{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,7]],"date-time":"2025-12-07T13:10:16Z","timestamp":1765113016794,"version":"build-2065373602"},"reference-count":35,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2024,2,1]],"date-time":"2024-02-01T00:00:00Z","timestamp":1706745600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Bioengineering"],"abstract":"<jats:p>Purpose: To investigate corneal densitometry artefacts found in Pentacam Scheimpflug scans and their potential effect on assessing keratoconic (KC) corneas compared to normal (N) corneas. Methods: The current study utilises Pentacam data of 458 N eyes, aged 35.6 \u00b1 15.8 (range 10\u201387), referred to as the \u201cN group\u201d, and 314 KC eyes, aged 31.6 \u00b1 10.8 (range 10\u201372), referred to as the \u201cKC group\u201d, where densitometry data were extracted and analysed via a custom-built MATLAB code. Radial summations of the densitometry were calculated at diameters ranging from 0.5 mm to 5.0 mm. The minimum normalised radial summation of densitometry (NRSD) value and angle were determined at each diameter and then linked. KC cone locations and areas of pathology were determined, and a comparison between N and KC groups was carried out both within the averaged area of pathology and over the corneal surface. Results: Joining minimum NRSD trajectory points marked a clear distortion line pointing to the nasal-superior direction at 65\u00b0 from the nasal meridian. The findings were found to be independent of eye laterality or ocular condition. Consistency was detected in the right and left eyes among both the N and KC groups. The location of the KC cone centre and the area of pathology were determined, and the densitometry output was compared both within the area of pathology and over the whole cornea. When the average densitometry was compared between N and KC eyes within the KC area of pathology, the N group recorded a 16.37 \u00b1 3.15 normalised grey-scale unit (NGSU), and the KC group recorded 17.74 \u00b1 3.4 NGSU (p = 0.0001). However, when the whole cornea was considered, the N group recorded 16.71 \u00b1 5.5 NGSU, and the KC group recorded 15.72 \u00b1 3.98 NGSU (p = 0.0467). A weak correlation was found between the Bad D index and NGSU when the whole measured cornea was considered (R = \u22120.01); however, a better correlation was recorded within the KC area of pathology (R = 0.21). Conclusions: Nasal-superior artefacts are observed in the densitometry Pentacam maps, and analysis shows no significant differences in their appearance between N or KC corneas. When analysing KC corneas, it was found that the cone positions are mostly on the temporal-inferior side of the cornea, opposite to the densitometry artefact NRSD trajectory. The analysis suggests that the corneal densitometry artefacts do not interfere with the KC area of pathology as it reaches its extreme in the opposite direction; therefore, weighting the densitometry map to increase the contribution of the inferior-temporal cornea and decreasing that of the superior-nasal area would improve the classification or identification of KC if densitometry is to be used as a KC metric.<\/jats:p>","DOI":"10.3390\/bioengineering11020148","type":"journal-article","created":{"date-parts":[[2024,2,1]],"date-time":"2024-02-01T08:44:08Z","timestamp":1706777048000},"page":"148","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Investigation of How Corneal Densitometry Artefacts Affect the Imaging of Normal and Keratoconic Corneas"],"prefix":"10.3390","volume":"11","author":[{"given":"Rami","family":"Alanazi","sequence":"first","affiliation":[{"name":"Department of Materials, Design and Manufacturing Engineering, School of Engineering, University of Liverpool, Liverpool L69 3GH, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2353-9442","authenticated-orcid":false,"given":"Louise Pellegrino Gomes","family":"Esporcatte","sequence":"additional","affiliation":[{"name":"Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro 20520-050, Brazil"},{"name":"Instituto de Olhos Renato Ambr\u00f3sio, Rio de Janeiro 20520-050, Brazil"},{"name":"Department of Ophthalmology, Federal