Biomedical subjects

Norihiko Yokoi

Publications and source records attributed to Norihiko Yokoi.

At least 19 recordsLinked to original sources

PubMed2006

Transplantation of autologous serum-derived cultivated corneal epithelial equivalents for the treatment of severe ocular surface disease.

PURPOSE: To evaluate the use of autologous serum (AS)-derived cultivated corneal epithelial transplantation for the treatment of severe ocular surface disease. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: Nine eyes from 9 patients with total limbal stem cell deficiency were studied. These consisted of 2 eyes with Stevens-Johnson syndrome, 1 with chemical injury, 1 with ocular cicatricial pemphigoid, 1 with Salzmann corneal dystrophy, 1 with aniridia, 1 with graft-versus-host disease, and 2 with idiopathic ocular surface disease. METHODS: Autologous serum obtained from patients was used for cultivating corneal epithelial cells on an amniotic membrane substrate. These AS-derived corneal epithelial equivalents were compared with those derived from fetal bovine serum (FBS)-supplemented medium. At the time of surgery, complete removal of the corneal pannus and conjunctiva up to 3 mm from the limbus was performed. Allogeneic (7 cases) and autologous (2 cases) AS-derived cultivated corneal epithelial equivalents were transplanted onto the ocular surface. Postoperative follow-up included serial slit-lamp examinations with fluorescein staining, as well as photographic documentation. MAIN OUTCOME MEASURES: Ocular surface reconstruction with corneal epithelialization, graft integrity, visual acuity, and postoperative complications. RESULTS: The corneal epithelial sheets cultivated in AS- and FBS-supplemented media were morphologically similar, and demonstrated the normal expression of tissue-specific keratins and junctional specialization assembly proteins. After transplantation, complete corneal epithelialization was achieved within 2 to 5 days. All eyes demonstrated an improvement in visual acuity by > or =2 lines. During the follow-up period of 14.6+/-4.36 months, the corneal surface of all patients remained stable and transparent, without significant complications. CONCLUSIONS: Transplantation of AS-derived cultivated corneal epithelial equivalents was shown to be a feasible method of treating patients with severe ocular surface disease. The use of AS is of clinical importance in the development of autologous xenobiotic-free bioengineered ocular surface equivalents for clinical transplantation.

Adult↗

PubMed2006

Design of metal cofactors activated by a protein-protein electron transfer system.

Protein-to-protein electron transfer (ET) is a critical process in biological chemistry for which fundamental understanding is expected to provide a wealth of applications in biotechnology. Investigations of protein-protein ET systems in reductive activation of artificial cofactors introduced into proteins remains particularly challenging because of the complexity of interactions between the cofactor and the system contributing to ET. In this work, we construct an artificial protein-protein ET system, using heme oxygenase (HO), which is known to catalyze the conversion of heme to biliverdin. HO uses electrons provided from NADPH/cytochrome P450 reductase (CPR) through protein-protein complex formation during the enzymatic reaction. We report that a Fe(III)(Schiff-base), in the place of the active-site heme prosthetic group of HO, can be reduced by NADPH/CPR. The crystal structure of the Fe(10-CH(2)CH(2)COOH-Schiff-base).HO composite indicates the presence of a hydrogen bond between the propionic acid carboxyl group and Arg-177 of HO. Furthermore, the ET rate from NADPH/CPR to the composite is 3.5-fold faster than that of Fe(Schiff-base).HO, although the redox potential of Fe(10-CH(2)CH(2)COOH-Schiff-base).HO (-79 mV vs. NHE) is lower than that of Fe(Schiff-base).HO (+15 mV vs. NHE), where NHE is normal hydrogen electrode. This work describes a synthetic metal complex activated by means of a protein-protein ET system, which has not previously been reported. Moreover, the result suggests the importance of the hydrogen bond for the ET reaction of HO. Our Fe(Schiff-base).HO composite model system may provide insights with regard to design of ET biosystems for sensors, catalysts, and electronics devices.

Binding Sites↗

PubMed2006

Autologous serum-derived cultivated oral epithelial transplants for severe ocular surface disease.

