Natural history and predictors for progression in pediatric keratoconus.

We studied the demographic and clinical predictors associated with keratoconus progression in a pediatric population. Retrospective cohort study. We evaluated 305 eyes without previous surgeries from 168 patients, 9 to < 18 years old, and with a minimum 36-month follow-up in a hospital corneal ambulatory. We used Kaplan-Meyer survival curves; the dependent variable (main outcome measure) was the interval time (months) until the event, defined as an increase of 1.5 D in the maximum keratometry (Kmax), obtained with Pentacam. We evaluated the predictors: age (< or ≥ 14 years), sex, keratoconus familial history, allergy medical history, and the baseline tomographic parameters: mean keratometry (Km), Kmax (< or ≥ 55 D); and thinnest pachymetry (TP). We used log-rank tests and compared median survival times for right (RE)/left eyes (LE) and better (BE)/worse eyes (WE). A p value < 0.05 was considered significant. The patients' mean ± SD age was 15.1 ± 2.3 years old; 67% were boys, 30% were < 14 years, 15% had keratoconus familial history, and 70% were allergic. The general Kaplan-Meyer curves showed no differences between RE/LE or BE/WE. RE with allergy and LE with Kmax ≥ 55 D had smaller survival times ((95%CI 9.67-32.1), p 0.031 and (95%CI 10.1-44.1), p 0.042, respectively). For BE and WE, Kmax ≥ 55 D had smaller survival times ((95% CI 6.42- ), p 0.031 and (95%CI 8.75-31.8), p 0.043, respectively). Keratoconus progression was similar between RE/LE and BE/WE. Steepest corneas are predictors of faster progression. Allergy is also a predictor of keratoconus progression in RE.

Herpes simplex keratitis revisited / Ceratite por Herpes simples revisitada

ABSTRACT The degree to which viral infection and the host's immune reaction to viral particles participate in the inflammatory process across various forms of herpetic keratitis has remained controversial. This fact has created conflicts regarding the classification of and therapeutic planning for such morbidities. This review aims to stimulate reflection on the classifications' adequacy, nomenclatures, and therapeutic approaches related to these entities.

RESUMO O grau de participação da infecção viral e da reação imunológica do hospedeiro às partículas virais no processo infamatório das diferentes formas de ceratites herpéticas ainda é objeto de controvérsia. Esse fato gera conflitos de classificação e planejamento terapêutico relativos a essas morbidades. Esta revisão visa estimular a reflexão sobre a adequabilidade das classificações, nomenclaturas e abordagens terapêuticas dessas entidades.

Herpes simplex keratitis revisited.

The degree to which viral infection and the host's immune reaction to viral particles participate in the inflammatory process across various forms of herpetic keratitis has remained controversial. This fact has created conflicts regarding the classification of and therapeutic planning for such morbidities. This review aims to stimulate reflection on the classifications' adequacy, nomenclatures, and therapeutic approaches related to these entities.

Three-year follow-up in advanced pediatric keratoconus: thin corneas may not have pachymetry properly assessed after crosslinking.

AIM: To analyze the crosslinking (CXL) effects in pediatric keratoconus, and to identify the patients' corneal characteristics whose pachymetry could not be adequately evaluated by Scheimpflug method after procedure. METHODS: Consecutive pediatric patients with progressive keratoconus underwent CXL were included. Best-corrected visual acuity (BCVA) and spheric equivalent (SE) were measured before and after CXL. After CXL, groups 1 and 2 were divided based on the posterior surface Pentacam quality specifications (QS): "OK" (Group 1) and "not OK" (Group 2). The mean (RmF and RmB) and minimum (RminF and RminB) radius of curvatures of the anterior and posterior corneal surfaces, and the thinnest pachymetry (Pmin) were measured preoperatively at 3, 6, 12, 24, and 36mo. Haze was annotated. RESULTS: Twenty-six patients (14 men, mean age 14±1.8y) and median Kmax of 59.9 D initially and 61.4 D preoperatively were treated. BCVA was not different before and 24mo after CXL. Group 2 statistically differed to group 1 in that SE was more myopic before and with no difference 24mo after CXL; RmF and RmB were steeper and Pmin was thinner pre-surgically. Group 2, in which pachymetric changes could not be adequately evaluated after surgery, presented with significant RmF flattening, a shift to hyperopia, and more haze after CXL. CONCLUSION: Patients whose pachymetry could not be adequately evaluated after CXL had steeper and thinner corneas before surgery. The predictive factors for impaired QS after CXL are RmF, RmB, and Pmin. In advanced keratoconus, alternative methods to analyze pachymetry and the posterior surface should be considered.

