Influence of medical student career aims on ophthalmic surgical simulator performance (part of the international forum for ophthalmic simulation studies).

BACKGROUND: To evaluate whether medical students who have expressed a strong desire to pursue ophthalmology as a career perform simulated ophthalmic surgical tasks to a higher level than medical students whose interests lie elsewhere. METHODS: All participants were fourth or fifth year students at University College London (UCL) Medical School, London, UK. One cohort was recruited from the Moorfields Academy, an ophthalmic forum designed to enhance collaboration and innovation within the specialty. These students were therefore seen as highly motivated, expressing a desire to pursue a career in ophthalmology. The other cohort of students was invited to participate during their fourth year UCL Ophthalmology attachment, but expressed interest in non-ophthalmic disciplines. Participants carried out a single attempt of three modules on the Eyesi Surgical Simulator, and total and mean scores were calculated out of 100. RESULTS: 13 academy and 15 non-academy students were enrolled. The overall mean scores were 51/100 for the academy group, range 0-97, and 45.5/100 for the non-academy group, range 0-90 (p=0.49). Scores for precision testing, forceps training and capsulorrhexis training for academy versus non-academy were 45.8 versus 37.8 (p=0.61), 57.1 versus 52.3 (p=0.8) and 50.2 versus 46.4 (p=0.55), respectively. CONCLUSIONS: This study is the first to suggest that medical students with a strong career interest in ophthalmology do not perform microsurgical tasks to a higher level than medical students who have no goal in this area. This also indicates variation in scores between novices, which may serve as a pitfall in the use of simulators as a tool for entry into training.

Higher surgical training in ophthalmology: trends in cumulative surgical experience 1993-2008.

INTRODUCTION: Recent years have seen significant changes in the provision surgical training for ophthalmology. The aim of this study is to establish the patterns in long-term trends of cumulative surgical experience of ophthalmology trainees in the United Kingdom. MATERIALS AND METHODS: Data were obtained from the department of training and education at the Royal College of Ophthalmologists (RCOphth). The cumulative surgical experience of all ophthalmology higher surgical trainees attaining accreditation, CCST, or CCT between 1993-2001 and 2005-2008 was included for descriptive analysis. RESULTS: Cumulative cataract surgical experience per trainee has been relatively stable at levels between 500 and 600 for most years. The cumulative experience vitreoretinal and corneal graft surgery have historically been low with a large outlier effect, although trends demonstrate a decrease in the median numbers of procedures. Squint surgery has seen a downward trend with a decrease in the median numbers from 121 in 1993 to 43 in 2008. Oculoplastics procedures demonstrate a decrease in overall numbers from 46 in 1993 to 15 in 2001. A jump from 2005 coincides with changes in the definition of what is counted as an oculoplastics procedure. The role of the RCOphth in legislating minimum levels of experience has had an impact on the data distribution manifest by the truncation of the inferior quartile of many of the dataspreads. DISCUSSION: These data demonstrate that although the cumulative experience of cataract surgery for trainees has remained stable, there has been a reduction in the median numbers of subspecialty procedures performed over the past 15 years.

Towards a better understanding of patient perspectives of clinical teaching in ophthalmology.

OBJECTIVE: To investigate of the perspectives of ophthalmology patients involved in clinical teaching. METHODS: In all, 26 patients attending a revision course for postgraduate Membership of the Royal College of Ophthalmologists examination were recruited. Every patient was examined by each of 36 residents who were present on this course making a total of 936 clinical examinations. Patient perspectives on their experience were investigated using a questionnaire. Four domains were investigated: interpersonal aspects, information exchange, discomfort, and overall perceptions. RESULTS: Four different examinations were carried out: neurological, orthoptic and slit-lamp examination of the anterior or posterior segment. The overwhelming proportion of patients learned much about their condition and felt that their contribution towards the training was valuable. Patients found the experience to be positive and satisfying, and all of the patients expressed a desire to reattend. No significant difference in patient discomfort (P=0.36) or perceptions of rough handling by doctors (P=0.62) between patients undergoing slit-lamp examination or non-slit-lamp examination was evident. CONCLUSIONS: Patients are willing to participate in clinical teaching and assessment, and they gain from the experience. Patients undergoing examinations using high luminance light sources were no more affected by discomfort than those undergoing eye movement or neurological examinations. Our data demonstrate the argument for a greater role of patient-based teaching as a training and assessment tool for fundoscopy.

