Air bag-related corneal rupture after radial keratotomy

PURPOSE: We studied a case of air bag-associated corneal rupture in a patient who had previously undergone radial keratotomy surgery. METHODS: The patient was struck in the right eye when his driver's side air bag inflated during a low-speed collision. RESULTS: Inflation of the air bag resulted in rupture of the patient's right cornea. The rupture involved all but one of his old radial keratotomy wounds. CONCLUSIONS: Patients who have undergone radial keratotomy may be at increased risk for corneal rupture caused by air bag trauma. These patients may benefit by wearing protective eyewear while driving cars equipped with air bags.     

Endophthalmitis after radial keratotomy enhancement

A 45-year-old man developed endophthalmitis after a radial keratotomy (RK) enhancement. He developed severe intraocular inflammation, hypopyon, and dense vitreous membranes 4 days after the enhancement surgery. Cultures of the corneal wound yielded a heavy growth of Streptococcus viridans. The inflammation subsided after treatment with intraocular, intravenous, and topical antibiotics. The patient subsequently developed a cataract and retinal detachment. This case demonstrates the risk of endophthalmitis after RK enhancement.     

Trauma after radial keratotomy and photorefractive keratectomy

A 25-year-old man sustained bilateral ocular trauma from an explosion, which resulted in ocular injuries from the blast, mineral projections, and heat. Before the accident, the patient had eight-incision radial keratotomy in the left eye followed 1 week later by photorefractive keratectomy in the right eye. After the accident, the left cornea had a full-thickness rupture of four incisions; the fellow cornea had a full-thickness laceration from a mineral projection. Five months after the accident, the left eye had an uncorrected visual acuity of 20/25; the right eye did not achieve an acuity of 20/200 until 20 months after the accident.     

The conjunctiva in corneal epithelial wound healing

BACKGROUND/AIMS: During the healing of corneal epithelial wounds with limbal involvement, conjunctival epithelium often migrates across the denuded limbus to cover the corneal surface. It is believed that, over a period of time, conjunctival epithelium covering the cornea assumes characteristics of corneal epithelium by a process referred to as conjunctival transdifferentiation. The purpose of this study was to examine, clinically, the fate of conjunctival epithelial cells covering the cornea and to assess the healing of corneal epithelial wounds when the conjunctival epithelium was removed or actively prevented from crossing the limbus and extending onto the cornea. METHODS: 10 patients with conjunctivalisation of the cornea were followed for an average of 7.5 months. Five patients in this group had their conjunctival epithelium removed from the corneal surface and allowed to heal from the remaining intact corneal epithelium. In another four patients with corneal epithelial defects, the conjunctival epithelium was actively prevented from crossing the limbus by mechanically scraping it off. RESULTS: The area of cornea covered by conjunctival epithelium appeared thin, irregular, attracted new vessels and was prone to recurrent erosions. Conjunctivalisation of the visual axis affected vision. Removal of conjunctival epithelium from the cornea allowed cells of corneal epithelial phenotype to cover the denuded area with alleviation of symptoms and improvement of vision. It was also established that migration of conjunctival epithelium onto corneal surface could be anticipated by close monitoring of the healing of corneal epithelial wounds, and prevented by scraping off conjunctival epithelium before it reached the limbus. CONCLUSION: This study shows that there is little clinical evidence to support the concept that conjunctival transdifferentiation per se, occurs in humans. "Replacement" of conjunctival epithelium by corneal epithelial cells may be an important mechanism by which conjunctival "transdifferentiation" may occur. In patients with partial stem cell deficiency this approach can be a useful and effective alternative to partial limbal transplantation, as is currently practised.     

The assistant's guide to radial keratotomy

1. The role of the ophthalmic assistant in radial keratotomy (RK) patient care involves three basic areas: patient preparation, suite preparation, and RK day. Complications as well as pros and cons of RK are covered. 2. A truly informed consent to RK must be achieved. 3. The key to managing refractive patients is preparation and organization. Every technician working with RK patients should know every detail of the RK practice. The patients must be prepared as well; there should be no real surprises during the postoperative course.     

