Densitometría corneal en el queratocono / Corneal Densitometry in Keratoconus

Objetivo: Evaluar la densitometría corneal en pacientes con queratocono. Métodos: Se realizó un estudio observacional descriptivo de corte transversal que incluyó 90 pacientes con queratocono (grupo de estudio) y 30 estudiantes con córneas aparentemente sanas (grupo control), que asistieron a la consulta de córnea del Instituto Cubano de Oftalmología Ramón Pando Ferrer, entre mayo del 2018 y junio del 2019. Se seleccionó el ojo derecho de cada caso. Se analizaron densitometría corneal con el tomógrafo corneal Pentacam AXL. Resultados: La densitometría fue mayor en el queratocono respecto a la córnea aparentemente sana, de 0 a 2 mm, en la capa anterior, central, y posterior, respectivamente (p < 0,001). La densitometría aumentó en los 0 a 2 mm en la capa anterior en el grupo moderado y en el grupo avanzado (p < 0,001), y entre los 2-6 mm en la capa central, de 10,86 ± 0,54 en el control, en el queratocono avanzado a 12,35 ± 1,16 y en el moderado a 12,16 ± 1,45 (p < 0,001). La densitometría aumentó en el avanzado de 27,64 ± 3,81, de 22,77 ± 2,14 en el leve, y de 24,04 ± 2,83 en el moderado y en los 0-2 mm, en la capa anterior. Conclusiones: La densitometría es mayor en la córnea queratocónica respecto a la córnea aparentemente sana, además que se incrementa al aumentar la gravedad del queratocono en el área central(AU)

Objective: To evaluate corneal densitometry in patients with keratoconus. Methods: A cross-sectional descriptive observational cross-sectional study was performed including 90 patients with keratoconus (study group) and 30 students with apparently healthy corneas (control group), who attended the cornea consultation at the Cuban Institute of Ophthalmology Ramón Pando Ferrer, between May 2018 and June 2019. The right eye of each case was selected. Corneal densitometry was analyzed with the Pentacam AXL corneal tomographer. Results: Densitometry was higher in keratoconus relative to apparently healthy cornea, from 0 to 2 mm, in the anterior, central, and posterior layer, respectively (p < 0.001). Densitometry increased in the 0 to 2 mm in the anterior layer in the moderate group and in the advanced group (p < 0.001), and between 2-6 mm in the central layer, from 10.86 ± 0.54 in the control, in the advanced keratoconus to 12.35 ± 1.16 and in the moderate to 12.16 ± 1.45 (p < 0.001). Densitometry increased in advanced from 27.64 ± 3.81, from 22.77 ± 2.14 in mild, and from 24.04 ± 2.83 in the moderate and 0-2 mm, in the anterior layer. Conclusions: Densitometry is higher in the keratoconic cornea with respect to the apparently healthy cornea, moreover it increases with increasing severity of keratoconus in the central area(AU)

Determination of the repeatability of corneal densitometry as measured with a Scheimpflug camera device in refractive surgery candidates.

Purpose: Corneal densitometry analysis provides an objective measurement of corneal transparency in patients undergoing photorefractive keratectomy (PRK). To date, no study that focuses on determining the reliability and smallest real difference (SRD), specifically in PRK candidates, has been published. Methods: The study was conducted at Clínica de Oftalmología Sandiego, Medellín, Colombia. This was a prospective and analytical study. Refractive surgery candidates underwent Pentacam measurements twice with five minutes of difference. Repeatability of measurements was evaluated for every area using Wilcoxon signed-rank test, Spearman's rank-order correlation, and the intraclass correlation coefficient, followed by a within-subjects factor (Sw) finishing with a determination of the SRD for all areas. Bland-Altman plots were created and analyzed. Results: A total of 110 eyes were included. The mean total densitometry was 18.67 ± 1.56 grayscale units (GSU) and 18.65 ± 1.49 GSU for the first and second measurements, respectively. Wilcoxon was non-significant (P > 0.05) while the intraclass correlation coefficient demonstrated an excellent agreement. SRD ranged from 0.21 GSU (posterior × 6-10 mm) to 1.79 GSU (total × 10-12 mm). Anterior depths and 10-12 mm annulus had consistently more variability and greater (worse) SRD. The 10-12 mm annulus showed great dispersion on the Bland-Altman plots. Conclusion: Corneal densitometry has an excellent repeatability in refractive surgery candidates for areas below 10 mm. Any densitometry change ≥1.0 GSU in areas under 10 mm should be considered as well above measurement noise and corresponding to a real change in measured parameters. The 10-12 mm area does not seem to be reliable enough in refractive surgery candidates to warrant surveillance after corneal-based surgery.

