Pediatric keratoconus epidemiology: a systematic scoping review.

BACKGROUND: Pediatric keratoconus (pediatric KC) causes progressive deformation of the cornea in children and adolescents, leading to a gradual loss of vision and a need for rehabilitation. However, new treatments may halt the disease and prevent worse outcomes that require penetrating keratoplasty and its associated morbidity and high cost, irreversible loss of vision, and amblyopia. Few systematic reviews focus on keratoconus-and even fewer, on pediatric KC. METHODS: Here, we report a systematic scoping review of pediatric KC epidemiology and discuss the studies reporting data on pediatric KC. We used PRISMA-ScR methodology and checklists in the elaboration of the manuscript. The inclusion criteria were: English language; publication between August 7, 1998, and August 7, 2019 (20 years); theme of the study pediatric KC epidemiology. The search strategy: searches of the PubMed-MEDLINE database and Cochrane Database of Systematic Reviews, using eight combinations of the following MeSH terms: keratoconus; child; incidence; prevalence; pediatrics; adolescent; epidemiology. RESULTS: We charted and reviewed the selected articles. Initial searches included 1802 records; after the exclusion of article duplicates, we screened 777 records, read 97 articles in full text, and included 76 articles in this review. CONCLUSIONS: Recent epidemiological studies with better methodologies demonstrated increased prevalence rates in comparison to the older literature. This effect may be due to better diagnostic methods and better sample selection than those in historical studies. Diagnosis remains a major challenge as the early disease is usually asymptomatic. Economic and social aspects of pediatric KC remain understudied in the pediatric literature. Global, inclusive, and proactive screening studies in schools are imperative to better understand the great impact of this disease in the young.

Preoperative Predictors for Acute Pain After Photorefractive Keratectomy.

PURPOSE: The aim of this study was to identify preoperative predictors for the occurrence of early severe postoperative pain in patients undergoing photorefractive keratectomy (PRK). The implementation of preoperative screening methods may facilitate more specific or aggressive pain therapies specifically targeted to individuals at a high risk of experiencing severe postoperative pain. METHODS: This was exploratory research that included patients who underwent PRK. Before PRK, patients were administered a sociodemographic questionnaire, the Pain Catastrophizing Scale, and the State-Trait Anxiety Inventory and underwent corneal sensitivity and conditioned pain modulation (CPM) tests. Post-PRK pain was assessed using a pain intensity visual analog scale (VAS), and the short-form McGill Pain Questionnaire (SF-MPQ) was completed 21 days before PRK and 1, 24, 48, and 72 hours after PRK. Spearman correlations were calculated for pain scores and preoperative predictors. RESULTS: This research included 34 eyes of 34 patients. Preoperative corneal sensitivity was positively correlated with post-PRK pain scores as assessed by VAS and SF-MPQ (rho = 0.39 and rho = 0.41, respectively, P < 0.05). No correlations were found between Pain Catastrophizing Scale, State-Trait Anxiety Inventory, and CPM scores and post-PRK pain scores ( P > 0.05). CONCLUSIONS: Abnormal presurgical corneal sensitivity was a protective marker for severe pain after PRK, while scores as assessed by VAS and SF-MPQ and CPM were not related to postoperative pain.

Codeine plus acetaminophen improve sleep quality, daily activity level, and food intake in the early postoperative period after photorefractive keratectomy: a secondary analysis.