University of S\u00e3o Paulo, S\u00e3o Paulo 04017-030, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6524-5071","authenticated-orcid":false,"given":"Lynn","family":"White","sequence":"additional","affiliation":[{"name":"Research and Development Department, LWVision, Leicester LE18 1DF, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8330-6432","authenticated-orcid":false,"given":"Marcella Q.","family":"Salom\u00e3o","sequence":"additional","affiliation":[{"name":"Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro 20520-050, Brazil"},{"name":"Instituto de Olhos Renato Ambr\u00f3sio, Rio de Janeiro 20520-050, Brazil"},{"name":"Department of Ophthalmology, Federal University of S\u00e3o Paulo, S\u00e3o Paulo 04017-030, Brazil"},{"name":"Instituto Benjamin Constant, Rio de Janeiro 22290-255, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bernardo T.","family":"Lopes","sequence":"additional","affiliation":[{"name":"Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro 20520-050, Brazil"},{"name":"Department of Ophthalmology, Federal University of S\u00e3o Paulo, S\u00e3o Paulo 04017-030, Brazil"},{"name":"Ophthalmology Eye Clinic, Alder Hey Children\u2019s NHS Foundation Trust, Liverpool L12 2AP, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6919-4606","authenticated-orcid":false,"given":"Renato","family":"Ambr\u00f3sio Jr.","sequence":"additional","affiliation":[{"name":"Instituto de Olhos Renato Ambr\u00f3sio, Rio de Janeiro 20520-050, Brazil"},{"name":"Department of Ophthalmology, Federal University of S\u00e3o Paulo, S\u00e3o Paulo 04017-030, Brazil"},{"name":"Department of Ophthalmology, Federal University the State of Rio de Janeiro, Rio de Janeiro 22290-240, Brazil"},{"name":"Brazilian Study Group of Artificial Intelligence and Corneal Analysis-BrAIN, Rio de Janeiro & Macei\u00f3, Rio de Janeiro 20520-050, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8622-4632","authenticated-orcid":false,"given":"Ahmed","family":"Abass","sequence":"additional","affiliation":[{"name":"Department of Materials, Design and Manufacturing Engineering, School of Engineering, University of Liverpool, Liverpool L69 3GH, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2024,2,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"501","DOI":"10.1016\/j.ophtha.2011.08.024","article-title":"Corneal Densitometry as an Indicator of Corneal Health","volume":"119","author":"Otri","year":"2012","journal-title":"Ophthalmology"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"941","DOI":"10.1007\/s00417-020-05027-6","article-title":"Corneal densitometry: A potential indicator for early diagnosis of Fabry disease","volume":"259","author":"Li","year":"2021","journal-title":"Graefes Arch. Clin. Exp. Ophthalmol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"162","DOI":"10.1167\/iovs.13-13236","article-title":"Normative Values for Corneal Densitometry Analysis by Scheimpflug Optical Assessment","volume":"55","author":"Rozema","year":"2014","journal-title":"Investig. Ophthalmol. Vis. Sci."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1675","DOI":"10.1038\/s41433-021-01707-7","article-title":"New algorithm for corneal densitometry assessment based on anterior segment optical coherence tomography","volume":"36","author":"Wang","year":"2022","journal-title":"Eye"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2621","DOI":"10.1109\/TUFFC.2022.3190400","article-title":"High-Frequency Ultrasound Elastography to Assess the Nonlinear Elastic Properties of the Cornea and Ciliary Body","volume":"69","author":"Zhang","year":"2022","journal-title":"IEEE Trans. Ultrason. Ferroelectr. Freq. Control"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1310","DOI":"10.1109\/TBME.2022.3215498","article-title":"Simultaneous Assessment of the Whole Eye Biomechanics Using Ultrasonic Elastography","volume":"70","author":"Li","year":"2023","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1032","DOI":"10.1111\/opo.13020","article-title":"Influence of eye tilt on corneal densitometry","volume":"42","author":"Consejo","year":"2022","journal-title":"Ophthalmic Physiol. Opt."