Effect of smoking on corneal and lens clarity: a densitometric analysis

PURPOSE

To assess the effect of chronic cigarette smoking on corneal and lens densitometry measurements using Pentacam HR and to compare the results obtained with those in non-smokers.

MATERIALS AND METHODS

This cross-sectional comparative study included 40 chronic-smokers and 40 age-matched healthy non-smokers between 18-40 years. After general ophthalmic examination, the Pentacam HR imaging system was used to evaluate corneal and lens densitometry measurements of smokers and non-smokers.

RESULTS

The mean corneal densitometry values were not statistically significantly different in all the concentric zones and layers in the eyes of the smokers and non-smokers (p > 0.05, for all). However, the mean values of zone 1, zone 2, zone 3 and average lens densitometry measurements of the smokers were statistically significantly higher compared to non-smokers (p < 0.05, for all). Additionally, significant positive correlations were detected between the number of pack-years smoked and lens densitometry measurements.

CONCLUSION

Lens densitometry measurements of smokers were significantly increased while corneal densitometry measurements were not significantly altered compared to non-smokers. Smoking may contribute to cataractogenesis and smoking and age-related changes may act synergistically to cataract development among smokers.

Scheimpflug Corneal Densitometry Patterns at the Graft-Host Interface in DMEK and DSAEK: A 12-Month Longitudinal Comparative Study

BACKGROUND

To compare corneal densitometry (CD) patterns at the graft-host interface between Descemet Membrane Endothelial Keratoplasty (DMEK) and Descemet Stripping Automated Endothelial Keratoplasty (DSAEK). Corneal densitometry is a quantitative assessment that objectively evaluates corneal clarity and optical quality by measuring the light backscatter from the cornea.

METHODS

Fifty-one eyes that received DMEK or DSAEK surgery for corneal endothelium dysfunction were evaluated. The primary endpoint included CD patterns at the graft-host interface, which were assessed by the Pentacam HR device at the center point of the corneal horizontal meridian (CDcentral), and at six points on the central circumference of the cornea (with a total diameter of 4 mm) (CDI,II,III,IV,V,VI). Secondary endpoints included the best-corrected distance visual acuity (BCDVA), central corneal thickness (CCT), and graft thickness (GT). All of the evaluations were performed at follow-up appointments one, three, six and twelve months after the procedure.

RESULTS

DMEK showed a significant overall CD reduction of -7.9 ± 8.5 grayscale unit (GSU) compared to DSAEK (p < 0.001). In addition, the DMEK group showed significantly lower CDCentral,I,II,III,IV,V,VI values at follow-up appointments one, three, six and twelve months after the procedure compared to the DSAEK group (p < 0.001). BCDVA, CCT and GT were in favor of the DMEK group with a mean value of 0.39 ± 0.35 LogMar, 552.2 ± 71.1 µm and 11.03 ± 1.4 µm, respectively (p < 0.001).

CONCLUSIONS

CD patterns at the graft-host interface seem to be different depending on the endothelial keratoplasty procedure. This provides specific insight into CD changes in this critical region of surgery, which may provide a better understanding of the postoperative evolution of these patients.

Relationship between corneal tissue and shape in short-term soft contact lens wear

PURPOSE

To investigate which morphometric and ocular surface tissue parameters are affected by short-term soft contact lens (CL) wear and to assess whether they carry related or independent information.

METHODS

Twenty-two healthy participants wore silicone hydrogel (SiHy; MyDay, CooperVision) soft CLs for 8 h in their left eye. Corneal tomography and corneoscleral topography were captured before and immediately after CL wear. Central corneal thickness (CCT), corneoscleral parameters (limbus position and corneoscleral junction [CSJ] angle) and corneal tissue parameters (corneal transparency and homogeneity) were evaluated.

RESULTS

Corneoscleral parameters (limbus position and CSJ angle) were independent of corneal tissue parameters (transparency and homogeneity) at baseline and after CL wear. CCT was independent of all the other parameters examined at baseline, but baseline values of corneal tissue parameters were moderately correlated with CCT change (transparency: r = -0.51; p = 0.007), homogeneity: r = -0.46; p = 0.02).

CONCLUSIONS

A complete characterisation of ocular surface changes following CL wear should consider corneoscleral topography and corneal densitometry simultaneously, since they carry complementary information.

The influence of pterygium on corneal densitometry evaluated using the Oculus Pentacam system

Purpose

To assess the effect of pterygium on corneal densitometry (CD) values.

