Practical observations on conical cornea, and on the short sight, and other defects of vision connected with it /

Nottingham, J.

doi:10.5962/bhl.title.160281

Cited by 38 publications

(32 citation statements)

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“…Normative data of stromal thickness profiles may prove to be a useful diagnostic tool in screening for keratoconus or pellucid marginal degeneration, as these conditions are associated with localized corneal thinning 24. We demonstrated that the standard deviation of the absolute stromal thickness progression from the thinnest point to the periphery was <7 μm within the central 6-mm diameter; therefore, absolute stromal thickness progression from the thinnest point towards the periphery appears to be similar in normal eyes.…”

Section: Discussionmentioning

confidence: 66%

Stromal Thickness in the Normal Cornea: Three-dimensional Display With Artemis Very High-Frequency Digital Ultrasound

Reinstein¹,

Archer²,

Gobbé³

et al. 2009

J Refract Surg

119

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PURPOSE-To characterize the stromal thickness profile in a population of normal eyes. METHODS-Stromal thickness profile was measured in vivo byArtemis very high-frequency digital ultrasound scanning (ArcScan, Morrison, Colo) across the central 10-mm corneal diameter on 110 normal eyes. Maps of the average, standard deviation, minimum, maximum, and range of stromal thickness were plotted. The average location of the thinnest stroma was found. The crosssectional hemi-meridional stromal thickness profile was calculated using annular averaging. The absolute stromal thickness progression relative to the thinnest point was calculated using annular averaging as well as for 8 hemi-heridians individually. RESULTS-The mean stromal thickness at the corneal vertex and at the thinnest point were 465.4 ±36.9 μm and 461.8±37.3 μm, respectively. The thinnest stroma was displaced on average 0.17±0.31 mm inferiorly and 0.33±0.40 mm temporally from the corneal vertex. The average absolute stromal thickness progression from the thinnest point could be described by the quadratic equation: stromal thickness = 6.411 × radius 2 + 2.444 × radius (R 2 = 0.999). Absolute stromal thickness progression was independent of stromal thickness at the thinnest point. The increase in hemi-meridional absolute stromal thickness progression was greatest superiorly and lowest temporally.CONCLUSIONS-Three-dimensional thickness mapping of the corneal stroma and stromal thickness progression in a population of normal eyes represent a normative data set, which may help in early diagnosis of corneal abnormalities such as keratoconus and pellucid marginal degeneration. Absolute stromal thickness progression was found to be independent of stromal thickness.The human corneal stroma represents approximately 90% of the total corneal thickness and has an accepted central thickness of approximately 478 to 500 μm. 1-3 Knowledge of the stromal thickness profile is of interest in the area of corneal refractive surgery, as changes in corneal refractive power are achieved through changes in the stromal thickness profile. Measurements of stromal thickness profile pre-and postoperatively allow stromal ablation rate to be quantified and changes in thickness profile to be determined. 4,5 Stromal thickness mapping could help further understand corneal biomechanics. Stromal thickness profiles could also be useful in identifying corneal disorders such as keratoconus; corneal thickness profile has previously been suggested for the early diagnosis of keratoconus 6 following characterization of corneal thickness progression by Mandell in 1969. 7 Different methods have been used to measure stromal thickness: optical coherence tomography, 8,9 confocal microscopy, 1-3,10 and through focusing confocal microscopy. 11,12 All studies measured the average central stromal thickness. Only two studies provided stromal thickness measurements in the peripheral cornea; however, the number of points measured was limited to one point in the temporal cornea. 1,2 NIH Public AccessVer...

