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PubMed2003

Ocular surface reconstruction: limbal stem cell transplantation.

In summary, the management of patients with severe ocular surface disease remains difficult. Significant progress has been made toward understanding limbal stem cell disease, and surgical treatments have been refined. Short- and long-term successes have been achieved and have improved the quality of life for patients who otherwise have had no other treatment options. Further research is needed to determine the factors leading to successful long-term stem cell transplantation and those factors associated with transplantation failure. Developments in the management of limbal stem cell disease are progressing rapidly, and the long-term outlook for patients with this challenging disease continues to improve.

Conjunctiva↗

PubMed2006

Autologous serum therapy of the ocular surface with novel delivery by platelet concentrate gel.

Application of autologous serum to treat a multitude of ocular surface diseases and conditions is a relatively new technique that has gained popularity over the past 10 years. This review focuses on the use of topical autologous serum and a new platelet gel delivery technique that utilizes autologous platelet concentrate mixed with calcium chloride and thrombin for gelling serum, which can then be applied easily to the corneal surface. Residual platelet serum concentrate can be mixed with artificial tears that are capable of gelling in a 25% concentrate, which is then used by the patient postoperatively. A review of the literature identifies various concentrations of autologous serum, frequency of application, and storage criteria.

Blood Transfusion, Autologous↗

PubMed1995

The use of epidemiological techniques to assess risk: the epidemiology of microbial keratitis.

The role of the three principal epidemiological study designs-- descriptive, cohort and case-control studies--for the evaluation of risk, is illustrated by describing their use for the investigation of microbial keratitis. Descriptive studies have identified potential risk factors and causes of microbial keratitis by both case reports and case series; trauma, ocular surface diseases and, latterly, contact lenses have been identified as potential risk factors. These studies have also shown that Pseudomonas aeruginosa and Acanthamoeba are particularly associated with contact lens wear. However, these studies are limited because they cannot be used to quantify risk. Cohort studies, in which the number of cases of a disease developing in a defined and initially unaffected population are identified, are usually inappropriate for assessing rare conditions because the size of the study often has to be too large, and follow-up too long, to generate sufficient numbers of cases. Some of the disadvantages of this study type can be overcome by sampling techniques and have been successfully carried out to obtain incidence figures for microbial keratitis. Case-control studies use multivariable analyses to examine the risk of microbial keratitis associated with various factors. This is an economical study design for investigating rare diseases because a group of subjects with the disease is compared with a control group from the same population who are unaffected. The selection of an appropriate control group is a difficult problem in epidemiology but this study design has been crucial in identifying risk factors and potential causes of microbial keratitis.

Acanthamoeba Keratitis↗

PubMed2002

Incidence and risk factors for microbial keratitis in Hong Kong: comparison with Europe and North America.

PURPOSE: To establish the incidence, etiology and risk factors for microbial keratitis (MK) in Hong Kong. METHODS: Two hundred and twenty-three new cases of presumed MK were recruited over a period of 17 months and comprehensive microbiologic studies performed. A nested case-control study was pursued for patients wearing contact lenses (CLW) to determine risk factors for MK with regards to types of CLW and hygiene practice. RESULTS: Of the 223 patients recruited, 59 (26%) wore contact lenses. Corneal scrapes yielded positive cultures from 77 patients (35% overall, 56 non-CLW, 21 CLW). Two hundred and six CLW volunteers were recruited to participate in the case-control study, of whom 135 were matched with 45 CLW patients. The annual incidence of MK was 0.63 per 10,000 population and 3.4 per 10,000 CLW with rates for daily, extended and rigid lens wear of 3.09, 9.30 and 0.44 per 10,000 CLW respectively. Pseudomonas aeruginosa was the dominant bacterial pathogen. Six cases of Acanthamoeba keratitis occurred, five in CLW (incidence 0.33 per 10,000 CLW) and one following corneal abrasion. Non-CLW developed MK at a peak age of 73, which is 10 years younger than expected for Scotland and USA. CONCLUSIONS: Previous ocular surface disease and trauma were the main risk factors for MK in Hong Kong. CLW appears at least as safe as that found in Scotland and the USA. Acanthamoeba keratitis was detected but with an incidence rate five times lower than Scotland. Factors predisposing hydrogel CLWs to MK, that were statistically significant, included overnight wear, poor hygiene and smoking.