Sagitta of ophthalmic lenses.

PURPOSE: To propose alternative formulas for the sagitta calculation of ophthalmic lenses. METHODS: Equation factoring. RESULTS: The conventional sagitta formula is algebraically inconsistent when applied to curves with direction-oriented radii. It is possible to correct this problem by factoring it. CONCLUSIONS: The conventional sagitta formula can and should be replaced by unambiguous equations.

Prescription for astigmatic ametropia revisited.

The approach to any refractive condition of the eye with regular astigmatism is more complicated than that for myopia or hyperopia alone. It requires familiarity with the complex images collectively identified as Sturm's conoid. Fortunately, only three of those play a critical role in the interpretation of ametropia with astigmatism. This manuscript discusses a prescription strategy for ametropias associated with regular astigmatism evolved from those three key images.

Prescription for astigmatic ametropia revisited / A prescrição do astigmatismo revisada

ABSTRACT The approach to any refractive condition of the eye with regular astigmatism is more complicated than that for myopia or hyperopia alone. It requires familiarity with the complex images collectively identified as Sturm's conoid. Fortunately, only three of those play a critical role in the interpretation of ametropia with astigmatism. This manuscript discusses a prescription strategy for ametropias associated with regular astigmatism evolved from those three key images.

RESUMO A abordagem de qualquer condição refrativa do olho com astigmatismo regular é mais complicada do que a da miopia ou hipermetropia isoladamente. Requer familiaridade com as imagens complexas coletivamente identificadas como o conóide de Sturm. Felizmente, apenas três deles desempenham um papel crítico na interpretação da ametropia com astigmatismo. Este manuscrito mostra como uma estratégia de prescrição para as ametropias associadas ao astigmatismo regular pode evoluir a partir dessas três imagens principais.

Clinical, Demographic, and Tomographic Aspects Related to Iris Mammillations Among Patients With Keratoconus: A Cross-Sectional Study.

PURPOSE: Iris mammillations (IM) were previously described in patients with keratoconus, but the clinical implications of this finding have never been studied. Our aim was to investigate demographic, tomographic, and clinical characteristics potentially associated with the presence of IM among patients with keratoconus. METHODS: This was a cross-sectional study performed among patients with keratoconus in a public-affiliated university hospital. All patients under follow-up were considered eligible to participate in the study. Participants were evaluated by 2 trained ophthalmologists and submitted to corneal tomography (Pentacam). Selected demographic, clinical, and tomographic characteristics were assessed and compared among participants with IM (IM group) and without IM (No-IM group) using the Wilcoxon test or 2-tailed Fisher exact test, as appropriate. RESULTS: The study population consisted of 106 subjects and 19 (17.9%) presented with IM. The median age and interquartile range were 18 years old (14-24) in the IM group and 20 years old (17-24) in the No-IM group (P = 0.135). The female proportion was 47.3% in the IM group and 52.8% in the No-IM group (P = 0.801). Median (interquartile ranges) pachymetric values of the right eyes were 498 (466-525) for the IM group and 459 (421-482) for the No-IM group (P = 0.005). For the left eyes, the values were 490 (456-523) in the IM group and 450 (418-485) in the No-IM group (P = 0.024). CONCLUSIONS: Subjects with keratoconus presenting with IM have thicker corneas than those without IM. Follow-up studies should be performed to evaluate the clinical implications of this finding.

Are iris mammillations correlated with keratoconus?