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Section: Discussionmentioning

confidence: 66%

Stromal Thickness in the Normal Cornea: Three-dimensional Display With Artemis Very High-Frequency Digital Ultrasound

Reinstein¹,

Archer²,

Gobbé³

et al. 2009

J Refract Surg

119

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“…KC is the most common ectatic disease of the cornea and was first described and named by Nottingham in 1854 (Nottingham, 1854). The disease is bilateral though asymmetric, characterized by progressive thinning and steepening of the cornea.…”

Section: Keratoconusmentioning

confidence: 99%

Pathogenesis of Keratoconus: The intriguing therapeutic potential of Prolactin-inducible protein

Sharif

Bak‐Nielsen

Hjortdal

et al. 2018

Progress in Retinal and Eye Research

103

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Keratoconus (KC) is the most common ectatic corneal disease, with clinical findings that include discomfort, visual disturbance and possible blindness if left untreated. KC affects approximately 1:400 to 1:2000 people worldwide, including both males and females. The aetiology and onset of KC remains a puzzle and as a result, the ability to treat or reverse the disease is hampered. Sex hormones are known to play a role in the maintenance of the structure and integrity of the human cornea. Hormone levels have been reported to alter corneal thickness, curvature, and sensitivity during different times of menstrual cycle. Surprisingly, the role of sex hormones in corneal diseases and KC has been largely neglected. Prolactin-induced protein, known to be regulated by sex hormones, is a new KC biomarker that has been recently proposed. Studies herein discuss the role of sex hormones as a control mechanism for KC onset and progression and evidence supporting the view that prolactin-induced protein is an important hormonally regulated biomarker in KC is discussed.

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“…Keratoconus is a condition involving corneal steepening, thinning, scarring and ectasia (Nottingham ; Rabinowitz ; Zadnik et al. ; Barr et al.…”

Section: Introductionmentioning

confidence: 99%

Lamellar changes in the keratoconic cornea

Mathew

Goosey

Söderberg

et al. 2015

Acta Ophthalmologica

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ABSTRACT.Purpose: The purpose of this study was to identify ultrastructural changes associated with ectasia and to determine the association between lamellar count and corneal thinning. Methods: Five surgically removed keratoconic corneal buttons and four, nonkeratoconic, normal eye bank control corneas were processed for transmission electron microscopy using an established protocol, ensuring minimal tissue distortion. A sequence of overlapping digital images, spanning the full apical cone corneal thickness, was assembled. A seamless digital montage was printed at 50003 magnification. Lamellae were counted in the anterior-posterior orientation, along a linear line, using established criteria for identification of individual lamellae. Results: The stromal thickness estimated as a 95% confidence interval for the mean, CI (0.95), in the keratoconic corneas was 372 AE 62 lm, while in the normal cornea, it was 446 AE 89 lm. All keratoconic corneas showed ultrastructural evidence of lamellar splitting and a loss of interweaving anterior lamellae. In the keratoconic corneas, the median total linear stromal lamellar absolute count tangential to the corneal surface was 362, (25th percentile; 75th percentile) = (355; 365) lamellae and in the normal cornea, 246, (25th percentile; 75th percentile) = (239; 251). The linear lamellar density in the keratoconic corneas was estimated as CI (0.95) 117 AE 22 and 86 AE19 lamellae per 100 lm in the anterior and posterior portion of the stroma, respectively. In normal cornea, the linear lamellar density was estimated as CI (0.95) 51 AE 8 and 80 AE 20 lamellae per 100 lm. The mean difference of linear lamellar count between the anterior and the posterior portion of the cornea was estimated as CI (0.95) 31 AE 23 for keratoconic corneas and À29 AE 28 for the normal corneas. Conclusions: The current morphometric analysis of ultrastructural changes suggests that ectasia and thinning in keratoconus is associated with lamellar splitting into multiple bundles of collagen fibrils and loss of anterior lamellae. These structural changes, possibly in addition to lateral shifting of lamellae due to the pressure gradient over the cornea, are a potential explanation to the central loss of mass.

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Practical observations on conical cornea, and on the short sight, and other defects of vision connected with it /

Cited by 38 publications

References 0 publications

Stromal Thickness in the Normal Cornea: Three-dimensional Display With Artemis Very High-Frequency Digital Ultrasound

Stromal Thickness in the Normal Cornea: Three-dimensional Display With Artemis Very High-Frequency Digital Ultrasound

Pathogenesis of Keratoconus: The intriguing therapeutic potential of Prolactin-inducible protein

Lamellar changes in the keratoconic cornea

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