Mohamed Elalfy

Collagen Cross-Linking with Photoactivated Riboflavin (PACK-CXL) for the Treatment of Advanced Infectious Keratitis with Corneal Melting

PURPOSE To investigate the efficacy and safety of corneal collagen cross-linking (CXL) with photoactivated riboflavin (photoactivated chromophore for infectious keratitis [PACK]-CXL) in the management of infectious keratitis with corneal melting. DESIGN Prospective clinical trial. PARTICIPANTS Forty eyes from 40 patients with advanced infectious keratitis and coexisting corneal melting. METHODS Twenty-one patients (21 eyes) underwent PACK-CXL treatment in addition to antimicrobial therapy. The control group consisted of 19 patients (19 eyes) who received only antimicrobial therapy. MAIN OUTCOME MEASURES The slit-lamp characteristics of the corneal ulceration, corrected distance visual acuity, duration until healing, and complications were documented in each group. The Mann-Whitney U test was used for statistical analysis. P values less than 0.05 were considered statistically significant. RESULTS The average time until healing was 39.76 ± 18.22 days in the PACK-CXL group and 46.05 ± 27.44 days in the control group (P = 0.68). After treatment and healing, corrected distance visual acuity was 1.64 ± 0.62 in the PACK-CXL group and 1.67 ± 0.48 in the control group (P = 0.68). The corneal ulcerations width and length was significantly bigger in the PACK-CXL group (P = 0.004 and P = 0.007). Three patients in the control group demonstrated corneal perforation; infection recurred in 1 of them. No serious complications occurred in the PACK-CXL group. CONCLUSIONS Corneal CXL with photoactivated riboflavin did not shorten the time to corneal healing; however, the complication rate was 21% in the control group, whereas there was no incidence of corneal perforation or recurrence of the infection in the PACK-CXL group. These results indicate that PACK-CXL may be an effective adjuvant therapy in the management of severe infectious keratitis associated with corneal melting.

The collagen matrix of the human trabecular meshwork is an extension of the novel pre-Descemet's layer (Dua's layer)

Background The trabecular meshwork (TM) located at the angle of the anterior chamber of the eye contributes to aqueous drainage. A novel layer in the posterior part of the human cornea has recently been reported (the pre-Descemets layer (Duas layer (PDL)). We examined the peripheral part of this layer in relation to the origin of the TM. Methods The PDL and TM of 19 human donor eyes and one exenterated sample were studied. Samples were examined by light and electron microscopy (EM) for tissue architecture and by immunohistology for four matricellular proteins, five collagen types and CD34. Results EM revealed that beams of collagen emerged from the periphery of PDL on the anterior surface of the Descemets membrane and divided and subdivided to continue as the beams of the TM. Long-spacing collagen was seen in the PDL and TM. Trabecular cells (CD34-ve) associated with basement membrane were seen in the peripheral part of the PDL and corresponded to the start of the separation of the collagen lamellae of PDL. Collagen VI was present continuously in PDL and extended into the TM. Matricellular proteins were seen predominantly in the TM with only laminin extending into the periphery of PDL. Conclusions This study provides an insight into the origins of the collagen core of the TM as an extension of the PDL of the cornea. This finding adds to the knowledge base of the TM and cornea and has the potential to impact future research into the TM and glaucoma.

Fine needle diathermy occlusion of corneal vessels

Aims To evaluate the efficacy of fine needle diathermy (FND) occlusion of corneal vessels in relation to defined clinical indications. Methods A retrospective, consecutive case series including all patients treated by FND for occlusion of corneal vessels between 2004 and 2012. Indications were lipid keratopathy, preparation for keratoplasty to reduce risk of rejection and treatment of recalcitrant corneal graft rejection associated with stromal vessels. Our outcome measures were occlusion of corneal vessels with reduced corneal vascularisation, reduction in amount of lipid deposition, and reduction of graft rejection episodes. Results FND effectively reduced lipid deposition associated with the treated vessels in 14 out of 17 eyes (82.3%). When used to reduce corneal vascularisation before keratoplasty and to reduce intraoperative bleeding, the 1-year survival of the high-risk grafts was (84.6%). FND prevented further rejection episodes in 3 out of 4 corneal grafts. Fourteen eyes required retreatment (2–5 times) of which 9 had lipid keratopathy and 5 were in preparation for corneal grafting. Conclusions FND is effective in occluding established corneal vessels. Corneal microperforation is a potentially serious adverse event, but other adverse events, such as striae, whitening and intracorneal haemorrhages are reversible. It should be considered for established corneal vessels, and can be combined with antivascular endothelial growth factors.

