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Cornea - Most Popular Articles
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Intraocular Pressure and Photorefractive Keratectomy: A Comparison of Three Different Tonometers
Purpose. To evaluate the intraocular pressure (IOP) with three different instruments, Goldmann applanation tonometer (GAT), noncontact tonometer, and Tono-Pen after photorefractive keratectomy (PRK) for myopia.
Methods. A prospective case series study to evaluate preoperative and postoperative IOP measurements of 149 eyes at 12 months. We performed GAT, noncontact tonometry, Tono-Pen central, and Tono-Pen temporal periphery measurements. We also performed measurements of the central corneal thickness (CCT) by ultrasonic pachymetry and keratometry. Preoperative IOP reading served as control for all studies.
Results. After PRK, IOP reading was significantly reduced in the treated eyes when compared with the control measurements (11.87 +/- 1.73 vs. 13.37 +/- 1.52 mmHg, p < 0.0001 with GAT; 12.07 +/- 1.6 vs. 13.51 +/- 1.59 mmHg, p < 0.0001 with noncontact tonometer; 12.18 +/- 1.6 vs. 13.48 +/- 1.55 mmHg, p < 0.0001 with Tono-Pen central; 13.48 +/- 1.65 vs. 13.71 +/- 1.56 Hg, p < 0.0104 with Tono-Pen temporal periphery). There was also a significant correlation between IOP reading changes measured by GAT, noncontact tonometer, Tono-Pen central, and change of CCT and between reduction of IOP reading and keratometry (r2> 0.39, p < 0.0001 for each). The correlation between IOP reading change by Tono-Pen temporal periphery and CCT was also significant but r2value was only 0.034. Tono-Pen temporal periphery postoperative IOP measurements had the best correlation with preoperative GAT IOP (r2= 0.57, p < 0.0001).
Conclusions. PRK reduced IOP reading as measured by GAT, noncontact tonometer, and Tono-Pen central; less so when measured by Tono-Pen temporal periphery. Early detection of glaucoma and IOP follow-up in glaucoma patients may be done best by peripheral Tono-Pen measurements over the nonablated cornea.
(C) 2001 Lippincott Williams & Wilkins, Inc.
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Ocular Surface Changes in Pterygium
Purpose. To evaluate ocular surface abnormalities in eyes with pterygium.
Methods. Impression cytology was performed on 56 pterygia in 50 eyes with primary or recurrent pterygium. Superior, inferior, nasal, and temporal bulbar conjunctivae were evaluated.
Results. The ocular surface morphology directly over the pterygium was found to be abnormal in 100% of cases. This was significant compared with abnormalities in 2.4% in the superior bulbar conjunctiva, 54.5% in the inferior bulbar conjunctiva, and 58.1% in the clinically unaffected interpalpebral conjunctiva. The epithelial cells in pterygium demonstrated squamous metaplasia in 73.2% of cases, with marked enlargement and elongation of the cells and pyknotic changes in the nuclei. Squamous metaplasia was also seen in the inferior conjunctiva (31.7%) and the clinically unaffected interpalpebral conjunctiva (54.8%) but without the advanced changes seen over the pterygium (p < 0.001). A low cellular yield was obtained over the pterygium in 98.2% of cases but only 22.7% in the inferior conjunctiva and 22.6% in the clinically unaffected interpalpebral conjunctiva (p < 0.001). Mucinous hyperplasia signifying increased goblet cell density was observed over the surface of the pterygium in 87.5% compared with 2.4% in the superior conjunctiva, 15.9% in the inferior conjunctiva, and 12.9% in the clinically unaffected interpalpebral conjunctiva (p < 0.001).
Conclusion. The cytology of surface cells in pterygium exhibits squamous metaplasia with increased goblet cell density. A graded series of ocular surface changes exists throughout the bulbar conjunctiva in eyes with pterygium, with the most advanced changes occurring directly over the pterygium surface.
(C) 2002 Lippincott Williams & Wilkins, Inc.
