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Pors LJ, Haasjes C, van Vught L, Hoes NP, Luyten GPM, van Rijn GA, Vu THK, Rasch CRN, Horeweg N, Beenakker JWM. Correction Method for Optical Scaling of Fundoscopy Images: Development, Validation, and First Implementation. Invest Ophthalmol Vis Sci 2024; 65:43. [PMID: 38271188 PMCID: PMC10829800 DOI: 10.1167/iovs.65.1.43] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 12/28/2023] [Indexed: 01/27/2024] Open
Abstract
Purpose Although fundus photography is extensively used in ophthalmology, refraction prevents accurate distance measurement on fundus images, as the resulting scaling differs between subjects due to varying ocular anatomy. We propose a PARaxial Optical fundus Scaling (PAROS) method to correct for this variation using commonly available clinical data. Methods The complete optics of the eye and fundus camera were modeled using ray transfer matrix formalism to obtain fundus image magnification. The subject's ocular geometry was personalized using biometry, spherical equivalent of refraction (RSE), keratometry, and/or corneal topography data. The PAROS method was validated using 41 different eye phantoms and subsequently evaluated in 44 healthy phakic subjects (of whom 11 had phakic intraocular lenses [pIOLs]), 29 pseudophakic subjects, and 21 patients with uveal melanoma. Results Validation of the PAROS method showed small differences between model and actual image magnification (maximum 3.3%). Relative to the average eye, large differences in fundus magnification were observed, ranging from 0.79 to 1.48. Magnification was strongly inversely related to RSE (R2 = 0.67). In phakic subjects, magnification was directly proportional to axial length (R2 = 0.34). The inverse relation was seen in pIOL (R2 = 0.79) and pseudophakic (R2 = 0.12) subjects. RSE was a strong contributor to magnification differences (1%-83%). As this effect is not considered in the commonly used Bennett-Littmann method, statistically significant differences up to 40% (mean absolute 9%) were observed compared to the PAROS method (P < 0.001). Conclusions The significant differences in fundus image scaling observed among subjects can be accurately accounted for with the PAROS method, enabling more accurate quantitative assessment of fundus photography.
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Affiliation(s)
- Lennart J. Pors
- Department of Radiation Oncology, Leiden University Medical Center, Leiden, the Netherlands
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - Corné Haasjes
- Department of Radiation Oncology, Leiden University Medical Center, Leiden, the Netherlands
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Luc van Vught
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Noor P. Hoes
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | | | - Gwyneth A. van Rijn
- Department of Ophthalmology, Amsterdam University Medical Center, Amsterdam, the Netherlands
- Department of Ophthalmology, Northwest Clinics, Alkmaar, the Netherlands
| | - T. H. Khanh Vu
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - Coen R. N. Rasch
- Department of Radiation Oncology, Leiden University Medical Center, Leiden, the Netherlands
| | - Nanda Horeweg
- Department of Radiation Oncology, Leiden University Medical Center, Leiden, the Netherlands
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - Jan-Willem M. Beenakker
- Department of Radiation Oncology, Leiden University Medical Center, Leiden, the Netherlands
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
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Naujokaitis T, Auffarth GU, Łabuz G, Kessler LJ, Khoramnia R. Diagnostic Techniques to Increase the Safety of Phakic Intraocular Lenses. Diagnostics (Basel) 2023; 13:2503. [PMID: 37568866 PMCID: PMC10417808 DOI: 10.3390/diagnostics13152503] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 07/25/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
Preoperative and postoperative diagnostics play an important role in ensuring the safety of patients with phakic intraocular lenses (pIOLs). The risk of endothelial cell loss can be addressed by regularly measuring the endothelial cell density using specular microscopy and considering the endothelial cell loss rate and the endothelial reserve in accordance with the patient's age when deciding whether to explant a pIOL. The anterior chamber morphometrics, including the anterior chamber depth and the distance between the pIOL and the endothelium, measured using Scheimpflug tomography and anterior segment optical coherence tomography (AS-OCT), can help to assess the risk of the endothelial cell loss. In patients undergoing posterior chamber pIOL implantation, accurate prediction of the vault and its postoperative measurements using AS-OCT or Scheimpflug tomography are important when assessing the risk of anterior subcapsular cataract and secondary glaucoma. Novel approaches based on ultrasound biomicroscopy and AS-OCT have been proposed to increase the vault prediction accuracy and to identify eyes in which prediction errors are more likely. Careful patient selection and regular postoperative follow-up visits can reduce the complication risk and enable early intervention if a complication occurs.
