Use of the Ishikawa diagram in a case-control analysis to assess the causes of a diffuse lamellar keratitis outbreak.

PURPOSE: To identify the causes of a diffuse lamellar keratitis (DLK) outbreak using a systematic search tool in a case-control analysis. METHODS: An Ishikawa diagram was used to guide physicians to determine the potential risk factors involved in this outbreak. Coherence between the occurrences and each possible cause listed in the diagram was verified, and the total number of eyes at risk was used to calculate the proportion of affected eyes. Multivariate analysis was performed using logistic regression to determine the independent effect of the risk factors, after controlling for confounders and test interactions. RESULTS: All DLK cases were reported in 2007 between June 13 and December 21; during this period, 3,698 procedures were performed. Of the 1,682 flap-related procedures, 204 eyes of 141 individuals presented with DLK. No direct relationship was observed between the occurrence of DLK and the presence of any specific factors; however, flap-lifting enhancements, procedures performed during the morning shift, and non-use of therapeutic contact lenses after the surgery were significantly related to higher occurrence percentages of this condition. CONCLUSIONS: The Ishikawa diagram, like most quality tools, is a visualization and knowledge organization tool. This systematization allowed the investigators to thoroughly assess all the possible causes of DLK outbreak. A clear view of the entire surgical logistics permitted even more rigid management of the main factors involved in the process and, as a result, highlighted factors that deserved attention. The case-control analysis on every factor raised by the Ishikawa diagram indicated that the commonly suspected factors such as biofilm contamination of the water reservoir in autoclaves, the air-conditioning filter system, glove powder, microkeratome motor oil, and gentian violet markers were not related to the outbreak.

Use of the Ishikawa diagram in a case-control analysis to assess the causes of a diffuse lamellar keratitis outbreak / Aplicando o diagrama de Ishikawa em uma análise caso-controle para identificar as causas de um surto de ceratite lamelar difusa

ABSTRACT Purpose: To identify the causes of a diffuse lamellar keratitis (DLK) outbreak using a systematic search tool in a case-control analysis. Methods: An Ishikawa diagram was used to guide physicians to determine the potential risk factors involved in this outbreak. Coherence between the occurrences and each possible cause listed in the diagram was verified, and the total number of eyes at risk was used to calculate the proportion of affected eyes. Multivariate analysis was performed using logistic regression to determine the independent effect of the risk factors, after controlling for confounders and test interactions. Results: All DLK cases were reported in 2007 between June 13 and December 21; during this period, 3,698 procedures were performed. Of the 1,682 flap-related procedures, 204 eyes of 141 individuals presented with DLK. No direct relationship was observed between the occurrence of DLK and the presence of any specific factors; however, flap-lifting enhancements, procedures performed during the morning shift, and non-use of therapeutic contact lenses after the surgery were significantly related to higher occurrence percentages of this condition. Conclusions: The Ishikawa diagram, like most quality tools, is a visualization and knowledge organization tool. This systematization allowed the investigators to thoroughly assess all the possible causes of DLK outbreak. A clear view of the entire surgical logistics permitted even more rigid management of the main factors involved in the process and, as a result, highlighted factors that deserved attention. The case-control analysis on every factor raised by the Ishikawa diagram indicated that the commonly suspected factors such as biofilm contamination of the water reservoir in autoclaves, the air-conditioning filter system, glove powder, microkeratome motor oil, and gentian violet markers were not related to the outbreak.

RESUMO Objetivos: Identificar as causas de um surto de ceratite lamelar difusa (DLK) uti­lizando uma ferramenta de busca sistemática em uma análise de caso-controle. Métodos: O diagrama de Ishikawa foi usado para orientar os médicos a identificar os potenciais fatores de risco envolvidos neste surto. Coerência entre as ocorrências e cada causa possível listada no diagrama foi verificada. O número total de olhos em risco foi usada para calcular a percentagem de olhos afetados. A análise multivariada foi realizada por meio de regressão logística para determinar o efeito independente dos fatores de risco, controle de fatores de confusão e interações de teste. Resultados: Todos os casos de ceratite lamelar difusa foram relatados em 2007 entre 13 de junho e 21 de dezembro, durante este tempo foram realizados no total 3.698 procedimentos. De um total de 1.682 procedimentos relacionados a confecção de um flap, 204 olhos de 141 indivíduos apresentaram ceratite lamelar difusa. Não foi observada relação direta entre a ocorrência de ceratite lamelar difusa e a presença de qualquer fator específico; no entanto, procedimentos que incluíam um novo levantamento do flap, procedimentos realizados no turno da manhã, e o não-uso de lentes de contato terapêuticas após a cirurgia foram significativamente relacionados com a ocorrência desta complicação. Conclusão: O diagrama de Ishikawa é uma ferramenta de visualização e organização do conhecimento. Essa sistematização permitiu aos investigadores pesquisar todas as possíveis causas do surto de ceratite lamelar difusa. Uma visão clara de toda a logística cirúrgica permitiu a gestão mais rígida dos principais fatores envolvidos no processo. A análise de caso-controle em relação a cada fatores levantados pelo diagrama indicou que fatores sempre suspeitos, tais como: contaminação do biofilme da água do reservatório das autoclaves, sistema de filtro de ar-condicionado, pó de luva, óleo de motor do microcerátomo e marcador violeta de genciana, não foram relacionados com o surto.