Outcome of phacoemulsification in patients with uveitis.

AIMS: To examine the visual outcome and identify risk factors for postoperative uveitis, macular oedema and neodymium-doped yttrium aluminium garnet (Nd:YAG) capsulotomy after phacoemulsification and intraocular lens (IOL) implantation in patients with uveitis. METHOD: This is a retrospective review of the medical records of 101 eyes of 101 patients. One eye was randomly selected for inclusion in patients who had bilateral surgery. Patients with juvenile arthritis, keratouveitis and lymphoma-associated uveitis were excluded. RESULTS: At the first postoperative and final visits, visual acuity was significantly better (p<0.001), and 64.4% and 71.3% of patients, respectively, had achieved >or=2 Snellen's lines of visual improvement. The cumulative probability of doubling of the visual angle was 52% over 6 years of follow-up, and this occurred at a higher rate in the presence of preoperative retinal or optic nerve lesions (HR (95% CI) 4.49 (1.41 to 14.29)). Within 3 months after operation, uveitis was more likely to develop in female patients (OR (95% CI) 6.21 (1.41 to 27.43)) and in the presence of significant intraoperative posterior synechiae (OR (95% CI) 8.43 (1.09 to 65.41)); macular oedema was more likely to develop in patients who developed postoperative uveitis (OR (95% CI) 7.45 (1.63 to 34.16)). Nd:YAG capsulotomy occurred at a higher rate in patients aged

Assessment of the effect of oral clarithromycin on visual outcome following presumed bacterial endophthalmitis.

PURPOSE: The use of clarithromycin was assessed as a biofilm reducing agent in the management of bacterial endophthalmitis. METHODS: 84 eyes of 83 patients presenting with clinical signs highly suggestive of bacterial endophthalmitis were treated using a standard regimen of intraocular vancomycin, amikacin and systemic steroids, which in addition included oral clarithromycin. Ocular penetration of oral clarithromycin in healthy and inflamed eyes was also assessed. RESULTS: Comparing visual acuities at presentation and 6 months, 66% of patients demonstrated an improvement. Intraocular samples were culture positive in 58% of eyes. As compared to culture positive cases, more culture negative cases achieved a visual acuity of 6/12 or better (p = 0.0047). As compared to patients receiving the standard protocol but without clarithromycin, a greater number of culture negative cases demonstrated an improvement in vision of > or = + 6 Snellen lines (p = 0.023). The ocular penetration of clarithromycin into the anterior chamber of inflamed eyes appears sufficient to allow anti-biofilm activity against bacteria at the basic pH encountered in eyes with endophthalmitis. CONCLUSIONS: The ocular penetration of clarithromycin appears adequate for anti-biofilm activity in inflamed eyes. The beneficial effects of oral clarithromycin on visual outcome has been demonstrated in culture negative eyes with clinical signs highly suggestive of bacterial endophthalmitis. The final visual outcome for culture positive cases remains poor.

Use of PCR in endophthalmitis.

In eyes with suspected endophthalmitis, early diagnosis and appropriate treatment have been noted to be associated with a better visual outcome. Currently, however, confirmation of the diagnosis of endophthalmitis (bacterial and/or fungal) is dependent on conventional techniques of microbiological isolation of organisms which require between one and twelve days. Furthermore, many samples prove to be culture-negative. In order to improve the rate of microbiological diagnosis, PCR technology has been successfully applied to the detection of bacteria and fungi in ocular samples. Specific oligonucleotide primers have been used to detect the presence of pathogens, which have been subsequently identified using RFLP analysis, DNA sequencing, and/or cloning techniques. Results demonstrated that PCR-based methods are rapidly able to confirm the presence of pathogens with high specificity and sensitivity. PCR-based techniques have also been used to rule out with confidence the presence of pathogens, a unique advantage of this methodology. The use of molecular methods has significantly increased the number of intraocular samples from which a confirmed diagnosis is made and reduced the time to laboratory diagnosis. PCR-based methods promise to be useful diagnostic tools in the management of these patients, especially those from whom ocular samples prove to be culture-negative.