Acanthamoeba Keratitis↗

PubMed2004

Keratolimbal allograft in corneal reconstruction.

The replenishment of corneal epithelial SC is a crucial step for reconstructing the ocular surface in patients suffering from devastating ocular surface diseases manifesting with total LSCD. KLAL is one of such procedures and has a long track record and a long follow-up for patients with bilateral total LSCD. This review summarizes the literature experiences and outline new strategies that are important to enhance the success of this procedure. Further research is needed to fully understand the biological processes involved in allogeneic tissue transplantation for preserving epithelial SC adhesion, migration, and survival.

Adult↗

PubMed2002

Immunosuppressive properties of human amniotic membrane for mixed lymphocyte reaction.

The combination of allograft limbal transplantation (ALT) and amniotic membrane transplantation (AMT) has been applied in the treatment of severe ocular surface diseases. The beneficial effect of this combination has been thought to result from possible immunosuppressive ability of amniotic membrane (AM). However, the mechanisms of any such ability remain unknown. In this study, we investigated whether human AM has the ability to suppress allo-reactive T cell responses in vitro. For mixed lymphocyte reaction (MLR), lymphocytes isolated from lymph nodes of C57BL/6 mice (Mls1b, Vbeta6+) were cultured with irradiated splenocytes from DBA/2 mice (Mls1a, Vbeta6-) with or without human AM. For carboxyfluorescein diacetate succinimidyl ester (CFSE) experiments, responder lymph node cells were labelled with a stable intracellular fluorescent dye and cultured with irradiated stimulator cells. The ratio of responder Vbeta6+ T cells was then determined by FACS analysis, and the division profiles of responder Vbeta6+ T cells were analysed by CFSE content. Furthermore, Th1 and Th2 cytokine synthesis by allo-reactive T cells in MLR culture supernatants was determined by enzyme-linked immunosorbent assay (ELISA). Addition of AM to the MLR culture resulted in the significant inhibition of thymidine incorporation compared with control culture lacking AM. The population of responder CD4+Vbeta6+ T cells was significantly reduced in the AM-treated culture in comparison to control. CFSE analysis revealed less division and lower proliferation of responder CD4+Vbeta6+ T cells in cultures with AM than without. In addition, allo-rective T cell synthesis of both Th1 (IL-2 and IFNgamma) and Th2 (IL-6 and IL-10) type cytokine was significantly decreased in the presence of AM. These results indicate that human AM has the ability to suppress allo-reactive T cells in vitro. This inhibitory effect likely contributes to the success of the ALT-AMT combination.

Amnion↗

PubMed2003

Relationship between goblet cell density and tear function tests.

AIM: The objective of this study was to find a relationship between goblet cell density (GCD) and other diagnostic tests of dry eye in a group of normal healthy Chinese subjects. The capability of using GCD as a tear function test was assessed. METHOD: A total of 42 optometry students with no contact lens wear history were recruited. Subjects were required to fill in a dry eye questionnaire. The non-invasive tear break-up time (NITBUT) of each subject was measured, followed by phenol red thread test (PRTT) and tear break-up time (TBUT) tests. Conjunctival epithelial cells from the inferior nasal bulbar conjunctiva were harvested by the impression cytology technique. The specimens collected were labelled and stained with PAS (Periodic Acid Schiff)-haematoxylin. The goblet cells and the conjunctival epithelial cells were counted under a light microscope of 100x magnification. Spearman's rho (rho) correlation test was used to analyse the relationship between GCD and the other tear function tests. RESULTS: With a probability level of 0.0051 (corrected for a cumulative familywise error rate of p = 0.05), GCD was found to have no correlation with NITBUT (rho = -0.193, p = 0.222), McMonnies Dry Eye Scores (MCDES) (rho = -0.052, p = 0.742), PRTT (rho = - 0.188, p = 0.234) and TBUT (rho = 0.246, p = 0.117). CONCLUSION: There was no correlation between GCD and MCDES, NITBUT, PRTT and TBUT. The GCD alone is not a useful diagnostic test for tear film instability in normal eyes although it is a good indicator in the diagnosis of ocular surface diseases.

Adult↗

PubMed1999

Altered cytokine balance in the tear fluid and conjunctiva of patients with Sjögren's syndrome keratoconjunctivitis sicca.