OBJECTIVE: To evaluate the use of autologous serum (AS)-derived cultivated oral epithelial transplants for the treatment of severe ocular surface disease. METHODS: We used AS from 10 patients with severe ocular surface disease and total limbal stem cell deficiency to develop autologous cultivated oral epithelial equivalents. These were compared with epithelial equivalents derived from conventional fetal bovine serum-supplemented medium. Surgery involved removal of the corneal pannus and surrounding diseased tissue and transplantation of the AS-derived epithelial equivalents. The oral equivalents were analyzed by review of histologic and immunohistochemical findings. RESULTS: Oral epithelial sheets cultivated in AS- and fetal bovine serum-supplemented media were similar in morphology, and both formed basement membrane assembly proteins important for maintaining graft integrity. Complete corneal epithelialization was achieved within 2 to 5 days postoperatively. The ocular surface remained stable without major complications in all eyes during a mean +/- SD follow-up of 12.6 +/- 3.9 months. The visual acuity improved by more than 2 lines in 9 of 10 eyes, with transplanted oral epithelium surviving up to 19 months. CONCLUSION: The successful use of an AS-derived oral epithelial equivalent to treat severe ocular surface disease represents an important advance in the pursuit of completely autologous xenobiotic-free bioengineered ocular equivalents for clinical transplantation.

Adult↗

PubMed2006

Midterm results on ocular surface reconstruction using cultivated autologous oral mucosal epithelial transplantation.

PURPOSE: To perform a midterm assessment of the integrity and reproducibility of cultivated autologous oral mucosal epithelial sheets, and to evaluate the clinical efficacy of their transplantation in ocular surface. DESIGN: Observational case series. METHODS: Cultivated autologous oral mucosal epithelial sheets were created using amniotic membrane and buccal mucosal epithelium from 12 patients with Stevens-Johnson syndrome, chemical and thermal injury, pseudo-ocular cicatricial pemphigoid, and idiopathic ocular surface disorder. They were transplanted onto 15 eyes from these patients who were then followed up for a mean of 20 months; with the longest follow-up being 34 months. We assessed their clinical outcomes with special reference to neovascularization. RESULTS: Cultivated autologous oral mucosal epithelial sheets could be generated from all patients. On the second postoperative day, 14 of 15 sheets transplanted demonstrated total re-epithelialization on the cornea. During the follow-up, the ocular surface was stable and transparent without any major complications in 10 of 15 eyes (67%), and the transplanted epithelium survived for at least 34 months. There were five eyes (33%) with small but long-standing epithelial defects, three of these healed spontaneously, and two (13%) required reoperation. In 10 eyes, postoperative visual acuity was improved by more than 2 lines. All eyes manifested some peripheral corneal vascularization. CONCLUSIONS: We established a successful tissue-engineering technique to generate cultivated autologous oral mucosal epithelial sheets and succeeded in reconstructing the ocular surface. We suggest that this surgical modality may be both safe and useful, especially in younger patients with the most severe ocular surface disorders.

Adolescent↗

PubMed2006

The features of dry eye disease in a Japanese elderly population.

PURPOSE: The purpose of this study is to assess the features of dry eye disease in a Japanese elderly population. METHODS: One hundred thirteen left eyes of 113 pensioners (50 males, 63 females; mean age, 67.5 +/- 5.7 years) aged over 60 years were recruited in this study. The subjects underwent careful slit-lamp examinations of the conjunctiva, ocular surface, and the eye lids. Tear film breakup time (BUT) examinations, Schirmer test-I, and fluorescein staining of the ocular surface and transillumination of the eyelids were also performed. Dry eye symptomatology was assessed with a symptom questionnaire. Japanese Dry Eye Diagnostic Criteria were used in this study. RESULTS: Ocular tiredness, irritation, dryness, and foreign body sensation were the most frequently reported symptoms by the patients. A total of 73.5% of the eyes had definite dry eyes. A total of 39.8% of the eyes had a Schirmer test reading <5 mm. Mean Schirmer test value was 9.4 +/- 7.8 mm. The mean BUT score was 4.0 +/- 2.8 seconds. A total of 76.9% of the eyes had positive fluorescein staining of the cornea. Meibomian gland dysfunction and conjunctivochalasis were found as frequent factors in relation to dry eye disease with meibomian grand dropout showing positive correlation with tear instability. CONCLUSION: Qualitative and quantitative disorders of the tear film were far more common than recognized in this population of elderly subjects, meibomian gland dysfunction being the most common associate of the tear film disorder and dry eye status. Conjunctivochalasis (conjunctival laxity), although commonly associated with dry eye disease in the elderly, was observed not to be related to age or gender in this study.