PURPOSE: To determine whether codeine plus acetaminophen after photorefractive keratectomy (PRK) have beneficial effects on sleep quality, activity levels, and food intake, beyond their effect of pain relief. METHODS: We enrolled 40 patients (80 eyes) in this randomized, double-blind, paired-eye, placebo-controlled, add-on trial. Each eye was treated 2 weeks apart, and the patients were randomly allocated to receive either the placebo or the intervention (30 mg codeine and 500 mg acetaminophen) (4 times a day for 4 days). Outcomes were sleep quality, daily activity level, and food intake within 24-72 h post-photorefractive keratectomy, as measured by the McGill Pain Questionnaire. RESULTS: Sleep quality and daily activity level were inversely associated with pain scores within the first 48 h post-photorefractive keratectomy. During the intervention, patients were significantly more likely to score their sleep quality as good at 24 h (relative risk=2.5; 95% confidence interval 1.48-4.21, p<0.001) and 48 h compared to during placebo (relative risk=1.37; 95% confidence interval: 1.03-1.84, p=0.023). The probability of reporting good daily activity level at 24 and 72 hours post-photorefractive keratectomy was three times higher when patients received the intervention compared to the placebo (relative risk=3.0; 95% confidence interval: 1.49-6.15, p=0.006 and relative risk=1.31; 95% confidence interval: 1.02-1.67, p=0.021, respectively). No difference was observed in food intake. CONCLUSION: The oral combination of codeine and acetaminophen significantly improves sleep quality and daily activity level within the first 24-72 h post-photorefractive keratectomy compared to a placebo.

Codeine plus acetaminophen improve sleep quality, daily activity level, and food intake in the early postoperative period after photorefractive keratectomy: a secondary analysis / Melhora da qualidade do sono e das atividades diárias pós PRK imediato utilizando codeína com paracetamol: análise secundária de um ensaio clínico randomizado, duplo-cego e placebo-controlado

ABSTRACT Purpose: To determine whether codeine plus acetaminophen after photorefractive keratectomy (PRK) have beneficial effects on sleep quality, activity levels, and food intake, beyond their effect of pain relief. Methods: We enrolled 40 patients (80 eyes) in this randomized, double-blind, paired-eye, placebo-controlled, add-on trial. Each eye was treated 2 weeks apart, and the patients were randomly allocated to receive either the placebo or the intervention (30 mg codeine and 500 mg acetaminophen) (4 times a day for 4 days). Outcomes were sleep quality, daily activity level, and food intake within 24-72 h post-photorefractive keratectomy, as measured by the McGill Pain Questionnaire. Results: Sleep quality and daily activity level were inversely associated with pain scores within the first 48 h post-photorefractive keratectomy. During the intervention, patients were significantly more likely to score their sleep quality as good at 24 h (relative risk=2.5; 95% confidence interval 1.48-4.21, p<0.001) and 48 h compared to during placebo (relative risk=1.37; 95% confidence interval: 1.03-1.84, p=0.023). The probability of reporting good daily activity level at 24 and 72 hours post-photorefractive keratectomy was three times higher when patients received the intervention compared to the placebo (relative risk=3.0; 95% confidence interval: 1.49-6.15, p=0.006 and relative risk=1.31; 95% confidence interval: 1.02-1.67, p=0.021, respectively). No difference was observed in food intake. Conclusion: The oral combination of codeine and acetaminophen significantly improves sleep quality and daily activity level within the first 24-72 h post-photorefractive keratectomy compared to a placebo.

RESUMO Objetivo: Determinar se codeína (30 mg) mais pa­racetamol (500 mg) após ceratectomia fotorrefrativa fornece efeitos benéficos sobre a qualidade do sono, níveis de atividade e ingestão de alimentos além de seu efeito analgésico. Métodos: Quarenta pacientes (80 olhos) foram incluídos neste estudo randomizado, duplo-cego, pareado, placebo-controlado, add-on. Cada olho foi tratado com 2 semanas de intervalo, sendo aleatoriamente alocado para placebo ou intervenção (4x/dia durante 4 dias). Os resultados incluíram a qualidade do sono, atividade diária e ingestão de alimentos dentro de 24-72 horas de pós-operatório, conforme medido pelo McGill Pain Questionnaire. Resultados: A qualidade do sono e os níveis de atividade foram inversamente associados aos escores de dor nas primeiras 48 horas após o ceratectomia fotorrefrativa. Durante a intervenção, os pacientes foram significativamente mais propensos a classificar seu sono como bom em 24 horas (risco relativo=2,5, intervalo de confiança de 95%: 1,48-4,21, p<0,001) e 48 horas comparado ao placebo (risco relativo=1,37, intervalo de confiança de 95%: 1,03-1,84, p=0,023). A probabilidade de relatar bons níveis de atividade em 24 e 72 horas após ceratectomia fotorrefrativa também foi significativamente maior durante a intervenção em comparação com placebo (risco relativo=3,0, intervalo de confiança de 95%: 1,49-6,15, p=0,006 e risco relativo=1,31, intervalo de confiança de 95%: 1,02 -1,67, p=0,021, respectivamente). Nenhuma diferença foi observada entre a intervenção e placebo em relação à alimentação oral. Conclusão: A combinação de codeína e paracetamol melhorou significativamente a qualidade do sono e atividades diárias nas primeiras 24-72 horas após o ceratectomia fotorrefrativa em comparação com placebo.

