Large Corneal Research Articles

Bungee cord-induced corneal lacerations correcting for myopic astigmatism

We present a patient with a refractive error of -3.00 -0.25x150 in the right eye and -3.50 -1.50x170 in the left eye who experienced bungee-cord-related corneal lacerations in the left eye. Slitlamp examination revealed a large radial corneal laceration in the vertical meridian and several smaller lacerations in the periphery. Corneal topography showed more central flattening in the left eye than in the right eye. Posttraumatic visual acuity in the left eye was 20/20 with a -1.50 diopter corrective lens. Myopic correction was a surprising outcome of a traumatic corneal laceration that produced a radial-keratotomy-like effect.

Use of Amniotic Membrane Graft and Corneal Transplantation in a Patient With Bilateral Keratomalacia Induced by Uncontrolled Phenylketonuria

To report a patient with a rare complication of bilateral keratomalacia induced by uncontrolled phenylketonuria (PKU) that was successfully treated with amniotic membrane transplantation in 1 eye and penetrating keratoplasty in the second eye. Case report and literature review. A 9-month-old girl with uncontrolled PKU was referred to our clinic because of bilateral keratomalacia. Slit-lamp examination of the right eye revealed 2 large corneal erosions with stromal thinning on the nasal and inferior regions of the right cornea. Left eye examination revealed a large area of melting involving two thirds of the cornea with corneal perforation and iris bulging on the temporal side and no anterior chamber. She underwent amniotic membrane transplantation on her right cornea and penetrating keratoplasty on her left cornea. Treatment after surgery included antibiotic and steroid eye drops and a special diet regimen with partial phenylalanine intake. Examination under anesthesia 4 months after surgery revealed intact cornea in her right eye and a clear corneal graft with a deep anterior chamber on her left eye. Intraocular pressure was normal in both eyes. Bilateral keratomalacia, although a rare ophthalmic manifestation of PKU, can cause a severe corneal injury that may threaten the eyeball integrity. Surgical treatments with amniotic membrane graft and corneal transplantation, along with the appropriate diet treatment, were found to be effective procedures, yielding rapid healing of the corneal surface.

The Skew Ray Ambiguity in the Analysis of Videokeratoscopic Data

Skew ray ambiguity is present in most videokeratoscopic measurements when azimuthal components of the corneal curvature are not taken into account. There have been some reported studies based on theoretical predictions and measured test surfaces suggesting that skew ray ambiguity is significant for highly deformed corneas or decentered corneal measurements. However, the effect of skew ray ambiguity in ray tracing through videokeratoscopic data has not been studied in depth. We have evaluated the significance of the skew ray ambiguity and its effect on the analyzed corneal optics. This has been achieved by devising a procedure in which we compared the corneal wavefront aberrations estimated from 3D ray tracing with those determined from 2D (meridional based) estimates of the refractive power. The latter was possible due to recently developed concept of refractive Zernike power polynomials which links the refractive power domain with that of the wavefront. Simulated corneal surfaces as well as data from a range of corneas (from two different Placido disk-based videokeratoscopes) were used to find the limit at which the difference in estimated corneal wavefronts (or the corresponding refractive powers) would have clinical significance (e.g., equivalent to 0.125 D or more). The inclusion/exclusion of the skew ray in the analyses showed some differences in the results. However, the proposed procedure showed clinically significant differences only for highly deformed corneas and only for large corneal diameters. For the overwhelming majority of surfaces, the skew ray ambiguity is not a clinically significant issue in the analysis of the videokeratoscopic data indicating that the meridional processing such as that encountered in calculation of the refractive power maps is adequate.

Eccentric Lamellar Keratolimbal Grafts Harvested with a Manually Guided Microkeratome

Background: To perform lamellar keratolimbal allograft transplantation in a one-step procedure with a single graft, we investigated the feasibility of harvesting eccentric lamellar keratolimbal grafts from conventionally processed corneoscleral buttons using a manually guided microkeratome in conjunction with an artificial anterior chamber system. Methods: We used the Moria LSK-One microkeratome and the automated lamellar therapeutic keratoplasty (ALTK) system (Antony, France). Ten human donor eyes were used to obtain single-piece lamellar keratolimbal grafts. Specimens were processed for light and electron microscopy. Results: Eccentric keratolimbal grafts could be obtained from all human donor buttons. Grafts include a crescent-shaped limbal and a large corneal portion. No visible damage to the limbal region was discernible. Conclusion: Our data show that the LSK-One microkeratome in conjunction with the ALTK system allows harvesting eccentric keratolimbal grafts from donor corneoscleral buttons.

