: 10.3928/1081597X-20130719-02.
- Background: PubMed 24972404Reinstein DZ, Archer TJ, Dickeson ZI, Gobbe M. Transepithelial phototherapeutic keratectomy protocol for treating irregular astigmatism based on population epithelial thickness measurements by artemis very high-frequency digital ultrasound. J Refract Surg. 2014 Jun;30(6):380-7. doi: 10.3928/1081597X-20140508-01.
- Background: PubMed 28991341Guglielmetti S, Kirton A, Reinstein DZ, Carp GI, Archer TJ. Repair of Irregularly Irregular Astigmatism by Transepithelial Phototherapeutic Keratectomy. J Refract Surg. 2017 Oct 1;33(10):714-719. doi: 10.3928/1081597X-20170721-04.
- Background: PubMed 17081871Reinstein DZ, Archer T. Combined Artemis very high-frequency digital ultrasound-assisted transepithelial phototherapeutic keratectomy and wavefront-guided treatment following multiple corneal refractive procedures. J Cataract Refract Surg. 2006 Nov;32(11):1870-6. doi: 10.1016/j.jcrs.2006.07.016.
- Individual participant dataSharing planned: No. Participant data will not be shared with other researchers.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Trans-epithelial PTK, Trans-epithelial PTK (retrospective data collection) and EpiMaster Application Software in people with Corneal Astigmatism, run by London Vision Clinic at 1 site in United Kingdom.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 24 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 12 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
The tendency of manifest sphere, cylinder and axis (time frame: 3-12 months). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT03841253, which also lists 5 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 12 Feb 2026.