Codeine Plus Acetaminophen for Pain After Photorefractive Keratectomy: A Randomized, Double-Blind, Placebo-Controlled Add-On Trial.

BACKGROUND: Pain after photorefractive keratectomy (PRK) is significant, and the analgesic efficacy and safety of oral opioids in combination with acetaminophen has not been fully investigated in PRK trials. PURPOSE: To assess the efficacy and safety of the combination of codeine plus acetaminophen (paracetamol) versus placebo as an add-on therapy for pain control after PRK. STUDY DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: Single tertiary center. METHODS: One eye was randomly allocated to the intervention, whereas the fellow eye was treated with a placebo. Eyes were operated 2 weeks apart. The participants were adults older than 20 years with refractive stability for ≥1 year, who underwent PRK for correction of myopia or myopic astigmatism. Codeine (30 mg) plus acetaminophen (500 mg) was given orally 4 times per day for 4 days after PRK. The follow-up duration was 4 months. The study outcomes included pain scores at 1 to 72 hours, as measured by the visual analog scale, McGill Pain Questionnaire, and Brief Pain Inventory, as well as adverse events and corneal wound healing. RESULTS: Of the initial 82 eyes, 80 completed the trial (40 intervention, 40 placebo). Median (interquartile range) pain scores as measured by the visual analog scale were statistically and clinically lower during treatment with codeine/acetaminophen compared with the placebo: 1 hour: 4 (2-4) versus 6 (3-6), P < 0.001; 24 hours: 4 (3-6) versus 7 (6-9), P < 0.001; 48 hours: 1 (0-2) versus 3 (2-5), P < 0.001; and 72 hours: 0 (0-0) versus 0 (0-2), P = 0.001. Virtually identical results were obtained by the McGill Pain Questionnaire and Brief Pain Inventory scales. The most common adverse events with codeine/acetaminophen were drowsiness (42%), nausea (18%), and constipation (5%). No case of delayed epithelial healing was observed in both treatment arms. CONCLUSIONS: When added to the usual care therapy, the oral combination of codeine/acetaminophen was safe and significantly superior to the placebo for pain control after PRK. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02625753.

Opioids for Ocular Pain - A Narrative Review.

BACKGROUND: Refractive surgery is a common procedure, but may be associated with severe post-operative pain. OBJECTIVES: To describe studies addressing the use of opioids for control of pain after ocular surgery, with an emphasis on refractive surgery. STUDY DESIGN: This is a narrative review of relevant articles on the physiology of corneal pain and the use of opioids for its treatment after surgery. SETTING: Single tertiary center. METHODS: A PubMed search was conducted for studies published from January 1985 to May 2015 on the physiopathology of corneal pain and opioid treatment of post-refractive surgical pain. Reviews, meta-analyses, and randomized clinical trials were included. Inclusion criteria focused on photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). RESULTS: Authors found 109 articles through the search strategies. A total of 75 articles were included based on the inclusion criteria. DISCUSSION: Pain after ocular surgery is likely to be a multifactorial phenomenon. A combination of topical and systemic analgesics is used to treat post-operative pain after refractive surgery. Pain may be severe during the first 72 to 96 hours, depending on the surgical procedure. No studies were found that directly analyze the benefits of opioids after PRK, although they are routinely prescribed in some centers. LIMITATIONS: This is a narrative review in contrast to a systematic review and did not include studies indexed in databases other than PubMed. CONCLUSIONS: Although opioids are used for the short-term treatment of post-operative pain in refractive surgery, their benefits and risks should be properly evaluated in randomized clinical trials before their use can be safely advised. KEY WORDS: Photorefractive keratectomy, in situ keratomileusis, pain, analgesia, opioid, codeine, review.