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"3871","DOI":"10.1364\/BOE.489054","article-title":"OCT based corneal densitometry: The confounding effect of epithelial speckle","volume":"14","author":"Consejo","year":"2023","journal-title":"Biomed. Opt. Express"},{"key":"ref_9","first-page":"2391","article-title":"Novel contact lenses designed to slow progress of myopia: 12 month results","volume":"58","author":"Sankaridurg","year":"2017","journal-title":"Investig. Ophthalmol. Vis. Sci."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Chen, X., Shen, Y., Xu, H., Wang, X., and Zhou, X. (2020). One-year natural course of corneal densitometry in high myopic patients after implantation of an implantable collamer lens (model V4c). BMC Ophthalmol., 20.","DOI":"10.1186\/s12886-020-1320-x"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"692","DOI":"10.1097\/ICO.0000000000002762","article-title":"Scheimpflug Corneal Densitometry Values and Severity of Guttae in Relation to Visual Acuity in Fuchs Endothelial Corneal Dystrophy","volume":"41","author":"Shah","year":"2022","journal-title":"Cornea"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Korm\u00e1nyos, K., Kov\u00e1cs, K., N\u00e9meth, O., T\u00f3th, G., S\u00e1ndor, G.L., Csorba, A., Czak\u00f3, C.N., M\u00f3dis, L., Langenbucher, A., and Nagy, Z.Z. (2022). Corneal Densitometry and In Vivo Confocal Microscopy in Patients with Monoclonal Gammopathy\u2014Analysis of 130 Eyes of 65 Subjects. J. Clin. Med., 11.","DOI":"10.3390\/jcm11071848"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"12","DOI":"10.1167\/tvst.8.3.12","article-title":"Correlation Between Corneal Topographic, Densitometry, and Biomechanical Parameters in Keratoconus Eyes","volume":"8","author":"Shen","year":"2019","journal-title":"Transl. Vis. Sci. Technol."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Zheng, Y., Xue, C., Wang, J., Chen, X., Wang, X., and Wang, Y. (2023). Analysis of the correlation between biomechanical properties and corneal densitometry in myopic eyes. Front. Bioeng. Biotechnol., 11.","DOI":"10.3389\/fbioe.2023.1182372"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1653","DOI":"10.2147\/OPTH.S168865","article-title":"Corneal imaging and densitometry measurements in keratoconus patients to monitor disease progression and treatment outcomes after contact lens or Intacs treatment","volume":"12","author":"Alzahrani","year":"2018","journal-title":"Clin. Ophthalmol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"3505","DOI":"10.1177\/11206721211020631","article-title":"Corneal densitometry in patients with keratoconus undergoing intrastromal Ferrara ring implantation","volume":"31","author":"Rodrigues","year":"2021","journal-title":"Eur. J. Ophthalmol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1282","DOI":"10.1097\/ICO.0000000000000266","article-title":"Corneal densitometry in keratoconus","volume":"33","author":"Lopes","year":"2014","journal-title":"Cornea"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"830","DOI":"10.4103\/ijo.IJO_1792_22","article-title":"Distribution of corneal densitometry in different grades of keratoconus","volume":"71","author":"Mounir","year":"2023","journal-title":"Indian J. Ophthalmol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1048","DOI":"10.1038\/s41433-018-0019-1","article-title":"The effect of the timing of the cessation of contact lens use on the results of biometry","volume":"32","author":"Goudie","year":"2018","journal-title":"Eye"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1186\/s40662-016-0036-8","article-title":"Corneal topography in keratoconus: State of the art","volume":"3","year":"2016","journal-title":"Eye Vis."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"20200271","DOI":"10.1098\/rsif.2020.0271","article-title":"Characterization of cone size and centre in keratoconic corneas","volume":"17","author":"Eliasy","year":"2020","journal-title":"J. R. Soc. Interface"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1404","DOI":"10.1080\/02713683.2018.1500609","article-title":"Positions of Ocular Geometrical and Visual Axes in Brazilian, Chinese and Italian Populations","volume":"43","author":"Abass","year":"2018","journal-title":"Curr. Eye Res."