Age Factors↗

PubMed2006

Novel clinical application of sterilized, freeze-dried amniotic membrane to treat patients with pterygium.

PURPOSE: To evaluate the use of sterilized, freeze-dried amniotic membrane (FD-AM) transplantation for pterygium surgery. METHODS: This study involved a prospective, non-comparative, interventional case series. Thirteen eyes of 13 patients with primary (eight eyes) or recurrent (five eyes) pterygium were studied. After excision of the pterygium fibrous tissues and application of intraoperative use of mitomycin-C, sterilized FD-AM was sutured over the bare scleral defect. The integrity of the FD-AM graft, epithelialization over the FD-AM, pterygium recurrence and postoperative complications were evaluated. RESULTS: Postoperatively, the FD-AM was well retained in all patients, and complete epithelialization over the transplanted membrane was achieved within 1-2 weeks. All patients demonstrated early resolution of ocular inflammation and there was no recurrence of pterygium in any of the treated patients during the mean follow-up of 13.9 +/- 6.0 months. No ocular complications were noted following transplantation. CONCLUSION: Sterilized FD-AM showed excellent biocompatibility on the human ocular surface. This novel and promising biomaterial may be a useful alternative to conjunctival grafting in the treatment of pterygium.

Adult↗

PubMed2006

Clusters of corneal epithelial cells reside ectopically in human conjunctival epithelium.

PURPOSE: The ocular surface is covered by two biologically distinct epithelia: corneal and conjunctival. The expression of keratin12 (K12) is currently considered a hallmark of cornea-type differentiation. In the current study, the biological features of K12-positive cells in human bulbar conjunctival epithelium were examined. METHODS: Human conjunctival tissues were subjected to investigate the K12-positive cells in conjunctiva by immunostaining, in situ hybridization, Western blot analysis, reverse transcriptase-polymerase chain reaction (RT-PCR), and fluorescence-activated cell sorting (FACS). Gene expression profiling of these cells was performed with introduced amplified-fragment length polymorphism (iAFLP). To determine the presence of stem- or progenitor cells, immunostaining and colony-forming assays were performed. RESULTS: Western blot analysis, RT-PCR revealed that K12 was expressed in conjunctival epithelium. Immunostaining analysis showed that K12-positive cells reside mainly in clusters in conjunctival epithelium. FACS analysis showed that 0.2% to 1.7% of conjunctival epithelial cells collected from the inferior bulbar conjunctiva were K12 positive. iAFLP analysis revealed that the gene expression patterns of these cells were highly similar to that of corneal epithelial cells. p63 and ABCG2 were expressed beneath the K12-positive cells. Some colony-forming cells expressed K12. CONCLUSIONS: The K12-positive cells appear to be ectopically residing, self-maintaining corneal epithelial cells in the conjunctival epithelium.

Aged↗

PubMed2006

Establishment of a cultivated human conjunctival epithelium as an alternative tissue source for autologous corneal epithelial transplantation.

