Possible Role of Descemet-Stroma Interface for Descemet's Membrane Detachment after Penetrating Keratoplasty.

PurposeTo report two cases of spontaneous Descemet's membrane detachment (DMD) and dehiscence following penetrating keratoplasty (PK).Case reportsSpontaneous DMD or Descemet's membrane (DM) dehiscence following PK is a rare occurrence. Here, we describe two cases of such an occurrence following PK arising from the graft-host interface. A possible causative relation between DMD/dehiscence and DM-stromal interface attachment is suggested.ConclusionDMD and dehiscence after PK can be explained by the peripheral thinning of DM and possible changes to the recently characterized anchoring zone of interwoven collagen fibers and proteoglycans at the Descemet-stroma interface

Conjunctival-corneal melt in association with carotid artery stenosis

Rosalind MK Stewart1, Say Aun Quah1, Dan Q Nguyen2, Stephen B Kaye11Royal Liverpool University Hospital, Liverpool, UK; 2Bristol Eye Hospital, Bristol, UKPurpose: To report a case of severe conjunctival-corneal melt in association with carotid artery stenosis.Methods: Observational case report.Results: A 76-year-old man with a history of bilateral severe carotid artery occlusion and nonarteritic ischemic optic neuropathy developed a spontaneous bulbar conjunctival defect. Despite intensive lubrication, and attempts at surgical closure including an amniotic membrane patch graft, it progressed with subsequent adjacent corneal perforation. Thorough investigations revealed no underlying disease, except markedly delayed episcleral vessel filling on anterior segment fluorescein angiography.Conclusions: Neovascularisation is a known factor in the inhibition of ulceration. In light of the findings in this report, ocular ischemia should be considered as a cause or contributing factor in the differential diagnosis of conjunctival-corneal melt.Keywords: conjunctival melt, corneal melt, ocular ischemia, carotid artery stenosi

Average paraxial power of a lens and visual acuity

To provide a solution for average paraxial lens power (ApP) of a lens. Orthogonal and oblique sections through a lens of power F were reduced to a paraxial representation of lens power followed by integration. Visual acuity was measured using lenses of different powers (cylinders of − 1.0 and − 2.0D) and axes, mean spherical equivalent (MSE) of S + C/2, ApP and a toric correction, with the order of correction randomised. A digital screen at 6 m was used on which a Landolt C with crowding bars was displayed for 0.3 s before vanishing. The general equation for a symmetrical lens of refractive index (n), radius of curvature R, in medium of refractive index n1, through orthogonal (θ) and oblique meridians (γ) as a function of the angle of incidence (α) reduces for paraxial rays (α∼0) to Fn, Rα, θ, γα∼0=n-n1Rcos2θcos2γ. The average of this function is Fn, Rα, θ, γα∼0=n-n14R providing a solution of F4 for ApP.For central (p = 0.04), but not peripheral (p = 0.17) viewing, correction with ApP was associated with better visual acuity than a MSE across all tested refractive errors (p = 0.04). These findings suggest that F4 may be a more inclusive representation of the average paraxial power of a cylindrical lens than the MSE

Intraoperative management of macroperforations of Descemet's membrane in deep anterior lamellar keratoplasty.

BackgroundTo describe a surgical approach for the completion of pre-descemetic deep anterior lamellar keratoplasty (pdDALK) in the presence of a macroperforation of Descemet's membrane (DM).MethodsUsing case notes, we recorded the details of the intra- and perioperative course of patients who underwent successful pdDALK in the presence of macroperforation. A literature search of pdDALK techniques available to the corneal surgeon in a similar scenario was undertaken.ResultsIn two very different scenarios with intra- or preoperative perforation of DM, a centripetal layered lamellar dissection was performed and allowed completion of pdDALK with a residual recipient central stromal thickness of 36 and 115 µm and good visual outcome.ConclusionDespite very different scenarios, a centripetal layered lamellar dissection offers an approach for the completion of pdDALK in the presence of a macroperforation

Comparison of preservation and transportation protocols for preloaded Descemet membrane endothelial keratoplasty

BACKGROUND/AIMS: Descemet membrane endothelial keratoplasty (DMEK) preparation is technically demanding and is a limiting factor for uptake of this kind of surgery. Supply methods that simplify the procedure for surgeons are key to increasing uptake. This study compares two different shipping protocols for DMEK. METHODS: An 8.5 mm DMEK graft was punched, marked and loaded for transportation in two different conditions: (A) endothelium trifolded inwards in organ culture conditions (n=7) and (B) endothelium rolled outwards in hypothermic conditions (n=7). Tissues were shipped from Italy to the UK, then analysed for orientation, endothelial cell density, denuded areas, cell mortality, triple viability staining (Hoechst/ethidium homodimer/calcein AM (HEC)), immunolocalisation of ZO-1 and Na/K-ATPase proteins, visualisation of actin filaments using phalloidin and histological analysis using H&E on paraffin-embedded sections. RESULTS: All tissues clearly showed the mark used for graft orientation. After shipping in condition A, there was an increase in cell mortality of 8.1% and in denuded areas of 22.4%, whereas for condition B there was an increase in cell mortality of 14.2% and in denuded areas of 34.3% after shipping. HEC staining revealed areas of viable cells and apoptotic cells, with large denuded areas found in the periphery for condition B and within folds for condition A. CONCLUSIONS: Prestripped preloaded DMEK grafts retained sufficient viable cells for transplantation, with condition A (endothelium-in) offering the advantage of greater flexibility of use due to a longer shelf-life. HEC analysis provides further detailed information as to the status of DMEK grafts and should be used in future similar studies