Comparison of laser epithelial keratomileusis with and without mitomycin C for wavefront customized surface ablations.

PURPOSE: To investigate the efficacy of mitomycin C (MMC) in preventing haze formation in surface wavefront customized ablations with successful refractive treatment (laser epithelial keratomileusis [LASEK]) and to evaluate the safety of this technique on corneal stroma and endothelium. METHODS: This study was a prospective, double-masked, randomized clinical trial involving 52 eyes (30 placebo and 22 MMC) of 26 patients. The manifest refractive spherical equivalent (MRSE), best spectacle-corrected visual acuity, uncorrected visual acuity, corneal pachymetry, topography, aberrometry, endothelial specular microscopy, contrast sensitivity, corneal confocal microscopy, and complaints of pain via a subjective questionnaire were recorded preoperatively and 90 days postoperatively. RESULTS: The mean MRSE at 90 days postoperatively was -0.56 diopters (D) (-4.95 +/- 1.85 D, range: -8.00 to -1.62 D) for the MMC group and -0.49 D (-4.51 +/- 1.81 D, range: -7.75 to -2.25 D) for the placebo group. Higher order aberrations were similar between the placebo and MMC groups 90 days postoperatively (0.538 +/- 0.228 microm and 0.478 +/- 0.134 microm, respectively). Analysis of the endothelial cell count indicated a statistically significant decrease in endothelial cell density (P = .017) after LASEK, independent of MMC use. CONCLUSIONS: The predictability of the final target refraction, induction of high order aberrations, and improvement in contrast sensitivity proved that the use of MMC was equally safe when compared to procedures that did not use MMC. In addition, the procedure was efficient in the prevention of corneal haze.

[LASIK interface fluid accumulation caused by glaucoma associated with herpetic keratouveitis: case report]. / Coleção fluídica na interface do LASIK causada por glaucoma secundário à ceratouveíte herpética: relato de caso.

Herpes simplex virus infection is a frequent cause of intraocular inflammation or anterior uveitis. Ocular hypertension is a common feature in herpetic keratouveitis. We describe a fluid accumulation and flap displacement in late postoperative period (28 months) of LASIK associated with ocular hypertension caused by herpetic keratouveitis. This finding supports the theory that flap attachment after LASIK is only partial and the virtual space remains indefinitely. The presence of ocular hypertension may lead to corneal edema and fluid accumulation in the interface.

Coleção fluídica na interface do LASIK causada por glaucoma secundário à ceratouveíte herpética: relato de caso / LASIK interface fluid accumulation caused by glaucoma associated with herpetic keratouveitis: case report

A infecção por Herpes simplex vírus (HSV) é causa freqüente de inflamação intra-ocular ou uveíte anterior. A hipertensão ocular é característica comumente observada nas ceratouveítes herpéticas. Neste relato descrevemos o acúmulo de fluido e descolamento do "flap" corneano da ceratomileusis, no pós-operatório tardio de LASIK (28 meses), associado a quadro hipertensivo ocular secundário a ceratouveíte herpética. Este achado corrobora a suposição que a cicatrização corneana após LASIK seja apenas parcial e o espaço virtual produzido pela ceratomileuisis permaneça indefinidamente. Condições de aumento excessivo da pressão intra-ocular podem causar edema corneano com acúmulo de fluido da interface.

