Investigation of How Corneal Densitometry Artefacts Affect the Imaging of Normal and Keratoconic Corneas.

PURPOSE: To investigate corneal densitometry artefacts found in Pentacam Scheimpflug scans and their potential effect on assessing keratoconic (KC) corneas compared to normal (N) corneas. METHODS: The current study utilises Pentacam data of 458 N eyes, aged 35.6 ± 15.8 (range 10-87), referred to as the "N group", and 314 KC eyes, aged 31.6 ± 10.8 (range 10-72), referred to as the "KC group", where densitometry data were extracted and analysed via a custom-built MATLAB code. Radial summations of the densitometry were calculated at diameters ranging from 0.5 mm to 5.0 mm. The minimum normalised radial summation of densitometry (NRSD) value and angle were determined at each diameter and then linked. KC cone locations and areas of pathology were determined, and a comparison between N and KC groups was carried out both within the averaged area of pathology and over the corneal surface. RESULTS: Joining minimum NRSD trajectory points marked a clear distortion line pointing to the nasal-superior direction at 65° from the nasal meridian. The findings were found to be independent of eye laterality or ocular condition. Consistency was detected in the right and left eyes among both the N and KC groups. The location of the KC cone centre and the area of pathology were determined, and the densitometry output was compared both within the area of pathology and over the whole cornea. When the average densitometry was compared between N and KC eyes within the KC area of pathology, the N group recorded a 16.37 ± 3.15 normalised grey-scale unit (NGSU), and the KC group recorded 17.74 ± 3.4 NGSU (p = 0.0001). However, when the whole cornea was considered, the N group recorded 16.71 ± 5.5 NGSU, and the KC group recorded 15.72 ± 3.98 NGSU (p = 0.0467). A weak correlation was found between the Bad D index and NGSU when the whole measured cornea was considered (R = -0.01); however, a better correlation was recorded within the KC area of pathology (R = 0.21). CONCLUSIONS: Nasal-superior artefacts are observed in the densitometry Pentacam maps, and analysis shows no significant differences in their appearance between N or KC corneas. When analysing KC corneas, it was found that the cone positions are mostly on the temporal-inferior side of the cornea, opposite to the densitometry artefact NRSD trajectory. The analysis suggests that the corneal densitometry artefacts do not interfere with the KC area of pathology as it reaches its extreme in the opposite direction; therefore, weighting the densitometry map to increase the contribution of the inferior-temporal cornea and decreasing that of the superior-nasal area would improve the classification or identification of KC if densitometry is to be used as a KC metric.

Assessment of Preoperative Risk Factors for Post-LASIK Ectasia Development.

Purpose: To evaluate preoperative risk factors (mainly those related to corneal topography/tomography) for post-LASIK ectasia development. Methods: A retrospective case review for post-LASIK ectasia for myopia or myopic astigmatism. The evaluated data included preoperative subjective refraction, method of flap creation, and topometric/tomographic parameters from Oculus Pentacam, including subjective curvature pattern, topometric, elevation, and pachymetric indices from the Belin Ambrosio display "BAD", and the Pentacam Random Forest Index (PRFI). Moreover, preoperative ectasia detection indices were calculated (including Percentage of Tissue Altered "PTA" index, Randleman Ectasia Risk Score System "ERSS", and Navarro Index for Corneal Ectasia "NICE"). Results: Twenty-four eyes of 15 patients were enrolled. Concerning the risk factors, age was lower than 25 in 19 eyes (79%); flaps were created using a microkeratome in 17 eyes (70.8%); thinnest pachymetry was lower than 510µm in eight eyes (33%); total deviation from BAD was higher than 1.6 in 50%; Ambrósio's relational thickness (ART) max was lower than 340 in 45.83%; PTA index was higher than 40% in 16%; ERSS was more than 3 points in 62.5%; NICE was higher than 8 points in three eyes (12.5%); PRFI index was more than 0.125 in 87.5%; two eyes (8%) had no identifiable risk factors. Conclusion: Current ectasia risk assessment criteria were insufficient for detecting a relatively large number of cases. There is an unequivocal need for more information, which may be derived from biomechanical assessment and epithelial thickness mapping. Novel corneal tomography indices derived from artificial intelligence may increase accuracy in characterizing ectasia susceptibility.

Multimodal diagnostics for keratoconus and ectatic corneal diseases: a paradigm shift.