PURPOSE: The corneal epithelium is essential for maintaining corneal transparency, and efforts have been made to develop improved techniques for corneal epithelial transplantation in patients with total limbal failure. We evaluated the suitability of transplanted cultivated human conjunctival epithelium (HCjE) as a corneal epithelium replacement in rabbits with total corneal and limbal deficiency. METHODS: HCjE cells, cultivated on human amniotic membrane (AM) to confluence and exposed to an air-liquid interface (air-lifted), were transplanted onto denuded rabbit corneas and monitored for 2 weeks. The cultivated HCjE sheet and the engrafted epithelium were analyzed by immunohistochemistry and transmission electron microscopy (TEM). RESULTS: The transplanted HCjE remained transparent, smooth, and without epithelial defects during the follow-up period. Both the cultivated HCjE cells and the engrafted epithelium manifested five to six layers of stratified squamous epithelium similar in morphology to normal corneal epithelium. The basal cells expressed the putative stem cell markers (ABCG2 and P63) and hemidesmosome and desmosome component proteins. The cytokeratins (CK4, CK13, CK3, and CK12) and MUC4 were found in the engrafted epithelium. However, MUC5AC was not expressed. The results indicate that HCjE cultivated on AM has the potential to be used as an alternative corneal epithelium. CONCLUSIONS: The transplantation of cultivated HCjE sheets is a promising technique for the treatment of eyes with limbal failure.

ATP Binding Cassette Transporter, Subfamily G, Mem↗

PubMed2006

The early efficacy of topical levocabastine in patients with allergic conjunctivitis.

BACKGROUND: We investigated the early efficacy of topical levocabastine, an H(1) histamine-receptor antagonist, in improving the clinical symptoms of allergic conjunctivitis. METHODS: Thirty-six patients with allergic conjunctivitis were enrolled. One drop of levocabastine was instilled in one eye and one drop of artificial tears in the contralateral eye. Clinical examinations were performed before, and 15 and 30 minutes after instillation. Symptoms of itching and signs of injection were assessed at each time point. RESULTS: Both levocabastine and artificial tears resulted in a statistically significant reduction in ocular itching. However, levocabastine was significantly more effective. CONCLUSIONS: Although artificial tears had a positive effect in reducing symptoms of allergic conjunctivitis, by the washing out of allergens, levocabastine was more effective than artificial tears in controlling acute symptoms of allergic conjunctivitis, demonstrating that the selective H1 histamine-receptor antagonist action of levocabastine is rapidly effective in a clinical setting.

Administration, Topical↗

PubMed2005

Pathological keratinisation in the conjunctival epithelium of Sjögren's syndrome.

Our previous gene expression analysis suggested that conjunctival epithelial cells of Sjögren's syndrome (SS) are inclined to hyper-proliferation and keratinisation status. The goal of this study is to elucidate whether such pathological situations really exist in the conjunctival epithelium of SS. Also, involvement of inflammatory cytokines in this disease was investigated. Conjunctival tissues or cells obtained from 12 SS patients and 13 normal subjects were subjected to indirect immunostaining to analyse expression of transglutaminase 1 (TGase1), involucrin, keratins 1, 4, 10 and 13. The number of proliferative cells was also analysed by immunostaining of Ki67 antigen. Additionally, changes in gene expression of TGase1 and involucrin after stimulation by IL-1 or IFN-gamma were quantified by real-time RT-PCR. TGase1 and involucrin were up-regulated in the conjunctival epithelium of SS patients. Although not statistically significant, Ki67 positive proliferative cells were slightly increased in SS patients. IFN-gamma stimulation significantly up-regulated TGase1 and unexpectedly repressed involucrin gene expression. IL-1 did not render any significant changes in the expression of these genes. These results suggest the existence of pathological keratinisation in the conjunctival epithelium of SS and also support our hypothesis that inflammatory cytokines may be involved in the ocular surface pathological changes in SS.

Aged↗

PubMed2005

Platelet aggregates in various stages of diabetic retinopathy: evaluation using the particle-counting light-scattering method.

