Severe corneal vascularization after intacs implantation and rigid contact lens use for the treatment of keratoconus

[Intracorneal ring segments in keratoconus management]

Intracorneal ring segments (ICRS), used in the management of keratoconus since the 2000s, have enjoyed significant technological development. Various types of ICRS exist, whose arc length, thickness, and diameter can be chosen according to the desired effect on the spherical equivalent, keratometry and asphericity. Individualized implantation strategies, based on each patient's topographic and tomographic pattern, are constantly evolving. The surgical procedure is standardized, and complications remain very rare. Combined procedures (corneal collagen cross-linking and refractive photokeratectomy±topo-guided, phakic and pseudophakic intraocular lenses) are increasingly used and require a good knowledge of the effect of ICRS alone on the keratoconic cornea. The objective of this review is to summarize clinical practices used in the visual rehabilitation of keratoconic patients using the ICRS+- combined procedures.

miR-184 exhibits angiostatic properties via regulation of Akt and VEGF signaling pathways

Corneal avascularity is critical for achieving transparency necessary for proper transmission of light to the lens and visual acuity. Although much is known about angiogenesis and angiostasis, the precise regulation of these processes in the cornea is unclear. MicroRNA (miR)-184, the most abundant corneal epithelial miRNA, has been suggested to function in corneal angiostasis by altering VEGF signaling; however, the mechanism(s) underlying this regulation have not been addressed. Using a combination of in vitro and in vivo assays to evaluate angiogenesis, we demonstrated that human limbal epithelial keratinocytes (HLEKs) engineered to overexpress miR-184 secreted lower amounts of angiogenic mitogens. Human dermal microvascular cells exposed to conditioned medium from miR-184-overexpressing HLEKs were less proliferative and failed to seal linear scratch wounds. The in vivo Matrigel plug assay showed that conditioned medium from miR-184-expressing HLEKs elicited a lesser degree of neovascularization compared with controls. We found that miR-184 directly targets and represses the proangiogenic factors, friend of Gata 2 (FOG2), platelet-derived growth factor (PDGF)-β, and phosphatidic acid phosphatase 2b (PPAP2B). FOG2 regulates VEGF expression, whereas PDGF-β and PPAP2B regulate Akt activity. By attenuating both VEGF and Akt signaling, miR-184 acts as a broad-spectrum negative regulator of corneal angiogenesis.-Park, J. K., Peng, H., Yang, W., Katsnelson, J., Volpert, O., Lavker, R. M. miR-184 exhibits angiostatic properties via regulation of Akt and VEGF signaling pathways.

Reshaping procedures for the surgical management of corneal ectasia

Corneal ectasia is a progressive, degenerative, and noninflammatory thinning disorder of the cornea. Recently developed corneal reshaping techniques have expanded the treatment armamentarium available to the corneal specialist by offering effective nontransplant options. This review summarizes the current evidence base for corneal collagen crosslinking, topography-guided photorefractive keratectomy, and intrastromal corneal ring segment implantation for the treatment of corneal ectasia by analyzing the data published between the years 2000 and 2014.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

[Keratoconus lenses: the small correction miracle]

Keratoconus is a non-inflammatory corneal disease associated with a cone-shaped protrusion and progressive corneal thinning. Apart from progression control and stabilizing interventions, correcting the optical error induced by a mostly highly irregular corneal surface is of paramount importance with respect to quality of life and ability to work. This goal can be achieved efficiently by contact lenses with only rare adverse conditions. This article provides a current overview on contact lens fitting in keratoconus and presents own associated results.

Keratoconus therapeutics advances

Keratoconus is a progressive, usually bilateral disease of the cornea that significantly diminishes visual acuity, secondary to a progressive corneal deformity which is characterized by corneal thinning, variable degrees of irregular astigmatism and specific abnormal topographic patterns. Normally it initiates during puberty and is progressive until the third or fourth decade of life, when normally the progression rate is diminished or waned. There are multiple scales to clinically classify keratoconus. One of the most commonly used is Amsler-Krumeich and recently with the development of morphometric and aberrometric techniques, additional scales have been created that allow keratoconus to be classified according to its severity. Despite certain etiology of keratoconus remains unknown, current treatment options are available in patients with ectatic corneas and they vary depending on the severity of the disease and they include spectacles, contact lenses, intrastromal rings, keratoplasty both penetrant or lamellar, cross-linking, refractive lens exchange with intraocular lens implant, phakic intraocular lenses and the combination of these alternatives. Some authors have been using excimer laser in patients with keratoconus but the safety of the procedure is controversial. Currently, the techniques for the management of keratoconus can be classified in 3 types: corneal strengthening techniques, optical optimization techniques and combined techniques.