Different diagnostic approaches for ectatic corneal diseases (ECD) include screening, diagnosis confirmation, classification of the ECD type, severity staging, prognostic evaluation, and clinical follow-up. The comprehensive assessment must start with a directed clinical history. However, multimodal imaging tools, including Placido-disk topography, Scheimpflug three-dimensional (3D) tomography, corneal biomechanical evaluations, and layered (or segmental) tomography with epithelial thickness by optical coherence tomography (OCT), or digital very high-frequency ultrasound (dVHF-US) serve as fundamental complementary exams for measuring different characteristics of the cornea. Also, ocular wavefront analysis, axial length measurements, corneal specular or confocal microscopy, and genetic or molecular biology tests are relevant for clinical decisions. Artificial intelligence enhances interpretation and enables combining such a plethora of data, boosting accuracy and facilitating clinical decisions. The applications of diagnostic information for individualized treatments became relevant concerning the therapeutic refractive procedures that emerged as alternatives to keratoplasty. The first paradigm shift concerns the surgical management of patients with ECD with different techniques, such as crosslinking and intrastromal corneal ring segments. A second paradigm shift involved the quest for identifying patients at higher risk of progressive iatrogenic ectasia after elective refractive corrections on the cornea. Beyond augmenting the sensitivity to detect very mild (subclinical or fruste) forms of ECD, ectasia risk assessment evolved to characterize the inherent susceptibility for ectasia development and progression. Furthermore, ectasia risk is also related to environmental factors, including eye rubbing and the relational impact of the surgical procedure on the cornea.

Enhanced Diagnostics for Corneal Ectatic Diseases: The Whats, the Whys, and the Hows.

There are different fundamental diagnostic strategies for patients with ectatic corneal diseases (ECDs): screening, confirmation of the diagnosis, classification of the type of ECD, severity staging, prognostic assessment, and clinical follow-up. The conscious application of such strategies enables individualized treatments. The need for improved diagnostics of ECD is related to the advent of therapeutic refractive procedures that are considered prior to keratoplasty. Among such less invasive procedures, we include corneal crosslinking, customized ablations, and intracorneal ring segment implantation. Besides the paradigm shift in managing patients with ECD, enhancing the sensitivity to detect very mild forms of disease, and characterizing the inherent susceptibility for ectasia progression, became relevant for identifying patients at higher risk for progressive iatrogenic ectasia after laser vision correction (LVC). Moreover, the hypothesis that mild keratoconus is a risk factor for delivering a baby with Down's syndrome potentially augments the relevance of the diagnostics of ECD. Multimodal refractive imaging involves different technologies, including Placido-disk corneal topography, Scheimpflug 3-D tomography, segmental or layered tomography with layered epithelial thickness using OCT (optical coherence tomography), and digital very high-frequency ultrasound (VHF-US), and ocular wavefront. Corneal biomechanical assessments and genetic and molecular biology tests have translated to clinical measurements. Artificial intelligence allows for the integration of a plethora of clinical data and has proven its relevance in facilitating clinical decisions, allowing personalized or individualized treatments.

Ocular manifestations of Chikungunya fever in the chronic phase / Manifestações oculares na fase crônica da febre Chikungunya

ABSTRACT Purpose: To identify ocular manifestations in patients with Chikungunya fever in the chronic phase and describe their sociodemographic profile. Methods: Patients with serologic confirmation of Chikungunya infection were included in this transverse study. All subjects underwent a comprehensive ophthalmologic evaluation, including specific lacrimal function tests (tear break-up time test, Schirmer test, and lissamine green). Results: Overall, 64 eyes of 32 patients were evaluated. Most patients were women (71.9%), with the mean age of 50.0 ±13.7 years. The mean interval between serologic confirmation and the examination was 12.7 ±7.7 months. Twenty patients (62%) presented with dry eye. No statistically significant association was observed between dry eye and infection diagnosis time (p=0.5546), age (p=0.9120), sex (p=1.00), race (p=0.2269), arthralgia in acute infection (p=0.7930), retro-orbital pain (p=0.3066), and conjunctivitis (p=1.00). Conclusion: Dry eye was the most prevalent manifestation observed. No signs of intraocular inflammation and affected visual acuity were observed.

RESUMO Objetivo: Identificar manifestações oculares em pacientes na fase crônica da febre Chikungunya e descrever seu perfil sociodemográfico. Métodos: Estudo transversal com a inclusão de pacientes com confirmação sorológica de febre Chikungunya. Todos os pacientes foram submetidos a exame oftalmológico completo, incluindo testes específicos de função lacrimal (teste de ruptura do filme lacrimal, teste de Schirmer e teste da lissamina verde). Resultados: Foram avaliados 64 olhos de 32 pacientes. A maioria dos pacientes eram do sexo feminino (71,9%) e a idade média foi 50,0 ±13,7 anos. O intervalo médio entre a confirmação sorológica e o exame oftalmológico foi de 12,7 ±7,7 meses. Vinte pacientes (62%) apresentaram olho seco. Não houve significância estatística na associação entre olho seco e o tempo de diagnóstico da infecção (p=0,5546), idade (p=0,9120), sexo (p=1,00), raça (p=0,2269), artralgia durante a infecção aguda (p=0,7930), dor retro-orbitária (p=0,3066) e conjuntivite (p=1,00). Conclusão: A presença de olho seco foi a manifestação mais prevalente observada. Não foram observa dos sinais de inflamação intraocular ou baixa acuidade visual.