Risk Factors Affecting Efficacy of Intracameral Amphotericin Injection in Deep Keratomycosis

Purpose: To investigate the clinical efficacy of intracameral amphotericin injection and to evaluate risk factors affecting primary treatment success in fungal infection invading the anterior segment of the eye. Methods: Twenty-six eyes of 26 patients diagnosed with fungal infection in the anterior segment were studied. The initial treatment regimen was a topical 0.15% amphotericin application and itraconazole oral administration after culture. Amphotericin (5 ug/0.1 ml, 0.1 cc) was repeatedly injected intracamerally when the infection intensified. Penetrating keratoplasty was conducted for eyes unresponsive to intracameral amphotericin injection. The relative risk ratios of ulcer size, infiltration depth, culture positivity, and hypopyon were compared in each treatment group to evaluate the treatment response. Results: Of patients with fungal infection, 30.7% were cured with intracameral amphotericin injection, while 30.7% needed penetrating keratoplasty. Intracameral amphotericin injection was needed in the presence of large corneal ulcers (>14 mm2), hypopyon, positive fungal culture, use of steroid eye drops, and deep infiltration at initial examination. Large ulcer size (>14 mm2) was the main risk factor for needing penetrating keratoplasty. Of the eyes Candida infection, 66.5% needed evisceration. Conclusions: Large ulcer size and the isolation of Candida were poor prognostic factors related to the efficacy of intracameral amphotericin injection.

Demonstration of “Owl’s Eye” Morphology by Confocal Microscopy in a Patient With Presumed Cytomegalovirus Corneal Endotheliitis

To report confocal microscopic observations of characteristic corneal endothelial lesions in a patient with presumed cytomegalovirus (CMV) corneal endotheliitis. Case report. A 77-year-old, immunocompetent man was admitted with corneal edema, keratic precipitates, and coin-shaped lesions in the right eye. Confocal microscopy was performed to examine the corneal endothelium. Polymerase chain reaction (PCR) was used to identify viral DNA in an aqueous humor sample. CMV DNA was detected by PCR. Confocal microscopy showed large corneal endothelial cells with an area of high reflection in the nucleus surrounded by a halo of low reflection. This "owl's eye" morphology is characteristic of CMV infection. Topical and intravenous ganciclovir treatment resulted in rapid resolution of the corneal precipitates and edema, followed by disappearance of the owl's eye morphology. Confocal microscopy can detect the owl's eye morphology in the corneal endothelium of patients with presumed CMV corneal endotheliitis.

Amniotic membrane transplantation for corneal surface reconstruction after excision of corneolimbal squamous cell carcinomas in nine horses

The purpose of this study was to evaluate the usefulness and effectiveness of permanent amniotic membrane transplantation as an adjunctive treatment to superficial keratectomy alone or combined with strontium-90 irradiation for treatment of equine corneolimbal squamous cell carcinoma (SCC) to decrease corneal scarring and recurrence rate. The retrospective case study included 11 horses (n = 12 eyes) diagnosed and treated for ocular SCC that involved the limbus and cornea. Nine of those horses (n = 9 eyes) were treated between 2002 and 2006, with superficial lamellar keratectomy alone or combined with strontium-90 irradiation and followed by placement of a permanent amniotic membrane graft in the surgical defect. The level of scarring (i.e. the clarity of the cornea) resulting with the use of amniotic membrane was subjectively compared to cases where a permanent bulbar conjunctival graft was performed following keratectomy combined with strontium-90 irradiation or cryotherapy (n = 3 eyes). Recurrence was defined as the postoperative and postirradiation regrowth of SCC in the same site and globe. The nine horses that received an amniotic membrane graft after keratectomy alone or combined with irradiation showed a minimal level of scarring in a cornea that regained a greater transparency in comparison to the horses that were treated with a bulbar conjunctival graft. All of the horses that received an amniotic membrane graft had 226 +/- 218 days of follow-up without tumor recurrence (mean +/- SD), ranging from 21 days to 778 days. The combination of superficial keratectomy alone or associated with beta-irradiation and permanent amniotic membrane transplantation is an effective treatment of corneal or corneolimbal SCC in horses. The placement of an amniotic membrane material represents an alternative surgical procedure to bulbar conjunctival grafts, especially if there is a lack of bulbar conjunctiva tissue available after tumor resection or if a particularly large corneal resection is necessary. The amniotic membrane is incorporated into the corneal defect and seems to create noticeably much less scarring than a corneal defect covered by bulbar conjunctiva.

