To report long-term outcomes and to search for immunological and genetic risk factors in Terrien marginal degeneration (TMD). Retrospective, in part prospective, hospital-based longitudinal follow-up study of 32 eyes of 16 Finnish patients from 2012 to 2023. Median follow-up was 7.3 years (range, 0.3-15.2). Symptoms, best corrected visual acuity, pattern in axial power map, astigmatism, corneal thickness, higher order irregularity, cavities, progression and human leukocyte antigen genes were analysed. In 13 blood samples, 483 corneal and inflammatory disease-related genes were analysed with exome sequencing. The median age at first examination was 61 years (range, 13-89). Eleven (69%) patients were male, and 13 (81%) had bilateral disease. The median annual rate of progression of topographic astigmatism and new thinning was 0.03 D (range, -1.50 to 3.60) and 12.9 μm (range, -107.8 to 93.0), respectively; 0.15 D (range -1.50 to 1.17) and 21.6 μm (range, 1.3-93.0) in 6 (38%) patients with fast progression, and 0.02 D (range, -0.06 to 3.60) and 4.1 μm (range, -107.8 to 24.7) in 10 (72%) patients with slow progression. Topographic pattern, unilaterality, cavities, sectoral hyperaemia, poor response to medical treatment and new thinning after surgery were associated with fast progression. Thickness at maximal thinning fell below 450 μm only with fast progression. Five eyes changed the topographic pattern. Coexisting keratitis fugax hereditaria was found in one patient. A subtype of TMD progresses faster. The most sensitive indicators of progression were thinning and topographic astigmatism. No shared genetic cause for TMD was identified.

To analyze central corneal in vivo confocal microscopy (IVCM) in Terrien marginal degeneration (TMD). An observational prospective case-control study. Ten Finnish patients with TMD from a tertiary referral center were compared with 10 age- and sex-matched healthy volunteers. Seven patients had bilateral TMD. Age, anterior segment optical coherence tomography, extent of thinning in clock hours, grade of microdots, and stage of TMD were analyzed. According to Süveges and Wang classification, the median stage of TMD was 2 (range, 2-3) and 2 (range, 2-6), respectively. Twelve (71%) of 17 eyes with clinical TMD showed corneal thinning at all clock hours. The median age at the time of examination was 70 years (range, 28-81), and the median time from diagnosis 8.8 years (range, 6.0-15.2). By IVCM, the epithelium, subepithelial nerve plexus, and endothelium were intact in all eyes. The anterior stroma showed bilateral hyperreflective dots in the central cornea beneath the subepithelial nerve plexus in all eyes, and larger patches were detected in the posterior stroma anterior to Descemet membrane; both were invisible by anterior segment optical coherence tomography. As compared with controls, the grade of anterior microdots increased faster with age before the age of 65, and that of posterior stromal patches was higher. Two patients additionally had bilateral hyperreflective needle-like deposits in the anterior and midstroma. By IVCM, TMD is characterized regardless of clinical laterality by bilateral microdots in the central corneal stroma. They might be a supporting diagnostic criterion and alone could suggest subclinical disease.

This case report presents a unique instance of a 55-year-old male patient exhibiting features of both Terrien marginal degeneration (TMD) and Fuchs' superficial marginal keratitis. Characterized by peripheral corneal thinning vascularization, and a pseudopterygium, the patient experienced recurrent photophobia, redness, and tearing over 15 years. This case challenges the traditional distinction between TMD and Fuchs' superficial marginal keratitis, suggesting a potential common underlying disorder. Mycophenolate mofetil provided a partial response, while pseudopterygium removal led to sustained remission, emphasizing its therapeutic significance. This case highlights the first documented use of mycophenolate in TMD and supports the notion of shared vasculitic origins between TMD and Fuchs' keratitis, raising intriguing questions about targeted therapeutic interventions.

The aim of this study was to analyze corneal topography relative to astigmatism, higher order aberrations, and corneal curvatures in Terrien marginal degeneration using 3-dimensional anterior-segment optical coherence tomography. Twenty-nine eyes of 15 Finnish patients from a tertiary referral center had topographic axial power maps classified into 4 patterns by visual grading: crab claw (CC), mixed (M), arcuate (A), and normal. Regular astigmatism, keratometry, higher order aberrations, maximal corneal thinning, apex thickness, and curvature changes relative to best fit sphere toward maximal peripheral thinning were compared. Four, 9, and 12 eyes were classified as CC, M, and A, respectively; 1 as normal with clinical disease; and 3 as normal with unilateral disease. Median follow-up was 2.3 (range, 0-7.2) years. Three eyes changed pattern. Patients with the CC pattern were the youngest when diagnosed, progressed more rapidly, exhibited cavities in superior quadrants with anterior bulging, and had greater higher order posterior aberrations. Patients with the M pattern were older, progressed slower, and showed superonasal asymmetric corneal steepening extending centrally, often with asymmetric bow tie. Patients with pattern A showed little progression and were the oldest when diagnosed, with maximal corneal thinning equally in all quadrants. According to the Wang classification, the median stage was 4, 2, and 2 in CC, M, and A patterns, respectively, whereas it was always 2 by the Süveges classification. Terrien marginal degeneration is characterized by distinct corneal topographic patterns that differ in tomographic features, suggesting existence of subtypes in addition to different stages of disease. Patients representing CC and M patterns might benefit from more frequent monitoring.