Mechanisms of Corneal Pain and Implications for Postoperative Pain After Laser Correction of Refractive Errors.

OBJECTIVE: The cornea is the target of most surgeries for refractive disorders, as myopia. It is estimated that almost 1 million patients undergo corneal refractive surgery each year in the United States. Refractive surgery includes photorefractive keratectomy (PRK) that produces intense postoperative pain. This review presents the main pain mechanisms behind PRK-related pain and the available therapeutic options for its management. METHODS: Data sources included literature of cornea anatomy, treatment of PRK postoperative pain, mechanisms of corneal pain, in 3 electronic databases: Pubmed, Scopus, and Web of Science. Only double-blinded controlled trials on pain control after PRK were selected to show the endpoints, treatment, and control strategies. RESULTS: A total of 18 double-blind, controlled trials were identified. These studies have shown the use of topical nonsteroidal anti-inflammatory drugs, topical steroidal anti-inflammatory drugs, systemic analgesics, cold balanced saline solution, topical anesthetic, gabapentin, and morphine to treat postoperative pain in PRK. DISCUSSION: The percentage of responders has seldom been reported, and few studies allow for the formal calculation of the number necessary to treat. Postoperative intense pain after PRK laser surgery remains the main challenge to its widespread use for the correction of refractive errors.

LASIK hipermetrópico pós-DSAEK (Descement Stripping Automated Endotelial Keratoplasty) / LASIK for hyperopia correction pos DSAEK(Descement Stripping Automated Endotelial Keratoplasty)

RESUMO O DSAEK (Descemet stripping automated endotelial Keratoplasty) é um dos procedimentos de escolha para tratamento das doenças que acometem o endotélio corneano. Apesar do sucesso terapêutico, o procedimento pode induzir uma hipermetropia residual. Em média a refração se estabiliza em um perído que varia de 6 a 12 meses após o transplante. O objetivo desse relato é descrever a evolução dessa opção terapêutica utilizada em um paciente de 54 anos portador de Distrofia de Fuchs. O paciente foi submetido ao transplante de córnea (DSAEK) e a remoção do cristalino no mesmo tempo cirúrgico o que resultou em hipermetropia residual. Após 3 anos de acompanhamento apresentava-se com a melhor visão corrigida de 20/20 (Snellen) no olho operado com uma refração de +3,25 -1,00 (5º). Optou-se por realização de LASIK (Laser assisted in situ Keratomileusis) hipermetrópico, obtendo um resultado visual satisfatório.

ABSTRACT DSAEK (Descemet stripping automated endothelial keratoplasty) is one of the options for corneal endothelium disease, which in some patients can result in a residual hyperopia after the procedure. Usually 6 to 12 months after corneal transplantation refraction is already stable. This report describes a therapeutic option used in a 54 years old patient with Fuchs' endothelial dystrophy submitted to cataract and corneal transplant that resulted in residual hyperopia, three years after the procedure the best corrected vision was 20/20 with a refraction of +3.25 -1.00 (5 º) treated with Hyperopic - LASIK (Laser-assisted In Situ Keratomileusis) with satisfactory visual result.

Corneal Collagen Cross-linking in Advanced Keratoconus: A 4-Year Follow-up Study.