Corneal densitometry in patients with keratoconus undergoing intrastromal Ferrara ring implantation.

OBJECTIVE: Evaluation of central corneal densitometry changes following Ferrara corneal ring segment implantation in patients with keratoconus, especially the correlation between corneal densitometry and keratometry. METHODS: Retrospective, non-comparative, interventional study based on the review of medical records of patients diagnosed with keratoconus who underwent Ferrara corneal ring segment implantation. Pre and post-operative corneal densitometry measurements obtained with Pentacam HR (Oculus, Wetzlar, Germany) were analyzed. The follow-up time was 3 months, and data comparison was made, using specific statistical analysis, with the data of 3 months postoperatively. RESULTS: The study sample consisted of 43 eyes of 36 patients. The mean corrected visual acuity improved from 0.82 LogMAR preoperatively (SD ± 0.33) to 0.19 LogMAR (SD ± 0.13) postoperatively. The mean spherical equivalent varied from -4.63 (SD ± 3.94) preoperatively to -2.16 (SD ± 2.63) postoperatively. Asphericity varied from -0.69 (SD ± 0.32) preoperatively to -0.27 (SD ± 0.31) postoperatively. The mean maximum K was 54.01D (SD ± 3.38) preoperatively and 51.50D (SD ± 2.90) postoperatively. The mean anterior densitometric value was 18.26 (SD ± 2.03) preoperatively and 17.66 (SD ± 1.84) postoperatively. CONCLUSION: Corneal densitometry is an interesting technology that should be studied in keratoconus patients. Our results suggest that the corneal densitometry in the cornea's anterior layer reduces after ICRS implantation and correlates with corneal keratometry. Further studies should be performed to increase the knowledge in this field.

The Effect of Corneal Thickness, Densitometry and Curvature on Intraocular Pressure Measurements Obtained by Applanation, Rebound and Dynamic Contour Tonometry.

Evaluate the effect of corneal thickness, densitometry and curvature on intraocular pressure (IOP) measurements obtained by Goldmann applanation tonometry (GAT), non-contact tonometry (NCT), rebound tonometry (RT), and dynamic contour tonometry (DCT). A cross-sectional prospective study involving 40 participants was performed. Corneal measurements were obtained using Pentacam (Oculus GMbH, Wetzlar, Germany), densitometry was measured at annuli of 0-2, 2-6, 6-10 and 10-12 mm. The relationship between corneal thickness (central, 4 and 6 mm), corneal astigmatism and corneal densitometry and IOP was examined. There was a significant relationship between corneal thickness (central, 4 and 6 mm) and GAT180, GAT90, RT, and NCT (P < 0.001 for all comparisons) but not for DCT. Higher corneal densitometry (6-10 mm and 10-12 mm zones) was associated with higher IOP from GAT180 and GAT90, and higher densitometry in the 6-10 mm zone correlated with higher IOP from NCT, however corneal densitometry increased with age. Accounting for age, the relationship between corneal densitometry and IOP measurements was not significant. In eyes with greater corneal astigmatism there was a greater difference between GAT90 and GAT180 measurements. IOP measurements may be affected by corneal thickness, densitometry and curvature. DCT was less affected by properties of the cornea compared to other devices.