Ocular media
Fiona Rowe in Visual Fields via the Visual Pathway, 2016
The cornea is the transparent area at the front of the eyeball continuous with the sclera. It is composed of five layers: Outer surface epitheliumBowman layerStromaDescemet membraneInner surface endothelium
How to master MCQs
Chung Nen Chua, Li Wern Voon, Siddhartha Goel in Ophthalmology Fact Fixer, 2017
Keratoconus is an ectatic condition characterised by progressive thinning of the cornea. The condition usually begins at adolescence. Progressive astigmatic myopia is the most common finding. Despite the thinning, perforation is rare. Hydrop results from a break in Descemets membrane leading to cornea swelling. With time, hydrops usually resolves, leaving behind a small scar. Compared with other inflammatory conditions, corneal graft in keratoconus has a higher success rate.
Corneal Disorders
Ching-Yu Cheng, Tien Yin Wong in Ophthalmic Epidemiology, 2022
Second, data collected through corneal transplant registries enable researchers to examine for important risk factors and prognostic factors of corneal transplantation, ultimately improving anatomical and visual outcomes.98–101 Ang et al.102 observed that patients who underwent Descemet membrane endothelial keratoplasty (DMEK) for FECD and bullous keratopathy achieved a better long-term graft survival when compared to Descemet stripping automated endothelial keratoplasty (DSAEK) and penetrating keratoplasty. National corneal transplant registries have also facilitated the identification of important prognostic factors for graft survival rate, including the indication for graft, number of previous grafts, corneal neovascularization, history of ocular inflammation or glaucoma, and postoperative events such as graft rejection or infection.103–107 Studies have shown that corneal transplantation performed for the most common causes of blindness mentioned above, such as IK and PBK, generally fare worse than those performed for “low-risk” conditions such as keratoconus and FECD,85 highlighting the need for improvement in management for the former indications and risk factors for graft failure.108 In addition, the registries enable examination and monitoring for any significant postoperative adverse events such as infection and endophthalmitis. Based on a UK nationwide study of 11,320 patients, Chen et al.109 demonstrated that the incidence of endophthalmitis after penetrating keratoplasty was only 0.7% in the UK. More importantly, they observed that the increased risk of endophthalmitis was associated with the cause of death, indications for graft, high-risk cases, and presumed transmission of infection from the donor corneas.
Studies on the Effectiveness of Ozone Therapy on the Treatment of Experimentally Induced Keratitis with Candida albicans in Rabbits
Published in Seminars in Ophthalmology, 2022
Kemal Varol, Ayşe Nedret Koç, Latife Çakır Bayram, Hatice Arda, İhsan Keleş, Metin Ünlü, Vehbi Güneş, Gencay Ekinci, İlknur Karaca Bekdik, Mustafa Altay Atalay
On light microscopic examination, the cornea was observed to consist of five layers. Basal columnar cells, intermediate polygon cells, and superficial squamous cells were present in the multi-layer squamous nonkeratinized layer. Under the corneal epithelium (Bowman’s layer). Secondary propria consisted of collagen fibers and scattered spindle-shaped stromal cells arranged at regular intervals. The Descemet membrane was present just below the stroma and was covered by the endothelium of Descemet. Normal corneal morphology was observed in the negative control group. In this group, the lamellar structure of the stroma was regular. There was no change in the size and shape of the corneal epithelial cells. Keratocytes are neatly sorted. Keratin is not available (Figure 2. A.1).
Göttingen Minipig is not a Suitable Animal Model for in Vivo Testing of Tissue-Engineered Corneal Endothelial Cell-Carrier Sheets and for Endothelial Keratoplasty
Published in Current Eye Research, 2020
Niklas Telinius, Daniele Spinozzi, Dusan Rasic, Isabel Dapena, Ulrik Baandrup, Alina Miron, Silke Oellerich, Jesper Hjortdal
Maintaining an AC proved difficult in all minipigs due to vitreous pressure and a rather soft cornea resulting in loose incisions. Descemetorhexis was attempted and achieved to some extent in minipigs 1–3. Descemet membrane was highly adherent to the stroma which complicated and prolonged the procedure, often resulting in corneal edema and therefore the endothelium was scraped off in the remaining animals (4–8). Minipig 5 was sacrificed immediately due to damage to the lens during surgery. Implementation of HALCs without pCEC was successful in minipigs 2 and 4, but unsuccessful in minipigs 1 and 3 because of poor visibility due to corneal edema and the HALC was left free-floating in the AC. HALCs with pCEC were successfully positioned onto the posterior stroma in minipigs 6–8, however, in minipig 6 the pCEC-HALC construct was placed upside-down with cells facing the posterior stroma.
Novel techniques to prevent apoptosis and improve regeneration in corneal endothelial cells
Published in Expert Review of Ophthalmology, 2020
Cell survival strategies are involved in many coordinated physiological processes that serve to ward off death. Currently, the classical surgical operation is still considered as the most efficient strategy to recover visual acuity of patients with severe endothelial failure. Descemet stripping endothelial keratoplasty (DSEK) and Descemet membrane endothelial keratoplasty (DMEK) are routinely applied in clinical treatments for patients with FECD owing to low rejection rate, intraoperative, and postoperative complications, and astigmatism [40–42]. These surgical modifications of endothelial keratoplasty to transplant a healthy cornea or part of cornea from a donor are also efficient in recovering the visual acuity of patients with chemical burnt cornea and mechanical trauma in HCE [43,44]. However, shortage of the donors is the bottleneck of its clinical application [45].
Related Knowledge Centers
- Basement Membrane
- Stroma of Cornea
- Corneal Endothelium
- Cornea
- Anterior Chamber of Eyeball
- Fuchs' Dystrophy
- Wilson's Disease
- Kayser–Fleischer Ring
- Haab'S Striae