Ocular manifestations of Chikungunya fever in the chronic phase.

PURPOSE: To identify ocular manifestations in patients with Chikungunya fever in the chronic phase and describe their sociodemographic profile. METHODS: Patients with serologic confirmation of Chikungunya infection were included in this transverse study. All subjects underwent a comprehensive ophthalmologic evaluation, including specific lacrimal function tests (tear break-up time test, Schirmer test, and lissamine green). RESULTS: Overall, 64 eyes of 32 patients were evaluated. Most patients were women (71.9%), with the mean age of 50.0 ±13.7 years. The mean interval between serologic confirmation and the examination was 12.7 ±7.7 months. Twenty patients (62%) presented with dry eye. No statistically significant association was observed between dry eye and infection diagnosis time (p=0.5546), age (p=0.9120), sex (p=1.00), race (p=0.2269), arthralgia in acute infection (p=0.7930), retro-orbital pain (p=0.3066), and conjunctivitis (p=1.00). CONCLUSION: Dry eye was the most prevalent manifestation observed. No signs of intraocular inflammation and affected visual acuity were observed.

Caracterização de ectasia subclínica com análise integrada da tomografia e biomecânica da córnea / Characterization of subclinical ectasia with integrated corneal tomography and biomechanics assessments

RESUMO O artigo tem como objetivo descrever de forma prospectiva diferentes casos de ectasias altamente assimétricas (very asymmetric ectasia, VAE) para diferenciar formas subclínicas ou "frustas" do ceratocone (forme fruste keratoconus - FFKC) de casos de doença ectásica unilateral. O Caso 1 é um paciente de 39 anos, que admitiu ter coçado intensamente apenas o olho direito (OD) na juventude, se apresentando com ectasia unilateral tratada com sucesso por meio de implante de anel intraestromal em OD. O olho esquerdo (OE) apresentou-se normal ao exame completo por meio de propedêutica multimodal e acuidade visual não corrigida (AVsc) de 20/20, estável por mais de 5 anos, com TBI (tomography and biomechanical index) de 0.02. No Caso 2 é um paciente de 15 anos com ectasia clínica em OD, e OE com topografia normal, mas alterações tomográficas e biomecânicas, incluindo o TBI 0,56, caracterizarando a doença subclínica (FFKC). O Caso 3 é a mãe do paciente do Caso 2, de 46 anos, que se apresentou com presbiopia, sem qualquer histórico oftalmológico relevante. A AVsc foi de 20/20 em cada olho, topografia de Placido com leve encurvamento inferior, mas sem sinais definitivos de ectasia. A avaliação biomecânica e tomográfica revelou sinais de ceratocone em ambos os olhos, com TBI de 1,0 e 0,99. Esses três casos estão de acordo com a definição do consenso global e a hipótese de dois acertos (two-hit hypothesis), que ceratocone é uma doença bilateral, mas ectasia pode ocorrer por causa estritamente mecânica unilateralmente (ou em qualquer olho). A relevância da propedêutica multimodal é destacada, destacando-se a integração do estudo biomecânico e tomográfico com imagens de Scheimpflug.

ABSTRACT The article aims to prospectively describe different cases of highly asymmetric ectasia (very asymmetric ectasia, VAE) to differentiate subclinical or "frustrated" forms of keratoconus (forme fruste keratoconus - FFKC) from cases of unilateral ectatic disease. Case 1 is a 39-year-old patient with unilateral ectasia treated with an intrastromal ring implant. The contralateral eye was normal due to multimodal propaedeutics, stable for more than 3 years, with a TBI of 0.02. The patient admitted to having intensely scratched only his right eye in his youth. In Case 2, a 15-year-old patient with clinical ectasia in the right eye, had a left eye with normal topography and tomographic and biomechanical changes characterizing FFKC. Case 3 is the mother of the case 2 patient, aged 46, who presented with presbyopia, without any relevant ophthalmological history. Uncorrected visual acuity of 20/20 in each eye, Placido topography with slight lower curving, but without definitive signs of ectasia. The biomechanical and tomographic evaluation revealed signs of keratoconus in both eyes. These three cases are in accordance with the definition of the global consensus: keratoconus is a bilateral disease, but ectasia can occur because of strictly mechanical unilateral (in any eye). The relevance of multimodal refractive imaging is highlighted, with a focus on integrating biomechanical and tomographic assessments with Scheimpflug images.