PURPOSE: To describe the presence of iris mammillations (IM) in keratoconus. DESIGN: Retrospective case series and literature review. OBSERVATIONS: This is a retrospective case series of eight patients presenting with keratoconus and IM, who were examined between January 2016 and December 2017 in the ophthalmology outpatient clinic. They had a median age of 14 (11-30), and all had bilateral keratoconus and diffusely distributed IM. The IM had similar presentations and similar iris colors. None had relevant medical or family diseases associated with IM. Three eyes previously had penetrating keratoplasty. Four (31%) out of 13 eyes had mean keratometry (Km) > 55D, and 4 (31%) had the thinnest pachymetry between 300 and 400µm. CONCLUSIONS AND IMPORTANCE: To the best of our knowledge , this is the first time that IM was observed in association with keratoconus patients. The possibility that IM is an early finding in otherwise healthy patients may help to predict the future diagnosis of keratoconus. Future studies are needed to show the frequency and possible association between IM and a keratoconus prognosis. This may also demonstrate that there is a subgroup of patients with a distinct etiology of keratoconus.

Unilateral floppy eyelid syndrome with ipsilateral intolerance to brimonidine / Síndrome da palpebral flácida unilateral com intolerância a brimonidina ipsilateral

Abstract The authors report a case of unilateral floppy eyelid syndrome with ipsilateral intolerance to brimonidine in a 65-year-old man. The singularity of this case is the combination of two rare illnesses of great phlogistic potentiality in the same eye. The purpose of this article is to report a case of unilateral floppy eyelid syndrome with ipsilateral intolerance to brimonidine, emphasizing a possible relation between them. The result was a unilateral keratopathy that emulated an intraepithelial neoplasia. The key to solving the problem was an unexplained anterior uveitis that raised the suspicion of drug toxicity.The upper eyelid eversion of the affected eye during sleep seemed to be the common denominator of both ailments. The bizarre aspect of the epitheliopathy most likely resulted from the combination of trauma, insufficient lubrication, and drug intolerance.

Resumo Os autores relatam um caso de síndrome da pálpebra flácida unilateral com intolerância ipsilateral à brimonidina em um homem de 65 anos de idade. A singularidade deste caso é a combinação de duas doenças raras de grande potencialidade inflamatória no mesmo olho. O objetivo deste artigo é relatar um caso de síndrome da pálpebra flácida com intolerância ipsilateral à brimonidina, enfatizando uma possível relação entre eles. O resultado foi uma ceratopatia unilateral que simulou uma neoplasia intra-epitelial. A chave para resolver o problema foi uma uveíte anterior inexplicável que levantou a suspeita de toxicidade medicamentosa. A eversão da pálpebra superior do olho afetado durante o sono parece ser o denominador comum de ambas as doenças. O aspecto bizarro da epiteliopatia provavelmente resultou da combinação de trauma, lubrificação insuficiente e intolerância ao medicamento.

Visual optics under the wavefront perspective.

Some intriguing concepts of visual optics cannot be explained by ray tracing. However, they can be clarified using wavefront formalism. Its main advantage is in the use of the concept of vergence, which is very helpful in interpreting the optical phenomena involved in the neutralization of the ametropias. In this line of thinking, the major role of a lens is in the creation of a new light source (the image point) that orientates the refracted waves. Once the nature and position of this source is known, one can easily predict the behavior of the wavefronts. The formalism also allows for an easier understanding on how wavefronts relate to light rays and on how algebraic signs are assigned to optical distances.

Visual optics under the wavefront perspective / Óptica visual sob a perspectiva das frentes de onda

Some intriguing concepts of visual optics cannot be explained by ray tracing. However, they can be clarified using wavefront formalism. Its main advantage is in the use of the concept of vergence, which is very helpful in interpreting the optical phenomena involved in the neutralization of the ametropias. In this line of thinking, the major role of a lens is in the creation of a new light source (the image point) that orientates the refracted waves. Once the nature and position of this source is known, one can easily predict the behavior of the wavefronts. The formalism also allows for an easier understanding on how wavefronts relate to light rays and on how algebraic signs are assigned to optical distances.

