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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.
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.
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Purpose: To evaluate the use of Scheimpflug tomography in corneal densitometry (CD) in comparing the stages of keratoconic eyes. Methods: Keratoconic (KC) corneas (stages 1–3 classified according to the topographic parameters) were examined using the Scheimpflug tomographer (Pentacam, Oculus) using the CD software. CD was measured over three different depths (anterior stromal layer [120 ?m], posterior stromal layer [60 ?m], and middle stromal layer between these two layers), and concentric annular zones (0.0 to 2.0, 2.0 to 6.0, 6.0 to 10.0, and 10.0 to 12.0 mm diameter area). Results: The study participants were divided into three groups: keratoconus (KC) stage 1 (KC1) with 64 participants, keratoconus stage 2 (KC2) with 29 participants, and keratoconus stage 3 (KC3) with 36 participants. Comparing CD of all three layers (anterior, central, and posterior) of the cornea over different circular annuli (0–2, 2–6, 6–10, and 10–12 mm) revealed a significant difference in the 6–10 mm annulus between all groups and in all layers (P = 0.3, 0.2, and 0.2, respectively). Area under curve (AUC) was done. It revealed that the central layer showed the highest specificity (93.8%) in comparing KC1 and KC2, whereas CD in the anterior layer between KC2 and KC3 had the highest specificity (86.2%). Conclusion: CD showed increased values in the anterior corneal layer and in the annulus 6–10 mm more than other locations in all stages of KC
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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
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AIM: To compare the changes in corneal densitometry after small incision lenticule extraction(SMILE)and femtosecond laser in situ keratomileusis(FS-LASIK)and investigate the effect of corneal interface haze on vision after SMILE.METHODS: Prospective cohort study. A total of 93 patients(186 eyes)who were scheduled to undergo refractive surgery at the Ophthalmic Refractive Surgery Center of the Affiliated Hospital of Nantong University from May 2020 to October 2021 were included in the study, and there were 48 patients(96 eyes)in the SMILE group and 45 patients(90 eyes)in the FS-LASIK group. The changes in corneal densitometry, spherical equivalent(SE), and uncorrected visual acuity(UCVA)were observed and compared between the two groups before and at 1d, 1wk, 1, 3 and 6mo after surgery.RESULTS: The 93 patients all successfully completed the surgery, and there were no related complications during and after the surgery, and there were no lost cases. The UCVA of FS-LASIK group was 0.044±0.064 and -0.001±0.065 respectively at 1d and 1wk after surgery, which was better than that of SMILE group(0.102±0.077 and 0.023±0.064; all P<0.05). There was no statistical difference in the SE between the two groups at the postoperative follow-ups(P>0.05). The corneal densitometry values at 0-2 and 2-6 mm from corneal vertex and total corneal densitometry at 1d postoperatively in the FS-LASIK group were 18.0(17.5, 18.6), 16.2(15.6, 16.7)and 16.7(16.1, 17.3), which were lower than those of SMILE group [18.6(18.1, 19.3), 16.8(16.4, 17.4), 17.2(16.6, 17.8)](all P<0.05); The corneal densitometry values at 0-2 and 2-6 mm from corneal vertex and total corneal densitometry at 1wk postoperatively in the FS-LASIK group were 17.2(16.7, 17.6), 15.5(15.0, 15.9)and 15.9(15.3, 16.7), which were lower than those of SMILE group [17.6(17.1, 18.3), 16.0(15.6, 16.5), 16.6(15.9, 17.1)](all P<0.05).CONCLUSIONS: The transient interface haze after SMILE is responsible for the early higher corneal densitometry than FS-LASIK. The presence of interface haze is probably a factor for the quality of vision.