PURPOSE: To analyze the safety and efficacy of standard corneal collagen cross-linking (CXL) in advanced cases of progressive keratoconus after 4 years of follow-up. METHODS: A retrospective case series of patients with advanced progressive keratoconus (stages 3 and 4 of Amsler-Krumeich classification) underwent standard CXL treatment. The parameters examined were changes in uncorrected visual acuity (UDVA), corrected visual acuity (CDVA), keratometry values (mean, flat, steep, and apical), pachymetry, and endothelial cell count at the baseline and at 12, 24, and 48 months postoperatively. RESULTS: Forty eyes of 40 patients were enrolled in the study. The mean patient age was 22.5 years (range: 15 to 37 years). Both mean UDVA and CDVA remained stable during the time points; no statistically significant change was noted. Although a slight reduction was observed in all keratometric readings, a statistically significant reduction was only reached in the apical keratometry (P = .037) at 4 years after CXL. A significant reduction in the corneal thickness was also found (ultrasonic: 388 ± 49 to 379 ± 48 µm; slit-scanning: 362 ± 48 to 353 ± 51 µm); however, this change was likely not clinically meaningful. Endothelial cell count was not significantly different at the end of the study. Treatment failure or progression was noted in two patients (5%) over the follow-up period. CONCLUSIONS: Standard CXL treatment was safe and able to stabilize both visual acuity and topographic parameters at 4 years of follow-up in eyes with advanced keratoconus. [J Refract Surg. 2016;32(7):459-464.].

Advances in femtosecond laser technology.

Femtosecond laser technology has become widely adopted by ophthalmic surgeons. The purpose of this study is to discuss applications and advantages of femtosecond lasers over traditional manual techniques, and related unique complications in cataract surgery and corneal refractive surgical procedures, including: LASIK flap creation, intracorneal ring segment implantation, presbyopic treatments, keratoplasty, astigmatic keratotomy, and intrastromal lenticule procedures.

Ectasia risk factors in refractive surgery.

This review outlines risk factors of post-laser in situ keratomileusis (LASIK) ectasia that can be detected preoperatively and presents a new metric to be considered in the detection of ectasia risk. Relevant factors in refractive surgery screening include the analysis of intrinsic biomechanical properties (information obtained from corneal topography/tomography and patient's age), as well as the analysis of alterable biomechanical properties (information obtained from the amount of tissue altered by surgery and the remaining load-bearing tissue). Corneal topography patterns of placido disk seem to play a pivotal role as a surrogate of corneal strength, and abnormal corneal topography remains to be the most important identifiable risk factor for ectasia. Information derived from tomography, such as pachymetric and epithelial maps as well as computational strategies, to help in the detection of keratoconus is additional and relevant. High percentage of tissue altered (PTA) is the most robust risk factor for ectasia after LASIK in patients with normal preoperative corneal topography. Compared to specific residual stromal bed (RSB) or central corneal thickness values, percentage of tissue altered likely provides a more individualized measure of biomechanical alteration because it considers the relationship between thickness, tissue altered through ablation and flap creation, and ultimate RSB thickness. Other recognized risk factors include low RSB, thin cornea, and high myopia. Age is also a very important risk factor and still remains as one of the most overlooked ones. A comprehensive screening approach with the Ectasia Risk Score System, which evaluates multiple risk factors simultaneously, is also a helpful tool in the screening strategy.

Intraocular straylight before and after low myopic photorefractive keratectomy with and without mitomycin C.

PURPOSE: To evaluate ocular straylight before and after photorefractive keratectomy (PRK) for low myopia with and without topical mitomycin (MMC) treatment. METHODS: Patients who underwent PRK for low myopia were enrolled into the study. PRK without MMC was performed in 21 eyes (12 patients), whereas PRK with topical 0.02% MMC was performed in 25 eyes (14 patients). Both groups were treated using the NIDEK EC5000 excimer laser. Measurements were performed using the C-Quant straylight meter preoperatively and at two and four months postoperatively. RESULTS: The mean patient age was 30 ± 4 years, and the mean spherical equivalent refractive error was -2.2 ± 0.75 D. The mean preoperative intraocular straylight values were 1.07 ± 0.10 in the PRK without MMC group and 1.07 ± 0.11 log(s) in the PRK with topical MMC group. At two months after surgery, there was a decrease in mean intraocular straylight values in both groups. However, a significant difference was only reached in the PRK with MMC group [0.98 ± 0.09 log(s), p=0.002] compared with preoperative values, which was likely due to a greater scatter of measurements in the PRK without MMC group [1.03 ± 0.13 log(s), p=0.082]. At four months postoperatively, ocular straylight values were not significantly different compared with those at baseline in either the PRK without MMC group [1.02 ± 0.14 log(s), p=0.26] or in the PRK with topical MMC group [1.02 ± 0.11 log(s), p=0.13]. CONCLUSION: PRK for low myopia decreases ocular straylight, and MMC application further reduces straylight in the early postoperative period. However, ocular straylight values do not significantly differ at four months after surgery compared with those at baseline.