Kératomycose et endophtalmie d′étiologie exceptionnelle : L asiodiplodia theobromae

We report a case of endophthalmitis caused by the fungus Lasiodiplodia theobromae. A 68-year-old man was referred to the hospital for right ocular pain since experiencing right ocular branch trauma 2 weeks before. The best-corrected acuity was limited to hand motion. Slit-lamp examination showed a large corneal abscess and an anterior chamber reaction. The patient underwent systemic and local antibiotic therapy, and corneal scraping for microbiological diagnosis. Sabouraud-chloramphenicol-gentamicin agar disclosed filamentous fungus, which was treated with oral itraconazole and topic amphotericin B. Molecular biology revealed Lasiodiplodia theobromae. Despite antimycotic drugs, severe panophthalmia occurred very quickly and led to evisceration. This case report describes Lasiodiplodia theobromae as the cause of keratomycosis and discusses risk factors and clinical features of fungal keratitis in order to improve prognosis by earlier treatment.

Severe Ocular Trauma in a Young Girl with a Paintball Pellet

A 10-year-old girl attended our department after sustaining a direct hit to the left eye from a paintball pellet at close range. She had been playing with a paintball gun at home unsupervised and without protective eyewear. On examination, her visual acuity was counting fingers. Extensive subconjunctival hemorrhage and a large corneal abrasion were noted. Examination of the anterior chamber revealed a 1.1-mm hyphema with normal intraocular pressure. Her pupil was mid-dilated and reacted very slowly to light.

Serratia Corneal Ulcers

To study the clinical and microbiological profile of Serratia corneal ulcers at the Cornea Service of the Wills Eye Hospital. This was a retrospective, observational case series. The clinical records of patients with Serratia marcescens corneal ulcers seen at the Cornea Service of the Wills Eye Hospital between January 1, 1998 and December 31, 2002 were reviewed. Twenty-four cases of Serratia keratitis were identified in 21 patients. Two patients (9.5%) had recurrent keratitis, 1 of which recurred twice. Both had corneal graft edema and were on topical steroids and antiglaucoma drops. The Serratia infection in 15 patients (71%) was associated with an abnormal corneal surface. Twelve of these patients (57%) had the ulcer in a corneal graft, 4 (19%) of which were associated with suture infiltrates. Fifteen patients (71%) were on topical medications-15 used corticosteroids and 13 used antiglaucoma drops. Six patients (29%) were contact lens wearers-1 had a concomitant suture infiltrate associated with a corneal graft, and 5 had otherwise healthy corneas. One isolate lacked in vitro susceptibility to ciprofloxacin and ofloxacin but was susceptible to gentamicin and tobramycin. Nineteen patients had a favorable response to medical therapy. Two patients with poor outcome had large corneal ulcers with severe necrosis and thinning associated with delay in treatment. Serratia marcescens keratitis is associated with the presence of an abnormal corneal surface, use of topical medications, and contact lens wear. Prompt medical therapy results in a good clinical response in the majority of cases.

Regression of Lid-Induced Corneal Topography Changes After Reading

The purpose of this article is to investigate the magnitude of lid-induced corneal topography changes as a function of time spent reading and the subsequent time course of regression of these changes. Six young subjects, five myopes and one emmetrope with normal ocular health, participated in the study. Corneal topography of one eye was measured with videokeratoscopy before four reading sessions of 10, 30, 60, and 120 min duration performed on four separate mornings. Corneal topography was again measured at fixed intervals up to 180 min after each reading session. A control trial without reading was also performed on a separate morning. All six subjects showed significant changes in corneal topography directly after each of the reading sessions. Longer reading periods caused larger corneal changes. Local instantaneous power changes reached up to 5.95 D (+/- 2.80 D), whereas refractive power changes in the superior cornea ranged up to 1.26 D (+/- 0.44) for the 120-min reading trial. The duration of regression of corneal changes showed slower recovery times after longer reading periods. The pattern of regression was similar for all reading times, showing a rapid recovery within the first 10 minutes followed by a slower regression period. The length of time spent reading has a cumulative effect on the period over which corneal topography remains altered as a result of lid forces.

