Clinical trial NCT02698709: Astigmatic Vector Analysis of Posterior Cornea - a Comparison Among Healthy, Forme Fruste and Overt Keratoconus Corneas
Official title: Astigmatic Vector Analysis of Posterior Corneal Surface - a Comparison Among Healthy, Forme Fruste and Overt Keratoconus Corneas
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Keratoconus
Keywords: Keratoconus
Corneal Topography
Diagnosis
Keratomileusis, Laser In Situ
Lead sponsor: University of Sao Paulo
Sponsor class: OTHER
First posted: 2016-03-04
Enrollment: 698
Sex: ALL
Standard ages: CHILD
ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: CASE_CONTROL
Time perspective: RETROSPECTIVE
Sampling method: PROBABILITY_SAMPLE
Study population: Two databases of patients were examined at the Instituto de Olhos Renato Ambrósio (Rio de Janeiro, Brazil), between July 2004 and October 2013. One of the databases contained information of normal candidates to refractive surgery who did not develop any sign of corneal ectasia after laser in situ keratomileusis during a two year follow-up period (C). The second database included information concerning corneas with keratoconus (Kc), categorized as overt Kc, if both eyes manifested classic Kc-suggestive topographic features, such as corneal steepness higher than 47.20 diopters (D), superior-inferior asymmetry higher than 1.40 D and thinnest pachymetric reading lower than 500 micrometers; or forme fruste (FFKc), if only one eye exhibited such features.

Brief summary: The main purpose of this study is to determine new diagnostic criteria for an eye disease called keratoconus.

Detailed description: Eyes of patients who distinctly present signs of keratoconus, for both eyes, at corneal tomography (an exam commonly used in such cases), and those who present such signs in only one eye were compared to eyes of unaffected patients. Several characteristics of anterior and posterior corneal astigmatism (special emphasis was given to the latter) were collectively assessed among all patients by a method referred to as vectorial analysis. Statistical tests were then performed, in an attempt to highlight differences among those three groups of patients and, eventually, define new diagnostic criteria.

Eligibility criteria: Inclusion Criteria:

* Good-quality Scheimpflug scans (approved by the device in the ''Examination Quality Specification'').

Exclusion Criteria:

* Previous eye surgery or trauma, and any sort of corneal scarring that might interfere with keratometric data acquisition.

Primary outcomes:
measure: Astigmatism corneal vectors (based on keratometric readings at the three millimeter optical zones for both corneal surfaces).
timeFrame: Through study completion, an average of 6 months.
Secondary outcomes:
Other outcomes:
Locations:
city: São Paulo
country: Brazil
facility: Clínica Oftalmológica do Hospital de Clínicas - FMUSP
Study officials:
affiliation: Clínica Oftalmológica HCFM/USP
name: Milton R Alves, MD, PhD
role: STUDY_DIRECTOR
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