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Purpose: To evaluate corneal densitometry (CD) of patients with arcus senilis (AS) and its association with the serum lipid markers. Methods: This is a cross?sectional, case?control study. The AS diagnosis was made clinically. Forty?five eyes of 45 patients with AS and 38 eyes of 38 age?matched control subjects with no noticeable AS were enrolled in the study. All participants underwent detailed ophthalmologic examination along with corneal Scheimpflug imaging with CD measurement. The evaluated serum lipid markers of the participants included total cholesterol, triglyceride, low?density lipoprotein (LDL), high?density lipoprotein (HDL), and very?low?density lipoprotein (VLDL). The Spearman correlation analysis was used to correlate the serum lipid values and the CD. P < 0.05 was defined as statistically significant. Results: The male to female ratio was 26/19 and 14/24 in the study and control groups, respectively (P = 0.057). The mean age was 59.56 ± 8.7 and 56.47 ± 8.6 years in the study and control groups, respectively (P = 0.117). The mean total CD values in the zones extending from 2 to 12 mm were higher in the study group than in the control group (P < 0.001). The serum HDL level was found to be significantly decreased in the study group compared to the control group (P = 0.048 and Z = ?1.976). There was a significant positive correlation between the serum triglyceride level and the CD value of the outermost zone (10–12 mm) (r = 0.334 and P = 0.025). Conclusion: The CD of patients with AS was found to increase not only in the peripheral zone but also in the cornea’s paracentral zone compared to the healthy controls. The serum triglyceride level should give an insight into the intensity of arcus senilis. The serum HDL levels were decreased in patients with AS
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@#AIM: To study the efficacy and safety of accelerated collagen cross-linking in keratoconus.<p>METHODS: Medical records of keratoconic corneas underwent accelerated collagen cross-linking at King Chulalongkorn Memorial Hospital, Thailand between April 2015 and August 2018 were reviewed. Preoperative and postoperative data at 1a of visual acuity, auto-refraction, corneal topography, higher-order aberrations(HOA), topometric indices and corneal densitometry were evaluated. Age of 24 and 30 years old, maximum keratometry value(Kmax)of 55 D, and baseline best corrected visual acuity(BCVA)of 20/40(or 0.3 in LogMAR unit)were used as cut-off values to highlight the cross-linking effects. The effect of age, preoperative Kmax and BCVA were analyzed. The association between the change of corneal densitometry and other factors including preoperative Kmax, Kmean, manifest refraction spherical equivalent(MRSE), visual acuity, thinnest pachymetry, the change in Kmax, and the change of those parameters were also analyzed. <i>P</i><0.05 was considered statistically significant.<p>RESULTS: One hundred and fifty-five patients(185 eyes)were included. One hundred and nineteen patients were male and thirty-six patients were female. According to Amsler-Krumeich classification, stages 1 and 2 were dominant(37.84% and 35.14% respectively). At 1a, mean LogMAR uncorrected visual acuity(UCVA)improved by 0.1(<i>P</i><0.05). The number of eyes of which postoperative BCVA improved more than 0.2 LogMAR was higher in the worse baseline BCVA group(preoperative BCVA ≥0.3)compared to the better baseline BCVA group(preoperative BCVA < 0.3)(78.26% <i>vs</i> 21.74%, <i>P</i><0.05). Mean Kmax decreased from baseline by 2.36 diopters(D)(<i>P</i><0.05). Seventy-three percent of the eyes of which Kmax reduced more than 2.0 D had preoperative Kmax ≥55 D. Corneal HOA at 6 mm from corneal apex decreased by 0.40(<i>P</i><0.05). Corneal densitometry at 0-6 mm zone increased at 1mo and persisted 1a postoperatively(<i>P</i><0.05). The relationship of the increase in densitometric value and the decrease of thinnest pachymetry at 1a were in linear fashion. Index of surface variance, index of vertical asymmetry, keratoconus index, index of height decentration decreased at 1a(<i>P</i><0.05). Success rate at 1a was 90.24%. Postoperative corneal haze was found 11.35%, 30.27%, 15.67%, 10.27% and 2.16% at 1wk, 1, 3, 6mo and 1a respectively. No eyes developed corneal edema. There was one case of sterile keratitis.<p>CONCLUSION: Accelerated collagen cross-linking in keratoconus was effective to flatten, reshape the cornea, improved visual acuity, HOA and topometric indices. Great Kmax reduction was found in advanced keratoconus. The magnitude of Kmax reduction is also greatest among previous reports.