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Affiliation(s)
| | | | | | | | - Ramin Khoramnia
- Department of Ophthalmology, University of Heidelberg, 69120 Heidelberg, Germany
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Comparison of Mean Corneal Power of Annular Rings and Zones Using Swept-Source Optical Coherence Tomography. Diagnostics (Basel) 2022; 12:diagnostics12030754. [PMID: 35328307 PMCID: PMC8946905 DOI: 10.3390/diagnostics12030754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/14/2022] [Accepted: 03/18/2022] [Indexed: 01/27/2023] Open
Abstract
This study aims to investigate differences in the mean corneal power of annular zones (corneal power measured over the inner annular zone of difference diameters) and rings (corneal power measured over a ring of different diameters) centered on the corneal apex using the swept-source optical coherence tomography technique. The mean anterior axial curvature (AAC), posterior axial curvature (PAC), and total corneal power (TCP) centered on the corneal apex with the annular rings (0−2 mm, 2−4 mm, 4−6 mm, and 6−8 mm) and zones were assessed using the ANTERION device. The paired-sample t-test was used for data comparison. For the 0−2 mm comparison, the AAC, PAC, and TCP values of rings and zones were interchangeable. For the 2−4 mm comparison, the AAC of the rings was lower than that of the zones (p = 0.004), and the TCP values of the rings were higher than that of the zones (p < 0.001). For the 4−6 mm comparison, the AAC of the rings was lower than that of the zones (p < 0.001), and the PAC and TCP values of the rings were higher than that of the zones (both p < 0.001). For the 6−8 mm comparison, the AAC of the rings was lower than that of the zones (p < 0.001), and the PAC and TCP values of the rings were higher than that of the zones (both p < 0.001). Comparisons between AAC and TCP in each sub-region showed significant differences both in the rings (p < 0.001) and the zones (p < 0.008). Differences in the AAC, PAC, and TCP measured at different diameters (2−4 mm, 4−6 mm, and 6−8 mm) of the rings and zones, centered on the corneal apex, should be noticed in clinical practice. As the diameter increases, the difference between the rings and the zones in terms of AAC, PAC, and TCP increase as well. Clinicians should also pay attention to differences between AAC and TCP for the rings and the zones within the same annular region.
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Kanclerz P, Khoramnia R, Wang X. Current Developments in Corneal Topography and Tomography. Diagnostics (Basel) 2021; 11:diagnostics11081466. [PMID: 34441401 PMCID: PMC8392046 DOI: 10.3390/diagnostics11081466] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/07/2021] [Accepted: 08/11/2021] [Indexed: 02/07/2023] Open
Abstract
Introduction: Accurate assessment of the corneal shape is important in cataract and refractive surgery, both in screening of candidates as well as for analyzing postoperative outcomes. Although corneal topography and tomography are widely used, it is common that these technologies are confused. The aim of this study was to present the current developments of these technologies and particularly distinguish between corneal topography and tomography. Methods: The PubMed, Web of Science and Embase databases were the main resources used to investigate the medical literature. The following keywords were used in various combinations: cornea, corneal, topography, tomography, Scheimpflug, Pentacam, optical coherence tomography. Results: Topography is the study of the shape of the corneal surface, while tomography allows a three-dimensional section of the cornea to be presented. Corneal topographers can be divided into large- and small-cone Placido-based devices, as well as devices with color-LEDs. For corneal tomography, scanning slit or Scheimpflug imaging and optical coherence tomography may be employed. In several devices, corneal topography and tomography have been successfully combined with tear-film analysis, aberrometry, optical biometry and anterior/posterior segment optical coherence tomography. Conclusion: There is a wide variety of imaging techniques to obtain corneal power maps. As different technologies are used, it is imperative that doctors involved in corneal surgery understand the science and clinical application of devices for corneal evaluation in depth.
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Affiliation(s)
- Piotr Kanclerz
- Hygeia Clinic, Department of Ophthalmologyul, Jaśkowa Dolina 57, 80-286 Gdańsk, Poland
- Helsinki Retina Research Group, University of Helsinki, 00100 Helsinki, Finland
- Correspondence:
| | - Ramin Khoramnia
- The David J. Apple International Laboratory for Ocular Pathology, Department of Ophthalmology, University of Heidelberg, 69120 Heidelberg, Germany;
| | - Xiaogang Wang
- Department of Cataract, Shanxi Eye Hospital, Taiyuan 030002, China;
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