PCR-based evidence of bacterial involvement in eyes with suspected intraocular infection.

PURPOSE: To assess the usefulness of polymerase chain reaction (PCR) in detection of bacteria in ocular samples. METHODS: Thirty-seven samples (aqueous and vitreous) were collected from 25 eyes showing typical symptoms and clinical signs of bacterial endophthalmitis. Ocular samples were also collected from 38 eyes that underwent routine surgery and from 15 eyes with intraocular inflammation due to nonbacterial causes. Panbacterial PCR was performed with a nested pair of 16S rRNA gene primers. Subsequent bacterial identification was completed for 18 paired samples (nine eyes) using restriction fragment length polymorphism (RFLP) and DNA sequencing. RESULTS: A 100% concordance was obtained between PCR and culture-positive samples. A PCR product was amplified from all 37 intraocular samples from eyes with suspected infection, whereas only 15 of 22 vitreous samples and 5 of 15 aqueous samples were culture positive. Culture-negative PCR-positive samples contained a preponderance of gram-negative bacterial sequences. Cloning and DNA analysis revealed 30 DNA sequences and included eight bacterial 16S rDNA, which currently remain unidentifiable. The presence of bacterial DNA was associated with an inflammatory response suggestive of infection and not colonization. All 15 samples from inflamed eyes with diverse uveitis diagnoses were PCR negative. The false-positive rate, due to contamination during sampling, was 5%. CONCLUSIONS: Bacterial DNA was detected in all patients with typical clinical signs of endophthalmitis. Gram-negative organisms seem to play a much more important role in the pathogenesis of this disease than previously thought. PCR-based techniques have great value in the confirmation of the diagnosis of bacterial endophthalmitis especially in culture-negative eyes.

Rapid detection and identification of Candida, Aspergillus, and Fusarium species in ocular samples using nested PCR.

A protocol for the rapid detection of fungal DNA in ocular samples, derived from three species, Candida albicans, Aspergillus fumigatus, and Fusarium solani, has been developed. Two novel panfungal primers complementary to 18S rRNA sequences present in all three species were designed. Panfungal PCR was followed by three nested PCRs utilizing species-specific primers. PCR sensitivity ranged from 50 to 100 fg of free DNA and between one and two C. albicans organisms. In addition, we also developed a rapid and reliable DNA extraction protocol. This protocol minimized DNA loss during extraction, whilst removing compounds from vitreous and aqueous fluids that have previously been shown to have inhibitory effects on PCR. Preliminary results obtained after testing the protocol on three patient samples support culture results and medical history. However, one patient was PCR positive but culture negative, suggesting that the sensitivity of this protocol may exceed that of traditional culture techniques. This system, therefore, constitutes an additional protocol that may significantly aid patient management in cases where fungal endophthalmitis is suspected.

PCR-RFLP-mediated detection and speciation of bacterial species causing endophthalmitis.

PURPOSE: To determine the usefulness of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in the identification and speciation of bacteria causing endophthalmitis. METHODS: PCR-RFLP was performed on 53 strains of 14 bacterial species (eight Gram positive and five Gram negative) collected from both keratitis and endophthalmitis patients. Two pairs of oligonucleotide primers based on the 16S rDNA gene were used to PCR-amplify 1.2- and 1.0-kb fragments of bacterial genomic DNA. RFLPs within the PCR product were used to speciate the organisms. RESULTS: The sensitivity of the nested PCR amplification reaction was one organism. All bacteria tested could be identified and speciated using RFLP analysis except for Escherichia coli and Serratia marcescens, which could not be interdifferentiated using RFLP. Molecular analysis of two vitreous samples from two eyes with typical signs of bacterial endophthalmitis confirmed the presence of E. coli in the vitreous from a culture-positive case with E. coli endophthalmitis and revealed the presence of Staphylococcus epidermidis in the vitreous of a culture-negative case. CONCLUSIONS: It is expected that this technique will provide a useful laboratory tool for future microbiologic diagnosis of patients presenting with endophthalmitis, especially for those eyes that prove culture negative.