Keratoconus (KC) must be distinguished from other corneal ectatic diseases and thinning disorders for stage-appropriate and suitable management of each condition. The most relevant corneal pathologies that may imitate the tomographic KC pattern are pellucid marginal degeneration (PMD), keratoglobus, posterior keratoconus, and Fuchs-Terrien marginal degeneration (FTMD). In moderate cases of KC, differentiation is typically possible using slit lamp examination and corneal tomography with evaluation of the location of the corneal thinning region. In early cases, however, differential diagnosis may be more challenging since the cornea may look relatively normal. In severe cases, the extended area of corneal thinning also complicates differentiation. Biomicroscopic findings cannot always give all the information needed to distinguish KC from related ectatic corneal conditions. The aim of this work is to discuss contemporary techniques and findings to assist physicians to identify the correct diagnosis. Corneal topography has been used in recent decades as the main tool for imaging in ectatic corneal diseases. Moreover, Scheimpflug cameras (corneal tomographers), which analyze both anterior and posterior corneal surfaces, curvatures, pachymetry, elevation data, higher order aberrations, Fourier analysis of keratometric data, and corneal density have become the most promising tools for diagnosis and follow-up of ectatic diseases. A noninvasive air pulse tonometer in conjunction with an ultrahigh-speed Scheimpflug camera complements tomographic findings by analyzing biomechanical corneal properties. Α confocal microscopy system, which is a novel clinical technique for the study of corneal cellular structure, could contribute effectively in the same direction. Moreover, anterior segment optical coherence tomography (AS-OCT) creates cross-sections, which can be generated into a three-dimensional structure to produce corneal epithelial thickness (ET) measurements. ET mapping is increasingly recognized as a sensitive tool for the diagnosis of ocular surface disorders. Combining information of all these systems could lead to a more effective identification and differential diagnosis of ectatic corneal disorders. Die Unterscheidung zwischen Keratokonus (KK) und anderen ektatischen Hornhauterkrankungen ist für eine angemessene Behandlung der jeweiligen Erkrankung unerlässlich. Die wichtigsten Hornhautpathologien, die bei der Differenzialdiagnose des KK in Betracht gezogen werden müssen, sind die pelluzide marginale Degeneration (PMD), der Keratoglobus, der posteriore Keratokonus und die Fuchs-Terrienʼsche marginale Degeneration (FTMD). In mittelschweren KK-Fällen ist die Differenzierung aufgrund der klassischen Lage der Hornhautverdünnungsregion möglich. In frühen Fällen ist die Differenzialdiagnose jedoch schwierig, da die Hornhaut relativ normal aussehen kann. In fortgeschrittenen Stadien hingegen ist die Differenzierung aufgrund des ausgedehnten Bereichs der Hornhautverdünnung mitunter ebenfalls schwierig. Biomikroskopische Befunde können nicht alle Informationen liefern, die zur Unterscheidung des KK von anderen ektatischen Hornhauterkrankungen erforderlich sind. Daher werden moderne Techniken und Befunde diskutiert, um die richtige Differenzialdiagnose sicherstellen zu können. Hornhauttopografiekarten wurden in den letzten Jahrzehnten als Hauptinstrument für die bildgebende Differenzialdiagnose verwendet. Darüber hinaus wurden Scheimpflug-Kameras (Hornhauttomografen), die sowohl die vordere als auch die hintere Hornhautfläche anhand von Krümmungsdaten, Pachymetrie, Elevationsmessungen, Aberrationen höherer Ordnung, Fourier-Analysen keratometrischer Daten und die Hornhautdichte analysieren, zum wichtigsten Instrument für die Diagnose und Verlaufskontrolle ektatischer Hornhauterkrankungen. Seit neuestem zeichnet ein nicht invasives Luftstoßtonometer in Verbindung mit einer Ultrahochgeschwindigkeits-Scheimpflug-Kamera die Reaktion der Hornhaut auf diesen mechanischen Stimulus auf und analysiert so ihre biomechanischen Eigenschaften. Des Weiteren könnte die konfokale Mikroskopie effektiv zur Differenzialdiagnose beitragen. Darüber hinaus erzeugt die optische Kohärenztomografie des vorderen Segments (AS-OCT) Querschnitte, die in eine 3-dimensionale Struktur umgewandelt werden können, um die Hornhautepitheldicke zu messen. Das Endothel-Mapping wird zunehmend als wirksames Instrument für die Diagnose von Erkrankungen der Augenoberfläche anerkannt. Die Kombination der Informationen all dieser Systeme könnte eine umfassendere Identifizierung und Differenzialdiagnose ektatischer Hornhauterkrankungen ermöglichen.