AIMS: To investigate the possible correlation between platelet aggregation and the severity of diabetic retinopathy using the light-scattering method. METHODS: Using a light-scattering platelet aggregometer, we measured spontaneous platelet aggregation in 86 diabetics with retinopathy of varying severity and 30 healthy volunteers (controls). Platelet aggregates were classified as small, medium, and large according to their light intensity; patients were grouped based on the severity of retinopathy. In each patient group, we recorded for 10 min the total light intensities emitted by each aggregate size in the area under the curve (AUC). Then, we compared the AUC of each level of retinopathy severity with the controls and determined the correlation between the AUC of each aggregate size and each severity level. RESULTS: Of the 86 diabetics, 22 had no apparent retinopathy (NAR), 13 had mild nonproliferative diabetic retinopathy (NPDR), 17 had moderate NPDR, 12 had severe NPDR, and 22 had proliferative diabetic retinopathy (PDR). While the NAR group manifested significantly more small aggregates than the controls (20.5 x 10(6) versus 8.3 x 10(6) a.u., p=0.024), none of the other groups showed a significant increase in aggregates of any size. In the AUC of large aggregates, there was a weak-positive correlation with the severity of retinopathy (r=0.255, p=0.018); in the AUC of small and medium aggregates, there was no correlation. CONCLUSION: Although we did not find a significant correlation between platelet aggregation and the severity of diabetic retinopathy, our pilot study did detect some tendencies. Further studies on larger populations are underway to determine whether these tendencies are real.

Aged↗

PubMed2005

Phlyctenular keratitis associated with meibomitis in young patients.

PURPOSE: To describe the unique clinical features of phlyctenular keratitis, including the association with meibomitis, in young patients. DESIGN: Observational case series. METHODS: The study population consisted of 23 Japanese patients aged under 35 years with phlyctenular keratitis. We examined their clinical history, signs and symptoms, human leukocyte antigen (HLA), bacterial cultures of meibum, and the efficacy of antibiotics. The minimal diagnostic criteria included corneal nodules consisting of cellular infiltrates and superficial neovascularization. RESULTS: Of the 23 patients, 20 (87%) were women, and 13 (56.5%) had a history of chalazia. In all cases, the lesions and the severity of corneal nodules and neovascularization corresponded well with the location and the severity of meibomitis. The frequency of HLA-A26 and HLA-B35 was significantly increased in our patients (P = .003 and .016, respectively). Propionibacterium acnes in bacterial cultures of pure meibum in 12 of the 20 patients (60%) was statistically more highly positive than those in four of the 17 age-matched normal control subjects (23.5%; P = .028). CONCLUSION: The characteristics of phlyctenular keratitis in our cases include significantly higher prevalence in female patients, severity variation of ocular surface manifestation corresponding to meibomitis, specific HLA association, and possible P. acnes involvement.

Adolescent↗

PubMed2005

Clinical impact of conjunctivochalasis on the ocular surface.

PURPOSE: To report the clinical impact of conjunctivochalasis on the ocular surface by evaluating the effect of a new concept of conjunctivochalasis operation on the resolution of patients' symptoms and corneal epithelial damage. Also, the association of inflammation with conjunctivochalasis is examined. PATIENTS AND METHODS: A total of 168 eyes of 131 conjunctivochalasis patients with (50 eyes) or without (118 eyes) dry eye who received the newly designed conjunctivochalasis operation were enrolled. All patients had prominent conjunctivochalasis at the lower tear meniscus and their ocular symptoms were not sufficiently controlled by the usual eyedrop therapy. Subjective symptoms of patients were assessed before and after the operation by questionnaires. Scores of corneal fluorescein staining were evaluated before and after the operation in patients with dry eye. Four samples of the lower part of conjunctiva from non-dry eye conjunctivochalasis patients were investigated by immunostaining and compared with samples from 4 normal conjunctiva and 3 conjunctiva showing inflammation due to Mooren ulcer, ocular cicatricial pemphigoid, and alkali burn. RESULTS: The most frequent chief subjective symptoms before the operation were irritation (51.7%) and lacrimation (31.4%) in conjunctivochalasis patients without dry eye and irritation (80.0%) in those with dry eye. Improvement of the chief symptoms was obtained in 88.2% and 78.0% of these 2 patient groups, respectively. Furthermore, in patients with dry eye, corneal fluorescein staining scores (mean+/-SD) were significantly improved after the operation compared with before the operation: A (area), 0.6+/-0.7 and D (density), 0.8+/-0.9 versus A, 1.3+/-0.5 and D, 1.9+/-0.9; P<0.0001. Based on the immunostaining study, conjunctival samples from eyes with conjunctivochalasis and normal eyes showed negligible inflammation compared with those from inflamed conjunctiva. CONCLUSIONS: This study suggests that conjunctivochalasis has a great clinical impact on the ocular surface, and the newly developed operation is very effective in resolving patient complaints and also ocular surface damage in conjunctivochalasis with dry eye. It may also be suggested that the conjunctivochalasis has a negligible association with conjunctival inflammation.