Detection of and discrimination between gram-positive and gram-negative bacteria in intraocular samples by using nested PCR.

A nested PCR protocol has been developed for the detection of and discrimination between 14 species of gram-positive and -negative bacteria in samples of ocular fluids. First-round PCR with pan-bacterial oligonucleotide primers, based on conserved sequences of the 16S ribosomal gene, was followed by a gram-negative-organism-specific PCR, which resulted in a single 985-bp amplification product, and a multiplex PCR which resulted in two PCR products: a 1,025 bp amplicon (all bacteria) and a 355 bp amplicon (gram-positive bacteria only). All products were detected by gel electrophoresis. The sensitivity of the assay was between 10 fg and 1 pg of bacterial DNA, depending on the species tested, equivalent to between 24 and 4 live bacteria spiked in water. The identification was complete in 3.5 h. The molecular techniques were subsequently applied to four samples of intraocular fluid, (three vitreous and one aqueous) from three patients with clinical signs of bacterial endophthalmitis (test samples) and two samples of vitreous from a patient with chronic intraocular inflammation (control samples). In all culture-positive samples (two of three vitreous and one of one aqueous), a complete concordance was observed between molecular methods and culture results. PCR correctly identified the gram stain classification of the organisms. The bacterial etiology was also identified in a culture-negative patient with clinical history and signs highly suggestive of bacterial endophthalmitis. Furthermore, control samples from a patient with chronic intraocular inflammation remained PCR negative. In summary, this protocol has demonstrated potential as a rapid diagnostic test in confirming the diagnosis of infection and also determining the Gram status of bacteria with high specificity and sensitivity.

Comparison of PCR detection methods for B1, P30, and 18S rDNA genes of T. gondii in aqueous humor.

PURPOSE: Comparison of polymerase chain reaction (PCR) amplification of three Toxoplasma gondii genes in aqueous humor. METHODS: Nested PCRs carried out using published methods were optimized for maximum sensitivity and specificity. Five pairs of oligonucleotide primers, directed against the B1, P30, and ribosomal genes, were used and compared to determine which sequences were most effective in detecting T. gondii DNA. Methods were developed with DNA templates in water and were subsequently applied to both normal and inflamed aqueous. RESULTS: After one round of PCR amplification, P30 and ribosomal primers were able to detect 1 pg genomic T. gondii DNA. However, those directed against the B1 gene were able to detect 50 fg (approximately single tachyzoite). This level of sensitivity was also achieved using the P30 primers after a second round of PCR; however, only primers based on the B1 gene maintained this level of sensitivity in both normal and inflamed aqueous. B1-specific primers did not amplify sequences from fungal, bacterial, or human lymphocyte DNA. The sensitivity of T. gondii detection using B1 gene-specific primers was not compromised when large amounts of human lymphocyte DNA were present, and application to an ocular sample or retinal section from patients with toxoplasma chorioretinitis was successful in confirming the presence of T. gondii DNA. CONCLUSIONS: The B1 PCR protocol appears to be the most sensitive protocol in the detection of T. gondii DNA and has been successful in identification of T. gondii DNA in ocular fluids and retinal sections. This provides direct evidence of the presence of T. gondii within the eye and may therefore help in the management of toxoplasma retinochoroiditis.

Elimination of bacterial DNA from Taq DNA polymerases by restriction endonuclease digestion.

The incidence of false positives due to the presence of bacterial DNA in Taq DNA polymerase is an obstacle to the use of PCR in the diagnosis of infection. We describe a method that uses a restriction enzyme to destroy the ability of contaminating sequences to act as templates for a nested PCR which uses primers based on the 16S rRNA genes. The method was used prior to a PCR that amplified 10 fg of bacterial DNA. This method can be readily adapted to suit other sensitive PCRs required for clinical applications.

Assessment of visual outcome after cataract surgery in patients with uveitis.