Alguns conceitos intrigantes da óptica visual não podem ser explicados pelo traçado dos raios luminosos. Entretanto, eles podem ser esclarecidos através do formalismo da frente de onda. A vantagem do mesmo está no uso do conceito de vergência, que facilita o entendimento dos fenômenos ópticos envolvidos na neutralização das ametropias. Nessa linha de raciocínio, a principal função de uma lente é o de criar de uma nova fonte de luz - o ponto de imagem - que orienta as ondas refratadas. Conhecendo-se a natureza e a posição dessa fonte pode-se facilmente prever o comportamento das frentes de onda. Este formalismo também ajuda a compreensão de como as frentes de onda se relacionam com os raios de luz e como os sinais algébricos são atribuídos às distâncias ópticas.

Analysis of low-energy and high-frequency femtosecond laser for the construction of deep anterior donor corneal lamellae / Laser de femtossegundo de baixa energia e alta frequência na confecção de lamelas corneanas doadoras

Purpose: To evaluate the efficacy and reliability of a low-energy femtosecond laser with a high repetition rate for construction of deep anterior donor corneal lamellae. Methods: This was a prospective laboratory investigation. Twenty-five human corneal buttons were femtosecond laser cut to create thick anterior lamellae (diameter, 10mm; thickness, 500µm). The laser cuts were made using an LDV® femtosecond laser in a Ziemer® anterior chamber. To obtain a better edge, the lamellae were trephined with an 8mm trephine (Katena®). The central corneal thickness and the anterior lamellae were measured using a Mitutoyo® thickness gauge with an accuracy of 0.001mm. Results: The central thickness of the 25 corneas ranged from 500 to 705µm (mean, 584 ± 51µm). The thickness of the anterior lamellae ranged from 420 to 480µm (mean, 455 ± 12.7µm). The anterior lamellae diameters were 7.90 ± 0.1mm, and all laser cuts were round. The lamellar interfaces appeared regular by surgical microscopy. There were no cases of inter-lamellar adhesion. Conclusion: The LDV® femtosecond laser appears to be a safe and reliable instrument for cutting deep anterior lamellae from donor corneoscleral buttons. Minimal variation in donor lamellar depth with the laser will be useful for creating donor corneal tissue for deeper anterior lamellar keratoplasty or endothelial keratoplasty surgery or both from a single donor cornea. .

Objetivo: Avaliar a eficácia e segurança de um laser de femtossegundo de baixa energia e alta taxa de repetição para confecção de lamelas corneanas doadoras anteriores profundas. Métodos: Este é um estudo prospectivo de investigação laboratorial. Vinte e cinco botões corneanos foram cortados com laser de femtossegundo para criar lamelas corneanas doadoras anteriores profundas (diâmetro, 10mm; espessura, 500µm). O corte a laser foi realizado com femtosecond laser LDV® na câmara anterior artificial da Ziemer®. Para obter-se uma melhor borda, as lamelas foram trepanadas com um trépano de 8mm da Katena®. A paquimetria corneana central e as lamelas anteriores foram aferidas utilizando o paquímetro Mitutoyo®, com acurácia de 0.001mm. Resultados: A paquimetria central das 25 córneas variou de 500 a 705µm (média de 584 ± 51µm). A espessura das lamelas anteriores variou de 420 a 480µm (media de 455 ± 12.7µm). O diâmetro das lamelas corneanas doadoras foi 7.90 ± 0,1mm, sendo todos os cortes redondos. As interfaces lamelares apresentaram-se regular ao microscópio cirúrgico. Não houve casos de adesão interlamelar. Conclusão: O laser de femtossegundo LDV® mostrou-se seguro e eficaz para confeccionar lamelas corneanas doadoras a partir de botões córneo-esclerais. Mínima variação na espessura das lamelas doadoras confeccionadas com o laser será útil para criação de tecidos corneanos doadores para ceratoplastia lamelar anterior profunda ou ceratoplastia endoteliais, ou ambas, a partir de uma só córnea. .

Uncovering intermittent entropion.

