Quantitative corneal anatomy in emmetropic subjects.

PURPOSE: Currently there is little information available about the corneal thickness values of healthy emmetropic subjects. Therefore, the authors decided to analyze the corneal thickness in healthy emmetropic subjects. METHODS: The authors analyzed the difference in thickness values between the thinnest corneal site and the central and paracentral cornea in 124 eyes of 124 healthy emmetropic white subjects. RESULTS: The mean difference between the thinnest site of the cornea and the thickness values obtained in the areas analyzed was as follows: 12+/-6 microm center; 140+/-19 microm superonasal; 133+/-23 microm nasal; 117+/-26 microm inferonasal; 122+/-19 microm superotemporal ; 89+/-22 microm temporal; and 99+/-29 microm inferotemporal (p<0.001; one way analysis of variance test). CONCLUSIONS: In healthy emmetropic white subjects the thinnest site of the cornea is statistically lower than the central and paracentral cornea.

[Orbscan pachymetry: differences between observers when carrying out measurements of the corneal thickness]. / Paquimetría Orbscan: diferencias entre observadores al realizar mediciones del espesor corneal.

PURPOSE: To study the corneal thickness and the inter-observer variability of corneal thickness measurements by means of Orbscan pachymetry. METHODS: We analysed the central and para-central corneal thickness of 30 subjects, whose age ranged from 19 to 38 years (mean 27.27, S.D. 5.25), with the Orbscan Topography System II (Orbscan, Inc., Salt Lake City, UT, USA). The mean of five consecutive measurements of the corneal thickness were obtained by two different observers and the results obtained were compared. RESULTS: No significant differences in mean corneal thickness between observers were found at central (p=0.749), nasal (p=0.931), supero-nasal (p=0.847), infero-nasal (p=0.930), temporal (p=0.918), supero-temporal (p=0.912) and infero-temporal (p=0.760) regions of the cornea. The maximum mean corneal thickness was found most commonly at the supero-nasal cornea (14 of 30 eyes for observer 1, and 16 of 30 eyes for observer 2). The difference between the central thickness and the maximum para-central thickness was 117 (S.D. 22) and 117 (S.D. 23) microns for observers 1 and 2 respectively (p=0.974). The difference between the central thickness and the minimum para-central thickness was 40 (S.D. 20) and 39 (S.D. 19) microns for observers 1 and 2 respectively (p=0.846). The difference between the minimum and the maximum para-central thickness was 76 (S.D. 24) and 77 (S.D. 23) microns for observers 1 and 2 respectively (p=0.895). CONCLUSIONS: Orbscan pachymetry allows central and para-central corneal studies to be carried out by different observers without any significant differences being found between them.

Corneal endothelial cell density decreases with age in emmetropic eyes.

PURPOSE: To analyze the corneal endothelial cell density in healthy adult emmetropic subjects. METHODS: We analyzed the corneal endothelial cell density of a group made up of 225 emmetropic subjects (n=225). As age-matched control groups we analyzed two other groups, one made up of myopic subjects (n=209) and the other made up of hyperopic subjects (n=203). We recorded the mean of three consecutive measurements of the corneal endothelial cell density using the Topcon SP-2000P non-contact specular microscope (Topcon Corp., Tokyo, Japan). RESULTS: The mean age was 38.6+/-11.8 years, 40.7+/-12.2 years, and 39.2+/-10.5 years for emmetropic, myopic and hyperopic subjects respectively (p=0.994). No significant differences (p=0.920) in endothelial cell density values were found between emmetropic (2985+/-245 cells/mm2), myopic (2936+/-258 cells/mm2) and hyperopic eyes (2946+/-253 cells/mm2). Lower corneal endothelial cell density values were found in older emmetropic (p<0.001), myopic (p<0.001), and hyperopic subjects (p<0.001). A significant correlation between endothelial cell density and age was found in emmetropic (r=-0.958; p<0.001), myopic (r= -0.954; p<0.001) and hyperopic subjects (r= -0.948; p<0.001). CONCLUSIONS: In healthy emmetropic subjects there is a reduction in corneal endothelial cell density with age although there are no differences in corneal endothelial cell density values between emmetropic, myopic and hyperopic subjects.