Morning-to-evening change in refraction, corneal curvature, and visual acuity 11 years after radial keratotomy in the prospective evaluation of radial keratotomy study. The PERK Study Group

One-hundred thirteen men (mean age, 23 years) who presented with inguinal buboes to a government-operated hospital for sexually transmitted diseases (STDs) in Bangkok were studied between February 1987 and February 1989. The median duration of preceding symptoms was 7 days (range, 1-62 days). The majority of patients (74; 65%) had received treatment previously; 31 (27%) were febrile, 13 (12%) had extrainguinal lymphadenopathy, and 31 (27%) had concurrent active genital ulcers. There was no history of genital ulceration in 66 (58%) of the patients. Pus was obtained from 51 of the 110 buboes aspirated for culture; 21 (41%) of these cultures yielded Haemophilus ducreyi, and 2 (3.9%) were positive for Chlamydia trachomatis on immunofluorescence microscopy. Saline (1 mL) was injected and reaspirated from the buboes of 35 of the other 59 patients; 3 buboes yielded H. ducreyi and 9 were positive for C. trachomatis. All cultures for other aerobic and anaerobic bacteria and viruses in intact buboes were negative. Syphilis serology was positive in only one case. Patients attending STD clinics in this region who have large, fluctuant, edematous inguinal buboes containing pus should receive presumptive treatment for chancroid. If there is no pus, then the bubo is more likely to be caused by lymphogranuloma venereum.     

Extracellular matrix changes in human corneas after radial keratotomy

It has been shown that an adenine (A) to guanine (G) transition at position 3243 of the mitochondrial transfer RNA(tRNA)leu(UUR) gene is associated with a subgroup of diabetes mellitus. Therefore, we screened for this transition in 86 patients with non-insulin-dependent diabetes mellitus (NIDDM) in which two or three generations were affected with diabetes, in 14 patients with insulin-dependent diabetes mellitus, and in 9 families with diabetes mellitus and/or associated disorders suggesting mitochondrial gene abnormalities. We failed to identify the mutation in 100 diabetic patients, 86 NIDDM and 14 insulin-dependent diabetes mellitus (IDDM). Out of the latter 9 families, we identified an A to G transition in 14 individuals in 5 families. Diabetes mellitus was shown to be maternally inherited in one family. In 9 of 14 patients with the mutation, insulin was required to treat diabetes mellitus, indicating impaired insulin secretion. A hyperglycemic clamp test performed in one subject revealed significant impairment of insulin secretion, whereas euglycemic clamp test showed normal insulin sensitivity in this patient. The heteroplasmy of the mutant mitochondrial DNA (mtDNA) in leukocytes does not appear to correlate with the severity of diabetes in terms of the insulin therapy required. Body mass index of the affected individuals was less than 23.3. In one family, in addition to diabetes mellitus and hearing loss, hypoparathyroidism was associated with the mutation, suggesting that hypoparathyroidism is caused by the impaired processing and/or secretion of proparathyroid hormone due to the mutation. In addition, the affected subjects presented with proteinuria at the time of diagnosis of diabetes mellitus which appeared not to be related with diabetic nephropathy.     

Fetal tissue repair and wound healing

The fibrosis and scar formation that characterize adult wound healing are also the cause of clinical problems; scar contracture, hypertrophic scar, and pulmonary and hepatic fibrosis are only a few examples. Studies of fetal wound healing can provide an insight into the initiation and regulation of a scarless repair process akin to regeneration. Studies of fetal repair have already suggested mechanisms that might favorably alter adult healing. Topical application of hyaluronic acid to wounds in adult diabetic rats leads to enhanced epithelial migration. It has been recognized that the addition of TGF-beta to fetal wounds causes an adultlike healing response with fibrosis and inflammation. A subsequent study using neutralizing antibody to TGF-beta in adult wounds showed enhanced healing with a more normal dermal architecture with fewer macrophages, fewer blood vessels, and less collagen. As our understanding of regenerative tissue repair increases, the opportunities to modulate adult fibrotic conditions should expand.     

Three-dimensional organization of collagen fibrils during corneal stromal wound healing after excimer laser keratectomy

PURPOSE: To investigate the structural changes in corneal stromal collagen fibrils after excimer laser keratectomy in relation to the degree of corneal haze. SETTING: University of Tokyo Hospital, Tokyo, Japan. METHODS: Corneal haze was quantitatively measured by analyzing the light scattering in Scheimpflug images of the corneas of white rabbits after excimer laser keratectomy. Collagen fibril structure was examined using scanning electron microscopy after chemical digestion with sodium hydroxide solution; the same specimens were examined by transmission electron microscopy after re-embedding. RESULTS: Corneal haze reached a peak 4 weeks after excimer laser keratectomy and then gradually decreased. The collagen fibrils of the normal cornea were regularly arranged parallel to the surface of the cornea, with small interfibrillar distances. After excimer laser keratectomy, the arrangement was highly disordered, with increased interfibrillar distances. These structural changes were most prominent 4 weeks after excimer laser keratectomy. CONCLUSION: The structural changes in the collagen fibrils of the corneal stroma, especially the increase in interfibrillar distances and the disordered arrangement, were associated with corneal haze after excimer laser keratectomy.     