PURPOSE: Intermittent entropion may go unnoticed by both patient and physician, in some instances resulting in ocular surface disorders. Unfortunately, the current work-up used to diagnose entropion is not always sufficient to uncover the problem. We present an alternative diagnostic test. CASES: Two case reports are presented showing different situations where the current methods for detection of entropion failed and the diagnosis was only made with an alternative diagnostic test. RESULTS: The common denominator of both cases is an intermittent entropion which could not be detected by the conventional clinical work-up. Diagnosis was easy however using the "TIE test" described in the text. CONCLUSION: The important clues for suspicion of intermittent entropion are an intermittent foreign-body sensation in the eye accompanied with central punctate keratopathy. The TIE test is a simple and useful test for the diagnosis of intermittent entropion.

Autoradiographic study on the regenerative capability of the epithelium lining the center of the cornea after multiple debridements of its peripheral region.

BACKGROUND: The epithelium lining the center of the cornea is assumed to lack stem cells.The purpose is to investigate by autoradiography the regenerative capability of the epithelium lining the central region of the rabbit cornea following seven scrapings of its peripheral lining, during several months. METHODS: After marking the center of the cornea with a 6 mm-diameter trephine, the epithelium outside this area was scraped until reaching the corneoscleral zone. This procedure was repeated seven times on the same eye at intervals of 20 days. One day after the last scraping, (3)H-thymidine was injected intravitreally and the corneas processed for autoradiography. RESULTS: At 2 days after injection, the corneal surface was entirely lined by an epithelium made up by two layers of squamous cells, most of them being labeled with the DNA precursor. A multilayered epithelium was visualized at the center with most of its basal cells also labeled. The limbal epithelium had at least two of its layers labeled with the precursor. At 9 days, the multilayered central unscraped epithelium exhibited labeled cells not only in the basal but also in its suprabasal layers. The labeling index (labeled nuclei/100 cells) for its basal stratum was very close to 100%. A similar feature was observed at 16 days, except that the mutilayered central epithelium was seen lining a larger area when compared to the precedent interval and that it exhibited evidences for vertical renewal. CONCLUSIONS: The epithelium lining the central region of the cornea--where it was assumed that stem cells do not exist--exhibited capability for regeneration and self-renewal in spite of seven consecutive debridements of its periphery. No evidence was found for transposition of limbal epithelial cells to the center of the cornea during the early merger of the epithelial sliding fronts.

Regeneration of the corneal epithelium after debridement of its central region: an autoradiographic study on rabbits.

PURPOSE: To investigate the proliferative behavior of the corneal and limbal epithelia after debridement on the central region of the rabbit cornea. METHODS: After scraping a circular epithelial area, 5 mm in diameter, in the center of the cornea, ([3]) H-thymidine ( ([3]) H-TdR) was injected intravitreally, and the rabbits killed from 1 to 49 days afterward. The cornea, together with the adjacent conjunctiva, was processed for autoradiography. RESULTS: The regenerating epithelium at the center of the cornea exhibited high frequencies of labeled nuclei when compared to controls. The mitotic indexes for the limbus were comparable in experimental and control eyes. The unique basal stratum of the limbal epithelium exhibited quick proliferation and vertical migration in all eyes. Cells that remained labeled for four weeks or more were observed throughout the corneal epithelium, including its basal stratum, and this did not depend on epithelial damage. CONCLUSION: Corneal epithelium wounds are healed by sliding and proliferation of cells surrounding the epithelial gap without any evidence for the participation of the limbal epithelium. Daughter cells labeled with ([3]) H-TdR were visualized in all layers of the corneal epithelium up to 7 weeks after the DNA precursor injection. However, at this long interval, the only labeled cells in the limbus were in the suprabasal layers.

Proliferation of the vascular endothelium of the iris following total debridement of the corneal epithelium and limbal excision of rabbits.

