Does spaced education improve clinical knowledge among Family Medicine residents? A cluster randomized controlled trial

Advances in Health Sciences Education - Spaced education is a learning strategy to improve knowledge acquisition and retention. To date, no robust evidence exists to support the utility of spaced...     

Phototherapeutic keratectomy versus mechanical epithelial removal followed by corneal collagen crosslinking for keratoconus

ObjectiveTo compare the visual outcomes of patients with keratoconus treated with either phototherapeutic keratectomy (PTK) or mechanical epithelial removal prior to corneal collagen crosslinking (CXL).DesignComparative study.ParticipantsThe records of 34 patients (34 eyes) who had PTK (17 eyes) or mechanical (17 eyes) epithelial removal prior to CXL for keratoconus were reviewed retrospectively.MethodsCXL was performed by 1 of 3 surgeons (G.M., W.B.J., or K.B.). Of the eyes, 17 had undergone mechanical epithelial removal prior to CXL and were consecutively selected, after matching with the 17 eyes in the PTK group, for the variables of procedure date, average keratometry, and pachymetry. All eyes had central cones. Manifest refraction spherical equivalent, sphere, cylinder, best-corrected distance visual acuity, and pachymetry were measured and compared preoperatively and in follow-up.ResultsThe mean change between the pre- and postoperative manifest refraction spherical equivalent for the PTK and mechanical groups was 1.68 ± 0.80 and 0.26 ± 0.90, respectively (p < 0.05). The mean change between pre- and postoperative cylinder for the PTK and mechanical groups was 0.53 ± 0.28 and 0 ± 0.18, respectively (p < 0.05). The mean number of lines of improvement in the PTK and mechanical groups were 0.33 ± 0.82 and ?0.58 ± 0.45 lines, respectively (p > 0.05).ConclusionsEarly results suggest that CXL with laser epithelial removal is superior to CXL with mechanical epithelial removal because it reduces refractive error in qualified patients. Although not statistically significant, there was also a trend for PTK CXL patients to have better visual outcomes.     

Acanthamoeba keratitis: persistent organisms without inflammation after 1 year of topical chlorhexidine

PURPOSE: To report a non-contact lens wearer with persistent Acanthamoeba organisms in the cornea after being treated with medical therapy that included topical chlorhexidine as 1 agent for 1 year. METHODS: A 53-year-old man with Acanthamoeba keratitis was treated with medical therapy for >1 year, followed by a penetrating keratoplasty. RESULTS: Histopathologic examination of the keratoplasty specimen revealed viable-appearing Acanthamoeba cysts and trophozoites within the deep corneal stroma in a focus of corneal scarring. CONCLUSIONS: The use of chlorhexidine as 1 agent in the medical management of Acanthamoeba keratitis may not eradicate the organisms.     

In vitro and in vivo effect of PC 904, a new broad-spectrum penicillin, on ocular strains of Pseudomonas aeruginosa.

The in vitro and in vivo activities of PC 904 were tested against Pseudomonas aeruginosa isolated from infected eyes and were compared with carbenicillin and gentamicin. By the microtiter plate method, we tested 30 strains of P. aeruginosa in vitro; PC 904 was very active against 29, but one strain was resistant. In a comparative study, PC 904 was more active than carbenicillin but less active than gentamicin. In vivo tests were conducted on rabbit corneas infected with a strain of P aeruginosa isolated in El Salvador. At moderate and high dosage levels, PC 904'S efficacy was comparable to carbenicillin's but much less than gentamicin's. When tested for ocular toxicity, the subconjunctival administration of PC 904 was well tolerated. The drug's greater activity in vitro than in vivo was probably due to its high serum-binding capacity.     

Infectious crystalline keratopathy

Crystalline deposits developed in the anterior third of the stroma in a 60-year-old woman. The deposits resolved only after aggressive treatment with intravenously given penicillin and topical erythromycin and vancomycin hydrochloride. Review of reported cases indicated that infectious crystalline keratopathy is caused by chronic colonization of the stroma by bacteria, usually streptococci of the viridans group. Local tissue trauma, concomitant use of topical corticosteroids, an intact overlying epithelium and use of a bandage-type soft contact lens are factors in the development of the infection. Patients with crystalline formations in this setting should undergo early lamellar biopsy for histologic examination, culture and sensitivity testing, followed by aggressive therapy with appropriate antibiotics.     

Corneal endothelial decompensation after argon laser iridotomy.

Focal corneal edema overlying the site of argon laser iridotomy followed by generalized corneal decompensation developed in six eyes of five patients. The average interval between the iridotomy and the development of focal edema was 3 years, with generalized edema appearing an average of 3.5 months later. Light, scanning and transmission electron microscopy of tissue removed at the time of corneal transplantation showed abnormalities characteristic of Fuchs' dystrophy in two patients. Possible contributing factors include episodes of intraocular pressure elevation, cornea guttata and the use of high total amounts of energy during laser iridotomy.     

Scheie's syndrome. An ultrastructural analysis of the cornea

The histopathology of a corneal graft specimen obtained from a patient with Scheie's syndrome (systemic mucopolysaccharidosis, type IS) is described with particular emphasis on the ultrastructural findings. Numerous vacuoles containing fibrillogranular material were found in the corneal epithelial cells, the keratocytes, and the endothelial cells. The basement membrane of the epithelium contained frequent breaks and peg-like undulations, and Bowman's layer was markedly attenuated. Fibrous long-spacing (FLS) collagen featured prominently in the stroma. Descemet's membrane was normal. The findings of a markedly attenuated Bowman's layer and FLS collagen may be abnormalities specific to Scheie's syndrome resulting from the altered glycosaminoglycan composition of the extracellular matrix.     

Corneal myxoma arising in a patient with repeated phototherapeutic keratectomies

PURPOSE: We report the clinical and pathologic findings of a corneal myxoma that was diagnosed in a cornea that had undergone phototherapeutic keratectomy (PTK). METHODS: A corneal myxoma was identified in a full-thickness keratoplasty specimen obtained from a 51-year-old man with a history of a forceps injury to his right eye at birth. The patient had presented with corneal edema and bullous keratopathy, which was treated on 3 occasions with PTK, resulting in progressive, persistent milky-white clouding of the cornea. This represents the eighth case of corneal myxoma in the reviewed literature and the first described after PTK. Thorough histopathologic and ultrastructural analyses were conducted. RESULTS: The histochemical, immunohistochemical, and electron microscopic findings were consistent with previously reported corneal myxomas. Most of the reported myxomas arising in the cornea presented with a history of prior corneal disease or injury and showed absence or disruption of Bowman layer histopathologically, as was found in our patient. CONCLUSION: The pathogenesis of corneal myxomas involves a reactive process that requires an antecedent affliction, in contrast to the neoplastic mesenchymal histogenesis of myxomas characterized in other parts of the body.