Diagnóstico do ceratocone: um artigo de revisão / A review of keratoconus diagnosis

Resumo Objetivo: Realizar uma revisão sobre o diagnóstico do ceratocone, com enfoque nos métodos propedêuticos disponíveis. Métodos: Foi realizada uma pesquisa no banco de dados PubMed com as palavras chave: Keratoconus, diagnosis, topography e tomography. Por se tratar de uma revisão, não houve restrição de período para a publicação dos artigos selecionados. Foram também utilizados o manual Prefered Practice Pattern(PPP) da academia americana de oftalmologia, assim como o site "eyewiki.aao.org". Resultados: Dos 641 artigos encontrados no PubMed, assim como os usados como referência para o PPP, 36 foram selecionados por serem considerados mais relevantes para o tema proposto. O site "eyewiki.aao.org" foi utilizado como referência para as figuras. Conclusão: O diagnóstico do ceratocone evoluiu consideravelmente desde quando foi primeiramente descrito. É desejável que seja feito em suas fases precoces devido ao alto potencial de morbidade desta doença. Uma possível integração entre os múltiplos índices diagnósticos, investigação genética, biologia molecular e inteligência artificial é almejado para uma maior acurácia diagnóstica.

Abstract Objective: To Perform a review on the diagnosis of keratoconus, focusing on the available propaedeutic methods. Methods: A search was performed in the PubMed database using the key words: Keratoconus, diagnosis, topography and tomography. As it is a review, there was no restriction regarding the publication period of the selected articles. Furthermore, both the preferred practice pattern(PPP) manual of the American Academy of Ophthalmology, as well as the website "eyewiki.aao.org" were used as reference. The project was submitted to the research ethics committee of the Federal University of São Paulo / UNIFESP / SP 2018 (# 2,568,770). Results: Out of the 641 papers found in PubMed, in adition to those used as a reference for PPP, 36 were selected while considered more relevant to the adopted theme. The website "eyewiki.aao.org" was used as a reference for the images. Conclusion: The diagnosis of keratoconus has evolved considerably since it was first described. It is desirable to diagnose it on the early stages due to its high potential of morbility. A possibility of an integration between the various diagnostic indices, genetic research, molecular biology and artificial intelligence is recommended for greater diagnostic accuracy.

Biomechanical diagnostics of the cornea.

Corneal biomechanics has been a hot topic for research in contemporary ophthalmology due to its prospective applications in diagnosis, management, and treatment of several clinical conditions, including glaucoma, elective keratorefractive surgery, and different corneal diseases. The clinical biomechanical investigation has become of great importance in the setting of refractive surgery to identify patients at higher risk of developing iatrogenic ectasia after laser vision correction. This review discusses the latest developments in the detection of corneal ectatic diseases. These developments should be considered in conjunction with multimodal corneal and refractive imaging, including Placido-disk based corneal topography, Scheimpflug corneal tomography, anterior segment tomography, spectral-domain optical coherence tomography (SD-OCT), very-high-frequency ultrasound (VHF-US), ocular biometry, and ocular wavefront measurements. The ocular response analyzer (ORA) and the Corvis ST are non-contact tonometry systems that provide a clinical corneal biomechanical assessment. More recently, Brillouin optical microscopy has been demonstrated to provide in vivo biomechanical measurements. The integration of tomographic and biomechanical data into artificial intelligence techniques has demonstrated the ability to increase the accuracy to detect ectatic disease and characterize the inherent susceptibility for biomechanical failure and ectasia progression, which is a severe complication after laser vision correction.

Manifestações oculares na febre Chikungunya / Ocular Manifestations of Chikungunya Fever

Resumo A febre Chikungunya é um problema de saúde pública mundial, com potencial para gerar epidemias de alta morbidade, visto que elevado número de pacientes pode apresentar sequelas articulares prolongadas e alterações oftalmológicas. As manifestações oftalmológicas podem estar presentes na fase aguda da doença ou ter início após várias semanas da instalação do quadro. Na literatura mundial é descrito desde alterações mais comuns e de fácil tratamento como conjuntivites até alterações mais complexas e que podem cursar com sequelas visuais graves como a retinite e neurite óptica.

Abstract Chikungunya fever is a world public health problem with the potential to generate epidemics of high morbidity, since a high number of patients may present prolonged joint sequelae and ophthalmological alterations. Ophthalmologic manifestations may be present in the acute phase of the disease or begin after several weeks of the onset of the disease. In the world literature is described from more common and easy to treat changes such as conjunctivitis to more complex changes and that can occur with severe visual sequelae such as retinitis and optic neuritis.