CHOICE OF SUBJECTIVE OCULAR REFRACTION TECHNIQUE AND CORNEAL TOPOGRAPHY OF KERATOCONUS

Not Applicable

Completed

• Conditions: Alteration of Visual Acuity; Keratoconus
• Interventions: Behavioral: Cylinder; Behavioral: Dial; Behavioral: Slit

• Registration Number: NCT04174209
• Lead Sponsor: University Hospital, Clermont-Ferrand

Brief Summary

Keratoconus is a rare evolving corneal ectasia that alters visual acuity. To improve spectacle-corrected visual acuity, various subjective refraction techniques can be used.

The subjective refraction techniques of keratoconus-carrying patients have never been studied.

The main hypothesis is that the most suitable subjective ocular refraction method varies with the corneal topography of the keratoconus.

The main objective is to define the most appropriate refractive technique(s) based on corneal topographies in order to provide keratoconus-affected patients with the best spectacle-corrected visual acuity.

Detailed Description

Keratoconus is a rare evolving corneal ectasia that alters visual acuity. To improve spectacle-corrected visual acuity, various subjective refraction techniques can be used. The Jackson Cylinder Cross Method, the Astigmatic Dial Technique and the Stenopeic Slit are three validated subjective refraction techniques for measuring astigmatism. The subjective refraction techniques of keratoconus-carrying patients have never been studied.

The main hypothesis is that the most suitable subjective ocular refraction method varies with the corneal topography of the keratoconus.

The investigators collect several characteristics of corneal topography of the keratoconus : the average value of the keratometry of the 3 central mm called Km ; the value of the point corresponding to the maximum keratometry (called Kmax), the distance between the center and the point of Kmax, (called d_Kmax) ; the corneal surface variance index called ISV ; the Belin/Ambrósio Enhanced Ectasia Display (called BAD-D).

The main objective is to define the most appropriate refractive technique(s) based on corneal topographies in order to provide keratoconus-affected patients with the best spectacle-corrected visual acuity.

Study Timeline

• Status Verified: 2019-11
• Study Start: 2019-11-18
• Study First Submitted: 2019-11-20
• Study First Submitted QC: 2019-11-21
• Study First Posted: 2019-11-22
• Primary Completion: 2020-03-06
• Study Completion: 2020-03-06
• Last Update Submitted: 2020-03-19
• Last Update Posted: 2020-03-20

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 52

Inclusion Criteria

• adult persons
• patients with keratoconus
• patients with alteration of visual acuity
• ability to give informed consent to participate in the study
• affiliation to a social security scheme

Exclusion Criteria

• Keratoconus grafted with cornea or with intracorneal rings.
• Central corneal opacities.
• Presence of other eye diseases affecting visual acuity.
• Patients under guardianship, curatorship or justice protection.
• Pregnant or breastfeeding women.
• Refusal to participate in the study.

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Cohort 1	Slit	70 patients are involved and will perform the three conditions.
Cohort 1	Cylinder	70 patients are involved and will perform the three conditions.
Cohort 1	Dial	70 patients are involved and will perform the three conditions.

Primary Outcome Measures

Name	Time	Method
Measure of keratometry (Km)	day 1	average value of the keratometry of the 3 central mm called Km
Measure of the Belin/Ambrósio Enhanced Ectasia Display (BAD-D)	day 1	Measure of the Belin/Ambrósio Enhanced Ectasia Display (BAD-D)
Measure of index of surface varaiance	day 1	measure of the corneal surface variance index called ISV
Measure of the maximum keratometry	day 1	value of the point corresponding to the maximum keratometry (called Kmax),
Measure d_Kmax	day 1	Measure of the distance between the center and the point of Kmax, (called d_Kmax)

Secondary Outcome Measures

Name	Time	Method
ametropia value	day 1	The values of the final corrective spheres (myopia or hyperopia).
Subsequent modification of the eyeglasses by the optician	day 30	The need (yes / no) for the optician to modify the prescribed spectacle lens (due to poor tolerance)
astigmatism axis	day 1	Collection of the astigmatism axis given by each method, by the autorefractometer and by the corneal topography
possible method	day 1	The impossibility (yes / no) of carrying out each of the 3 refraction methods.

Trial Locations

Locations (1)

Chu Clermont Ferrand; 🇫🇷 Clermont-Ferrand, France