CHOICE OF SUBJECTIVE OCULAR REFRACTION TECHNIQUE AND CORNEAL TOPOGRAPHY OF KERATOCONUS

Keratoconus Clinical Trial

— RE-CON  

Official title:

CHOICE OF SUBJECTIVE OCULAR REFRACTION TECHNIQUE AND CORNEAL TOPOGRAPHY OF KERATOCONUS

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT04174209
• Other study ID #: RBHP 2019 CHIAMBARETTA
• Secondary ID: 2019-A01624-53
• Status: Completed
• Phase: N/A
• Start date: November 18, 2019
• Est. completion date: March 6, 2020

Study information

• Verified date: November 2019
• Source: University Hospital, Clermont-Ferrand
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial 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.

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.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 52
• Est. completion date: March 6, 2020
• Est. primary completion date: March 6, 2020
• Accepts healthy volunteers: No
• Gender: All
• Age group: 18 Years and older

Eligibility

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.

Related Conditions & MeSH terms

• Alteration of Visual Acuity
• Keratoconus

Intervention

Behavioral:
• Cylinder
Patients who receive the Jackson Cross Cylinder Method
• Dial
Patients who receive the Astigmatic Dial Technique Method.
• Slit
Patients who receive the Stenopeic slit Method.

Locations

Country	Name	City	State
France	Chu Clermont Ferrand	Clermont-Ferrand

Sponsors (1)

Lead Sponsor	Collaborator
University Hospital, Clermont-Ferrand

Country where clinical trial is conducted

France, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Measure of keratometry (Km)	average value of the keratometry of the 3 central mm called Km	day 1
Primary	Measure of the maximum keratometry	value of the point corresponding to the maximum keratometry (called Kmax),	day 1
Primary	Measure d_Kmax	Measure of the distance between the center and the point of Kmax, (called d_Kmax)	day 1
Primary	Measure of index of surface varaiance	measure of the corneal surface variance index called ISV	day 1
Primary	Measure of the Belin/Ambrósio Enhanced Ectasia Display (BAD-D)	Measure of the Belin/Ambrósio Enhanced Ectasia Display (BAD-D)	day 1
Secondary	astigmatism axis	Collection of the astigmatism axis given by each method, by the autorefractometer and by the corneal topography	day 1
Secondary	Subsequent modification of the eyeglasses by the optician	The need (yes / no) for the optician to modify the prescribed spectacle lens (due to poor tolerance)	day 30
Secondary	possible method	The impossibility (yes / no) of carrying out each of the 3 refraction methods.	day 1
Secondary	ametropia value	The values of the final corrective spheres (myopia or hyperopia).	day 1