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Corneal Defects, Abrasions and Foreign Bodies
Published in Amy-lee Shirodkar, Gwyn Samuel Williams, Bushra Thajudeen, Practical Emergency Ophthalmology Handbook, 2019
Epithelial defects: Will heal spontaneously in the presence of a healthy tear film, limbal stem cells and normal corneal sensation. It is customary to treat epithelial abrasions with topical antibiotics to prevent secondary infections, usually with chloramphenicol 4 times per day for one week, but many will improve with lubricants alone. In the case of contact lens wearers with an epithelial defect, treat with topical fluoroquinolones one drop 4–6 times per day for one week to provide cover against Pseudomonas. Patients should be advised not to wear their contact lenses while the cornea heals.
Retinal stem cell research
Published in A Peyman MD Gholam, A Meffert MD Stephen, D Conway MD FACS Mandi, Chiasson Trisha, Vitreoretinal Surgical Techniques, 2019
Henry Klassen, Michael J Young, Robert Ritch, Julia E Richards, Teresa Borrάs, Leonard A Levin
An examination of tissue-specific stem cells of current clinical significance illustrates how the strict definition of ‘stem cell’ does not necessarily apply. For instance, hematopoietic stem cells generate every type of blood cell, yet persistent blood shortages drive home the point that these cells have not been induced to effectively self-renew ex vivo. On the other hand, limbal stem cells do not normally exhibit multipotency, giving rise to only corneal epithelial cells. In either case, the failure of biology to live up to ideology has not impeded the successful clinical application of these cells.
Treatment of Ocular Disease
Published in Howard Green, Therapy with Cultured Cells, 2019
Chemical burns of the eye, if they destroy the limbal stem cells, can lead to a very nasty condition of inflammation, pain and loss of vision. The limbus can be restored by grafts from the healthy eye to the affected one (Kenyon and Tseng 1989). This requires large transfers of limbal tissue from the healthy eye. But limbal stem cells belong to the same family as epidermal keratinocytes and can therefore be cultivated in the same way, starting with a tiny biopsy. This was first shown in the laboratory of J. Rheinwald (Fig. 24). (Lindberg et al., 1993).
Neurotrophic keratopathy: current challenges and future prospects
Published in Annals of Medicine, 2022
Erin NaPier, Matthew Camacho, Timothy F. McDevitt, Adam R. Sweeney
Beyond corneal sensitivity testing, several other tests are helpful to identify comorbid conditions, classify the severity of NK, and monitor response to treatment or disease progression. Assessing tear film health is performed using the Schirmer test and tear osmolarity testing. Tear film health may be followed to assist in tracking subclinical disease progress [2,18]. In vivo confocal microscopy evaluates corneal nerve density in the stromal and sub-basal nerves. Eyes affected with NK can show decreased nerve density, decreased corneal epithelial and endothelial cell density, and increased hyperreflective keratinocytes. Patients who have had long disease duration typically have lower endothelial cell density. Unfortunately, cornea nerve evaluations involving confocal microscopy may have low reproducibility [2]. Ocular surface impression cytology identifies corneal conjunctivalization which can suggest limbal stem cell deficiency.
Accelerating precision ophthalmology: recent advances
Published in Expert Review of Precision Medicine and Drug Development, 2022
Loay Rahman, Ammaarah Hafejee, Rajeevan Anantharanjit, Wei Wei, Maria Francesca Cordeiro
The corneoscleral limbus is a key structure within the eye, containing limbal stem cells which play an essential role in the regeneration of the corneal epithelium [61]. Identifying the position of the corneoscleral limbus is important for clinical tasks such as contact lens fitting, where proper fitting is determined by the distance between the contact lens edge and the corneoscleral limbus [62], and in the estimation of the iridocorneal angle that can play role in diagnosis of angle-closure glaucoma [63]. Corneoscleral limbal points (external and internal) can be identified using anterior segment OCT images. A fully automated method for this has been designed which locates the external limbal point at the anterior ocular surface by estimating the local radii of curvature along the whole anterior ocular surface, and the internal limbal point using the estimation of the actual thickness profile of the cornea [64]. This method was compared to manual delineation by an ophthalmologist and optometrist that is typically a time-consuming process. The automated method found to overestimate the external limbus diameter by 0.24 mm and 0.21 mm when compared to the ophthalmologist and optometrist, respectively, and underestimate internal limbus diameter by 0.04 mm and 0.13 mm when compared to the ophthalmologist and optometrist, respectively. Consequently, despite the small discrepancies shown, the automated methods provided more precise results with excellent repeatability, suggesting the possibility of its use in larger scale image processing.
Surgical Management and Recent Advances in Chemical Injury: A 5-year Review
Published in Seminars in Ophthalmology, 2022
Priyanshi Awasthi, Prabhakar Singh, Amit Raj
Conjunctival limbal autograft (CLAU): CLAU is often done in cases of unilateral total LSCD with healthy fellow eye. It involves transfer of conjunctival autograft from limbal area of healthy eye to the affected eye. Traditionally, 2 limbal arcs measuring 5–7 mm are dissected from the healthy eye for transplantation. The damaged limbal stem cells are replaced by healthy limbal cells allowing restoration of corneal surface. The smallest CLAU discussed in literature is 60 degrees CLAU. But this procedure renders the donor eye at risk of sectoral LSCD.22 Though there are studies which suggest that the risk of LSCD in the donor eye is minimal following CLAU. A long-term follow-up (with longest follow-up of 20 years) of the donor eyes revealed that despite harvesting CLAU tissue of 120–180 degrees there was no evidence of overt LSCD. Patients were maintaining stable ocular surface till the last follow-up.23 To overcome this potential problem of iatrogenic LSCD in the donor eye, combined CLAU and living-related CLAL have been advised for severe ocular surface burn. The procedure while minimizes donor site LSCD and antigenic burden; it also provides maximum healthy limbal stem cells and conjunctiva.24