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1","DOI":"10.18637\/jss.v008.i18","article-title":"Evaluating Kolmogorov\u2019s Distribution","volume":"8","author":"Marsaglia","year":"2003","journal-title":"J. Stat. Softw."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Everitt, B.S., and Skrondal, A. (2010). The Cambridge Dictionary of Statistics, Cambridge University Press. [4th ed.].","DOI":"10.1017\/CBO9780511779633"},{"key":"ref_25","first-page":"147.e141","article-title":"Assessment of corneal and lens clarity in children with Wilson disease","volume":"23","year":"2019","journal-title":"J. Am. Assoc. Pediatr. Ophthalmol. Strabismus"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"34","DOI":"10.1167\/tvst.10.9.34","article-title":"Scheimpflug-Based Analysis of the Reflectivity of the Cornea in Marfan Syndrome","volume":"10","author":"Tack","year":"2021","journal-title":"Transl. Vis. Sci. Technol."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1745","DOI":"10.1038\/eye.2017.132","article-title":"Increased corneal densitometry as a subclinical corneal change associated with multiple myeloma","volume":"31","author":"Busch","year":"2017","journal-title":"Eye"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Ishikawa, S., Kato, N., and Takeuchi, M. (2018). Quantitative evaluation of corneal epithelial edema after cataract surgery using corneal densitometry: A prospective study. BMC Ophthalmol., 18.","DOI":"10.1186\/s12886-018-0998-5"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1647","DOI":"10.1038\/eye.2017.107","article-title":"Corneal densitometry after photorefractive keratectomy, laser-assisted in situ keratomileusis, and small-incision lenticule extraction","volume":"31","author":"Poyales","year":"2017","journal-title":"Eye"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"408","DOI":"10.1097\/ICO.0000000000002439","article-title":"Scheimpflug Corneal Densitometry Changes After Trabeculectomy","volume":"40","author":"Pillunat","year":"2021","journal-title":"Cornea"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"163","DOI":"10.3109\/02713683.2016.1146774","article-title":"Changes in Corneal Densitometry in Patients with Fuchs Endothelial Dystrophy after Endothelial Keratoplasty","volume":"42","author":"Alnawaiseh","year":"2017","journal-title":"Curr. Eye Res."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"60","DOI":"10.1097\/ICO.0000000000002722","article-title":"Corneal Densitometry Assessed With Scheimpflug Camera in Healthy Corneas and Correlation With Specular Microscopy Values and Age","volume":"41","author":"Karmiris","year":"2022","journal-title":"Cornea"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"495","DOI":"10.1590\/1678-4685-gmb-2018-0076","article-title":"A systematic scoping review of the genetic ancestry of the Brazilian population","volume":"42","author":"Souza","year":"2019","journal-title":"Genet. Mol. Biol."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"787","DOI":"10.1097\/IJG.0000000000000738","article-title":"Reproducibility of Central Corneal Thickness Measurements in Healthy and Glaucomatous Eyes","volume":"26","author":"Realini","year":"2017","journal-title":"J. Glaucoma"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1948","DOI":"10.1167\/iovs.04-1253","article-title":"Changes in collagen orientation and distribution in keratoconus corneas","volume":"46","author":"Meek","year":"2005","journal-title":"Investig. Ophthalmol. Vis. Sci."}],"container-title":["Bioengineering"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2306-5354\/11\/2\/148\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T13:53:14Z","timestamp":1760104394000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2306-5354\/11\/2\/148"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,2,1]]},"references-count":35,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2024,2]]}},"alternative-id":["bioengineering11020148"],"URL":"https:\/\/doi.org\/10.3390\/bioengineering11020148","relation":{},"ISSN":["2306-5354"],"issn-type":[{"type":"electronic","value":"2306-5354"}],"subject":[],"published":{"date-parts":[[2024,2,1]]}}}