Effect of incision direction on refractive outcome after radial keratotomy

PURPOSE: To determine whether the direction of radial keratotomy (RK) incisions (centripetal versus centrifugal) affects refractive outcome. SETTING: Private ophthalmology office. METHODS: The database of a single surgeon was retrospectively reviewed. Stepwise regression was used to select significant predictors of refraction change in the population. In addition to incision direction, variables evaluated were optic zone diameter, number of incisions, patient age, corneal curvature, and planned incision depth. RESULTS: All variables except planned incision depth and corneal power affected refractive outcome. After controlling for number of incisions, optic zone diameter, and patient age, centripetal incisions decreased myopia 0.87 diopters more than centrifugal incisions. CONCLUSIONS: Our results, consistent with previous investigations, found that number of incisions, optic zone diameter, and patient age were significant predictors of refractive outcome after RK. Incision direction was also a significant predictor by itself or coupled with optic zone diameter and number of incisions, with the centripetal incision decreasing myopia more.     

Radial keratotomy. III. Relationship between wound gape and corneal curvature in primate eyes

The relationship between changes in wound gape and corneal curvature after radial keratotomy (RK) was evaluated in five primates. Four-incision RK was performed using a diamond knife set to 100% of central corneal thickness with a 3-mm optical zone. In vivo measurements of wound gape were obtained using tandem scanning confocal microscopy at 3, 7, 14, and 45 days after surgery. The changes in corneal contour were measured at the same time points using a corneal modeling system with a specially designed primate cone. Wounds progressively increased in width to a maximum of 38 +/- 1 microns (n = 5) at day 7. After day 7, wounds showed increasing fibrosis which correlated with decreasing wound gape to 20 +/- 1 microns at day 45. A similar temporal change was detected in central corneal curvature (K), with maximum flattening occurring at day 7 (delta K = -3.17 +/- 0.90 diopters, n = 5), and progressive regression of effect to -1.32 +/- 0.61 diopters (n = 5) at day 45. Although there was interanimal variation, the mean temporal changes in corneal curvature significantly paralleled the changes in wound gape (r = -0.96, n = 4, P < 0.05). Based upon these findings, a simple geometric model was proposed which provides a hypothetic foundation for the relationship between corneal curvature and wound gape after RK. Calculations of wound gape made from this analytic model (using the measured topographic data) showed significant correlation with the actual wound gape measurements (r = 0.96, n = 4, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Real-time confocal microscopic observations on human corneal nerves and wound healing after excimer laser photorefractive keratectomy

PURPOSE: Corneal wound healing after excimer laser photorefractive keratectomy (PRK) passes through a series of characteristic stages which have earlier been defined by means of histological, histochemical, and biochemical approaches. We investigated the potential of confocal microscopy to verify morphological changes in human corneas in vivo after PRK. METHODS: Ten corneas of eight patients that had earlier undergone PRK were examined at different postoperative time points (7 days-34 months). One of the PRK patients was examined sequentially three times. Three additional corneas, which had earlier undergone corneal grafting surgery and then were subjected to excimer laser photoastigmatic keratectomy (PARK), were studied as well. Seven healthy untreated corneas served as controls to define the normal morphology of human cornea. A tandem scanning confocal microscope (TSCM) was used to generate real-time images of the corneas on an S-VHS videotape. The images were either digitized and further processed or the individual video frames were produced with a video printer. RESULTS: Seven days post-PRK in vivo confocal microscopy revealed the presence of morphologically immature surface epithelial cells. Delicate nerves, activated keratocytes and deposition of extracellular light-reflecting scar tissue were perceived. The epithelium appeared normal one month post-PRK. Ongoing activation of the anterior stromal keratocytes along with extracellular scar tissue were detected. We also observed increasing numbers of regenerating subepithelial nerve leashes with somewhat twisted pattern. Highly reflective, presumably activated keratocytes were no longer detected 6-7 months post-PRK. Hypercellularity with scar tissue could still be found up to 30 months post-PRK. Only one cornea examined 34 months post-PRK showed normal keratocyte morphology and recovery of the anterior stroma. However, the morphology of subepithelial nerves was still somewhat abnormal. The two corneal grafts examined 11 or 32 months post-PARK exhibited a normal-appearing epithelium but considerable stromal hypercellularity and extracellular scar deposition. The subepithelial nerves were poorly regenerated in one eye and fairly well detectable in the other. The third graft examined 15 months post-PARK revealed the presence of enlarged surface epithelial cells and dense stromal scarring but no nerves. CONCLUSION: TSCM clinically confirms the earlier histological data on healing of excimer laser wounds. It offers a distinct improvement in the assessment of excimer laser-treated corneas, as it enables cellular details and nerves to be perceived in vivo. In addition the thickness of the stromal scar can be be measured for e.g. planning of phototherapeutic keratectomy.     