PURPOSE: To compare epidermal growth factor (EGF) concentration in tear fluid and levels of inflammatory cytokines in the conjunctival epithelium of patients with Sjögren's syndrome keratoconjunctivitis sicca with those of normal controls. METHODS: Schirmer 1 tear testing, corneal fluorescein staining and conjunctival impression cytology for quantitation of goblet cell density were performed in ten patients with Sjögren's syndrome-associated keratoconjunctivitis sicca and ten asymptomatic normal controls. ELISA was used to detect the concentration of EGF in tear fluid and interleukin 6 in lysates of conjunctival cytology specimens obtained from all subjects. The levels of RNA transcripts encoding inflammatory cytokines [interleukin 1alpha_(IL-1alpha), interleukin 6 (IL-6), interleukin 8 (IL-8), tumor necrosis factor alpha_(TNF-alpha), and transforming growth factor beta1 (TGF-beta1)] as well as a housekeeping gene (G3PDH) were evaluated in conjunctival cytology specimens taken from all subjects by semiquantitative competitive reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: Decreased tear fluid EGF concentration was noted in Sjögren's syndrome patients (mean 0.68 +/- 0.59 ng/ml) compared to controls (mean 1.66 +/- 0.45 ng/ml, P = 0.004). Significantly increased levels of IL-1alpha, IL-6, IL-8, TNF-alpha and TGF-beta1 RNA transcripts were found in the conjunctival epithelium of Sjögren's syndrome patients compared to controls (P < 0.05), while the level of G3PDH was similar in both groups. The concentration of IL-6 protein was significantly higher in Sjögren's syndrome conjunctiva samples (P = 0.012). Tear EGF concentration correlated with Schirmer 1 scores (rho 0.767, P < 0.001), corneal fluorescein staining scores (rho -0.562, P = 0.01), conjunctival goblet cell density (rho 0.661, P = 0.001) and the levels of IL-1alpha_and IL-8 RNA in the conjunctival epithelium (rho -0.677 and -0.747, respectively, P = 0.001). Both IL-1alpha_and IL-8 RNA in the conjunctival epithelium increased as Schirmer 1 scores decreased (P </= 0.001). IL-8 RNA level correlated with corneal fluorescein staining (rho 0.690, P = 0.001) and conjunctival goblet cell density (rho -0.767, P < 0.001). A significant decrease in IL-8 RNA level, corresponding to improvement in irritation symptoms and ocular surface disease, was observed in six eyes after two weeks of topical corticosteroid therapy. CONCLUSIONS: The balance of cytokines in the tear fluid and conjunctival epithelium is altered in Sjögren's syndrome. The severity of keratoconjunctivitis sicca in this condition increases as tear fluid EGF concentration decreases and levels of inflammatory cytokines in the conjunctival epithelium increase. These findings provide new insight into the pathogenesis of keratoconjunctivitis and provide potential targets for therapy.

Adult↗

PubMed2005

Ocular surface and MUC5AC alterations in atopic patients with corneal shield ulcers.

PURPOSE: To describe MUC5AC alterations and the ocular surface disorder in atopic patients with or without corneal ulcers. METHODS: Atopic patients' eyes were divided into two groups according to the presence and absence of corneal ulceration. The subjects underwent corneal sensitivity measurements, Schirmer test, tear film break-up time (BUT), fluorescein and Rose Bengal staining of the ocular surface and conjunctival impression cytology and brush cytology. Impression cytology samples underwent PAS and immunohistochemical staining for MUC5AC. Brush cytology specimens underwent evaluation for inflammatory cell expression and quantitative real-time PCR for MUC5AC mRNA expression. The differences related to the tear function and ocular surface examination parameters between patients with and without corneal ulceration and healthy control subjects were studied. In addition, the differences of the study parameters related to ocular surface epithelial health and inflammatory status between patient eyes with atopic keratoconjunctivitis (AKC) and vernal keratoconjunctivitis (VKC) were investigated. RESULTS: The mean corneal sensitivity and BUT values were significantly lower in atopic patients with corneal ulcers, compared to patients without ulcers and controls (p < 0.001). Brush cytology specimens from patients with corneal ulcers revealed significantly higher expression of inflammatory cells compared to patients without ulcers and controls (p < 0.001). Impression cytology samples from eyes with corneal ulcers showed significant squamous metaplasia and reduction in goblet cell density compared to eyes without ulcers and eyes of control subjects. The mean squamous metaplasia grade was significantly higher in eyes with AKC compared to eyes with VKC (p < 0.02). The mean goblet cell density was significantly lower in eyes with AKC compared to eyes with VKC (p < 0.01). Specimens from eyes with corneal ulcers showed PAS positive mucin pickup and did not stain positive for MUC5AC. MUC5AC mRNA expression was significantly lower in eyes with corneal ulcers compared to eyes without ulcers and eyes of control subjects. MUC5AC mRNA expression was also significantly lower in eyes with AKC compared to eyes with VKC. CONCLUSIONS: Ocular surface inflammation, tear film instability, and decreased conjunctival MUC5AC mRNA expression were thought to be important in the pathogenesis of noninfectious corneal shield ulcers in atopic ocular surface disease.

