Diagnosing Keratoconus Using VHF Digital Ultrasound Epithelial Thickness Profiles

Reinstein, Dan Z.; Archer, Timothy J; Gobbé, Marine; Urs, Raksha; Silverman, Ronald H.

doi:10.1007/978-3-319-43881-8_13

Cited by 3 publications

(3 citation statements)

References 85 publications

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“…9 Furthermore, due to epithelial remodeling, changes in the anterior curvature maps may be masked as the corneal epithelium becomes thinner in the steepened and thicker in the flattened areas. 10 A thinner epithelium in the relatively more ectatic region and a thicker epithelium in the opposite quadrant in our case corroborates the epithelial remodeling theory. Remarkably, although the difference in the corneal thicknesses between the central 2-mm zone (391 µm) and the superior 2-to 5-mm zone (386 µm) was only 5 µm, the difference in the epithelial thicknesses between the respective zones was 24 µm, further lending support to the role of epithelial remodeling in the cone area (Fig.…”

Section: Discussionsupporting

confidence: 88%

A Case of True Superior Keratoconus Confirmed Using Multiple Imaging Modalities

Özalp¹,

Atalay²,

Yıldırım³

2019

International Journal of Keratoconus and Ectatic Corneal Diseases

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Aim: To report an unusual case of a newly diagnosed bilateral superior keratoconus in an elderly patient. Background: We report a case of bilateral superior keratoconus in a 64-year-old woman who was diagnosed after having presented with hydrops in one eye. Case description: Uncorrected visual acuity was counting fingers from 3 and 1 meter for the right and left eyes, respectively. A superiorly located deep stromal scar and chronic corneal edema consistent with a diagnosis of corneal hydrops were noted for the left eye. Although the cornea was clear, there was superior corneal protrusion in the right eye. Pentacam and Orbscan demonstrated overlapping focal corneal thinning, increased back elevation, and steepening in the superior cornea. Anterior segment optical coherence tomography (AS-OCT) showed stromal and epithelial thinning in the superior cornea and significant compensatory epithelial thickening in the opposing quadrant. In light of these findings, a diagnosis of superior keratoconus was established. Conclusion: Superior keratoconus is a rare condition. Meticulous evaluation of corneal tomography and epithelial thickness profile is crucial for localizing the superior cone in keratoconus. Clinical significance: This is the first case report demonstrating epithelial thickness profile in a superior keratoconus case.

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Section: Discussionsupporting

confidence: 88%

A Case of True Superior Keratoconus Confirmed Using Multiple Imaging Modalities

Özalp¹,

Atalay²,

Yıldırım³

2019

International Journal of Keratoconus and Ectatic Corneal Diseases

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“…The in vitro nature of the aforementioned study limits the conclusions that can be drawn as the cornea is also under the influence of surrounding adnexal tissues. As such, pressure applied by the eyelids also follow a differential pattern on the superior and inferior cornea with more force exerted on the superior cornea by blinking . Considering the fact that the superior cornea is supported by a tarsal plate that is longer in vertical dimension than the inferior tarsal plate (10–12 versus 4 mm), the force exerted by the superior eyelid thus creates an unopposed pressure differential on the inferior cornea upon blinking.…”

Section: Discussionmentioning

confidence: 99%

Corneal elevation changes after forced eyelid closure in healthy participants and in patients with keratoconus

Atalay

Najjar

Tun

et al. 2019

Clinical and Experimental Optometry

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Background: To assess pointwise corneal elevation changes after forced eyelid closure test (FECT) in the eyes of healthy subjects and in eyes with keratoconus. Methods: Twenty-nine subjects with keratoconus and 31 healthy volunteers were evaluated. Patients with keratoconus who had corneal hydrops, apical scarring, corneal thickness ≤ 400 μm, ocular surface disease, contact lens wear on the examination day and a history of corneal cross-linking were excluded. Exclusion criteria for healthy participants were spherical error > +3.00 D and < −3.00 D, corneal astigmatism > 1.50 D, corneal curvature > 47 D, ocular allergy, clinical findings and family history of keratoconus. Pentacam was performed before and after 20 seconds of FECT and raw data were extracted from the built-in software. Pointwise anterior and posterior elevation changes in the central 8 mm cornea were assessed using paired samples t-test and heat maps were constructed to reflect mean changes and statistically significant data points. Statistical significance was assumed at p < 0.01. Results: Age and gender were similar between healthy subjects (24.5 AE 1.6 years, 46.4 per cent female) and subjects with keratoconus (28.6 AE 9.2 years, 46.4 per cent female, p = 0.19, 0.61, respectively). Healthy eyes displayed posterior depression clustering in the inferotemporal and inferonasal areas (mean change: −4.5 AE 7.8 μm and −5.2 AE 9.8 μm, respectively, all p < 0.01). In contrast, keratoconus eyes exhibited a wider area of posterior elevation clustering in the inferior cornea (mean change: 8.1 AE 14.5 μm, all p < 0.01) with a small extension in the inferotemporal cornea (mean change: 12.1 AE 22.3 μm, all p < 0.01). Conclusion: FECT elicits corneal elevation changes mainly in the inferior cornea with the change being more pronounced and wider in eyes with keratoconus.

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“…This hypothesis is also supported by the presence of a similar apical scar in patients with advanced keratoconus who similarly have an extremely curved cornea and exceptionally thin epithelium. 14,15 Therefore, in this long-term retrospective study, SCTK was performed with the described multi-step procedure with the aim of reducing HOAs and the corneal curvature gradient to prevent apical scar recurrence. Functional results showed a significant improvement in CDVA after the treatment and were stable after a minimum follow-up of 12-months, without long-term apical scar recurrence.…”

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confidence: 99%