Intraobserver reproducibility of retinal nerve fiber layer measurements using scanning laser polarimetry and optical coherencetomography in normal and ocular hypertensive subjects.

PURPOSE: To evaluate quantitatively the intraobserver reproducibility of measurements of the retinal nerve fiber layer (RNFL) in healthy subjects and an ocular hypertensive population using two nerve fiber analyzers. METHODS: Sixty eyes of normal (n=30) and ocular hypertensive subjects (n=30) were consecutively recruited for this study and underwent a complete ophthalmologic examination and achromatic automated perimetry. RNFL were measured using scanning laser polarimeter (GDx-VCC) and optical coherence tomography (OCT Model 3000). Reproducibility of the RNFL measurements obtained with both nerve fiber analyzers were compared using the coefficient of variation. RESULTS: In both groups the authors found fair correlations between the two methods in all ratio and thickness parameters. The mean coefficient of variation for measurement of the variables ranged from 2.24% to 13.12% for GDx-VCC, and from 5.01% to 9.24% for OCT Model 3000. The authors could not detect any significant differences between healthy and ocular hypertensive eyes, although in normal eyes the correlations improved slightly. Nev-ertheless, the testretest correlation was slightly better for GDx-VCC than for OCT Model 3000 (5.55% and 7.11%, respectively). CONCLUSIONS: Retinal mapping software of both nerve fiber analyzers allows reproducible measurement of RNFL in both healthy subjects and ocular hypertensive eyes, and shows fair correlations and good intraobserver reproducibility. However, in our study, GDx showed a better testretest correlation. (Eur J Ophthalmol 2004; 14: 523-30).

Intraobserver reproducibility of retinal nerve fiber layer measurements using scanning laser polarimetry and optical coherence tomography in normal and ocular hypertensive subjects.

PURPOSE: To evaluate quantitatively the intraobserver reproducibility of measurements of the retinal nerve fiber layer (RNFL) in healthy subjects and an ocular hypertensive population using two nerve fiber analyzers. METHODS: Sixty eyes of normal (n=30) and ocular hypertensive subjects (n=30) were consecutively recruited for this study and underwent a complete ophthalmologic examination and achromatic automated perimetry. RNFL were measured using scanning laser polarimeter (GDx-VCC) and optical coherence tomography (OCT Model 3000). Reproducibility of the RNFL measurements obtained with both nerve fiber analyzers were compared using the coefficient of variation. RESULTS: In both groups the authors found fair correlations between the two methods in all ratio and thickness parameters. The mean coefficient of variation for measurement of the variables ranged from 2.24% to 13.12% for GDx-VCC, and from 5.01% to 9.24% for OCT Model 3000. The authors could not detect any significant differences between healthy and ocular hypertensive eyes, although in normal eyes the correlations improved slightly. Nevertheless, the test-retest correlation was slightly better for GDx-VCC than for OCT Model 3000 (5.55% and 7.11%, respectively). CONCLUSIONS: Retinal mapping software of both nerve fiber analyzers allows reproducible measurement of RNFL in both healthy subjects and ocular hypertensive eyes, and shows fair correlations and good intraobserver reproducibility. However, in our study, GDx showed a better test-retest correlation.

[Comparative clinical study of visual results between two different types of bifocal intraocular lenses]. / Estudio clínico comparativo de los resultados visuales en dos lentes intraoculares bifocales.