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Summary of Corneal Transplant Activity: Eye Bank Association of America
No abstract available
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Keratoprosthesis: Preoperative Prognostic Categories
Purpose. Recent advances aimed at preventing and treating complications after keratoprosthesis surgery have improved prognosis, but it has been suspected that various preoperative diagnoses may carry substantially different postoperative outcomes. This article attempts to clarify the ranking of prognostic categories for patients undergoing keratoprosthesis surgery.
Methods. A retrospective review of the outcome in a recent series of 63 patient eyes operated at the Massachusetts Eye and Ear Infirmary between 1990 and 1997 and followed up for a minimum of 21 months. Anatomic retention of the device and the loss of vision caused by complications were recorded. The patients were divided into four categories according to preoperative cause.
Results. Anatomically, one keratoprosthesis extruded spontaneously. Another 10 were permanently removed because of complications. Of the 63 eyes, 10 never achieved a visual acuity of at least 20/200 vision because of preexisting retinal or optic nerve damage. The remaining 53 had a visual acuity of 20/200 to 20/20 as follows: Stevens-Johnson syndrome (n = 7), after 2 years: 33%, after 5 years: 0%; chemical burn (n = 17), after 2 years: 64%, after 5 years: 25%; ocular cicatricial pemphigoid (n = 20), after 2 years: 72%, after 5 years: 43%; graft failure in noncicatrizing conditions (dystrophies, degenerations, or bacterial or viral infections) when a repeat graft was expected to have a poor prognosis (n = 19), after 2 years: 83%, after 5 years: 68%. The difference in outcome between the Stevens-Johnson syndrome outcome group and the graft failure group or the ocular cicatricial pemphigoid group was statistically significant. In the group of 53 eyes, visual acuity was restored to 20/200 to 20/20 for a cumulative total of 138 years.
Conclusion. Outcome of the keratoprosthesis surgery varied markedly with preoperative diagnosis. Most favorable was graft failures in noncicatrizing conditions, whereas Stevens-Johnson syndrome was the worst. Ocular cicatricial pemphigoid and chemical burns occupied a middle ground. The difference between the groups seemed to correlate with the degree of past preoperative inflammation.
(C) 2001 Lippincott Williams & Wilkins, Inc.
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Adenovirus Epithelial Keratitis
The authors sought to determine whether adenovirus could infect human corneal epithelium in vivo. They reviewed the medical records of six patients with adenovirus-positive viral corneal cultures who were examined at the Bascom Palmer Eye Institute between March 21, 1986, and December 31, 1992. The six patients with adenovirus-positive viral corneal cultures included one patient with dendritic epithelial keratitis, one with geographic epithelial ulceration, three with both geographic ulceration and contiguous dendrites, and one with heaped-up corneal epithelium but no ulceration. Four patients had rose bengal solution applied to their ocular surface, and in all four patients rose bengal uptake was seen at the epithelial edges of the dendrite or geographic ulceration in a manner characteristic of herpes simplex viral keratitis. Serotype determination of the isolates showed adenovirus type 3 (one patient), type 8 (three patients), type 19 (one patient), and indeterminate (one patient). Results of monoclonal antibody staining of cultures against herpes simplex virus (types 1 and 2) antigens was negative for all six cases. Adenovirus epithelial keratitis may result from infection of human corneal epithelium by the virus and rarely may mimic infection of corneal epithelium by herpes simplex virus.
(C) Lippincott-Raven Publishers.
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The IC3D Classification of the Corneal Dystrophies
No abstract available
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Herpes Simplex Virus Epidemiology and Ocular Importance
Purpose. To review the changing epidemiology of herpes simplex disease and correlate it with the epidemiology of ocular herpes simplex disease.
Method. A review of pertinent reports in the world literature about the epidemiology of herpes simplex and specifically about ocular herpes simplex.
Results. In developed countries, many individuals are reaching adolescence and adulthood without prior herpesvirus infection. Herpes simplex genital infection is increasing at a rapid rate in sexually active adolescents and adults, with about one in six adults now infected in the United States. Similar statistics are confirmatory worldwide in developed countries. Active herpes simplex infection is a risk factor for acquisition of human immunodeficiency virus. The Herpetic Eye Disease Study, as well as prior studies from Moorfields Eye Hospital and the Mayo Clinic in Rochester, Minnesota, provides us with the epidemiology of ocular herpes simplex. Recent studies suggest an older age of onset and perhaps overall more severe ocular disease as compared with the older literature.
