(1/900) Causes of corneal graft failure in India.
The success of corneal grafting in visual rehabilitation of the corneal blind in India depends on survival of the grafts. Understanding the causes of graft failure may help reduce the risk of failure. We studied these causes in a series of 638 graft failures at our institution. Multivariate logistic regression analysis was used to evaluate the association of particular causes of graft failure with indications for grafting, socioeconomic status, age, sex, host corneal vascularization, donor corneal quality, and experience of surgeon. The major causes of graft failure were allograft rejection (29.2%), increased intraocular pressure (16.9%), infection excluding endophthalmitis (15.4%), and surface problems (12.7%). The odds of infection causing graft failure were significantly higher in patients of lower socioeconomic status (odds ratio 2.45, 95% CI 1.45-4.15). Surface problems as a cause of graft failure was significantly associated with grafts done for corneal scarring or for regrafts (odds ratio 3.36, 95% CI 1.80-6.30). Increased intraocular pressure as a cause of graft failure had significant association with grafts done for aphakic or pseudophakic bullous keratopathy, congenital conditions or glaucoma, or regrafts (odds ratio 2.19, 95% CI 1.25-3.84). Corneal dystrophy was the indication for grafting in 12 of the 13 cases of graft failure due to recurrence of host disease. Surface problems, increased intraocular pressure, and infection are modifiable risk factors that are more likely to cause graft failure in certain categories of patients in India. Knowledge about these associations can be helpful in looking for and aggressively treating these modifiable risk factors in the at-risk categories of corneal graft patients. This can possibly reduce the chance of graft failure. (+info)
(2/900) Excimer laser ophthalmic surgery: evaluation of a new technology.
The aim of this article is to provide information and an overview of the potential risks and benefits of excimer laser surgery, a new and promising technique in ophthalmic surgery. Although this review concentrates on the use of the laser for refractive purposes, novel therapeutic techniques are also discussed. It is hoped that this will enable general practitioners, optometrists and physicians to provide appropriate advice and counselling for patients. (+info)
(3/900) TNF-alpha production in the cornea in response to Pseudomonas aeruginosa challenge.
Pseudomonas aeruginosa can cause ulcerative bacterial keratitis or contact lens-induced acute red eye (CLARE) in humans. The present study used a mouse model of ocular infection and inflammation to examine the relationship between TNF-alpha and inflammation in the cornea in response to challenge with either a strain of P. aeruginosa causing keratitis or a CLARE strain. Constitutive TNF-alpha mRNA was detected in the epithelium, mainly towards the periphery. After infection with the keratitis-inducing strain (6294), TNF-alpha expression was elevated four-fold by 24 h post-challenge. No detectable induction of TNF-alpha mRNA was seen with CLARE strain (Paer1) challenge at any time point. The TNF-alpha protein production detected by ELISA showed a corresponding pattern to the mRNA expression, which also correlated with pathological changes. These results suggest that invasive strains of P. aeruginosa create greater pathological changes as a result of elevated TNF-alpha production, which contributes to inflammation during keratitis in vivo. (+info)
(4/900) Matrix metalloproteinases in epithelia from human recurrent corneal erosion.
PURPOSE: To assay for the presence of matrix metalloproteinases (MMPs) in human corneal epithelium affected by recurrent erosion compared with that in normal corneal epithelium. METHODS: Corneal epithelial debridement samples were obtained from 13 patients with recurrent epithelial erosion. For control specimens, epithelia were obtained from healthy patients undergoing photorefractive keratectomy. Zymography was performed on all samples to identify MMPs. Immunolocalization of MMP-2, laminin, and collagen type VII was determined in two samples with human recurrent epithelial erosion and compared with that in control epithelium. RESULTS: Twelve of 13 erosion samples showed MMP-2 enzymatic activity; one of the 12 also showed MMP-9 activity. Only one erosion sample showed no MMP enzymatic activity. All normal control specimens were negative for MMP. Immunohistochemical analysis of two recurrent erosion samples showed MMP-2 presence in basal cells, whereas, in normal epithelium it was not detected. One sample with epithelial erosion showed laminin localization in basal epithelial cells and basal lamina. Type VII collagen localized in basal epithelial cells only in this sample. A second erosion sample showed localization of laminin and type VII collagen in basal epithelial cells only. Normal corneal epithelium showed presence of laminin and type VII collagen in basal epithelium and basal lamina. CONCLUSIONS: Matrix metalloproteinase-2 expression is upregulated in human epithelia affected by recurrent erosion compared with that in normal control samples. Immunolocalization studies suggest that this enzyme is concentrated in basal epithelial cells where it may play an important role in degradation of the epithelial anchoring system and the recurrent epithelial slippage and erosion observed in these patients. (+info)
(5/900) Ocular ochronosis in alkaptonuria patients carrying mutations in the homogentisate 1,2-dioxygenase gene.
AIMS: To assess the involvement of the recently identified human homogentisate 1,2-dioxygenase gene (HGO) in alkaptonuria (AKU) in two unrelated patients with ochronosis of the conjunctiva, sclera, and cornea. METHODS: A mutation screen of the entire coding region of the HGO gene was performed using single stranded conformational analysis after polymerase chain reaction with oligonucleotide primers flanking all 14 exons of the HGO gene. Fragments showing aberrant mobility were directly sequenced. RESULTS: Two homozygous missense mutations, L25P and M368V, were identified, each of which leads to the replacement of a highly conserved amino acid in the HGO protein. CONCLUSIONS: The authors describe a novel mutation, L25P, in the German population and bring to 18 the total number of known HGO mutations. (+info)
(6/900) Confocal microscopy in the iridocorneal endothelial syndrome.