Aged↗

PubMed2005

[Study of change of size of the punctum before insertion and after extrusion of a punctal plug and selection of an appropriate plug for reinsertion].

PURPOSE: In cases when the reinsertion of punctal plugs is considered, enlargement of the punctum is often experienced and a larger punctal plug is sometimes required for reinsertion. We therefore investigated the change in the size of the punctum before insertion and after extrusion of a punctal plug and the selection of an appropriate punctal plug for reinsertion. SUBJECTS AND METHODS: There were 70 cases where punctal plugs were reinserted (37 eyes from 32 patients) because of extrusion of the plugs. A retrospective study was performed with regard to the change in the size of the punctum before insertion and after extrusion of the punctal plugs, and with regard to the type of plug reinserted. RESULTS: There were significant changes in the size of the punctum before insertion [0.70 +/- 0.09 (mean +/- standard deviation) mm] and after extrusion (0.78 +/- 0.07 mm) of the punctal plug (p < 0.001). In 22 cases of 23 cases which experienced extrusion of the 0.8 mm Eagle plug (EP; Eagle Vision), Punctal plugs (PP; FCI) of M size were selected for reinsertion, because there are no EPs larger than 0.8 mm available for reinsertion. DISCUSSION: After extrusion of the punctal plug, the punctum is likely to be enlarged, resulting in the need to select a larger punctal plug. Therefore, cases which experienced extrusion of an EP were likely to eventually have the EP replaced by a PP during follow-up treatment.

Aged↗

PubMed2004

Relationship between tear volume and tear meniscus curvature.

OBJECTIVE: To investigate the relationship between tear volume and tear meniscus curvature by means of the video meniscometer. METHODS: Eleven eyes of 11 patients with severe dry eye were studied (all female; mean +/- SD age, 66.2 +/- 7.7 years; 7 left eyes and 4 right eyes), each of whose puncta had been therapeutically occluded. Four instillations of balanced salt solution were given at intervals of 1 minute in each studied eye, with the concentration increasing in 5-microL steps from 5 to 20 microL. Before and after the instillation of balanced salt solution, tear meniscus changes were recorded by video meniscometer and radius of the meniscus was calculated from the printed images by means of the concave mirror formula. RESULTS: The mean radius of the meniscus increased linearly with increased drop volume (r(2) = 0.65, P<.001), with mean +/- SD radius values of 0.24 +/- 0.08 mm at baseline and 0.48 +/- 0.13, 0.62 +/- 0.13, 0.84 +/- 0.26, and 1.00 +/- 0.32 mm after separate instillations of 5, 10, 15, and 20 microL of balanced salt solution, respectively. For each subject, a significantly different slope defining the relationship between instilled volume and meniscus radius was seen (0.016-0.063 mm/ microL; mean +/- SD, 0.039 +/- 0.015 mm/ microL), which was thought to depend on the difference in capacity of the fluid reservoir over the ocular surface. CONCLUSIONS: This study confirmed that the volume of instilled eyedrops is linearly related to the resulting radius of the tear meniscus, suggesting that this radius is a useful measure in monitoring the tear volume. This is likely to have implications both for dry eye diagnosis and for confirming the efficacy of punctal occlusion in this condition.

Aged↗

PubMed2004

Comparative effect of antiplatelet therapy in retinal vein occlusion evaluated by the particle-counting method using light scattering.