Evaluation of increased aqueous outflow after radial keratotomy in enucleated bovine eyes

In spite of the availability of high-tech devices for wound assessment, plastic surgeons recognize that the color and confluence of granulation tissue are the most important indicators of open-wound healing. We developed a simple and inexpensive pocket-size scale--the Granulometer--to facilitate a finer assessment and to standardize the documentation of wound healing. This device overcomes limitations set by conditions such as lighting or recent exposure to other wounds that could distort the examiner's perception of the wound in question. In this study we examined the inter- and intraobserver variations in judgment, and the validity of the Granulometer. Our results demonstrate that skin graft viability can be predicted accurately by this eight-grade scale. Since graft survival depends on proper wound healing, we believe that the Granulometer can also be used for fine assessment of wound treatment. The low inter- and intraobserver variations indicate that the Granulometer measurements are both reproducible and accurate.     

Late clear corneal wound failure after trivial trauma

A clear corneal cataract wound ruptured after trivial trauma. The wound did not meet the criteria for wound stability as previously recommended. This case illustrates the potential public health hazard with the increasing use of clear corneal cataract surgery. Proper wound design can eliminate this risk. Patients without proper wound design should be cautioned to wear protective eyewear to avoid serious or blinding trauma.     

Arcuate keratotomy to treat corneal astigmatism after cataract surgery: a prospective evaluation of predictability and effectiveness

OBJECTIVE: Although several nomograms are available for the incisional keratotomy to correct naturally occurring astigmatism, astigmatic keratotomy in eyes after cataract surgery has not been well analyzed. The predictability and effectiveness of arcuate keratotomy in pseudophakic eyes were studied. DESIGN: A prospective, multicenter study. PARTICIPANTS: One hundred four eyes of 86 patients with residual corneal astigmatism of 1.5 diopters (D) or more after cataract surgery were examined. INTERVENTION: Arcuate keratotomy was performed in nine centers by nine surgeons. MAIN OUTCOME MEASURES: The amount of astigmatic correction was calculated using the vector analysis of preoperative and 6-month postoperative refractive cylinder results. RESULTS: Multiple regression analysis showed that optical zone size, number of incisions, and incision length had significant correlations with the amount of astigmatic correction. The regression equation was expressed as effects = (-0.643 x optical zone size) + (0.998 x incision number) + (0.057 x incision length) + 2.356. The parameter of predictability (r2: 35%) was lower than that reported for congenital astigmatism (48 to approximately 56%). A new nomogram was derived based on the multiple regression equation. CONCLUSIONS: Astigmatic keratotomy in pseudophakic eyes is less predictable than that in eyes with idiopathic astigmatism, but the procedure is sufficiently effective in reducing the residual astigmatism after cataract surgery. Individual nomograms are necessary for astigmatic keratotomy in eyes with naturally occurring and postsurgical astigmatism.     

A study of perineal wound healing after abdominoperineal resection

A comparative study of 53 cases has revealed that a technique of complete primary closure of the perineal wound after abdominoperineal resection of the rectum and anal canal appears to be a superior, more rational approach than other orthodox techniques. (It is unsuitable for any case contaminated with pus or faeces during operation.) Redivac apparatus used through a separate route for continuous drainage from the sacral cavity has made the postoperative care easier for nurses and surgeons and this period more comfortable for the patient. It provides a simple method compared with other suction apparatus used for the same purpose. Of the 53 cases, 12 were operated on using a traditional technique involving the closure of the perineal wound around a tube drain connected to an underwater seal, while in the remaining 41 the approach described here was used. Primary healing of the perineal wound with the later approach was obtained in about 88 per cent. With the other technique the figures were 34 and 66 per cent respectively for early healing within 3 weeks and delayed healing between 3-8 weeks. Primary healing of the perineal wound reduces the total stay in hospital and the morbidity.