Clinical trial NCT04174209: CHOICE OF SUBJECTIVE OCULAR REFRACTION TECHNIQUE AND CORNEAL TOPOGRAPHY OF KERATOCONUS
Official title: CHOICE OF SUBJECTIVE OCULAR REFRACTION TECHNIQUE AND CORNEAL TOPOGRAPHY OF KERATOCONUS
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Keratoconus
Alteration of Visual Acuity
Keywords: Keratoconus
Corneal Topography
Eyeglasses
Ocular Refraction
Jackson Cross Cylinder
Astigmatic Dial Technique
Stenopeic slit
Lead sponsor: University Hospital, Clermont-Ferrand
Sponsor class: OTHER
First posted: 2019-11-22
Enrollment: 52
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: NA
Intervention model: SINGLE_GROUP
Primary purpose: TREATMENT

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.

Eligibility criteria: 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.

Primary outcomes:
measure: Measure of keratometry (Km)
timeFrame: day 1
measure: Measure of the maximum keratometry
timeFrame: day 1
measure: Measure d_Kmax
timeFrame: day 1
measure: Measure of index of surface varaiance
timeFrame: day 1
measure: Measure of the Belin/Ambrósio Enhanced Ectasia Display (BAD-D)
timeFrame: day 1
Secondary outcomes:
measure: astigmatism axis
timeFrame: day 1
measure: Subsequent modification of the eyeglasses by the optician
timeFrame: day 30
measure: possible method
timeFrame: day 1
measure: ametropia value
timeFrame: day 1
Other outcomes:
Locations:
city: Clermont-Ferrand
country: France
facility: Chu Clermont Ferrand
Study officials:
affiliation: University Hospital, Clermont-Ferrand
name: Frédéric Chiambaretta
role: PRINCIPAL_INVESTIGATOR
References:
citation: Metzger M, Navel V, Barriere JV, Kwiatkowski F, Hebraud J, Mulliez A, Beral L, Chiambaretta F, Dutheil F. Benefits of using corneal topography to choose subjective refraction technique in keratoconus (RE-CON): a prospective comparative crossover clinical study. Graefes Arch Clin Exp Ophthalmol. 2022 Jan;260(1):197-207. doi: 10.1007/s00417-021-05382-y. Epub 2021 Aug 20.