BACKGROUND: Damage to the corneal epithelium causes not only a reaction for its repair but also affects other parts of the cornea as well as different components of the anterior segment of the eye. The purpose of this investigation was to analyze the consequences, following epithelial and limbal damage, to the iris of rabbits (Oryctolagus cuniculus). METHODS: The corneal epithelium was thoroughly scraped followed by surgical excision of the limbus. Next, (3)H-thymidine ((3)H-TdR) was injected intravitreally both into the right (experimental) and left (control) eyes which had their anterior segments processed for autoradiography at intervals of 2, 7 and 21 days after surgery (three rabbits per interval). The irises were also examined with scanning-electron and confocal microscopy after Evans blue injection. RESULTS: There was a high frequency of labeling in the cells of the iris blood vessels in the experimental eye, particularly the endothelial ones. The ratio of labeled cells between experimental and control irises was 40:1, with a population of nuclei increasing by 25% and remaining labeled up to 21 days. There was also an increase in the volume of the iris vasculature as shown by confocal microscopy. The high labeling frequencies of the vascular cells were observed throughout the iris from the ciliary to the pupillary regions. CONCLUSIONS: The lesions on the corneal epithelium elicit proliferation of the iris vascular cells, mainly its endothelium, as well as an early breakdown of the blood-aqueous barrier. The daughter cells resulting from the damage to the eye surface were detected up to 21 days after a single injection of (3)H-TdR, most likely due to their slow turnover. As a consequence of this proliferation, the vasculature of the iris increased in volume.

Morphological and autoradiographic studies on the corneal and limbal epithelium of rabbits.

The investigation was centered on the morphological features of the conjunctiva-cornea transition (limbus) of the rabbit eye and the proliferative behavior of its epithelium. The eyes were processed for examination with light and electron microscopy, as well as for autoradiography after intravitreal injection of [(3)H]thymidine ([(3)H]TdR). At the sites of extraocular muscle insertion, the vascularization of the stroma extended to the peripheral cornea, and the limbal epithelium was thin with its basal stratum made up by clear cuboidal cells. In between the muscle insertions, the cuboidal clear cells, as well as the stroma blood vessels, were scarce. At the light microscope level, the basement membrane was distinct in the cornea but not in the limbus or the conjunctiva. Autoradiographs demonstrated that, at the limbus, the basal cells migrated very quickly to the suprabasal region and remained there up to the 28-day interval. Labeled cells were identified in all epithelial layers of the cornea, including the basal one, at 21 and 28 days but not in the limbal basal clear cells. The rate of renewal of conjunctival epithelium was similar to that observed for the transition with scarce clear cells. The high-resolution autoradiographs demonstrated that the basal cuboidal clear limbal cells exhibit a quick renewal and that they are not label-retaining cells. These latter ones were detected all over the corneal epithelium and in the suprabasal layers of the limbus up to 28 days, in physiological conditions, without the need of stimulation by damage to the corneal epithelium.

[MALKS: specifications and development]. / MALKS: especificações e desenvolvimento.

PURPOSE: To describe the characteristics of a new artificial anterior chamber (MALKS, Loktal, São Paulo, Brazil). METHODS: Characteristics analysis and description of a new artificial anterior chamber MALKS (Micro automated lamellar keratoplasty system). RESULTS: MALKS is composed of eight parts: a) artificial chamber; b) cornea's fix ring; c) nut to join the cornea's fix ring; d) rail and adjuster of lamellar diameter; e) flatteners, to pre-determine lamellar diameter; f) infusion system, that allows the digital objective peroperative control of the intracameral pressure; g) automated microkeratome, and h) marker. CONCLUSION: MALKS uses the same automated microkeratome developed for LASIK, can allow corneal lamella obtention with predetermined thickness and diameter, as well as the digital objective peroperative control of the intracameral pressure. This new artificial anterior chamber can be an important tool for superficial and endothelial keratoplasty.

Fisiologia e desenvolvimento da visäo / Physiology and development of vision

A visäo é feita pelo cérebro. Os olhos funcionam como orgäos de conversäo seletiva do estímulo luminoso em sinais elétricos. Durante todo o trajeto através do sistema visual, os estímulos väo sendo depurados até gerarem uma impressäo visual única, provavelmente no córtex occipital. Existe um período da vida em que esse processo se desenvolve e no fim do qual se consolida, chamado período de maturaçäo visual. Didaticamente, dividimos a visäo em central e periférica. A medida da primeira chama-se "acuidade visual" e se faz por meio de tabelas, geralmente usadas a cinco metros. A medida da segunda chama-se "campo visual" e, geralmente, se faz através de campímetros. O presente trabalho discute todos esses assuntos.