Keratoconus Natural Progression

Abstract

Purpose: We set out to describe the natural history of keratoconus. We included untreated patients, and our key outcome measures were vision, refraction, and corneal curvature. Clinical Relevance: Keratoconus affects 86 in 100 000 people, causing visual loss due to increasing irregular corneal astigmatism, and the quality of life declines in patients. Interventions are used to stabilize the disease or improve vision, including corneal cross-linking (CXL) and grafting, but these carry risks. Detailed knowledge of the natural history of keratoconus is fundamental in making informed decisions on when their benefits outweigh these risks. Methods: We included prospective or retrospective studies of pediatric or adult patients who reported 1 or more of visual acuity, refraction, and corneal curvature measures: steep keratometry (K 2), mean keratometry (K mean), or maximum keratometry (K max), thinnest pachymetry, corneal transplantation rates, corneal scarring incidence, and patient-reported outcome measures (PROMs). Databases analyzed included Medline, Embase, CENTRAL, and CINAHL. Searches were carried out until October 2018. Bias assessment was carried out using the Joanna Briggs Institute model of evidence-based healthcare. Results: Our search yielded 3950 publication titles, of which 41 were included in our systematic review and 23 were incorporated into the meta-analysis. Younger patients and those with greater K max demonstrated more steepening of K max at 12 months. The meta-analysis for K max demonstrated a significant increase in K max of 0.7 diopters (D) at 12 months (95% confidence interval [CI], 0.31e1.14; P ¼ 0.003). Our meta-regression model predicted that patients had 0.8 D less K max steepening over 12 months for every 10-year increase in age (P ¼ 0.01). Patients were predicted to have 1 D greater K max steepening for every 5 D of greater baseline K max (P ¼ 0.003). At 12 months, there was a significant increase in the average K mean of 0.4 D (95% CI, 0.18e0.65; P ¼ 0.004). Conclusions: We report the first systematic review and meta-analysis of keratoconus natural history data including 11 529 eyes. Younger patients and those with K max steeper than 55 D at presentation have a significantly greater risk of progression of keratoconus. Closer follow-up and a lower threshold for cross-linking should be adopted in patients younger than 17 years and steeper than 55 D K max .

Assessment of the Association between In Vivo Corneal Morphogeometrical Changes and Keratoconus Eyes with Severe Visual Limitation

“…The geometric decompensation that causes the conical shape is localized mainly in the temporal lower quadrant of the mean peripheral region [2] due to a loss of tenacity that the corneal structure suffer by a reorientation of its anatomophysiology [3]. In addition, this morphologic decompensation inducts an increase of the high-order optical aberrations [4], showing the patients high values of irregular astigmatism and presenting as their main refractive sign the impossibility of a complete optical compensation of their ametropia by spherocylindrical lenses. Consequently, their corrected visual acuity will be diminished with respect to patients without corneal pathology [5].…”

Baseline factors predicting the need for corneal crosslinking in patients with keratoconus

“…Ferdi et al [15] conducted a systemic review and meta-analysis on keratoconus progression and concluded that patients aged less than 17 years, and those with a Kmax > 55 D, are at significantly greater risk of keratoconus progression. When we classified eyes according to an Rmin cut-off value of 6.13 mm (equivalent to 55.0 D) and age cut-off of 17 years, according to Ferdi's study, the incidence of CXL was 85.7% in the eyes of the younger age group with the lower Rmin values.…”

<p>Visual Acuity and Refractive Error Improvement in Keratoconic Patients: A Low-Income Context Management Perspective</p>

“…4,11 Cited risk factors include individual gene composition, ultraviolet and sun exposure, eye rubbing, gender, hormonal variation, age, atopy, floppy eyelid syndrome and parental education. 4,6,12 In addition, connective tissue disorders such as Ehler-Danlos syndrome, Marfan syndrome, Lonstein disease, Down syndrome and mitral valve prolapse are the most common associated disease conditions. 6 There is a huge disparity in access to eye care services, diagnostic equipment and management options between low-and high-income countries.…”