Adolescent↗

PubMed2005

Platelet-activating factor in human normal tears.

PURPOSE: To measure the concentrations of platelet-activating factor (PAF) and lyso-PAF in tears of human eyes. METHODS: Unilateral tear samples were collected from the conjunctival cul-de-sac of 12 healthy volunteers without any past histories of ocular surface diseases and 10 patients with allergic conjunctivitis (AC) by graduated disposable microcapillaries. C18:0-PAF, C18:0-lyso-PAF, C16:0-PAF, and C16:0-lyso-PAF levels were determined by liquid chromatography-tandem mass spectrometry (LC/MS/MS). RESULTS: The concentrations of C18:0-PAF, C18:0-lyso-PAF, C16:0-PAF, and C16:0-lyso-PAF in tears from healthy volunteers were 0.44 +/- 0.39, 51.7 +/- 63.4, 61.9 +/- 75.9, and 10.7 +/- 14.7 ng/ml, respectively. Higher, but not significantly different, concentrations of all the four kinds of PAF molecules were detected in tears from AC patients. Significant correlations were demonstrated between the concentrations of C18:0-PAF and C18:0-lyso-PAF (r = 0.906; p < 0.01 in normal healthy volunteers and r = 0.939; p < 0.01 in AC patients), and between those of C16:0-PAF and C16:0-lyso-PAF (r = 0.944; p < 0.01 in normal healthy volunteers and r = 0.806; p = 0.015 in AC patients). Moreover, C18:0-PAF concentrations correlated significantly with those of C16:0-PAF (r = 0.885; p < 0.01 in normal healthy volunteers and r = 0.927; p < 0.01 in AC patients), while C18:0-lyso-PAF concentrations correlated significantly with those of C16:0-lyso-PAF (r = 0.972; p < 0.01 in normal healthy volunteers and r = 0.891; p < 0.01 in AC patients). CONCLUSIONS: To our knowledge, this is the first report of the concentrations of different species of PAF (C18:0-PAF, C18:0-lyso-PAF, C16:0-PAF, and C16:0-lyso-PAF) in human tears.

Adult↗

PubMedDate not supplied

Corneal stem cells: bridging the knowledge gap.

Stem cell research offers hope to countless patients whose conditions have heretofore been deemed incurable. Better understanding of stem cell behaviors and functions will lead to insights into biological mysteries encompassing the fields of angiogenesis, development, tissue homeostasis, wound healing, and carcinogenesis. Clarity of vision requires smooth ocular surface on which the corneal epithelial cells undergo continuous turnover every 3 to 10 days. Tragically, many patients are blinded and devastated by severe ocular surface diseases due to limbal stem cell deficiency even though, besides opaque cornea, their eyes are otherwise healthy. Corneal stem cell transplantation offers hope by creating clear windows for these eyes; unfortunately, the long-term successful outcome remains limited. The nature of corneal epithelial stem cell is poorly understood, but many circumstantial evidences suggest the presence of "source cells" in the limbal region of the eye. Nonetheless, the precise biomarker of corneal stem cell remains elusive. The stem cell puzzle can be solved with application of the fundamental scientific method-asking salient questions at the right time and finding answers using keen observations and proper tools. Readily accessibility and structural simplicity of the cornea lend themselves to study of the stem cell biology. The ability to identify and isolate corneal stem cell will be a gateway to meaningful investigation into its biology. This advance will also have direct impact on improving the efficacy of promising stem-cell-based therapies, including limbal stem cell transplantation.

Cornea↗

PubMed2005

Preservation of tear film integrity and inhibition of corneal injury by dexamethasone in a rabbit model of lacrimal gland inflammation-induced dry eye.

