Ectatic Disorders Associated With a Claw-shaped Pattern on Corneal Topography

Lee, Brandon W.; Jurkunas, Ula V.; Harissi‐Dagher, Mona; Poothullil, Antony M.; Tobaigy, Faisal M.; Azar, Dimitri T.

doi:10.1016/j.ajo.2007.02.032

Cited by 77 publications

(53 citation statements)

References 7 publications

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“…13 At present, PMD is diagnosed based solely on clinical signs and the classic crab-claw topography pattern. However, previous studies 16,27 found that most of these patterns do not represent true PMD but rather reflect limitations of the reflected Placido image and the difficulty extrapolating shape from curvature maps. Topographic analyses with quantitative indices have been devised to aid clinicians to diagnose the presence of early forms of keratoconus before the development of clinical signs or symptoms.…”

Section: Discussionmentioning

confidence: 92%

“…In addition, in early stages of PMD, the central corneal topographic pattern resembles that of typical minimal to moderate ATR astigmatism and the keratometry readings are not as steep as in keratoconus and are also associated with normal central corneal thickness. 14 This ectatic disorder results in a characteristic crabclaw or butterfly pattern on corneal topography (Figure 1), representing inferior steepening with flatter vertical corneal meridian, as first reported by Maguire et al 15 However, Lee et al 16 found that these topography patterns also manifested in eyes with keratoconus and other corneal peripheral ectatic disorders. Therefore, a characteristic claw-shaped pattern on corneal topography may not always be associated with a diagnosis of PMD.…”

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confidence: 90%

“…The manifestation of the classic pattern in various forms of ectatic disorders may suggest a sensitive indicator rather than a necessary differential diagnosis. 16 Pellucid marginal degeneration and keratoconus differ markedly in the prognosis and management, and distinguishing between these 2 conditions is of potential clinical importance, especially in terms of contact-lens fitting and designing surgical management. 17,18 The aim of this study was to determine and compare various quantitative topographic and tomographic indices of PMD with keratoconus and normal corneas assessed by an Orbscan IIz scanning-slit topographer (Bausch & Lomb) and to formulate a reliable model to distinguish PMD corneas from keratoconus and normal corneas.…”

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confidence: 99%

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Evaluation of corneal elevation and thickness indices in pellucid marginal degeneration and keratoconus

Tummanapalli¹,

Maseedupally²,

Mandathara³

et al. 2013

Journal of Cataract and Refractive Surgery

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Section: Discussionmentioning

confidence: 92%

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confidence: 90%

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confidence: 99%

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Evaluation of corneal elevation and thickness indices in pellucid marginal degeneration and keratoconus

Tummanapalli¹,

Maseedupally²,

Mandathara³

et al. 2013

Journal of Cataract and Refractive Surgery

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“…Investigational modalities include ultrasonic pachymetry that would demonstrate reduced corneal thickness and corneal topography by Orbscan TECHNOLAS Perfect Vision GmbH (Munich, Germany) that would show diffuse thinning. 17,19,25,26 However, these investigational modalities may not be possible to carry out in cases of more severe corneal distortion. There is limited literature describing exact topographical pictures of keratoglobus.…”

Section: Aetiological Factorsmentioning

confidence: 99%

Keratoglobus

Wallang

Das²

2013

Eye

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Keratoglobus is a rare noninflammatory corneal thinning disorder characterised by generalised thinning and globular protrusion of the cornea. It was first described as a separate clinical entity by Verrey in 1947. Both congenital and acquired forms have been shown to occur, and may be associated with various other ocular and systemic syndromes including the connective tissue disorders. Similarities have been found with other noninflammatory thinning disorders like keratoconus that has given rise to hypotheses about the aetiopathogenesis. However, the exact genetics and pathogenesis are still unclear. Clinical presentation is characterised by progressive diminution resulting from irregular corneal topography with increased corneal fragility due to extreme thinning. Conservative and surgical management for visual rehabilitation and improved tectonic stability have been described, but remains challenging. In the absence of a definitive standard procedure for management of this disorder, various surgical procedures have been attempted in order to overcome the difficulties. This article reviews the aetiological factors, differential diagnosis, histopathology, and management options of keratoglobus.

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“…However, Lee et al [8] found that these topography patterns also manifest in eyes with KC and other corneal peripheral ectatic disorders. Therefore, a claw-shaped pattern on corneal topography may not always be associated with a diagnosis of PMD.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Scheimpflug Imaging Analysis of Pellucid Marginal Corneal Degeneration and Keratoconus

et al. 2014

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Aim: To determine and compare various quantitative parameters of pellucid marginal degeneration (PMD) and keratoconus with against-the-rule astigmatism (KC-ARA) obtained by elevation-based Scheimpflug imaging and to identify characteristics that can be used to discriminate PMD from KC-ARA. Setting: Ophthalmology Clinic, Ministry of Health Ankara Training and Research Hospital, Ankara, Turkey. Design: Retrospective case-control study. Patients and Methods: Patients with ARA, a butterfly or crab claw pattern in the curvature maps, a kissing bird pattern in the elevation maps and the bell sign in the pachymetric maps were identified, and 60 eyes of 40 patients were chosen for the evaluation. The patients were divided into two groups: the PMD group (29 eyes of 18 patients) and the KC-ARA group (31 eyes of 22 patients). By moving the cursor manually, the pachymetric maps and Scheimpflug images were searched for a thinner location than the automatically identified thinnest location. The coordinates and thickness of this manually identified location were evaluated. Results: In the PMD group, 7 (24.1%) eyes did not have any thinner location than the automatically identified thinnest location on the pachymetric maps and the Scheimpflug images, and in 22 (75.8%) eyes, a thinner location, which was located more peripherally, was found by manual evaluation of the pachymetric maps or Scheimpflug images. In 9 (31.0%) eyes of these 22, the manually identified thinnest locations were visible on pachymetric maps, and in 13 (44.8%) eyes the more peripheral thinnest locations were not visible on pachymetric maps but on Scheimpflug images. In the KC group, no patients had thinner locations than the automatically identified thinnest points on the pachymetric maps and the Scheimpflug images. Conclusion: A more peripheral thinner location than the automatically identified thinnest location exists in most of the eyes with PMD. In KC-ARA eyes, a thinner location than the automatically found thinnest point does not exist. Accordingly, a more peripheral thinner point than the identified thinnest point is a very strong indication for PMD. © 2014 S. Karger AG, Basel

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Ectatic Disorders Associated With a Claw-shaped Pattern on Corneal Topography

Cited by 77 publications

References 7 publications

Evaluation of corneal elevation and thickness indices in pellucid marginal degeneration and keratoconus

Evaluation of corneal elevation and thickness indices in pellucid marginal degeneration and keratoconus

Keratoglobus

Comparison of Scheimpflug Imaging Analysis of Pellucid Marginal Corneal Degeneration and Keratoconus

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