Repeated radial keratotomy

38 cases 59 eyes received repeated radial keratotomy in which the secondary incisions were performed along the scars of old incisions. The average follow-up after the reoperation was 13 months. Before reoperation, the mean spherical equivalent of the refraction was -3.78D and the mean keratometry was 40.15D. 13 months after the reoperation, the mean spherical equivalent of the refraction decreased by 2.30D, and the mean keratometry decreased by 2.04D. After the reoperation, the mean uncorrected visual acuity increased by 5 lines. There was no relationship between the therapeutic effect of the reoperation and the degree of initial myopia or pre-reoperative keratometry. The repeated radial keratotomy can decrease the degree of astigmatism and its complications are few.     

Refractive outcome following radial keratotomy and combined radial and astigmatic keratotomy

PURPOSE: To determine whether the visual and refractive outcomes of combined astigmatic and radial keratotomy (AK/RK) procedures was different from that following RK for the correction of naturally occurring compound myopic astigmatism and spherical myopia. SETTING: Private professional practice, San Diego, California, USA. METHODS: The computer database of all incisional procedures performed by one surgeon over 10 years was reviewed to compare the visual acuity outcome of AK/RK and RK procedures. Enhancement procedures were excluded. Only data from the last office visits were analyzed to establish the relationship between visual acuity and type of keratotomy procedure performed. A multiple regression model was constructed, which included covariates of age, postoperative keratometric cylinder, and postoperative refraction. RESULTS: After controlling for covariates, the AK/RK population had significantly lower postoperative uncorrected visual acuity levels than the RK population (P < .03) after one operation (prior to enhancement surgery). CONCLUSIONS: Using the nomograms for myopia correction for unenhanced RK cases, combined AK and RK procedures appeared to reduce the expected visual results. Surgeons may consider modifying surgical nomograms to account for the expected spherical undercorrection that can occur when myopia and astigmatism are corrected simultaneously.     

Histopathologic comparison of conventional radial keratotomy and minimally invasive radial keratotomy in rabbits

CLINICAL OBSERVATIONS: Three patients with previous pulmonary infections were recently admitted with rapidly progressive renal failure. Renal biopsy showed crescentic glomerulonephritis with deposits of IgA, C3c and C3d. Serology disclosed P-ANCA with high-titer anti-myeloperoxidase antibodies. Two out of three patients became dialysis dependent despite immunosuppression with methylprednisolone and cyclophosphamide. Renal function improved in both patients after 2 weeks and 9 months, respectively, permitting termination of hemodialysis. All patients benefited from immunosuppressive treatment which is currently still being continued. CONCLUSION: The data suggest that early immunosuppression is beneficial in patients presenting with crescentic rapidly progressive IgA GN and anti-myeloperoxidase antibodies, which may represent a novel subset of crescentic IgA GN associated with high-titer anti-myeloperoxidase antibodies constituting an overlap group between microscopic polyangiitis and IgA GN.     

Photorefractive keratectomy following radial keratotomy

A purification and on-line monitoring procedure for IgM was developed. Perfusion ion-exchange chromatography was used for rapid purification of IgM from ascites fluid and hybridoma supernatant. Crude ascites was directly loaded onto an ion exchanger. Due to the complexity of IgM, a two-step ion-exchange procedure had to be developed. This procedure involved a rapid cation-exchange chromatography capture step followed by further purification using anion-exchange chromatography. High linear velocities, in excess of 3500 cm/h, enabled separations to be performed under 5 min. Purity of the final product by SDS-PAGE was shown to be greater than 95%. Furthermore, the antibodies retained biological activity as measured by indirect immunofluorescence (IIF) and ELISA. The IgM peak was also monitored on-line using a novel peak tracking approach. This involved placing an antibody column (specific to the IgM) prior to the ion-exchange column and operating the ion-exchange column with and without the antibody column in-line. The missing peak that is identified by comparing the two chromatograms indicates where the IgM elutes.     

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.     

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.     

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.     

New technique for knife and radial keratotomy

Low-flow (1 litre min-1) sevoflurane anaesthesia was used in 16 patients undergoing laparoscopic cholecystectomy (group LSC, n = 8) or tympanoplasty (group TP, n = 8), and concentrations of sevoflurane degradation products were measured. Degradation products in the circuit were measured hourly, and end-tidal carbon dioxide concentration, inspired and end-tidal sevoflurane concentrations, and carbon dioxide elimination were monitored. The only degradation product detected was CF2=C(CF3)-O-CH2F (compound A). The mean maximum concentrations of compound A were 21.6 (SEM 1.6) ppm and 19.6 (0.8) ppm in the LSC and TP groups, respectively (ns). The maximum temperatures of soda lime were 46.4 (0.5) degrees C and 44.8 (0.5) degrees C, respectively (P < 0.05). Hourly end-tidal sevoflurane concentrations and concentrations of sevoflurane degradation products were the same for both groups. Carbon dioxide elimination was the same for both groups 1 h after the start of anaesthesia, but was higher in group LSC after 2 h (P < 0.05). Intraperitoneal carbon dioxide insufflation associated with laparoscopic cholecystectomy had no effect on the concentration of sevoflurane degradation products.     

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.     