PURPOSE: The aim of this study was to establish a clinically relevant short-term animal model of dry eye with utility in identifying compounds with potential therapeutic efficacy. METHODS: Rabbit lacrimal glands were injected with the T-cell mitogen Concanavalin A (Con A) and inflammation, tear function, and corneal epithelial cell integrity were subsequently assessed. The inflammatory response was characterized by quantifying biochemical markers of inflammation ex vivo and by confirming inflammatory cell influx by histology. Matrix metalloproteinase-9 (MMP-9) and proinflammatory cytokines IL-1beta, IL-8, and TGF-beta1 were quantified in tissue extracts. Tear function was monitored by measuring tear fluorescein clearance and tear breakup time (TBUT). Corneal epithelial cell integrity was determined by quantifying the uptake of methylene blue dye following the exposure of rabbits to a low-humidity environment. The anti-inflammatory corticosteroid, dexamethasone, was administered topically as indicated for each study. RESULTS: Histopathologic evaluation of lacrimal glands injected with Con A revealed a pronounced inflammatory process characterized by lymphocytic infiltration, multifocal necrosis, and fibroplasia. Elevated levels of MMP-9 and cytokines IL-1beta, IL-8, and TGF-beta1 were detected in the lacrimal gland and cornea. Inflammation of the rabbit lacrimal gland following an injection of Con A significantly reduced tear clearance and TBUT and increased susceptibility to desiccation-induced corneal damage. Dexamethasone was prophylactically and therapeutically effective in this inflammation model of dry eye, restoring tear function and inhibiting corneal injury following topical ocular application. CONCLUSIONS: Characteristics of this rabbit lacrimal gland inflammation model of dry eye are consistent with the current understanding of dry eye as a local ocular surface inflammatory response to abnormal tear volume and composition. These results suggest that this rabbit model of dry eye may be employed to assess the therapeutic efficacy of mechanistically diverse agents on clinically relevant signs of ocular surface disease. These methods were strategically developed to be applicable for advancing drug discovery for a broad spectrum of dry eye patients.

Animals↗

PubMed1994

Photoinactivation of herpes simplex virus by rose bengal and fluorescein. In vitro and in vivo studies.

Rose bengal and fluorescein are photosensitive dyes in widespread use in the evaluation of ocular surface diseases, including herpes simplex virus (HSV) keratitis. These dyes have recently been shown to penetrate living cells, and rose bengal was previously reported to possess antiviral activity. Several experiments reported herein suggest that these dyes do possess the potential for potent antiviral activity against extracellular virus, but only in the presence of light. Rose bengal is substantially more effective in vitro than fluorescein, and the effect is greater with increasing concentration of dye and duration of light exposure. Electron microscopic evaluation of treated virus showed no structural difference from untreated virus, in spite of 4- to 5-log decreases in virus titer. Intracellular virus was found to be markedly resistant to photoinactivation. In a rabbit model of acute primary HSV keratitis, daily application of topical rose bengal followed by light exposure had no therapeutic effect, although an adverse effect on culture sensitivity testing was seen.

Animals↗

PubMed1998

Bacterial load and protein deposits on 15-day versus 1-day disposable hydrophilic contact lenses.

PURPOSE: This study quantified the bacterial load and protein deposits on 1- and 15-day disposable contact lenses after use in normal wearers. METHODS: Sixteen patients were randomly assigned to a 1-day contact lens (1-Day Acuvue) in one eye and to a 15-day contact lens (Acuvue) in the contralateral eye. Only one specified solution was allowed for the care of 15-day lenses. All patients were evaluated every month for 6 months (at times T1, T2, T3, T4, T5, T6). At times T1, T3, and T5, the lenses were removed in a sterile fashion and sent for laboratory quantification of Staphylococcus aureus and Pseudomonas aeruginosa. At T2, T4, and T6, quantification of protein deposits was determined, and at T0 and T6, impression cytology of the conjunctiva was performed. RESULTS: P. aeruginosa was not identified on any lens. At T1, T3, and T5, S. aureus was significantly greater on the 1-day versus 15-day lenses (p < 0.001). In contrast, protein deposits were significantly greater on the 15-day lenses at all time points (T2, T6: p < 0.01; T4: p < 0.05). Impression cytology of the 15-day lens eyes revealed a worsening trend compared to the 1-day lens; however, no statistically significant differences were found between the two groups (p = 0.29). CONCLUSION: Results of this study suggest that the use of cleaning and preservative solutions can alter the ocular surface bacterial environment of the contact lens wearer and that these changes are not a direct consequence of contact lens wear. The bactericidal activity of these solutions could, with time, also affect ocular surface cells, leading to contact lens intolerance and ocular surface disease.