Conclusions. Herpes simplex is a significant health concern at present with genital infections increasing in epidemic proportions. This is also reflected in a rise in the incidence of neonatal herpes. Herpes simplex virus type 1 (HSV-1) infection is being acquired for the first time in an older age group. A significant and increasing proportion of genital herpes is caused by HSV-1. Serologic studies are no longer as useful in distinguishing orofacial herpes from genital herpes. More acute retinal necrosis syndrome cases are associated with HSV-2. Speculation about the future of ocular herpes is made based on this changing epidemiology.
(C) 2001 Lippincott Williams & Wilkins, Inc.
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Keratitis in Methamphetamine Abusers
We report four cases of severe corneal ulceration in methamphetamine abusers. Methamphetamine abuse has been increasing in California and may exceed cocaine abuse in some regions. Methamphetamine's extensive physiologic effects, inconsistent street purity, and multiple routes of administration offer many possibilities for injury to the cornea. Potential causes of methamphetamine-related keratitis can be divided into four categories resulting from (a) direct pharmacologic and physical effects of methamphetamine; (b) the toxic effects of diluting or "cutting" agents such as lidocaine and quinine; (c) effects related to the route of drug administration (intravenous, inhalation, smoking); and (d) manufacturerelated effects of exposure to unintentional caustic contaminants in the final product. The increasing prevalence of methamphetamine abuse and the severity of the associated ulcers should alert ophthalmologists to the problem of methamphetamine-related keratitis.
(C) Lippincott-Raven Publishers.
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Lamellar Intrastromal Corneal Tattoo for Treating Iris Defects (Artificial Iris)
Purpose: Defects in the iris are associated with clinically significant optical anomalies, such as glare and peripheral light scatter; however, current artificial-iris technology remains inadequate. The purpose of this study was to explore the practicality of a lamellar intrastromal tattoo technique as a treatment modality to correct optical and cosmetic defects resulting from simulated iris abnormalities in eye-bank eyes. Methods. Simulated iris defects (abnormally large pupil, sector iridectomy, iridodialysis, and aniridia) were produced in a series of eye-bank eyes. Depending on the simulated iris defect, one or two lamellar channel(s) were created at 50% depth of the cornea via a peripheral incision (1.8 mm) with specialized proprietary instruments (Kera Vision, Inc., Fremont, CA, U.S.A.). Commercially available tattoo pigment was inserted through the lamellar channel(s) and blended into the detective region of the iris. Results. The tattoo treatment was relatively simple to perform. Tattoo pigment was inserted uniformly through the small incision, and adequate color blending to match the recipient iris was achieved. The intrastromal tattoo effectively obscured light. Conclusion. The lamellar intrastromal tattoo technique appeared to be efficacious for treating different types of iris defects in eye-bank eyes. Further investigation of this technique in nonsighted patient eyes is warranted.
(C) Lippincott-Raven Publishers.
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Chronic Localized Conjunctival Chemosis
Conjunctival chemosis is a commonly encountered clinical finding stemming from the presence of excess fluid in the conjunctiva. It is typically self-limiting or reversible if the underlying condition is treated. The authors present a series of seven cases of chronic localized conjunctival chemosis. Each patient had a localized area of dependent conjunctival edema for >= months. Evaluation of each patient included clinical examination, laboratory studies, and neuroimaging to attempt to elucidate the pathogenesis of the chemosis. Conjunctival biopsy was performed in six of the seven patients. In all of the patients studied, clinical examination uncovered no definitive signs of local inflammation. Laboratory evaluation was normal, and neuroimaging failed to confirm obstruction of venous or lymphatic drainage. Conjunctival biopsies showed chronic tissue inflammation or lymphangiectasia. The diagnosis of chronic localized conjunctival chemosis (CLCC) can be made if localized conjunctival edema persists for 6 months. Evaluation of biopsy specimens supports the theory that CLCC may result from scarring and structural alteration of conjunctival lymphatics, which appears to irreversibly affect the distribution of fluid in the conjunctiva.
(C) Lippincott-Raven Publishers.