OBJECTIVE: To assess the outcome of cataract surgery in eyes of patients with uveitis. DESIGN: Prospective, noncomparative case series. PARTICIPANTS: A total of 90 eyes of 76 patients fulfilled the enrollment criteria. INTERVENTION: All patients had their surgery performed using standard cataract extraction techniques. Unless contraindicated, preoperative systemic steroids were administered to all patients with posterior disease, chronic anterior uveitis, with known macular edema, and those in whom outcome of cataract surgery on the fellow eye had been poor. RESULTS: Patients were divided into those with anterior disease (n = 53) and those with posterior disease (n = 37). Overall, 81 (90%) of 90 eyes showed improvement in vision (median +4 Snellen lines). In those with anterior disease, the development of severe uveitis in the first week postsurgery was associated with a greater incidence of macular edema (P = 0.014). The single largest diagnosis in those with posterior disease was that of panuveitis (n = 24). This group showed the poorest visual outcomes in this study. The majority of patients, however, were noted to have visual loss secondary to conditions present before surgery. CONCLUSION: Cataract surgery in eyes with uveitis leads to an improvement of vision in the majority of cases. Severe postoperative uveitis is the most common postoperative complication and is associated with a significant risk of macular edema in those with anterior disease. In the posterior group, poor visual outcome after surgery is most commonly the result of preoperative vision-limiting conditions.

Polymerase chain reaction and restriction fragment length polymorphism mediated detection and speciation of Candida spp causing intraocular infection.

PURPOSE: To determine the usefulness of polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis in the identification and speciation of Candida spp that causes ocular infection. METHODS: Oligonucleotide primers based on the cytochrome P450 L1 A1 demethylase gene were used to successfully amplify by PCR a single 1.0-kb and a single 500-bp DNA fragment from C. albicans, C. tropicalis, C. krusei, C. glabrata, C. parapsilosis, and C. pelliculosa genomic DNA. RFLPs within the PCR product were identified after restriction enzyme digestion. RESULTS: The sensitivity of the amplification reaction after two rounds of PCR was 10 fg genomic C. albicans DNA or one copy of the gene. No amplification product was obtained when DNA from C. guilliermondii, Aspergillus fumigatus, Fusarium solani, human leukocytes, or 10 species of bacteria was used as a template. Experiments with spiked normal vitreous demonstrated equal sensitivity as long as the volume of vitreous did not exceed 20% of the total PCR volume. RFLP analysis of the PCR product generated from each species obtained from the first- and second-round amplification products enabled species identification after digestion with specific endonucleases. Application of the technique to four clinical samples was successful. CONCLUSIONS: It is expected that the simplicity of the DNA extraction technique allied with the broad specificity of the outer primers for all ophthalmically relevant Candida spp and the sensitivity of the second-round PCR will aid in the detection of fungal DNA in small intraocular samples. PCR-RFLP analysis has great potential in the rapid detection and identification of Candida spp and in the provision of a useful laboratory tool for the future.

Enterobacter cloacae endophthalmitis: report of four cases.

Members of the genus Enterobacter are commensal organisms of the gastrointestinal tract and are considered pathogenic only for patients with lowered resistance to infection (e.g., chronic infection, cancer, or diabetes mellitus) or those with impaired immunity (congenital, acquired, or impaired immunity secondary to therapy). We report on four cases of endophthalmitis caused by Enterobacter cloacae: two in patients with acute postoperative endophthalmitis, one in a patient with delayed bleb-related endophthalmitis, and one in a patient presenting with presumed posttraumatic endophthalmitis. Each patient presented with severe disease many days after the onset of ocular symptoms, and two patients had systemic risk factors accounting for a reduced resistance to infection. Endophthalmitis caused by gram-negative bacilli is characterized by acute onset, rapid progression, and poor final visual outcome. Each of these patients was treated by a standard protocol with intravitreal, systemic, and topical antibiotics and systemic steroids. Despite treatment, the final visual outcomes for three of these patients was no perception of light, and that for one patient remained perception of hand movements only. In common with endophthalmitis caused by other gram-negative organisms, intraocular infection secondary to Enterobacter cloacae infection is a devastating disease which, despite treatment, results in extensive ocular damage and severe visual loss. Since 1966, only four cases of endophthalmitis secondary to infection with members of this genus have been reported. This report presents four cases which occurred over a period of 14 months and, to the best of our knowledge, the first case of bleb-related endophthalmitis secondary to E. cloacae infection.