ABSTRACT
ABSTRACT Purpose: To evaluate the effect of accelerated corneal crosslinking on corneal biomechanics with an ocular response analyzer in patients with progressive keratoconus. Methods: In this retrospective study, 50 eyes of 45 patients with progressive keratoconus who underwent accelerated corneal crosslinking were evaluated with ocular response analyzer waveform parameters before and one year after corneal crosslinking. Paired two-tailed Student's t-test was performed to compare the parameters before vs. after corneal crosslinking. Results: Mean patient age was 17.6 ± 3.6 (range 9-25) years. A significant increase was observed in p1 area, p2 area, h2, and dive2 values. No significant difference in corneal hysteresis, corneal resistance factor, or other waveform-derived parameters was observed at one year postoperatively. Conclusion: For estimating the effect of accelerated corneal crosslinking on corneal biomechanics, parameters such as p1 area, p2 area, h2, and dive2 are more sensitive than corneal hysteresis and corneal resistance factor. These results may help us to find out which corneal crosslinking method is most effective for stiffening the cornea.
RESUMO Objetivo: Avaliar o efeito do cross-linking corneano acelerado na biomecânica corneana com analisador de resposta ocular em pacientes com ceratocone progressivo. Métodos: Neste estudo retrospectivo, 50 olhos de 45 pacientes com ceratocone progressivo submetidos à cross-linking corneano acelerado foram avaliados com os parâmetros da forma de onda do analisador de resposta ocular antes e um ano após o tratamento com cross-linking corneano. O teste t de Student pareado bicaudal foi realizado para comparar os parâmetros antes e depois do cross-linking corneano. Resultados: A média de idade dos pacientes foi de 17,6 ± 3,6 (variação de 9 a 25) anos. Um aumento significativo foi observado nos valores de p1area, p2area, h2 e dive2. Nenhuma diferença significativa foi encontrada na histerese da córnea, fator de resistência da córnea ou outros parâmetros derivados da forma de onda foi observada em um ano de pós-operatório. Conclusão: Para estimar o efeito do cross-linking corneano acelerado na biomecânica corneana, parâmentros como p1area, p2area, h2 e dive2 são mais sensíveis que histerese da córnea e fator de resistência corneana. Esses resultados podem nos ajudar a descobrir qual método cross-linking corneano é mais eficaz no enrijecimento da córnea.
Subject(s)
Humans , Male , Female , Child , Adolescent , Adult , Young Adult , Keratoconus/surgery , Keratoconus/pathology , Reference Values , Riboflavin/therapeutic use , Vitamin B Complex/therapeutic use , Biomechanical Phenomena , Visual Acuity , Linear Models , Reproducibility of Results , Retrospective Studies , Treatment Outcome , Cornea/surgery , Cornea/pathology , Corneal Topography/instrumentation , Cross-Linking Reagents/therapeutic use , Corneal Pachymetry/methods , Keratoconus/physiopathologyABSTRACT
PURPOSE: To evaluate the effect of accelerated corneal crosslinking on corneal biomechanics with an ocular response analyzer in patients with progressive keratoconus. METHODS: In this retrospective study, 50 eyes of 45 patients with progressive keratoconus who underwent accelerated corneal crosslinking were evaluated with ocular response analyzer waveform parameters before and one year after corneal crosslinking. Paired two-tailed Student's t-test was performed to compare the parameters before vs. after corneal crosslinking. RESULTS: Mean patient age was 17.6 ± 3.6 (range 9-25) years. A significant increase was observed in p1 area, p2 area, h2, and dive2 values. No significant difference in corneal hysteresis, corneal resistance factor, or other waveform-derived parameters was observed at one year postoperatively. CONCLUSION: For estimating the effect of accelerated corneal crosslinking on corneal biomechanics, parameters such as p1 area, p2 area, h2, and dive2 are more sensitive than corneal hysteresis and corneal resistance factor. These results may help us to find out which corneal crosslinking method is most effective for stiffening the cornea.
Subject(s)
Keratoconus/pathology , Keratoconus/surgery , Adolescent , Adult , Biomechanical Phenomena , Child , Cornea/pathology , Cornea/surgery , Corneal Pachymetry/methods , Corneal Topography/instrumentation , Cross-Linking Reagents/therapeutic use , Female , Humans , Keratoconus/physiopathology , Linear Models , Male , Reference Values , Reproducibility of Results , Retrospective Studies , Riboflavin/therapeutic use , Treatment Outcome , Visual Acuity , Vitamin B Complex/therapeutic use , Young AdultABSTRACT
ABSTRACT Purpose: To investigate the relationship between biomechanical properties of the cornea and postoperative refractive changes in patients with low-level astigmatism after cataract surgery. Methods: This prospective study recruited patients undergoing cataract surgery involving 2.8-mm superior incisions. Biomechanical properties of the cornea were evaluated preoperatively using the Ocular Response Analyzer, and corneal profiles were evaluated using a Scheimpflug system (Pentacam HR). Topographic astigmatism, total corneal aberrations (TCA) and higher-order corneal aberrations (HOCA) analyses were performed preoperatively and during 1- and 3-month postoperative exams. The incidences of surgically-induced astigmatism (SIA) and HOCAs were calculated using vector analyses. Associations of the preoperative biomechanical properties of the cornea with SIA and HOCAs were evaluated. Results: This study included 28 eyes of 28 patients. The preoperative corneal hysteresis (CH) was 8.68 ± 1.86 mmHg, and the corneal resistance factor (CRF) was 8.66 ± 1.61 mmHg. At the 1-month postoperative evaluation, significant changes were observed in HOCAs (p=0.023), TCAs (p=0.05), astigmatism (p=0.02), and trefoil (p=0.033); in contrast, differences in coma (p=0.386) and spherical aberration (SA) were not significant (p=0.947). At the 3-month visit, significant changes were only observed in TCAs (p=0.02) and HOCAs (p=0.012). No relationships between the preoperative corneal hysteresis and corneal resistance factor and postoperative SIA and HOCA were identified, other than a positive correlation between the 3-month postoperative incidence of corneal hysteresis and spherical aberration. Conclusions: Despite the observed lack of relationships of preoperative biomechanical properties of the cornea with SIA and postoperative aberrations (except for SA), further studies involving larger patient groups are needed to explore the unexpected refractive deviations after cataract surgery.