Adult↗

PubMed2002

The clinical efficacy of silicone punctal plug therapy.

PURPOSE: To evaluate the clinical efficacy and safety of silicone punctal plugs in various ocular surface disorders. PATIENTS AND METHODS: Medical records of patients who underwent silicone punctal plug insertion from January 1996 to November 2000 were retrospectively reviewed. The clinical data collected included sex and age of the patients, indications for plug insertion, symptoms, corneal fluorescein staining and frequency of lubricant use at baseline and at 4 +/- 2 weeks after the insertion, location (upper versus lower punctum), initial versus replacement plug, spontaneous extrusion or removal of the plug, and percentage of complications and punctum cauterization. RESULTS: There were 203 eyes of 153 patients (126 women and 27 men) in the study group. The total number of silicone punctal plug procedures was 312. Dry eye syndrome was the most common indication for punctal plug treatment (127 eyes, 62.5%), followed by epitheliopathy after penetrating keratoplasty (32 eyes, 15.8%). The symptoms improved in 150 (73.9%) of 203 eyes at 4 +/- 2 weeks' follow-up. The mean score of the fluorescein staining of the cornea was reduced from 2.7 +/- 0.1 to 1.3 +/- 0.1 with silicone punctal plug treatment at 4 +/- 2 weeks' follow-up. This reduction was statistically significant (p< 0.01). The overall success rate at 4 +/- 2 weeks follow up was 76.8%. The frequency of the lubricant use was significantly decreased with punctal plug treatment (p< 0.001). Considering all plugs, the estimated probability of plug retention was 49.4% with 85.1 +/- 7.3 weeks as the mean survival time. There was no statistical difference in plug retention rates between lower (49.6%) and upper (48.7%) plugs (p= 0.15). Retention rate of first plugs (53.5%) was significantly higher than that of second plugs (32.0%) (p= 0.05). The spontaneous total extrusion of silicone punctal plug was the most common complication in our study (158 plugs, 50.7%). The plug was removed in 14 eyes (14 plugs, 6.9%) because of epiphora in 11 eyes and conjunctival erosion in three eyes. The percentage of punctum cauterization performed in our population was 10.8%. CONCLUSIONS: Punctal plug insertion is a simple, effective, safe, and reversible method to treat aqueous tear deficiency and other ocular surface diseases, such as epitheliopathy after penetrating keratoplasty, superior limbic keratoconjunctivitis, neurotrophic keratitis, recurrent corneal erosions, and toxic epitheliopathy not controlled by lubrication with preservative-free tears. However, spontaneous extrusion of silicone plug occurs commonly. Careful choosing of the optimal plug size and close follow-up are recommended to ensure the success of the treatment.

Adult↗

PubMed2002

Topical cyclosporin A in the management of therapeutic keratoplasty for mycotic keratitis.

PURPOSE: To investigate the efficacy of topical cyclosporine A 0.5% as a substitute for corticosteroids in the management of therapeutic keratoplasties for mycotic keratitis. METHODS: Prospective, nonrandomized interventional case series. Three patients with culture-proven mycotic keratitis underwent therapeutic keratoplasties. All were treated with topical cyclosporine A 0.5% postoperatively as a primary or an adjunctive therapy for prevention of allograft rejection. The patients were followed up from 15 to 42 months for maintenance of graft clarity and best-corrected visual acuity. RESULTS: Two of three patients maintained clear grafts while using topical cyclosporine A 0.5% twice daily with best-corrected visual acuity of 20/40 and 20/50. One patient developed an opacified graft secondary to preexisting ocular surface disease. CONCLUSIONS: Topical cyclosporine A 0.5% may be a useful adjunct in the management of therapeutic keratoplasties for mycotic keratitis.

Administration, Topical↗

PubMed2003

Analysis of limbal stem cell deficiency by corneal impression cytology.