Herpes simplex virus infection is a frequent cause of intraocular inflammation or anterior uveitis. Ocular hypertension is a common feature in herpetic keratouveitis. We describe a fluid accumulation and flap displacement in late postoperative period (28 months) of LASIK associated with ocular hypertension caused by herpetic keratouveitis. This finding supports the theory that flap attachment after LASIK is only partial and the virtual space remains indefinitely. The presence of ocular hypertension may lead to corneal edema and fluid accumulation in the interface.

Wavefront analysis in Asian-Brazilians.

PURPOSE: To compare the distribution of ocular higher order wavefront aberrations (third to sixth order) in the Brazilian population of Asian and non-Asian refractive surgery patients. METHODS: Preoperative refractive and wavefront data were reviewed for 648 eyes in 324 patients who underwent custom ablation at the Excimer Laser Santa Cruz refractive surgery center in São Paulo, Brazil, from March 2002 to July 2005. Patients were divided into two groups: Asian patients and non-Asian patients, based on family history. Statistical analysis was performed to assess the differences between the groups with respect to manifest refractive spherical equivalent, astigmatism, pachymetry, OPD-root-square-mean (RMS) for a 6.0-mm pupil, total wavefront aberrations, third- to sixth-order higher order aberrations, and individual aberrations. RESULTS: The mean spherical equivalent refraction in the Asian group of -4.38 diopters (D) was significantly higher than the spherical equivalent refraction of -3.46 D in the non-Asian group (t= -4.32; P=.00001). Comparison of the differences between groups with respect to higher order aberrations, coma, trefoil, quadrafoil, spherical aberration, higher order astigmatism, and pachymetry was not statistically significant. CONCLUSIONS: Asian patients have a higher prevalence of myopia than non-Asian patients. No differences were noted in higher order aberrations between Asian and non-Asian patients.

Intraoperative microkeratome complications in 47,094 laser in situ keratomileusis surgeries.

PURPOSE: We evaluated the incidence and intraoperative microkeratome-related complications in laser in situ keratomileusis (LASIK). METHODS: We present non-randomized, retrospective, comparative, interventional case series. We reviewed the records of patients who underwent LASIK from August 2000 to March 2004 at Excimer Laser Santa Cruz, São Paulo, Brazil (47,094 eyes). We identified 369 eyes (0.0078%) with an intraoperative complication. Data were collected regarding microkeratome, average keratometric power, and type of complication. RESULTS: The Hansatome microkeratome was the most common microkeratome used (34,182 eyes; 73%), followed by the Automated Corneal Shaper-ACS (11,164 eyes, 24%) and the Nidek MK-2000 (1748 eyes, 3.7%). Intraoperative complications were more common with the ACS (1.26%) than with the Hansatome (0.63%) and MK-2000 (0.63%) (P<.001; P=.03; respectively). Complications included incomplete flaps (0.23%), buttonholes (0.13%), thin flaps (0.08%), and free flaps (0.08%). Buttonholes were more frequent with the ACS (0.34%) than with the Hansatome (0.06%) (P<.001) and free flaps were more common with the ACS (0.20%) and MK-2000 (0.29%) than with the Hansatome (0.04%) (P<.001). Keratometric power of eyes with intraoperative complications was significantly higher in the ACS group compared to the Hansatome group. CONCLUSIONS: Intraoperative complications were more common with the ACS than with the Hansatome or MK-2000. Buttonholes were most frequent with the ACS, and the Hansatome had the lowest incidence of free flaps.

Confocal microscopy in early diagnosis of Acanthamoeba keratitis.

PURPOSE: This study correlated confocal microscopic images obtained using the Nidek ConfoScan 2.0 System in corneas with clinical suspicion of Acanthamoeba keratitis, with diagnosis confirmed by either cytological and/or histological analysis. METHODS: Fifteen eyes of 14 patients with a clinical diagnosis of Acanthamoeba keratitis underwent confocal microscopy evaluation. RESULTS: Fifteen eyes of 14 patients (one bilateral case) showed Acanthamoeba keratitis alterations that ranged from massive infestation to cicatricial opacity in the stroma. Ten patients (71%) were females. Mean age was 26 years (range 19 to 37 yr). All patients were contact lens wearers. CONCLUSION: Confocal microscopy was a useful, noninvasive technique in the diagnosis and treatment of Acanthamoeba keratitis, especially in those cases in which corneal scraping, cytological analysis, and culture are negative. It also eliminated the necessity of tissue biopsy, considered an invasive procedure.