RESUMO Objetivo: Investigar a relação entre as propriedades biomecânicas da córnea e as mudanças refrativas pós-operatórias em pacientes com baixa astigmatismo após a cirurgia de catarata. Método: Neste estudo prospectivo, recrutamos os pacientes submetidos a cirurgia de catarata com incisões superiores de 2,8 mm. As propriedades biomecânicas da córnea foram avaliadas no pré-operatório pelo Ocular Response Analyzer (ORA, Reichert, EUA) e o perfil corneano foi avaliado por um sistema Scheimpflug (Pentacam HR, Oculus Optikgeräte, GmbH). As avaliações do astigmatismo topográfico e das aberrações corneanas de alta ordem (HOCA) foram feitas no pré-operatório e no 1º e 3º mês pós-operatório. O astigmatismo induzido cirurgicamente (SIA) e aberrações corneanas de alta ordem foram calculados pela análise vetorial. Associações das propriedades biomecânicas da córnea no pré-operatório com astigmatismo induzido cirurgicamente e aberrações corneanas de alta ordem foram avaliadas. Resultados: O estudo foi realizado em 28 olhos de 28 pacientes. A histerese corneana (CH) pré-operatória foi 8,68 ± 1,86 mmHg, e o fator de resistência da córnea (CRF) foi de 8,66 ± 1,61 mmHg. No pós-operatório de 1 mês houve mudanças significativas aberrações corneanas de alta ordem (p=0,023), aberração total (p=0,05), astigmatismo (p=0,02) e trifóglio (p=0,033), mas as diferenças em coma (p=0,386) e aberração esférica (SA) foram insignificantes (p=0,947). No terceiro mês, a única mudança significativa foi em RMS total (p=0,02) e aberração total (p=0,012). Não houve relação entre histerese corneana e o fator de resistência da córnea pré-operatórios e astigmatismo induzido cirurgicamente e aberrações corneanas de alta ordem pós-operatórios, além de uma correlação positiva entre o histerese corneana e o aberração esférica do 3º mês pós-operatório. Conclusões: Apesar de não haver relação entre as propriedades biomecânicas pré-operatórias da córnea e astigmatismo induzido cirurgicamente e aberrações (exceto SA) após a cirurgia em nosso estudo, são necessários mais estudos com grupos de pacientes maiores de explicar os erros refrativos inesperados após a cirurgia de catarata.
Subject(s)
Humans , Male , Female , Adult , Middle Aged , Aged , Postoperative Complications/etiology , Astigmatism/etiology , Cataract Extraction/adverse effects , Cornea/surgery , Lens Implantation, Intraocular/adverse effects , Corneal Wavefront Aberration/etiology , Postoperative Period , Biomechanical Phenomena , Prospective Studies , Preoperative PeriodABSTRACT
PURPOSE:: To investigate the relationship between biomechanical properties of the cornea and postoperative refractive changes in patients with low-level astigmatism after cataract surgery. METHODS:: This prospective study recruited patients undergoing cataract surgery involving 2.8-mm superior incisions. Biomechanical properties of the cornea were evaluated preoperatively using the Ocular Response Analyzer, and corneal profiles were evaluated using a Scheimpflug system (Pentacam HR). Topographic astigmatism, total corneal aberrations (TCA) and higher-order corneal aberrations (HOCA) analyses were performed preoperatively and during 1- and 3-month postoperative exams. The incidences of surgically-induced astigmatism (SIA) and HOCAs were calculated using vector analyses. Associations of the preoperative biomechanical properties of the cornea with SIA and HOCAs were evaluated. RESULTS:: This study included 28 eyes of 28 patients. The preoperative corneal hysteresis (CH) was 8.68 ± 1.86 mmHg, and the corneal resistance factor (CRF) was 8.66 ± 1.61 mmHg. At the 1-month postoperative evaluation, significant changes were observed in HOCAs (p=0.023), TCAs (p=0.05), astigmatism (p=0.02), and trefoil (p=0.033); in contrast, differences in coma (p=0.386) and spherical aberration (SA) were not significant (p=0.947). At the 3-month visit, significant changes were only observed in TCAs (p=0.02) and HOCAs (p=0.012). No relationships between the preoperative corneal hysteresis and corneal resistance factor and postoperative SIA and HOCA were identified, other than a positive correlation between the 3-month postoperative incidence of corneal hysteresis and spherical aberration. CONCLUSIONS:: Despite the observed lack of relationships of preoperative biomechanical properties of the cornea with SIA and postoperative aberrations (except for SA), further studies involving larger patient groups are needed to explore the unexpected refractive deviations after cataract surgery.