June 2021
Volume 62, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2021
A novel diagnostic tool for Keratoconus and its severity
Author Affiliations & Notes
  • Einat Shneor
    Dept. of Optometry, Hadassah Academic College, Jerusalem, Jerusalem, Israel
  • Ariela Gordon-Shaag
    Dept. of Optometry, Hadassah Academic College, Jerusalem, Jerusalem, Israel
  • Arige Gedeon Abou Said
    Dept. of Optometry, Hadassah Academic College, Jerusalem, Jerusalem, Israel
  • Footnotes
    Commercial Relationships   Einat Shneor, None; Ariela Gordon-Shaag, None; Arige Gedeon Abou Said, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2021, Vol.62, 778. doi:
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      Einat Shneor, Ariela Gordon-Shaag, Arige Gedeon Abou Said; A novel diagnostic tool for Keratoconus and its severity. Invest. Ophthalmol. Vis. Sci. 2021;62(8):778.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose : An arc shaped black shadow ("black sign") has been observed when using ophthalmoscopy on keratoconus patients (fig. A). We aimed to develop and validate a novel method (Patent pending) for detection of clinical and subclinical keratoconus (KC and KCS) based on the presence of this black sign.

Methods : A device was designed to enable to the clinician to hold the ophthalmoscope at an appropriate angle and distance and attach it to a smartphone (iPhone XS Max) to take a picture of the eye. The clinician using the device was masked to the KC status of the subjects. A masked observer determined the presence of the black sign in the downloaded images. AutoCAD software was used to measure the sign’s width. KC, KCS and healthy subjects were included in this study. A diagnosis of KC was based on abnormal tomography and at least one clinical sign of KC. KCS had only abnormal topography. Both eyes were included in the analysis for KC and KCS, while only the right eye for controls. Subjects underwent corneal tomography (Sirius, CSO) and a full ocular exam. KC severity was graded based on Belin ABCD Criteria. Sex, age and tomography parameter differences between groups were evaluated by Chi square and Mann Whitney tests. Spearman correlations were performed between the width of the black sign and ABCD Criteria.

Results : Twenty KC and KCS subjects (24 eyes with KC and 12 eyes with KCS, 10 males, mean age 28.2±9.1, range 20-56 years) and 35 healthy controls (19 males, mean age 25.1±6.7, range 20-52 years) participated in this study. Groups were similar in age (U=246.5, p=0.07) and sex (x2=0.09, p=0.76) but different in spherical equivalent (p<0.01), anterior and posterior keratometry (p<0.001), thinnest and central corneal thickness
(p<0.0001) and front and back apex curves (p<0.0001).
The black sign was observed in all KC and KCS images but in none of the controls. The width of the black sign was negatively correlated to Belin Criteria (A, Anterior Elevation: r=-0.74, p<0.0001; B, Back Elevation: r=-0.79, p<0.0001; C, Thinnest Corneal Thickness: r=-0.58, p<0.0001; D, Distance Visual Acuity: r=-0.36, p=0.03).

Conclusions : This novel method may differentiate between KC and KCS and healthy controls based on the presence of the black sign. The thickness of the black sign is negatively correlated to KC severity. Therefore, this method can be used for screening population and following the progression of the diseases.

This is a 2021 ARVO Annual Meeting abstract.


Figure A. The black sign in KC subject

Figure A. The black sign in KC subject


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