Comparison of Central Corneal Thickness Measurements by Pentacam and Ultrasound Pachymetry in Normal Myopic Patients

Abstract

IntroductionPrecise measurement of corneal thickness is of crucial importance in corneal refractive procedures. The aim of this work is to compare the central corneal thickness measurements using Scheimpflug imaging (Pentacam) and contact US pachymetry in normal myopic patients.MethodsThis retrospective cohort study was conducted on in 144 eyes of 72 normal myopic patients during 6 months. The study location was the Research Institute of Ophthalmology (Giza, Egypt), and Magrabi Eye Hospital (Dubai, United Arab Emirates). Central corneal thickness was measured with the two devices. Data were analyzed by descriptive statistics, independent-samples t-test, paired-samples t-test, Mann-Whitney U test and Pearson-Product Moment Correlation Coefficient.ResultsThe mean age was 25.3±5.6 years (range 18 to 38 years). The median age for our patients is 24 years. The average measurements of CCT were 526.8±35.3 and 529.1±37.9 for the Pentacam pachymetry and US pachymetry values, respectively. Mean difference between both measurements was 2.3±2.6μm which is statistically insignificant (p=0.08). Bland Altman Plot shows border line agreement of the two methods US pachymetry and Pentacam in detection of central corneal thickness.ConclusionThe results of this study showed no significant differences in CCT readings between the measurements obtained by Pentacam and US pachymetry in normal myopic patients.

Comparison of different correction formulas and measurement methods for the accurate determination of intraocular pressure after SMILE and FS-LASIK surgery

“…Pentacam corneal topography is used to measure the corneal thickness as well as the curvature of the anterior and posterior corneal surface [ 10 ]. Here, valid measurements were obtained following the same process as during NCT readings, and the recorded data were used to calculate the corrected IOP values based on the following formulas [ 11 ]: Ehlers IOP (IOPe) = IOPmeasured + [0.071 × (545 − corneal thickness)] [ 12 ]; Shah IOP (IOPs) = IOPmeasured + [0.050 × (550 − corneal thickness)] [ 13 ]; Dresden IOP (IOPd) = IOPmeasured + [0.040 × (550 − corneal thickness)] [ 14 ]; Kohlhaas IOP (IOPk) = IOPmeasured + [(540 − corneal thickness)/71] + [(43-K)/2.7] + 0.75 [ 15 ]; and Orssengo-Pye IOP (IOPo) = Goldmann IOP /K [ 16 ].…”

Avaliação de córneas de crianças brasileiras usando um sistema de topografia de Scheimpflug

“…Os detalhes fornecidos pelo Pentacam são confiáveis porque o equipamento apresenta um alto nível de repetibilidade das medidas ceratométricas e paquimétricas(32,33). Diversos estudos demonstraram que as medidas da espessura corneana realizadas com o Pentacam e seus mapas apresentam alta confiança e reprodutibilidade(15,(34)(35)(36)(37) com uma alta correlação com as medidas obtidas por paquimetria ultrassônica em olhos normais e em olhos com ceratocone(5,38,39). Estudos demonstraram também baixa variabilidade das medidas de ceratometria obtidas tanto em pacientes normais quanto com ceratocone(40).Alguns estudos forneceram extensa informação sobre dados normativos do segmento anterior de adultos (41-45) assim como as alterações da elevação posterior da Estudos anteriores mostraram que o perfil de espessura no adulto fornecido pelo Pentacam associado ao programa do BAD pode diferenciar ceratocone de córneas normais com uma sensibilidade e especificidade de 96,7%-100% e 94,8%-100% respectivamente; e diferenciar formas de ceratocone subclínico com uma sensibilidade e especificidade de 60%-81,1% e 73,2%-90% respectivamente(25,47,50,51).É importante reconhecer as influências do envelhecimento na forma da superfície anterior e posterior da córnea(52) especialmente em pacientes com catarata e que realizaram tratamentos corneanos no passado, isto é, pacientes que necessitam de medidas precisas da ceratometria para o cálculo da lente intraocular a ser usada durante o procedimento cirúrgico da catarata(53).…”