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Topical Cyclosporin A in the Treatment of Anterior Segment Inflammatory Disease
Topical cyclosporin A was used in the management of 43 patients with a variety of anterior segment inflammatory disorders that had failed corticosteroid treatment. Treatment with topical cyclosporin A ranged from 1 week to 43 months, with a mean treatment period of 13 months. Thirty-five patients (81%) with disorders including highrisk keratoplasty, atopic and vernal keratoconjunctivitis, ligneous conjunctivitis, ulcerative keratitis, and Mooren's ulcer had a beneficial result, with resolution, reduction, or prevention of inflammation. Six patients (14%) with scleritis, ocular cicatricial pemphigoid, or endotheliitis showed no clinical improvement. Two patients (5%) had significant ocular discomfort, and the drug had to be discontinued in them. None of the other patients developed local side effects. Twenty-seven of these patients were followed with serial cyclosporin A blood levels and serum creatinine. None of these patients developed measurable drug blood levels or renal toxicity.
(C) Lippincott-Raven Publishers.
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Central Corneal Thickness Measurement with a Retinal Optical Coherence Tomography Device Versus Standard Ultrasonic Pachymetry
Purpose. To demonstrate the capability of a standard, commercially available optical coherence tomography device (originally designed to measure retinal thickness) to image the human cornea in vivo and to measure central corneal thickness (CCT) in normal and edematous corneas. The intrapatient precision and interpatient variability of this novel application was compared to standard ultrasonic pachymetry. Also, the correlation of both methods was investigated.
Methods. CCT measurements using optical coherence tomography (OCT) and ultrasonic pachymetry (PACH) were obtained in 36 normal eyes and 16 eyes with corneal edema.
Results. Direct in vivo imaging of the cornea and measurements of CCT by OCT could be performed in all eyes. In normal subjects, CCTOCT was 530 +/- 32 [mu]m and CCTPACH was 581 +/- 34 [mu]m. The two methods showed a highly significant correlation with a standardized regression coefficient of 0.988. The difference between both methods was constant over the range of CCT (mean difference, 49.4 +/- 5.9 [mu]m). The mean intrapatient SD of CCT measurements was 4.90 [mu]m and 4.96 [mu]m for OCT and PACH, respectively. In patients with corneal edema, mean CCTOCT was 601 +/- 59 [mu]m, and mean CCTPACH was 667 +/- 68 [mu]m. The difference between the two techniques increased slightly with increasing corneal edema (mean difference, 66.9 +/- 10.9 [mu]m).
Conclusion. Imaging of the human cornea can be performed by a standard retinal OCT device, and OCT measurement of CCT shows excellent correlation to values obtained by PACH, giving similar readings separated by a constant difference. In corneal edema, the difference between the two methods is additionally increased, but continues to demonstrate excellent consistency.
(C) 2001 Lippincott Williams & Wilkins, Inc.
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Unpreserved Carboxymethylcellulose Artificial Tears Evaluated in Patients with Keratoconjunctivitis Sicca
In order to evaluate the therapeutic value of an unpreserved carboxymethylcellulose-based artificial tear in treatment of keratoconjunctivitis sicca (KCS), 56 patients with severe keratoconjunctivitis sicca were enrolled, at a single study center, in a randomized, double-masked, 8-week comparison with a preserved hydroxypropylmethylcellulose (HMC)-based artificial tear. Patients treated with the carboxymethylcellulose (CMC)-based tear showed significant improvement in fluorescein staining, symptoms, and impression cytology grades. Patients treated with HMC-based tears showed minimal improvement in a few variables. Impression cytology specimens were analyzed by a modified technique that maps the distribution of the various grades present on the specimen. With this technique, improvement in the cytology grades was noted in the group of patients using CMCbased tears. The improvement correlated with observed decreases in symptoms of discomfort and with scores for superficial punctate staining. This study supports the observed therapeutic value of unpreserved CMC-based artificial tears and suggests the possible reversal of squamous metaplasia in patients with KCS. Further studies are required to separate the benefit of the CMC formulation from the benefits of preservative elimination.
(C) Lippincott-Raven Publishers.
