NCT03841253

Treatment of Vision Disturbances Due to Corneal Irregularities by Trans-epithelial Optical Phototherapeutic Keratectomy (TE-oPTK)

• Status: Active Not Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 45 (estimated)
• Sponsor: London Vision Clinic · Academic / Other
• Sex: All
• Age: 21 Years – 70 Years
• Healthy volunteers: Accepted

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. 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.

Conditions

• Corneal Astigmatism

Interventions

Type	Name	Description
PROCEDURE	Trans-epithelial PTK	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	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	EpiMaster Application Software	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.

Timeline

• Start date: 2019-08-01
• Primary completion: 2028-03-01
• Completion: 2028-11-01
• First posted: 2019-02-15
• Last updated: 2026-02-12

Locations

1 site across 1 country: United Kingdom