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.

A comparative study of visual quality between implantable collamer lens implantation and femtosecond LASIK for myopia / 中华实验眼科杂志

Background The incidence of myopia is gradually increasing,and how to choose a better corrective method of myopia for the best visual demand is very important.Objective This study was to compare visual quality of implantable collamer lens (ICL) implantation with femtosecond laser in situ keratomileusis (FSLASIK) for moderate and high myopia using double-pass optical quality analysis system (OQAS).Methods A non-randomized controlled clinical trail was performed.Fifty-two eyes with-4.00 to-9.00 D of 26 consecutive patients were included in NO.1 Hospital of Xi'an from January 2015 to January 2016.Twenty-four eyes of 12 patients with the corneal thickness ＜500 μm received ICL implantation as ICL group and 28 eyes of 14 patients which corneal thickness was ≥500 μm underwent FS-LASIK surgery as FS-LASIK group.The demography was matched between the two groups (all at P＞0.05).All the patients were followed-up for 3 months after surgery.The preoperative best corrected distance visual acuity (BCDVA),spherical equivalent (SE),postoperative uncorrected distance visual acuity (UCDVA),BCDVA and SE were examined and compared between two groups.The parameters from OQAS were evaluated and intergrouply compared,including the objective scattering inders (OSI),modulation transfer function (MTF) cut off frequency,Strehl ratio and OQAS values under the contrast of 100％,20％ and 9％ (OV100,OV20,OV9).Results The postoperative BCDVA was not significantly different from preoperative UCDVA in both ICL group and FS-LASIK group (-0.04±t0.10 vs.0.05±0.12;-0.07±0.12 vs.0.00±0.12) (t=3.128,2.358,both at P＞0.05).No statistically significant differnces were found in SE,UCDVA and BCDVA after operation between ICL group and FS-LASIK group (t =1.292,0.900,-0.653,all at P＞0.05).OQAS examination showed that MTF cut off,OSI,Strehl ratio,OV100 were not significantly different after operation between ICL group and FS-LASIK group (t=-2.032,-1.440,-0.224,all at P＞0.05).The postoperative OV20 and OV9 were 0.82±0.14 and 0.80±0.21 in the ICL group,which were significantly higher than those in the FS-LASIK group(0.59±0.15 and 0.47±0.13) (t =4.105,4.702,both at P＜0.05).Conclusions Both ICL implantation and FS-LASIK provide good optical and visual quality for moderate to high myopic eyes,and ICL appears to have a better visual quality in comparison with FS-LASIK under the contrasts of 20％ and 9％.

Quality of vision in refractive and cataract surgery, indirect measurers: review article / Qualidade visual em cirurgia refrativa e catarata, medidores indiretos: artigo de revisão

Visual acuity is the measurement of an individual's ability to recognize details of an object in a space. Visual function measurements in clinical ophthalmology are limited by factors such as maximum contrast and so it might not adequately reflect the real vision conditions at that moment as well as the subjective aspects of the world perception by the patient. The objective of a successful vision-restoring surgery lies not only in gaining visual acuity lines, but also in vision quality. Therefore, refractive and cataract surgeries have the responsibility of achieving quality results. It is difficult to define quality of vision by a single parameter, and the main functional-vision tests are: contrast sensitivity, disability glare, intraocular stray light and aberrometry. In the current review the different components of the visual function are explained and the several available methods to assess the vision quality are described.

Qualidade Visual é a medida da capacidade individual de reconhecer detalhes de um objeto no espaço. Medições de função visual na clínica oftalmológica são limitadas por vários fatores, tal como máximo contraste e assim podem não refletir adequadamente as condições visuais reais, bem como os aspectos subjetivos da percepção do mundo pelo paciente. O sucesso em uma cirurgia está não apenas em restaurar linhas de visão, mas sim qualidade visual. Portanto, as cirurgias refrativas e de catarata têm a responsabilidade de alcançar resultados de qualidade. É difícil definir qualidade visual por um único parâmetro, sendo os principais testes de função visual: sensibilidade ao contraste; glare; dispersão intraocular da luz e aberrometria. Nesta revisão os diferentes componentes da função visual são explicados e os diversos métodos disponíveis para se avaliar a qualidade de visão são descritos.