Predictors of Early Postoperative Pain After Photorefractive Keratectomy.

PURPOSE: To compare the profiles of postoperative photorefractive keratectomy (PRK) pain between both eyes under the same conditions and to verify the preoperative predictors of pain such as gender, anxiety, knowledge of the procedure, and spherical equivalent refractive error (SERE). METHODS: This prospective study included 86 eyes of 43 patients with myopia who underwent PRK in both eyes at an interval of 14 days between the procedures. Before surgery, subjects answered the State Anxiety Inventory. After surgery, usual PRK pain treatment was given. Subjects answered the Visual Analog Scale, the Brief Pain Inventory (BPI), and the McGill Pain Questionnaire at 1, 24, 48, 72, and 96 hours after surgery. Pain scores and anxiety were compared between each eye using the Wald test and paired Student t test, respectively. The Wald test was performed for gender and SERE for each eye separately. RESULTS: There were no statistically significant differences between both eyes for all time points regarding the Visual Analog Scale, BPI, and McGill Pain Questionnaire-Pain Rating Index pain scores. Subjects were less anxious on average before the second surgery compared with before the first surgery (P < 0.001); however, it was not related to pain ratings after surgery. Gender did not significantly affect any scale of pain, and the SERE between -3 diopters (D) and -5 D (P = 0.035) revealed effects on the BPI. CONCLUSIONS: The profiles of postoperative pain after PRK were similar between both eyes under the same conditions. In this study, a high SERE was the only predictor for increased pain after PRK.

Intraocular straylight before and after low myopic photorefractive keratectomy with and without mitomycin C / Dispersão de luz intraocular antes e depois da ceratectomia fotorrefrativa para baixa miopia com e sem mitomicina C

ABSTRACT Purpose: To evaluate ocular straylight before and after photorefractive keratectomy (PRK) for low myopia with and without topical mitomycin (MMC) treatment. Methods: Patients who underwent PRK for low myopia were enrolled into the study. PRK without MMC was performed in 21 eyes (12 patients), whereas PRK with topical 0.02% MMC was performed in 25 eyes (14 patients). Both groups were treated using the NIDEK EC5000 excimer laser. Measurements were performed using the C-Quant straylight meter preoperatively and at two and four months postoperatively. Results: The mean patient age was 30 ± 4 years, and the mean spherical equivalent refractive error was -2.2 ± 0.75 D. The mean preoperative intraocular straylight values were 1.07 ± 0.10 in the PRK without MMC group and 1.07 ± 0.11 log(s) in the PRK with topical MMC group. At two months after surgery, there was a decrease in mean intraocular straylight values in both groups. However, a significant difference was only reached in the PRK with MMC group [0.98 ± 0.09 log(s), p=0.002] compared with preoperative values, which was likely due to a greater scatter of measurements in the PRK without MMC group [1.03 ± 0.13 log(s), p=0.082]. At four months postoperatively, ocular straylight values were not significantly different compared with those at baseline in either the PRK without MMC group [1.02 ± 0.14 log(s), p=0.26] or in the PRK with topical MMC group [1.02 ± 0.11 log(s), p=0.13]. Conclusion: PRK for low myopia decreases ocular straylight, and MMC application further reduces straylight in the early postoperative period. However, ocular straylight values do not significantly differ at four months after surgery compared with those at baseline.