AIMS: To report the appearances of iridocorneal endothelial (ICE) syndrome from real time, white light confocal microscopy. METHODS: Three consecutive patients, each with ICE syndrome, were examined prospectively. Corneal specular and confocal microscopic examinations were performed in all three patients. In the first patient, a penetrating keratoplasty was performed and the cornea was examined by light and scanning electron microscopy. No surgery was performed in the remaining two patients. RESULTS: In the first patient corneal oedema prevented endothelial specular microscopy. Confocal microscopy performed before penetrating keratoplasty successfully revealed abnormal epithelial-like endothelial cells. Histological examinations of the cornea following penetrating keratoplasty revealed the presence of multilayered endothelial cells with epithelial features (microvilli). In the remaining two patients, specular microscopy showed the presence of ICE cells with typical dark/light reversal. Confocal microscopy demonstrated groups of endothelial cells with epitheloid appearances. In all three patients, the contralateral endothelial appearance was normal by specular and confocal microscopy, except for moderate endothelial polymegathism in one patient. Epithelial-like endothelial cells were characterised by prominent nuclei on confocal microscopy. CONCLUSIONS: The application of confocal microscopy indicates that the ICE syndrome is characterised by epitheloid changes in the endothelium. Confocal microscopy may be used to diagnose the ICE syndrome by demonstrating epithelial-like endothelial cells with hyperreflective nuclei. This technique is especially of value in cases of corneal oedema, since specular microscopy may fail to image the endothelium in such cases. (+info)
(7/900) Treatment of severe ocular-surface disorders with corneal epithelial stem-cell transplantation.
BACKGROUND: Conditions that destroy the limbal area of the peripheral cornea, such as the Stevens-Johnson syndrome, ocular pemphigoid, and chemical and thermal injuries, can deplete stem cells of the corneal epithelium. The result is scarring and opacification of the normally clear cornea. Standard corneal transplantation cannot treat this form of functional blindness. METHODS: We performed and evaluated 70 transplantations of corneal epithelial stem cells from cadaveric eyes into 43 eyes of 39 patients with severe ocular-surface disorders and limbal dysfunction. Medical treatment had failed in all patients. The patients had a mean preoperative visual acuity of 0.004 (only being able to count the number of fingers presented by the examiner) in the affected eyes, which satisfies the criteria for legal blindness in most countries. In 28 eyes, we also performed standard corneal transplantation. Stem-cell transplantations were performed as many as four times on 1 eye if the initial results were not satisfactory; 19 eyes had multiple transplantations. Patients were followed for at least one year after transplantation. RESULTS: A mean of 1163 days after stem-cell transplantation, 22 of the 43 eyes (51 percent) had corneal epithelialization; of the 22 eyes, 7 eyes had corneal stromal edema and 15 eyes had clear corneas. Mean visual acuity improved from 0.004 to 0.02 (vision sufficient to distinguish the largest symbol on the visual-acuity chart from a distance of 1 m) (P<0.001). The 15 eyes in which the cornea remained clear had a final mean visual acuity of 0.11 (the ability to distinguish the largest symbol from a distance of 5 m). Complications of the first transplantation included persistent defects in the corneal epithelium in 26 eyes, ocular hypertension in 16 eyes, and rejection of the corneal graft in 13 of 28 eyes. The epithelial defects eventually healed in all but two of the eyes. CONCLUSIONS: Transplantation of corneal epithelial stem cells can restore useful vision in some patients with severe ocular-surface disorders. (+info)
(8/900) The p53 tumor suppressor gene of the marsupial Monodelphis domestica: cloning of exons 4-11 and mutations in exons 5-8 in ultraviolet radiation-induced corneal sarcomas.
Inactivating p53 mutations are found in many ultraviolet radiation (UVR)-induced skin tumors. We examined 12 UVR-induced corneal tumors of the marsupial Monodelphis domestica for mutations in exons 5-8 of p53 and compared their mutational spectrum with that of UVR-induced skin tumors of other species. First we cloned and characterized a cDNA extending from the middle of exon 4 through exon 11 of the Monodelphis p53 gene. Based on the sequence information obtained, primers were designed to amplify introns 4-9 of the gene; intron primers to amplify individually exons 5-8 were subsequently developed. 'Cold' single strand conformational polymorphism analysis followed by reamplification of DNA with altered mobility and cycle sequencing revealed single p53 mutations in four of 12 tumors (33%), including one mutation in exon 5, two identical mutations in exon 7 and one mutation in exon 8. All mutations were at dipyrimidine sites and occurred on the non-transcribed strand. Three of the four were hallmark UVR-induced C-->T alterations. Three of the mutations were found at sites corresponding to human codons 248 and 273, which are mutational hotspots in human and murine UVR-induced squamous cell carcinomas. Our findings suggest that UVR-induced corneal sarcomas in Monodelphis will be valuable in studying mechanisms of p53 mutation in UVR-induced tumors. (+info)