Big bubble deep anterior lamellar keratoplasty: the collagen layer in the wall of the big bubble is unique

In big bubble (BB), deep anterior lamellar keratoplasty intracorneal injection of air separates Descemets membrane (DM) and the pre‐Descemets layer (Duas layer [DL]) to create a type 1 BB. We tested the hypothesis that air injection after excision or ablation of DL will fail to produce a BB.

Deep anterior lamellar keratoplasty—triple procedure: a useful clinical application of the pre-Descemet’s layer (Dua’s layer)

PurposeTo describe a technique which exploits the transparency and toughness of the pre-Descemets layer (Dua’s layer) to safely perform deep anterior lamellar keratoplasty (DALK) and phacoemulsification at the same time.MethodsThree DALK procedures combined with phacoemulsification were performed by the same surgeon using the big-bubble (BB) technique at the Research Institute of Ophthalmology, Cairo, Egypt. In two cases a type-1 BB, baring Dua’s layer, was achieved and in one case a type-2 BB, baring the Descemet’s membrane (DM), was achieved. The surgeries were video recorded and photo slit-lamp images were taken in the follow-up visits.ResultsDALK with phacoemulsification and lens implant was carried out in both patients where a type-1 BB was achieved. At a follow up of 18 months (first case) and 6 months (second case), the best corrected vision was 6/12 for each. In the case where a type-2 BB was achieved, the DM ruptured during injection of viscoelastic prior to capsulorhexis. The procedure was converted to a penetrating keratoplasty without phacoemulsification.ConclusionWhen a type-1 BB is achieved simultaneous DALK and phacoemulsification can be safely accomplished. Dua’s layer allows a clear view for performing phacoemulsification with the added benefit of its toughness, which can maintain a stable anterior chamber for cataract surgery. This should not be attempted when a type-2 BB is achieved.

Endothelial cell loss following tissue harvesting by pneumodissection for endothelial keratoplasty: an ex vivo study

Aims To study ex vivo the difference in endothelial cell density (ECD) in tissue harvested by pneumodissection for pre-Descemets endothelial keratoplasty (PDEK) and Descemets membrane endothelial keratoplasty (DMEK). Methods Tissue for PDEK and DMEK were obtained from 10 eye bank sclerocorneal discs by trephination after air injection into corneal stroma and big bubble (BB) formation. PDEK tissue was prepared in five corneas after achieving a type 1 BB and DMEK after a type 2 BB in five corneas. Five sclerocorneal discs for each group were used as controls. Endothelial cell counts were obtained from all samples before and after injection using phase-contrast microscopy with an eyepiece reticle. We used paired t test to analyse the results using the GraphPad Prism V.6 software. Results The range of change of ECD before and after injection in the PDEK sample group varied from −9% to +0.2% with an average of −5.36% ±3.8%. The difference was not statistically significant (p=0.0512). On the other hand, the range of change of ECD of the DMEK groups before and after injection varied from −0.4 to −20.6, with an average of −12.44% ±8.11%. This difference was statistically significant (p=0.0456). Also, there was a significant difference between DMEK test samples (postinjection) and their controls (p=0.028). Conclusions Corneal endothelial cell loss in PDEK tissue preparation is no worse, if not slightly better than, in DMEK tissue prepared by pneumodissection. PDEK preparation by pneumodissection represents a viable graft preparation technique.