Mucous Membrane Graft Versus Gunderson Conjunctival Flap for Fitting a Scleral Shell Over a Sensitive Cornea

To assess the efficacy of full-thickness mucous membrane grafts in forming a total and permanent corneal cover. The records of all patients with a phthisical globe or microphthalmos who underwent a corneal covering procedure to allow comfortable wearing of a cosmetic scleral shell between March 1999 and July 2004 were reviewed. Ten eyes underwent a Gunderson conjunctival flap (group A), and 9 eyes underwent a full-thickness mucous membrane graft (group B). In group A, 3 eyes had total flap retraction and one eye had partial flap retraction. In group B, only one eye had partial graft retraction. The flap retraction in group A occurred in those eyes with a corneal diameter of 9 mm or more. The results from this small series of patients indicate that a full-thickness mucous membrane graft might be a better alternative for corneal coverage than a Gunderson conjunctival flap, especially in eyes with conjunctival scarring or relatively large corneal diameter.

Use of refractive direct ophthalmoscopy for estimation of refractive error

The purpose of this study was to find if direct ophthalmoscopy, a simple technique, could be used to give an approximate value of the refractive correction for a patient. This would shorten the time and lessen the effort to be expended during the following retinoscopic examination done for finding the patient's refractive correction. The use of direct ophthalmoscopy for this specific purpose is especially desirable where retinoscopic examination is quite tedious, e.g. uncooperative patients like children, bed-ridden patients and mentally retarded subjects, in patients with a large central corneal opacity and in patients having a large refractive error. The study was divided into two phases. In phase I, refractive direct ophthalmoscopy followed by classical retinoscopy was done for 92 subjects (184 eyes) in the age group of 11-35 years. The method of regression analysis was used to find a regression equation relating the readings to refractive error determined by the two above techniques. In phase II of study, the refractive correction needed for 50 other subjects in the similar age group was estimated using this regression equation by inserting their respective direct ophthalmoscopy readings. Then, these estimated values and classical retinoscopic examination values were compared. The refractive error determined after retinoscopy and that derived from regression equation (incorporating direct ophthalmoscopy readings) was statistically comparable (t = 0.52, p = 0.60). The correlation coefficient (r value) between the two methods was 0.37. Direct ophthalmoscopic lens reading can be used to give a fairly accurate estimate of refractive error in a patient's eye by using a linear regression equation, which relates these two examination techniques. The magnitude of astigmatic error, however, cannot be obtained.

Corneal ulcers at a Nigerian eye hospital

Objectives: To determine the incidence, pattern, predisposing factors and treatment outcome of corneal ulcers at the Guinness Eye Center Onitsha, Nigeria. Methods: A retrospective study of corneal ulcer patients treated between July 1998 and June 2000. Results: One hundred and twenty eyes of 117 patients (1.2% of new patients) were treated. Farmers, pensioners and housewives presented late to hospital compared to students, preschool children, traders, artisans and civil servants (p < 0.001). 66 eyes (55%) had peripheral ulcers; 45% were central ulcers. Central ulcer patients presented late to hospital (p < 0.01; OR – 3.0; CI: 1.29, 6.97) and also had worse visual acuity (p < 0.001; OR – 8.8; CI: 3.3, 22.9). 89 eyes were culture-negative. Organisms identified in other specimens were fungi (14 eyes); herpes simplex keratitis (9 eyes) staphylococcus aureus (3 eyes); streptococcus pneumonia in (2 eyes); coliforms (2 eyes); mixed infection with staphylococcus aureus and coliforms (1 eye). Major predisposing factors were trauma (54.8%); traditional eye medicines (23.1%) and self-medication with corticosteroids (10.5%). Post-treatment, 44 eyes (36.7%) gained 1-7 lines of visual acuity and blindness was reduced by 40.5% (p < 0.01; OR – 2.3; CI: 1.33, 3.99). Complications included leucoma (18 eyes); corneal vascularisation (5 eyes); anterior staphyloma (1 eye); panophthalmitis (1 eye) and large corneal perforation (1 eye). Conclusions: Optimal results from treatment of corneal ulcers require patients to report early to hospital; upgrading diagnostic facilities and provision of relevant drugs. Key Words: Corneal ulcers, predisposing factors, Nigeria Nigerian Journal of Surgical Research Vol.5(1&2) 2003: 152-159

Further assessment of the size, shape and surface features of superficial cells of the bovine corneal epithelium, using scanning electron microscopy