PURPOSE: To evaluate platelet aggregation in patients with retinal vein occlusion (RVO) by the light-scattering method and compare the effects of three antiplatelet drugs on aggregate formation. DESIGN: Prospective, nonrandomized, interventional clinical trial. METHODS: (1) Platelet aggregation was measured in 42 patients with untreated branch RVO (BRVO), 26 patients with central RVO (CRVO), and 30 healthy control subjects using a light-scattering platelet aggregometer. Platelet aggregates were classified as small, medium, and large according to light intensity. Total light intensities of each aggregate size were compared between BRVO, CRVO, and control subjects. (2) In 33 patients with RVO, platelet aggregation before and 2 weeks after the administration of ticlopidine, beraprost, or aspirin were compared. RESULTS: (1) There was a statistically significant difference (P = 0.0073) between the control subjects (8.3 x 10(6) a.u.) and CRVO patients (22.9 x 10(6) a.u.) with respect to small aggregates. There was no statistically significant difference with respect to medium and large aggregate formation between the control subjects and either patient group. (2) Compared with aggregates formed in the absence of antiplatelet drugs, ticlopidine significantly inhibited only the formation of small aggregates and beraprost that of all sizes; aspirin did not significantly inhibit the formation of any aggregate sizes. CONCLUSIONS: Increase in small platelet aggregates may be attributable to RVO pathogenesis. Beraprost and ticlopidine appear to inhibit small aggregate formation in RVO patients and may represent effective antiplatelet treatments. The light-scattering method is useful to investigate the pathogenesis of RVO and the effects of antiplatelet drugs.

Aged↗

PubMed2004

Non-invasive methods of assessing the tear film.

The interaction between the tear film and the ocular surface epithelium is crucial for the maintenance of ocular surface health; interference with this relationship may cause dry eye. Several diagnostic techniques have been developed to assess the tear film and diagnose dry eye but many of these tests are invasive and modify the parameter which they are designed to measure. Non-invasive or minimally invasive tests may overcome this problem and provide more reproducible and objective data. One test of this kind is meniscometry, which is particularly useful in assessing tear volume indirectly by measuring tear meniscus radius. The newly developed video-meniscometer, which enables calculation of the meniscus radius digitally, is useful for the diagnosis of tear-deficient dry eye. Video-meniscometry also has other applications, to the study of tear and eye drop turnover, determining the indication for punctal plugs and in demonstrating dysfunction of the tear meniscus. Interferometry of the tear film lipid layer is useful in screening and evaluating dry eye severity and in selecting dry eye candidates for punctal occlusion. It is also useful for analysing tear lipid layer pathophysiology more clearly, especially in combination with meniscometry. Meibometry is a minimally invasive technique to quantify the amount of meibomian lipid on the lid margin. Lipid is blotted onto a plastic tape and the change in optical density is used to calculate lipid uptake. Laser meibometry has increased the scope of this technique for the assessment of meibomian gland dysfunction; also, the delivery of lipids from the lid reservoir to the preocular tear film can be analysed using interferometry and laser meibometry. The present report reviews the application of these techniques to the study of tear film physiology and dry eye.

Diagnostic Techniques, Ophthalmological↗

PubMed2004

Clinicopathologic study of conjunctivochalasis.

OBJECTIVE: To clarify the structural features of conjunctivochalasis histopathologically. METHODS: A biopsy of redundant conjunctiva from the same anatomic location of 44 +/- 7.5 years (mean +/- SD, 50.87 years), underwent conjunctivoplasty (termed tear meniscus reconstruction). RESULTS: In all 44 cases, histologic examination disclosed normal conjunctival epithelium and negligible inflammation and lymphocyte infiltration; 39 patients manifested microscopic lymphangiectasia. Elastica van Gieson staining demonstrated elastic fiber fragmentation and sparsely assembled collagen fibers in all 44 cases. There was no discernible difference between specimens from patients with and without complications including tear-deficient dry eye, meibomian gland dysfunction, and clinically observable lymphangiectasia and/or pinguecula. CONCLUSION: Based on our histopathologic findings, we hypothesize that mechanical forces between the lower lid and conjunctiva gradually interfered with lymphatic flow. Chronic, prolonged mechanical obstruction of lymphatic flow may result in lymphatic dilation and eventually give rise to clinical conjunctivochalasis.

Adolescent↗