Objective method to measure corneal clarity before and after laser in situ keratomileusis

Chan, Jay W.W; Edwards, Marion H.; Woo, George C.; Woo, Victor C.P.

doi:10.1016/s0886-3350(02)01645-0

Cited by 4 publications

(8 citation statements)

References 16 publications

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“…The small amount of scattered light produced by this tissue has in particular been extensively researched in the literature [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. All previous theories explaining corneal transparency [21][22][23][24][25][26][27] have focused on light propagation in the stromal extracellular matrix.…”

Section: Introductionmentioning

confidence: 99%

“…They can be caused by microstructural alterations, the irregular organization of the extracellular matrix, or by cells [22]. Many studies have attempted to relate form, density, and cell size to the structure of the scattered light [1][2][3][4][5][6][7]17,18]. Mourant et al [12,13] suggest that the cell itself is responsible for scattering at a small angle.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Measurement of correlation between transmission and scattering during wound healing in hen corneas

Mar

Martínez-García

Blanco–Mezquita

et al. 2009

Journal of Modern Optics

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The aim of this work is to provide experimental data for corneal transparency and scattering to help create a more complete model of corneal transparency. The scattered light in 96 healing hen corneas was measured for three wavelengths by a scatterometer constructed in the Optics Laboratory (The University of Valladolid, Spain). With the help of mirrors and beamsplitters, the light from the three lasers is directed toward the cell containing the sample to be measured. The measured scattered light varies between six orders of magnitude. Corneal transmissivity, mean cosine of a scattering angle, and angular distribution of scattered light were all computed. The total transmitted light remained practically constant over a wide range of light values transmitted in a forward direction (direct transmissivity). The value of the mean cosine of the scattering direction is very close to the unit (g 4 0:98), even in corneas with high opacities. The behavior of g indicates that even damaged corneas evidence extremely small scattering, compared to other biological tissues. The transmission reduction of each cornea is related to an increase in scattered light. In all cases, scattered light is concentrated at very small angles. This behavior is acceptable in corneas that are healthy or which evidence small lesions, but remains in corneas that are severely injured.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Measurement of correlation between transmission and scattering during wound healing in hen corneas

Mar

Martínez-García

Blanco–Mezquita

et al. 2009

Journal of Modern Optics

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“…Overall, the cellular (or fibril) detail that can be seen with CFM or TEM is not evident in most in vivo assessments of the cornea. Notwithstanding, an optical section of the cornea viewed with modern day photo-slitlamps can be readily captured as a (fairly) high resolution image suitable for some type of analysis of transparency, clarity, opacity or density [25][26][27]; such assessments required customized image acquisition and special image-processing software.…”

Section: The Normal Human Cornea and Its Assessment In Vivomentioning

confidence: 99%

Corneal structure, transparency, thickness and optical density (densitometry), especially as relevant to contact lens wear—a review

Doughty

Jonuscheit

2019

Contact Lens and Anterior Eye

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Clinical instruments using Scheimpflug image-based methods to obtain optical sectional images of the cornea have been introduced in recent years along with proposals that it should be possible to routinely and reliably measure the optical density (referred to as the densitometry) of the human cornea in situ. Such a concept is reviewed from the perspective of what might be considered as the basic principles underlying the understanding of corneal transparency (from the 1950's) and the progressive changes in these ideas from subjective slitlamp-based clinical observations from the late 1960's, especially in contact lens wearers.Much more has been learned about the overall macrostructure (including corneal thickness) and the ultrastructure of the cornea from contemporary studies in the 1990's, and these aspects of the cornea will be reviewed alongside consideration of the methods of assessing the optical characteristics of the cornea in the living eye. From these perspectives, in this review systematic consideration will be given to what objective (quantitative) output one of these Scheimpflug-based systems provides and how this information might be actually related 2 to corneal transparency characteristics that might be observed clinically, particularly after long-term contact lens wear.

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“…23 Recent advances allow the size, shape, and haze of corneal disorders to be determined, nearly as accurately as with slitlamp biomicroscopy. 9,[24][25][26] Image analysis systematizes the representation of ophthalmic disease.…”

Section: Attributes Of Severitymentioning

confidence: 99%

Slitlamp Biomicroscopy and Photographic Image Analysis of Herpes Simplex Virus Stromal Keratitis

Wilhelmus

Mitchell²,

Dawson³

et al. 2009

Arch Ophthalmol

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To validate photographic bioimaging for evaluating the severity of herpes simplex virus keratitis. Methods: Stromal keratitis of patients in the Herpetic Eye Disease Study was clinically measured with a slitbeam micrometer and then photographed at trial entry. Calibrated images of 169 eyes were analyzed for the size, location, and density of stromal keratitis and endotheliitis, with shape factor as a function of area and perimeter. Validity was assessed by comparing clinical and computerized measurements and by correlating the keratitis area with visual acuity. Logistic regression explored characteristics associated with larger or denser corneal inflammation. Results: Stromal keratitis had a median area of 22.4 mm 2 (interquartile range, 12.8-31.6 mm 2) with a median shape factor of 0.69 (interquartile range, 0.56-0.79); 126 eyes (75%) had their midpoint within 2 mm of the cornea's geometric center. Photoanalytical area estimates of herpetic stromal keratitis correlated closely with clinical measurements (correlation coefficient, 0.83). Eyes with larger stromal keratitis had worse vision (correlation coefficient, 0.32) and were more likely to have iritis (P=.01). Necrotizing stromal keratitis was significantly whiter (P=.02). Conclusions: Image analysis validly assesses the disciform geometry of herpetic stromal keratitis and confirms that increased severity is associated with uveitis and reduced vision.

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Objective method to measure corneal clarity before and after laser in situ keratomileusis

Cited by 4 publications

References 16 publications

Measurement of correlation between transmission and scattering during wound healing in hen corneas

Measurement of correlation between transmission and scattering during wound healing in hen corneas

Corneal structure, transparency, thickness and optical density (densitometry), especially as relevant to contact lens wear—a review

Slitlamp Biomicroscopy and Photographic Image Analysis of Herpes Simplex Virus Stromal Keratitis

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