Purpose. To qualitatively and quantitatively assess the size and shape of the surface cells of the bovine corneal epithelium as assessed by scanning electron microscopy. Methods. After quality-control measures on recent postmortem bovine eyes obtained from a slaughterhouse, the ocular surface was aggressively washed with 0.97% saline and then fixed for scanning electron microscopy (SEM) by a dropwise application, in 37°C moist chamber, of a 2% glutaraldehyde solution (in 80 mM cacodylate, pH 7.2 to 7.4). A set of images were taken from the central region of the surface of the corneal epithelium. The cell areas, perimeter and dimensions of 25 to 30 cells from 18 different samples were measured with a digitiser pad or rule, and number of bordering cells (sides) counted manually. Cell shape was assessed by comparing the longer and shorter dimensions (LS ratio) and calculation of the figure coefficient (FC, 4?A/P 2) . Results. With the washing protocol, surface cells were evident that displayed a range of electron reflexes (light, medium and dark) and that were decorated with microplicae and some crater-like features. These features were generally not evident if the surface was only rinsed with saline. The cell surface areas ranged from 58 to 6444µm 2 (mean 1748 ± 1169µm 2) , and increased as the number of sides increases. Cells with a higher number of sides (n = 10) tended to be more rounded (LS ratio averaging 1.24) while cells with small number of sides (n = 3) were more elongated (LS ratio 1.94). Shape (FC) values ranged from 0.379 to 0.967, and increased as the number of cell sides increases. Assessment of cell shape in relation to the number of cell sides identified only a small proportion of surface cells with unusually low FC values. Conclusions. With an appropriate preparative procedure (aggressive washing with saline), bovine corneal epithelial surface (squamous) cells can be shown to have a similar appearance by SEM to that previously observed for rabbit and human corneas. The cell sizes are however substantially greater than those seen in rabbits, presumably because of the much larger corneal diameter (c. 28 mm vs. 13 mm). Based on detailed analysis of cell size and shape, the results indicate that the squamous cells have reasonably predictable characteristics.

Applications of contact lens devices in the management of corneal disease.

Contact lens devices have a variety of therapeutic applications in the management of corneal diseases. A wide range of devices is available, some with very specific indications for use, including scleral lenses, silicone elastomer, collagen shields, large diameter corneal lenses, and silicone hydrogels. The traditional hydrogel contact lens is the most frequently used device and is indicated in at least 80% of cases. Common indications for use are relief of pain, promotion of corneal healing, mechanical protection and support, and control of corneal hydration, often a combination of effects being achieved. Visual improvement may be achieved but this is not the primary role of such devices.

Biodendrimers: New Polymeric Biomaterials for Tissue Engineering.

Dendrimers composed entirely of building blocks known to be biocompatible or degradable in vivo to natural metabolites were synthesized using a high yield divergent approach. This synthesis is amenable to the design and development of new biomaterials that are of interest for a variety of medical applications, including tissue engineering. In a novel application, photocrosslinkable dendrimers are used to seal large corneal lacerations.

Biodendrimers: New Polymeric Biomaterials for Tissue Engineering

Dendrimers composed entirely of building blocks known to be biocompatible or degradable in vivo to natural metabolites were synthesized using a high yield divergent approach. This synthesis is amenable to the design and development of new biomaterials that are of interest for a variety of medical applications, including tissue engineering. In a novel application, photocross-linkable dendrimers are used to seal large corneal lacerations.

Pneumococcal keratitis at the flap interface after laser in situ keratomileusis

A 28-year-old woman had uneventful laser in situ keratomileusis in the right eye. Six days postoperatively, she reported ocular pain and a large corneal stromal infiltrate was observed at the flap interface. A second surgery including lifting and excising the flap and scraping the stromal bed was performed. Topical antibiotics were prescribed. A bacterial culture revealed Streptococcus pneumoniae. The keratitis responded well to topical vancomycin. Twelve days after the second surgery, the stromal infiltrate had regressed, the hypopyon had resolved, and visual acuity was hand movements at 0.5 m.

A Case of Peters» Anomaly in a Springer Spaniel

An 8-week-old springer spaniel presented with a large central corneal opacity of the left globe, which was accompanied by cords of tissue spanning from the iris collarette to the posterior cornea. A posterior cortical cataract was noted in the right eye. At the owner's request the puppy was humanely destroyed, and a necropsy was performed. Upon sectioning the left globe in the vertical plane, a circle of pigmented strands of tissue was observed spanning the anterior chamber from the iris to the posterior aspect of the cornea. The right globe appeared normal when inspected grossly. Histologically, a membrane of pigmented tissue covered the posterior aspect of the broad central corneal leukoma of the left globe. This membrane and the cords traversing the anterior chamber were composed of vascular uveal tissue. Descemet's membrane and the corneal endothelium were reduced or absent in the zone of corneal opacity. Other than the changes associated with cataract, the right globe was histologically normal. The clinical and histological findings in the left globe were identical with those described for Peters» anomaly in human beings.