PURPOSE: To compare visual results after cataract surgery in patients who underwent bilateral implantation of two different types of bifocal intraocular lenses: the model 811E (Pharmacia), and the model MF4 (Ioltech). METHODS: This prospective study comprised 99 patients who underwent phacoemulsification with bifocal IOL implantation. The model 811E was implanted in forty-seven eyes of 47 patients (group I) and the model MF4 in fifty-two eyes of 52 patients (group II). Visual acuity (distance and near), complications, and adverse events were measured. The postoperative follow-up in all patients was of 6 months. Patient satisfaction was also valued using a questionnaire. RESULTS: There was no significant difference in uncorrected distance visual acuity between both groups, which was respectively 0.63 (S.D.: 0.2) for group I and 0.58 (S.D.: 0.16) for group II (p=0.17). Nonetheless a significant difference was found when measuring corrected distance visual acuity, which was 0.86 (S.D.: 0.1) for group I and 0.77 (S.D.: 0.12) for group II (p=0.01). Mean uncorrected near visual acuity was statistically better in group I: J2.00 (S.D.:1.16) in comparison with J2.48 (S.D.:0.83) for group II (p=0.021). Subjectively, both groups indicated high levels of satisfaction, without significant difference between them, being respectively 78% (group I) and 73.4% (group II). CONCLUSIONS: Our results reveal a superiority of the bifocal diffractive lens over the refractive bifocal lens for corrected distance visual acuity and distance-corrected near visual acuity. Postoperatory complications and satisfaction degree were similar for both IOL models.

Estudio clínico comparativo de los resultados visuales en dos lentes intraoculares bifocales / Comparative clinical study of visual results between two different types of bifocal intraocular lenses

Introducción: Comparar los resultados visuales tras cirugía de cataratas con implante de dos tipos de lentes intraoculares (LIO) bifocales: el modelo 811E (Pharmacia), y el modelo MF4 (Ioltech).Métodos: Para ello realizamos un estudio prospectivo en 99 pacientes intervenidos de cataratas mediante facoemulsificación con posterior implante de LIO bifocales. En 47 pacientes se implantó el modelo 811E, y en 52 pacientes se implantó el modelo MF4. Se valoraron agudezas visuales (AV) (lejos y cerca) y refracción postoperatoria tras un periodo de seguimiento de 6 meses. La satisfacción de los pacientes se evaluó mediante un cuestionario. Resultados: No se observaron diferencias entre ambos tipos de lentes al valorar la AV para lejos sin corrección, siendo 0,63 (D.E.: 0,2) para la 811E y 0,58 (D.E.: 0,16) para la MF4 (p=0,17). Por el contrario, se observaron diferencias significativas al valorar la AV media para lejos con corrección, siendo 0,86 (D.E.: 0,1) para la 811E y 0,77 (D.E.: 0,12) para la MF4 (p=0,01), y la AV media para cerca sin corrección, siendo J2,00 (D.E.: 1,16) para la 811E y J2,48 (D.E.: 0,83) para la MF4 (p=0,021). El porcentaje de satisfacción de los pacientes fue similar en ambos tipos de LIOs, siendo respectivamente del 78 por ciento (811E) y del 73,4 por ciento (MF4).Conclusiones: Nuestros resultados muestran una superioridad de las lentes difractivas bifocales sobre las lentes refractivas bifocales en la agudeza visual corregida para lejos y en la agudeza visual de cerca con la corrección de lejos. Las complicaciones postoperatorias y el grado de satisfacción fueron similares para ambos modelos (AU)

NGF and TGF-beta mRNA expression during pregnancy in a rat corneal wound healing model.

BACKGROUND: Growth factors seem to play a major role in corneal wound healing and TGF-beta seems to be associated with abnormal healing after corneal surgical procedures. Few studies have analysed the role of NGF and TGF-beta on corneal wound healing during pregnancy. The aim of the present study was to create an animal model to evaluate the expression of NGF and TGF-betas during corneal wound healing in two groups: control and pregnant rats. METHODS: Corneal mRNA for NGF and the three isoforms of TGF-beta were analysed by RT-PCR, in a time-course experiment on different days after epithelial wounding (2, 7, 14 days) in pregnant and control groups RESULTS: The results show high corneal mRNA expression for NGF and TGF-beta1 without any variation throughout the healing process or pregnancy evolution. However, we detected a different expression of corneal mRNAs for TGF-beta2 and TGF-beta3 in the control group. This data was not detected in the pregnant group. DISCUSSION: Our results suggested that pregnancy could have a relevant role on TGF-beta2 and TGF-beta3 mRNA expression during the corneal wound healing process. Additional research should be performed to corroborate these findings.