Nova técnica para o tratamento cirúrgico da cabeça do pterígio - Exérese com álcool absoluto diluído a 50 por cento / New surgical technique for treatment of the pterygium head - Excision with 50 percent ethanol

OBJETIVO: Descrever nova técnica cirúrgica para o tratamento do pterígio utilizando álcool absoluto diluído 50 por cento. MÉTODO: A cabeça do pterígio foi submetida à exposição de gotas de álcool absoluto, diluído a 50 por cento em água destilada, durante 40 segundos e posteriormente removida com espátula de divulsão. RESULTADOS: A excisão da cabeça do pterígio foi facilitada por plano de clivagem epitelial promovido pela aplicação do álcool diluído. O exame biomicroscópico evidenciou, após a cirurgia, superfície corneana com aspecto regular e homogêneo, o que pode contribuir para melhor qualidade de visão. CONCLUSAO: O uso do álcool absoluto diluído a 50 por cento com água destilada pode ser utilizado como nova técnica cirúrgica para a exérese da cabeça do pterígio da região corneana.

Refractive outcome of Nidek OPD-scan customized ablations.

PURPOSE: Custom ablation is an improved refractive laser treatment that aims to optimize the optical system of the eye. We report preliminary results of laser in situ keratomileusis (LASIK) using customized ablation and the Nidek OPD-Scan. METHODS: We report a prospective, non-comparative interventional case series. After OPD-Scan analysis, patients underwent LASIK. Eighty-four eyes were included: 44 eyes were treated with Flex Scan, 22 eyes with customized ablation based on Nidek OPD-Scan analysis, and 18 eyes were treated with conventional (scanning slit) ablation. RESULTS: Visual outcome did not differ among groups. No patient experienced a significant decrease (more than 1 Snellen line) in best spectacle-corrected visual acuity. CONCLUSIONS: LASIK with the Nidek OPD-Scan system was safe and effective in this small group of patients.

Cleaning solutions as a cause of diffuse lamellar keratitis.

PURPOSE: To assess the capability of two microkeratome cleaning solutions in causing diffuse lamellar keratitis (DLK) in a rabbit model of laser in situ keratomileusis (LASIK). METHODS: Two cleaning solutions (Palmolive 2:100 and Cidezyme 2:250) were tested. These solutions were diluted with balanced salt solution according to directions from the Hansatome microkeratome manual. Two additional solutions were prepared using an additional ten-fold dilution, creating a total of four study solutions. A LASIK flap was created in one eye each of 25 rabbits using the ALK Chiron microkeratome. The rabbits were divided into five study groups. The flaps were reflected and a drop of one of the study solutions (or BSS, control group) was placed on the interface. After 1 minute, the solution was washed out from the interface and the flap was repositioned. The eyes were examined at the slit lamp on postoperative days 1, 2, 3, 5, and 7. RESULTS: In 12 eyes, a flap displacement was identified. Four eyes showed flap retraction and five others, epithelial ingrowth in flap margins. The incidence of these events did not differ among groups. Thirteen eyes were then evaluated for DLK. No DLK-like interface inflammation was seen in the studied eyes. CONCLUSION: The cleaning solutions, when diluted as recommended by the microkeratome manufacturer, when in contact with the corneal stroma, and provided that the interface was washed with BSS did not cause DLK interface inflammation in rabbit LASIK models.

Cirurgia da catarata em olhos irradiados por retinoblastoma / Cataracts surgery in irradiated retinoblastoma eyes

Os autores descrevem o resultado de cirurgia de catarata em 3 pacientes portadores de retinoblastoma nesse olho, submetidos previamente à quimioterapia, radioterapia e foto ou criocoagulação. Optam pela etiologia radiogênica dessa catarata. Não se observou qualquer dificuldade técnica ou compplicações intransponíveis durante a facectomia com a técnica extra-capsular. Dois pacientes desenvolveram boa recuperação visual e um desenvolveu catarata secundária e opacidade de vítreo anterior refratários a tratamento com YAG laser e discisão cirúrgica, culminando com o diagnóstico ultrassonográfico de descolamento parcial da retina e presença de traves vítreas. Os autores discutem indicação da facectomia extra-capsular com LIO em crianças e referindo que na experiência de alguns a vitrectomia anterior poderia ser uma recomendação de rotina nesses casos. Essa experiência nos encoraja à manipulação do vítreo sem temor de uma possível disseminação extra-ocular do retinoblastoma pela presença eventual de alguma célula tumoral viável residual.