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@#AIM: To explore the correlation between corneal biomechanics and corneal densitometry.<p>METHODS: Prospective study. Patients who examined before corneal refractive surgery in the Second People's Hospital of Yunnan Province from March 2019 to June 2019 were selected as research objects. Pentacam HR system was used to evaluate corneal densitometry. The corneal was divided into three areas around the corneal apex with diameters of 0-2mm, >2-6mm, >6-10mm,and the corneal thickness was divided into anterior, middle and posterior layers. The thinnest point thickness of cornea in Pentacam HR was selected to be included in the study. Corvis ST was used to measure the biomechanical parameters, including the first applanation length(AP1L)and applanation velocity(AP1V),the second applanation length(AP2L)and applanation velocity(AP2V),the highest concavity peak distance(PD),highest concavity radius(HCR)and deformation amplitude(DA). Pentacam & Corvis ST comprehensive diagnostic platform software was used to comprehensively analyze the examination results and obtain comprehensive corneal biomechanical parameters(CBI), as well as other independent parameters including stiffness parameters(SP), integrated radius(IR), Ambrosio relational thickness-horizontal(ARTh)and deformation amplitude ratio(DAR). Variance analysis was used for the difference of corneal densitometry in each region, the correlation between corneal biomechanical parameters and corneal densitometry was analyzed by Pearson or Spearman.<p>RESULTS: The difference of optical density between different diameter ranges and different layers was statistically significant(<i>F</i>=35.101, <i>P</i><0.01; <i>F</i>=1002.897, <i>P</i><0.01), CBI was correlated with AP2L,AP2V,PD,DA,SP,IR,ARTh and DAR in the independent biomechanical parameters(<i>r</i>s= -0.502, <i>P</i><0.01; <i>r</i>s=-0.457, <i>P</i>=0.001; <i>r</i>s=0.428, <i>P</i>=0.002; <i>r</i>s=0.539, <i>P</i><0.01; <i>r</i>s=-0.687, <i>P</i><0.01; <i>r</i>s=0.716, <i>P</i><0.01; <i>r</i>s=-0.728, <i>P</i><0.01; <i>r</i>s=0.750, <i>P</i><0.01). CBI was positively correlated with optical density within the range of 0-2mm(<i>r</i>=0.343, <i>P</i>=0.015). The corneal densitometry within a range of 0-2mm is correlated with AP2L, IR, ARTH and DAR in independent biomechanical parameters(<i>r</i>s=-0.298, <i>P</i>=0.035; <i>r</i>s=0.368, <i>P</i>=0.009; <i>r</i>s=-0.419,<i> P</i>=0.002; <i>r</i>s=0.493, <i>P</i><0.01).<p>CONCLUSION: There is a correlation between corneal biomechanics and corneal densitometry in the central region of cornea, which has a more significant correlation with the biomechanics.
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· AIM:To evaluate the corneal densitometry in treatmentnaive patients with keratoconus and its relevance with anterior and posterior corneal elevation.· METHODS:Keratoconic corneas were examined using the Pentacam.Corneal densitometry was measured over a 12-mm diameter area,divided by annular concentric zones and depths,more over anterior and posterior corneal elevation was measured.Keratoconus was classified according to the topographic keratoconus classification.· RESULTS:A total of 152 subjects [72 patients with keratoconus (46 male,26 female) and 80 healthy control subjects (50 male,30 female)] were included in the study.There were significant differences in corneal densitometry values of the groups in central 2 mm keratoconus (KC)=19.62±4.17 gray scale unit (GSU),N=15.38±1.54 GSU(P＜0.0001),and in annulus of 2 to 6 mmin diameter (K=16.40±2.18 GSU,N=15.31±1.25 GSU,P＜0.0001).When densitometry values for different depths were examined,the anterior layer presented the highest value (KC =23.69±3.71 GSU,N =20.91 ±2.52 GSU,P＜0.0001),which was significantly higher than the values obtained in the central and posterior layer (KC =14.34± 1.70 GSU,N=13.61±1.21 GSU,P=0.001 and KC=11.40± 1.23 GSU,N =12.35±0.88,P=0.002 respectively).Analysis of the correlation between corneal densitometry for each layer depth (anterior,central and posterior) with posterior corneal elevation values demonstrated significant association (r =0.293,r =0.278 and r =0.294 respectively).The similar correlation was not found between corneal densitometry for each layer depth and anterior corneal elevation (r=-0.211,r=-0.101,r=0.99 respectively).In the control patients such a significant correlation between posterior/anterior corneal elevation and corneal light backscatter for each layer depth was not found.· CONCLUSION:The densitometry map reveals that light backscatter was higher in the central portion of the anterior keratoconic cornea.Corneal densitometry values of keratoconus patients were correlated with posterior corneal elevation in 0-2,6-10 and 10-12 annuli and in all anterior,central and posterior layers.The densitometry level was higher in more advanced stages.