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Piggyback Lenses in Keratoconus
Intolerance to rigid contact lenses in keratoconus may occur as a result of epithelial pathology or a suboptimal fitting. The application of a soft lens as a bandage makes it possible to tolerate a rigid lens over it. This study gives the results of 40 eyes in 26 patients who were consecutively fitted with a new aspheric combination lens. Thirty-five eyes (87.5%) showed no discomfort, acceptable wearing time, and visual acuity. Four of these eyes showed an improvement of the corneal condition, eliminating the need for a further piggyback wearing system. Failures were found in five eyes (12.5%), which were caused by giant papillary conjunctivitis (two eyes), severe keratoconus (one eye), difficulty in lens handling and lack of motivation (two eyes). The successful use of an aspheric piggyback combination lens in rigid lensintolerant keratoconus may preclude early surgical therapy.
(C) Lippincott-Raven Publishers.
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The Topcon SP 1000 and Image-NET Systems: A Comparison of Four Methods for Evaluating Corneal Endothelial Cell Density
The objective of this study was to compare four methods of counting corneal endothelial cell density using the Topcon SP 1000 microscope and Image-NET digital graphic software. Two independent observers quantified cell density from 63 endothelial photomicrographs using the various standardized techniques. The first method was that suggested for use with Topcon SP 1000, employing five different reference grids to compare subjectively with the endothelial cell density of the unknown sample. The other three methods involved the automated, semiautomated, and manual procedures developed for use with the Image- NET system software. The manual Image-NET system is presently considered to yield accurate cell morphology data. Confidence limits and standard errors of mean differences between values obtained by different methods were used to evaluate agreement and reproducibility of computerized methods. Sensitivity and specificity were calculated for two different threshold limits of endothelial cell density. Results showed that the automated Image- NET system is not reliable for clinical use because of its poor agreement with other methods and its lack of sensitivity and specificity at the selected threshold limits of endothelial cell density. The comparative Topcon method of using reference grids, although inexpensive and accurate for 500 cell/mm2 increments, was considered too imprecise for most clinical situations. The semiautomated Image-NET system, in half the analysis time required by the manual method, provided endothelial cell count estimates that were not clinically different from those obtained with manual counting.
(C) Lippincott-Raven Publishers.
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Acyclovir Treatment for Linear Endotheliitis on Grafted Corneas
Two patients with previous corneal transplants developed unusual rejection-like episodes of the grafted cornea. Both had a migrating line of keratic precipitates and stromal edema involving both the donor and recipient corneas. Intensive steroid treatment attained little effect, but oral acyclovir treatment dramatically suppressed the disease process. The facts suggest that a virus-related immune mechanism against both the donor and recipient endothelia, rather than simple allograft rejection, may have been responsible for the clinical presentations. Oral acyclovir therapy might be considered in patients with steroid-nonresponsive corneal endotheliitis mimicking allograft rejection.
(C) Lippincott-Raven Publishers.
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The CORTES Study: Corneal Transplant Indications and Graft Survival in an Italian Cohort of Patients
Purpose: To describe the corneal transplantation activity in Italy, to assess the long-term graft survival, and to begin to outline the potential risk factors for graft outcome.
Methods: We followed a consecutive series of penetrating (PK) and lamellar (LK) keratoplasties performed with corneas procured and distributed by the Veneto Eye Bank Foundation, which provides about one third of the corneas grafted in Italy each year.
Results: Data on 4415 PKs and 489 LKs performed in 174 clinical centers are reported. Keratoconus was the major transplant indication (47% and 66%, respectively, for the 2 groups), followed by regraft (14%) and bullous keratopathy (14%) in the PK group and keratitis (8%) and refractive reasons (4%) for the LKs. In the 2 groups, graft survival, after 1 year, was estimated to be 95% and 93%, respectively, showing a decrease of the survival rate during the second and third years of study. Graft survival in patients with keratoconus indication was 98% in the PK group and 95% in the LK group for the whole period of observation, whereas the patients with other indications reported a survival rate ranging from 92% after 1 year to 52% after 3 years (PK) and from 89% to 85% (LK).