PURPOSE: The impaired function of corneal epithelial stem cells, located in the limbus, is responsible for corneal surface damage and is clinically characterized by recurrent epithelial defects, conjunctivalization, neovascularization, and corneal opacity. The aim of this study was to investigate corneal limbal stem cell deficiency (LSCD) by means of the impression cytology (IC) technique, using antibodies against cytokeratin 19 (CK19) and cytokeratin 3 (CK3), and to evaluate the diagnostic potential of this approach. METHODS: Over a 3-year period (October 1998-June 2001), we collected 113 pairs of IC samples from the eyes of 85 patients with a range of ocular surface diseases and performed an immunocytochemical analysis of CK19 and CK3. Samples with more than 50% cellularity were considered suitable for diagnostic purposes, while samples with less than 50% cellularity were considered with caution. CK19-positive cells in corneal IC were considered an expression of LSCD. We arbitrarily scored LSCD as mild (<25% of CK19-positive cells), moderate (25-50%), and severe (>50%). RESULTS: One hundred thirteen pairs of IC specimens were obtained from 85 patients; 32 patients (37.6%) had alkaline burns, 18 (21.2%) had other chemical or physical corneal injuries, 13 (15.3%) had complications from wearing contact lenses, 8 (9.4%) had severe microbial keratitis, and 14 (16.5%) had suspicious limbal deficit due to other causes. Nine patients underwent bilateral sampling and 12 had to be resampled. Thirteen pairs of IC specimens were obtained during the follow-up of 8 patients who had undergone limbal stem cell transplantation. In 3 of these patients, IC confirmed reversion to corneal immunophenotype (CK3+/CK19-), whereas in 4, residual limbal damage was still evident; 1 patient relapsed. In the remaining 100 pairs of impressions, we found 77 cases of LSCD, whereas in 16 pairs, we did not find LSCD. Seven pairs were defined as "not valuable" because of the poor quality of both CK samples. Diffuse LSCD, moderate or severe in degree, was found in 26 of 32 patients (81.2%) with alkali burns, whereas mild diffuse LSCD or sectoral LSCD was found in 13 of 18 patients (72.2%) with other chemical-physical injuries, in 10 of 13 patients (76.9%) wearing contact lenses, in 7 of 8 patients (87.5%) with severe microbial keratitis, and in 12 of 14 patients (85.7%) with other corneal pathologies. The quality of impressions was assessed in 77 cases and found to be good or discrete for both CKs in 32 cases (41.5%) and poor in 45 (58.5%): in 46.7% of these cases, the IC was poor only for CK19 and in 45.4% only for CK3. CONCLUSIONS: Immunocytochemistry for seeking out CK19- and CK3-positive cells on corneal IC is a simple and practical method to investigate LSCD. We believe that this technique could have an important role in evaluating patients undergoing therapeutic penetrating keratoplasty to select those who would benefit from limbal stem cell transplantation. Since sampling has been shown to be a critical point, we believe that any improvement in this area will also help to improve the methodology and will contribute to its wider utilization.

Burns, Chemical↗

PubMed2003

Alterations in conjunctival cytology and tear film dysfunction in patients with beta-thalassemia.

PURPOSE: Patients with beta-thalassemia (beta-tha) represent a group with lifelong transfusion-dependent anemias. This study aimed to describe the conjunctival changes and tear film parameters in these patients. METHODS: A total of 52 patients (104 eyes) with beta-tha major and 22 normal control subjects (44 eyes) were studied during 1999 through 2000. Tear film break-up time (BUT), Schirmer test, rose Bengal staining, and cytologic evaluation of the conjunctival epithelium were performed in all subjects. The Papanicolaou and May-Grümwald-Giemsa staining procedures were performed on all smears. Patients and control subjects were compared for tear function parameters and conjunctival changes. RESULTS: The BUT, Schirmer test, and rose Bengal staining values were significantly lower (P < 0.001) in beta-tha patients than in control subjects. Keratinized cells were observed in conjunctival samples in 41% of patients, with a decrease in the number of goblet cells per slide in 64% of patients. In 9% of beta-tha patients, there were a slightly greater number of inflammatory cells than in control eyes. CONCLUSION: Ocular surface disorder of these patients was characterized by goblet cell loss and conjunctival squamous metaplasia. Our findings were correlated positively with the variable age. Epithelial damage by toxic reaction and disorder of tear quality and quantity are implicated as important factors in the pathogenesis of the ocular surface disease in beta-tha patients.

Adolescent↗