Intra-lesional 5 fluorouracil for the management of recurrent pterygium

AimRecurrence is the most common complication arising from pterygium surgery. The aim of this study was to investigate the effectiveness of 5 fluorouracil (5FU) in halting the recurrence of pterygium after surgical excision.MethodsA retrospective review of patients treated for pterygium recurrence was carried out. Patients with recurrent (secondary) pterygium were treated with multiple weekly intra-lesional injections of 0.1–0.2 ml (2.5–5 mg) 5FU post-operatively depending on the size of the recurrence. The treatment was started within 1 month from the date of recurrence. The time from surgery to start of recurrence, previous treatment modalities, and number of recurrences were documented. The number of injections required to induce arrest of progression and/or regression of vascularity and fleshiness of the pterygium and any complications related to 5FU treatment were examined.ResultsFifteen eyes from 14 patients with recurrent pterygium treated with intra-lesional 5FU injections were analysed. Three of the 15 eyes had undergone a secondary excision and 12 had undergone a primary excision. In all, 93.3% of patients showed regression of the fibrovascular tissue (thickness and vascularity) and arrest of progression following a dose of 0.1–0.2 ml (2.5–5 mg) 5FU. Twelve eyes required three injections or fewer, whereas one patient required eight injections. This beneficial effect was maintained over an average follow-up period of 17 months. No complications from 5FU were observed.ConclusionThe use of weekly intra-lesional 5FU injections for the treatment of recurrent pterygium is safe and effective in limiting the progression and inducing the regression of recurrent pterygium. The number of injections can be tailored according to clinical need.

Sequential selective same-day suture removal in the management of post-keratoplasty astigmatism

AimsIn a previous study, we proposed that corneal topography performed 30–40 min after the initial suture removal can identify the next set of sutures requiring removal, for the treatment of post-keratoplasty astigmatism. The aim of this study was to evaluate the effect of removing subsequent sets of sutures at the same sitting.Methods10/0 nylon interrupted sutures were placed, to secure the graft–host junction, at the time of keratoplasty. Topography was performed using Pentacam (Oculus) before suture removal. The sutures to be removed in the steep semi-meridians were identified and removed at the slit-lamp biomicroscope. Topography was repeated 30–40 min post suture removal, the new steep semi-meridians determined, and the next set of sutures to be removed were identified and removed accordingly. Topography was repeated 4–6 weeks later and the magnitude of topographic astigmatism was recorded. A paired-samples t-test was used to evaluate the impact of selective suture removal on reducing the magnitude of topographic and refractive astigmatism.ResultsTwenty eyes of 20 patients underwent sequential selective same-day suture removal (SSSS) after corneal transplantation. This study showed that the topographic astigmatism decreased by about 46.7% (3.68 D) and the refractive astigmatism decreased by about 37.7% (2.61 D) following SSSS. Vector calculations also show a significant reduction of both topographic and refractive astigmatism (P<0.001).ConclusionSSSS may help patients to achieve satisfactory vision more quickly and reduce the number of follow-up visits required post keratoplasty.

Dynamics of big bubble formation in deep anterior lamellar keratoplasty by the big bubble technique: in vitro studies

To examine the movement of air injected in the cornea in simulated deep anterior lamellar keratoplasty (DALK), from the needle tip to the formation of different types of big bubbles (BB) and to ascertain how air travels through the stroma and pre‐Descemets layer [Duas layer (PDL)] to create a type‐1 (air between PDL and deep stroma) and type‐2BB (air between PDL and Descemets membrane).

Optical coherence tomography characteristics of different types of big bubbles seen in deep anterior lamellar keratoplasty by the big bubble technique

PurposeTo define optical coherence tomography (OCT) characteristics of type-1, type-2, and mixed big bubbles (BB) seen in deep anterior lamellar keratoplasty.MethodsHuman sclero-corneal discs were obtained from UK (30) and Canada (16) eye banks. Air was injected into corneal stroma until a BB formed. UK samples were fixed in formalin before scanning with Fourier-domain (FD-OCT). One pair of each type of BB was scanned fresh. All BB obtained from Canada were scanned fresh with time-domain (TD-OCT). For each OCT machine used, type-1 BB from which Descemets membrane (DM) was partially peeled, were also scanned. The morphological characteristics of the scans were studied.ResultsFD-OCT of the posterior wall of type-1 (Dua’s layer (DL) with DM) and type-2 BB (DM alone) both revealed a double-contour hyper-reflective curvilinear image with a hypo-reflective zone in between. The anterior line of type-2 BB was thinner than that seen with type-1 BB. In mixed BB, FD-OCT showed two separate curvilinear images. The anterior image was a single hyper-reflective line (DL), whereas the posterior image, representing the posterior wall of type-2 BB (DM) was made of two hyper-reflective lines with a dark space in between. TD-OCT images were similar with less defined component lines, but the entire extent of the BB could be visualised.ConclusionOn OCT examination the DM and DL present distinct features, which can help identify type-1, type-2, and mixed BB. These characteristics will help corneal surgeons interpret intraoperative OCT during lamellar corneal surgery.