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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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Lal B, Alonso-Caneiro D, Read SA, Carkeet A. Changes in retinal and choroidal optical coherence tomography angiography indices among young adults and children over 1 year. Clin Exp Optom 2023:1-8. [PMID: 37848182 DOI: 10.1080/08164622.2023.2259907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 09/13/2023] [Indexed: 10/19/2023] Open
Abstract
CLINICAL RELEVANCE Optical coherence tomography angiography (OCT-A) indices are likely to change across time and optometrists should be aware of the variability expected during childhood development and in healthy adults. BACKGROUND Cross-sectional studies have shown that OCT-A indices are associated with age in adults and children. The aim of this study is to investigate longitudinal changes in retinal and choroidal OCT-A indices over 1 year among healthy children and young adults. METHODS This prospective longitudinal study captured macular OCT-A and OCT scans, and biometry measures at baseline and 1-year follow-up for 22 adults (18-30 years; -6.87 to +0.37 D) and 21 children (6-15 years; -5.75 to +0.25 D). Superficial and deep retinal layer, choriocapillaris and deep choroidal en face OCT-A images were analysed to extract magnification-corrected vascular indices in foveal, parafoveal and perifoveal regions. The retinal indices included foveal avascular zone metrics, perfusion, and vessel density. Flow deficit number, size, and density were extracted from choriocapillaris and perfusion density from deep choroid. Associations between annual changes in the OCT-A indices and axial length and baseline refraction were also studied. RESULTS Among children, significant reductions were noted only in parafoveal superficial retinal and foveal and perifoveal deep retinal layer indices over 1 year (p < 0.05). Choroidal OCT-A indices in children and both retinal and choroidal OCT-A indices in adults did not show significant changes. Myopia was associated with a larger reduction in the perifoveal retinal OCT-A indices in children, and with increases in sub-foveal and sub-parafoveal choroidal indices in adults. There were associations between OCT-A indices and axial length changes but differently in adults and children. CONCLUSIONS Significant changes were noted in retinal OCT-A indices over 1 year among children but not adults. In comparison, choroidal OCT-A indices in adults and children showed a stable morphology over this period of time.
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Affiliation(s)
- Barsha Lal
- Centre for Vision and Eye Research, Optometry & Vision Science, Queensland University of Technology, Kelvin Grove, Brisbane, Australia
| | - David Alonso-Caneiro
- School of Science, Technology and Engineering, University of Sunshine Coast, Sunshine Coast, Queensland, Australia
| | - Scott A Read
- Centre for Vision and Eye Research, Optometry & Vision Science, Queensland University of Technology, Kelvin Grove, Brisbane, Australia
| | - Andrew Carkeet
- Centre for Vision and Eye Research, Optometry & Vision Science, Queensland University of Technology, Kelvin Grove, Brisbane, Australia
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