RESUMO Objetivo: Avaliar a dispersão de luz intraocular antes e depois da ceratectomia fotorrefrativa (PRK) para baixa miopia com e sem a aplicação tópica de mitomicina C. Métodos: Pacientes submetidos à PRK para baixa miopia foram selecionados para o estudo. PRK sem MMC foi realizado em 21 olhos (12 pacientes) e PRK com MMC tópica a 0,02% foi realizado em 25 olhos (25 pacientes). Ambos os grupos foram tratados com o excimer laser da Nidek EC5000. Avaliações foram realizadas usando o medidor de dispersão de luz C-Quant no pré-operatório e com 2 e 4 meses de pós-operatório. Resultados: A média de idade dos pacientes foi 30 ± 4 anos e a média do equivalente esférico foi -2,2 ± 0,75 D. As médias da dispersão de luz intraocular no pré-operatório foram 1,07 ± 0,10 no grupo PRK sem MMC e 1,07 ± 0,11 log(s) no grupo PRK com MMC tópica. Após 2 meses da cirurgia houve uma diminuição na média da dispersão de luz intraocular em ambos os grupos. Entretanto uma diferença estatisticamente significante, comparado com os valores pré-operatórios, foi observada apenas no grupo PRK com MMC (0,98 ± 0,09 log(s), p=0,002), provavelmente devido as medidas com maior espalhamento de luz no grupo sem MMC (1,03 ± 0,13 log(s), p=0,082). Após 4 meses de pós-operatório, os valores de dispersão de luz não apresentavam diferença estatisticamente significantes quando comparados com os valores iniciais, tanto no grupo sem MMC (1,02 ± 0,14 log(s), p=0,26) quanto no grupo com MMC tópica (1,02 ± 0,11 log(s), p=0,13). Conclusão: PRK para baixa miopia diminui a dispersão de luz ocular e a aplicação de MMC contribui para uma ainda menor dispersão de luz no período pós-operatório inicial. Entretanto, quatro meses após a cirurgia a dispersão de luz intraocular não é significantemente diferente das medidas pré-operatórias.

Femtosecond Laser-Assisted LASIK Flap Complications.

PURPOSE: To discuss intraoperative and postoperative femtosecond laser-assisted LASIK flap complications and their management. METHODS: Review of published literature. RESULTS: Flap creation is a critical step in LASIK. The femtosecond laser has improved the overall predictability and safety of the lamellar incision, but complications can still occur during or after flap creation. Although many complications (eg, epithelial ingrowth and flap striae) were reduced with the femtosecond laser application, other specific complications have emerged, such as vertical gas breakthrough, opaque bubble layer, and transient light-sensitivity syndrome. CONCLUSIONS: The application of femtosecond laser technology to LASIK flap creation has increased greatly since its introduction. These lasers have improved the safety and predictability of the lamellar incision step. The majority of the femtosecond laser-assisted flap complications can be well managed without significant effects on refractive outcomes.

Improved Evaluation of Postoperative Pain After Photorefractive Keratectomy.

PURPOSE: Postoperative pain remains an important limiting factor to the selection of photorefractive keratectomy (PRK). There is a consensus in neurology pain research that pain should be evaluated as a multidimensional concept, which differs from current practice in ophthalmology. The purpose of this paper was to validate the use of multidimensional questionnaires, such as the Brief Pain Inventory (BPI) and the McGill Pain Questionnaire (MPQ), to provide an improved analysis of pain after PRK and to better describe its temporal profile. METHODS: This prospective study included 43 eyes of 43 myopic patients who underwent unilateral PRK. After surgery, usual pain treatment was administered. All of the participants responded to the Visual Analogue Scale (VAS), the BPI and the MPQ 1, 24, 48, 72, and 96 hours after surgery. The internal consistency was evaluated, different postoperative periods were compared, and convergent validity was assessed using correlation testing. RESULTS: The Cronbach alpha test showed high internal consistency for each of the questionnaire subscales. Patients reported higher postoperative pain values at the first measurement of the VAS (4.93 ± 2.38), MPQ-pain rating index (26.95 ± 10.58), BPI-pain severity index (14.53 ± 7.36), and BPI-pain interference index (22.30 ± 15.13). Almost all of the scales and subscales showed a statistically significant direct correlation with the VAS at all of the evaluation periods. CONCLUSIONS: This study validated the utility of multidimensional questionnaires to expand the assessment of the PRK postoperative pain profile, including intensity and other qualitative aspects.