Statistical study of the results of radial keratotomy

The statistical study of 384 R.K. performed by the same surgeon shows that in 82% of R.K., preoperative myopia was between -1.5 to -6 diopters and in 77.5% of R.K., postoperative refraction was between -1 to +1. The 90% confidence interval was between -2 to +1 for all preoperative myopias and was the best when preoperative myopia was between -0.5 to -3 diopters (-1 to +1 D). The study of the stability and security shows that this surgical technique is stable and gives a good security.     

Retrospective comparison of photorefractive keratectomy and radial keratotomy

BACKGROUND: The efficacy and predictability of photorefractive keratectomy and radial keratotomy become increasingly relevant. This retrospective study compares one surgeon's experience with photorefractive keratectomy and radial keratotomy over a 3-year period from 1990 to 1993. METHODS: Photorefractive keratectomy was performed on 103 eyes of 76 patients that met the inclusion criteria for the phase IIb, phase III, and phototherapeutic keratectomy studies as delineated by the United States Food and Drug Administration. Radial keratotomy was performed on 117 eyes of 81 patients with up to 9.00 diopters (D) of myopia. RESULTS: In the photorefractive keratectomy group, 83% of the eyes achieved uncorrected visual acuity of at least 20/40; 37% saw 20/20; 88% had a refraction within 1.00 D of emmetropia, and 63% within 0.50 D of emmetropia. For the radial keratotomy group, 85% of the eyes achieved an uncorrected visual acuity of 20/40 or better; 27% saw 20/20; 88% had a refraction within 1.00 D of emmetropia; and 55% within 0.50 D of emmetropia. There were no serious complications, and only one single eye in each of the photorefractive keratectomy and radial keratotomy groups lost two lines or more of spectacle-corrected visual acuity. CONCLUSION: Photorefractive keratectomy and radial keratotomy are both effective procedures, and result in similar refractive outcomes for myopia of -1.00 to -9.00 D.     

Two-incision radial keratotomy for low myopia with astigmatism

PURPOSE: To evaluate the effectiveness of two-incision radial keratotomy (RK) in correcting low-magnitude refractive myopic astigmatism. SETTING: Two clinical study sites, one in St. Louis, Missouri, USA, the other in Caracas, Venezuela. METHODS: Fifty-seven eyes of 43 patients with low-magnitude myopic astigmatism had two-incision RK at one of two clinical study sites. In the initial phase of this series, 10 eyes with amblyopia at the 20/30 level had surgery at one center. Refractive keratotomy was performed with the radial incision placed in the plus cylinder axis of refraction. This axis was verified as the meridian of greatest corneal curvature by standard keratometry and computer-assisted corneal topographic analysis. Two eyes received a second operation (enhancement). RESULTS: Mean follow-up was 11.1 months (range 6 to 12 months). Mean preoperative and postoperative myopic spherical equivalent measured -1.42 diopters (D) +/- 0.51 (SD) and -0.14 +/- 0.39 D, respectively; the mean reduction was 1.28 +/- 0.59 D (P = .0001). Mean preoperative and postoperative refractive astigmatism was 1.41 +/- 0.45 D and 0.48 +/- 0.33 D, respectively (P = .0001). Mean preoperative and postoperative keratometric astigmatism was 1.26 +/- 0.54 D and 0.31 +/- 0.35 D, respectively, a mean reduction of 0.95 D (P = .0001). The surgical meridian was flattened by an average of 2.06 D by keratometry and the orthogonal meridian, by an average of 1.10 D. Preoperative uncorrected visual acuity (UCVA) was 20/40 or better in five (9%) eyes (range counting fingers to 20/40). Postoperative UCVA acuity was 20/40 or better in all eyes (mean acuity 20/25). In the nonamblyopic subgroup mean postoperative UCVA was 20/24. CONCLUSIONS: A limited number of radial incisions placed in the topographically confirmed axis of greatest curvature are effective in the treatment of low-magnitude myopic astigmatism.     

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.     

Keratitis as a complication of bilateral, simultaneous radial keratotomy

During a one-month period, we examined four patients referred for evaluation of probable microbial keratitis after bilateral, simultaneous radial keratotomy. Each patient had midstromal infiltrates compatible with microbial keratitis that involved one or more of the radial incisions. In two patients the keratitis was bilateral. All patients had been treated empirically with antibiotic agents; superficial cultures with cotton-tipped applicators and corneal scraping by inserting a platinum spatula into the radial incisions were negative. Corneal biopsy of one patient disclosed gram-positive rods and culture of the biopsy specimen grew diphtheroids. The infiltrates gradually resolved over a period of several months with intensive antibiotic therapy. Sight-threatening infectious keratitis can occur after radial keratotomy, and we believe that simultaneous bilateral ocular surgery of any kind should be discouraged.     

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.     

The effect of radial keratotomy on ocular integrity in an animal model

The safety of deep corneal incisions in radial keratotomy was evaluated in a porcine model of blunt trauma. One eye of each enucleated pair (right and left) of porcine eyes was subjected to a variation of radial keratotomy; the fellow eyes served as unoperated-on controls. All eyes were subjected to a standard injury. Control eyes ruptured at the equatorial sclera. Eyes with radial incisions cut through approximately 70% of corneal thickness also ruptured at the equator. When incisions of this depth (70%) were extended across the limbus (rather than to the corneal-scleral junction), all ruptures occurred at the limbal incisions. Eyes cut 95% to 100% of corneal thickness tended to rupture at the incisions. The safety of deep radial keratotomy incisions with respect to ocular integrity is discussed.     

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.