Conclusions: CORTES is the most extensive survey on corneal transplantation in Italy that involves a large cohort of patients and a significant number of surgeons with corneal tissues processed and distributed by a single eye bank. In the first 3 years, a picture of the epidemiology of the corneal transplant has been defined. The graft survival rates were comparable to those reported by other studies for the same follow-up period. However, the follow-up of a sample of this cohort for a further 3 years will allow us to precisely estimate the long-term graft survival and to better evaluate the risk factors related to graft failure.
(C) 2006 Lippincott Williams & Wilkins, Inc.
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Spectacle Side Panels and Moist Inserts for the Treatment of Dry-Eye Patients
To increase the moisture level around the eyes, small, wet, acute, triangular sponges, from which water steadily evaporates, were attached to special side panels of modified eyeglasses. The moisture level in the region between the cornea and the spectacle lens was measured in 10 patients with moderately severe dry eyes and in 10 normal controls, by a miniature moisture sensor under ambient conditions of 22.3[degrees]C and 29.8% humidity. The humidity was 32.0 +/- 4.2% with spectacles, frame only (no lenses); 32.3 +/- 6.0% with spectacles; 37.9 +/- 5.1% with spectacles equipped with side panels, and 42.7 +/- 5.7% with side panel moist inserts attached for dry eye patients. Humidity was the highest with moist inserts added to the spectacles of the control group, with or without moderate wind. All dry eye patients noticed symptomatic relief with the inserts, and the rose bengal score and fluorescein staining improved after 2 weeks of their use. Our findings indicate that the combination of side panels and periodically moistened sponge inserts offer a simple and noninvasive approach to increasing the humidity surrounding the eyes, thus decreasing the tear evaporation from the ocular surface and providing amelioration of frequently debilitating symptoms of dry eye.
(C) Lippincott-Raven Publishers.
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Topical FK-506 Prevents Experimental Corneal Allograft Rejection
We evaluated the efficacy of topical cyclodextrin-encapsulated FK-506 in the prevention of experimental corneal allograft rejection. Two weeks after inducing corneal inflammation and neovascularization with 8-0 silk sutures, 23 albino rabbits received a unilateral 8-mm diameter central penetrating corneal allograft from pigmented donors. Rabbits were randomly assigned to no treatment (eight eyes), topical cyclodextrin four times daily for 28 days (seven eyes), or topical FK-506 0.3 mg/ml in a cyclodextrin suspension (eight eyes) four times daily for 28 days. Grafts were examined daily for degree of inflammation, neovascularization, edema, and signs of rejection for up to 100 days. Seven of eight (88%) untreated grafts and five of seven (71%) cyclodextrin-treated grafts rejected at a median of 3 weeks after transplantation, whereas only two (25%) of eight FK-506-treated grafts rejected and did so at a significantly longer interval (p < 0.005). Topical FK-506 prevents or delays corneal allograft rejection after experimental corneal transplantation.
(C) Lippincott-Raven Publishers.
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Cytotoxicity of Intracameral Injection Drugs to Corneal Endothelium as Evaluated by Corneal Endothelial Cell Culture
The cell culture method was used to quantitatively evaluate the cytotoxicity to porcine corneal endothelial cells by drugs in the usual concentrations of intracameral injections (ICI). Time-dependent cytotoxicity of drugs was evaluated quantitatively; dye exclusion assay by trypan blue was used as a viability assay; and cytotoxicity to corneal endothelium was tested using amphotericin-B, amikacin, colistin, sulbenicillin, and cephradine in their original, 10-fold, and 100-fold ICI concentrations. Original and 10-fold ICI concentrations of betamethasone also were used. In original and 10-fold ICI concentrations, only amphotericin-B had significant cytotoxicity. In 100-fold ICI concentrations, amphotericin-B, colistin, and sulbenicillin had significant cytotoxicity. Betamethasone had neither a cytotoxic nor a proliferative effect in its original and 10-fold ICI concentrations. A 0.1-fold ICI concentration of amphotericin-B also showed 42.75% cytotoxicity after a 32-min exposure. Evaluating drug cytotoxicity to corneal endothelium by monolayer cultured cells and the time-dependent cytotoxicity of drugs as a quantitative method is efficient and objective.
(C) Lippincott-Raven Publishers.
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