Intense Early Flattening After Corneal Collagen Cross-linking.

PURPOSE: To report two cases of significant flattening after corneal cross-linking (CXL) for keratoconus and discuss its potential explanations and implications. METHODS: Observational case report. RESULTS: One year after standard CXL protocol (3 mW/cm(2) for 30 minutes and total energy of 5.4 J/cm(2)), a 28-year-old woman presented a flattening of greater than 14 diopters and a 14-year-old boy presented a flattening of 7 diopters. CONCLUSIONS: Although rare, a significant flattening effect may occur during the first year after CXL, probably related to intense wound healing, increase in corneal elasticity, CXL effective depth, and central cone location. These cases suggest the necessity of a patient-specific approach and a better understanding regarding the actual mechanism behind its potent effect.

Crosslinking: an updated and effective insight / Cross-linking: uma visão objetiva e atualizada

The corneal cross-linking has been used in order to reduce and stabilize the progression of ectatic diseases through its effects on the biomechanics of the cornea. Different protocols are being conducted worldwide to expand its indications as well as its use at different ages, different stages of the disease, combinations with other techniques, besides the utilization for non-ectatic diseases. There is still no consensus on the indications of the cross-linking procedure, but the results published in the literature show significant changes in the properties of the corneal tissue. The aim of this study is to review some of these protocols already published and discuss their results, indications and complications.

O cross-linking corneano é utilizado com o objetivo de reduzir e estabilizar a progressão das patologias ectásicas através de seus efeitos na biomecânica da córnea. Diferentes protocolos estão sendo realizados pelo mundo para expandir suas indicações, assim como seu uso em diversas faixas etárias, diferentes estágios da doença, combinações com outras técnicas, além de utilizações para doenças não ectásicas. Não há ainda um consenso nas indicações do procedimento de cross-linking, mas os resultados publicados na literatura evidenciam mudanças significativas nas propriedades do tecido corneano. O objetivo desse estudo é revisar alguns desses protocolos já publicados e discutir seus resultados, indicações e complicações.

Screening of refractive surgery candidates for LASIK and PRK.

PURPOSE: The aim of this study was to evaluate exclusion criteria in screening patients for refractive surgery. METHODS: Patients screened for initial refractive surgery by a single surgeon at the Cole Eye Institute (Cleveland Clinic) between 2007 and 2012 were reviewed. Exclusion criteria for patients who were not offered refractive surgery based on history and/or examination parameters were analyzed. RESULTS: A total of 1067 refractive candidates were enrolled in the study. Five hundred nineteen (48.6%) were male and 548 (51.4%) were female with a mean age of 39 ± 12 (range, 17-78) years. Refractive surgery was performed in 657 (61.6%) patients, and photorefractive keratectomy was considered the best option for 106 (9.9%) patients. Four hundred ten (38.4%) of all screened patients did not have refractive surgery, and 134 of these patients (12.6%) were considered to have contraindications for laser in situ keratomileusis and photorefractive keratectomy. Among the excluded patients, 69 (51.5%) were male and 65 (48.5%) were female with a mean age of 40 ± 14 (range, 18-78) years. Abnormal corneal topography (34.3%) and low or insufficient corneal thickness (23.1%) were the most common reasons for exclusion. High myopia (10.5%) and (insipient or definite) cataract (9.7%) were also common reasons for exclusion. Other common factors for exclusion were high hyperopia (3.7%), need to wear reading glasses after surgery (3.7%), and severe dry eye unresponsive to treatment (3.7%). CONCLUSIONS: Abnormal corneal topography and low, or insufficient, corneal thickness remain the most common exclusion factors for corneal refractive surgery. Factors such as cataract, too high of correction, and severe dry eye are also common reasons for exclusion of patients.

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.