Methods

One hundred and nine patients (155 eyes) with primary pterygium were divided into a severe pterygium group (79 eyes) and a mild-to-moderate pterygium group (76 eyes) according to pterygium severity. Among them, 63 patients had monocular pterygium; and 25 patients (38 eyes) underwent pterygium excision combined with conjunctival autograft follow-up. A Pentacam anterior segment analyzer was used to obtain the CD values and corneal morphological parameters, including central corneal thickness (CCT), flat-axis keratometry (K1), steep-axis keratometry (K2), corneal astigmatism, irregular astigmatism, and spherical aberration. CD was subdivided into four concentric radial regions based on corneal diameter and three layers according to depth.

Results

CD values at 0-12 mm of the anterior 120 μm layer, 0-10 mm of the center layer and full thickness, and 2-6 mm of the posterior 60 μm layer were significantly higher in eyes affected by pterygium than in the contralateral unaffected eyes (all P < 0.05). CD values were significantly higher in the severe pterygium group than in the mild to moderate pterygium group (all P < 0.05). Corneal astigmatism, irregular astigmatism, K1, K2, CCT, and spherical aberration correlated with CD values in eyes with pterygium (all P < 0.05). CD values at 6-10, 0-12 mm in the anterior 120 μm layer and full thickness, 10-12 and 0-12 mm in the center layer were significantly decreased 1 month after pterygium surgery compared with those before surgery (all P < 0.05).

Conclusion

Patients with pterygium had increased CD values, particularly in the anterior and central layers. CD values were correlated with pterygium severity grading and corneal parameters. Pterygium surgery partially reduced the CD values.

Analysis of the correlation between biomechanical properties and corneal densitometry in myopic eyes

Background: To investigate the correlation between corneal biomechanical characteristics (in vitro and in vivo) and corneal densitometry in myopia. Methods: The Pentacam (Oculus, Wetzlar, Germany) corneal densitometry (CD) and Corvis ST (Oculus, Wetzlar, Germany) exams were conducted prior to surgery for myopic patients who were intended to undergo small-incision lenticule extraction (SMILE). CD values (grayscale units, GSUs), and in vivo biomechanical parameters were obtained. The stromal lenticule was subjected to a uniaxial tensile test to obtain the elastic modulus E in vitro. We exam the correlations among in vivo, in vitro biomechanical characteristics and CD values. Results: In this study, 37 myopic patients (63 eyes) were included. The mean age of participants was 25.14 ± 6.74 years (range:16-39 years). The mean CD values of the total cornea, anterior layer, intermediate layer, posterior layer, 0-2 mm region and 2-6 mm region were 15.03 ± 1.23 GSU, 20.35 ± 1.98 GSU, 11.76 ± 1.01 GSU, 10.95 ± 0.83 GSU, 15.57 ± 1.12 GSU and 11.94 ± 1.77 GSU, respectively. Elastic modulus E (in vitro biomechanical indicator) was negatively correlated with intermediate layer CD (r = -0.35, p = 0.01) and 2-6 mm region CD (r = -0.39, p = 0.00). A negative correlation was also found between 0-2 mm central region CD and in vivo biomechanical indicator SP-HC (r = -0.29, p = 0.02). Conclusion: In myopic patients, densitometry is negatively correlated with biomechanical properties both in vivo and in vitro. With an increase in CD, the cornea deformed more easily.

Forward-scattered and backward-scattered light in moderate keratoconus

INTRODUCTION

To evaluate the backscattered light, objective scatter index (OSI) and retinal straylight in patients with moderate keratoconus and healthy control subjects.

METHODS

A prospective observational study was developed with 33 patients in the moderate-keratoconus group (KC) and 34 in the non-keratoconus group (NKC). Corneal densitometry was obtained using Scheimpflug corneal tomography and measurements were expressed in grayscale units (GSU) over four zones within a 12.00 mm diameter around the corneal apex. A straylight meter was used to determine the amount of intraocular straylight under scotopic conditions, and the straylight parameter (LOG(s)) and test duration were recorded. The Optical Quality Analysis System based on the double-pass technique determined the OSI value.

RESULTS

Significant differences were observed between the KC and NKC groups for corneal densitometry (except in the 6-10 mm zone), OSI and retinal straylight. A moderate and significant correlation was found between OSI and retinal straylight LOG(s) (r = 0.52, p = 0.002). Weaker and non-significant correlations were found between corneal densitometry and the other parameters analysed (i.e., OSI, retinal straylight LOG(s) and retinal straylight times).

CONCLUSIONS

Backscattered light, retinal straylight and the OSI show clear differences between healthy eyes and those with moderate KC. The changes present in the stages of KC evaluated in the current study (stages II and III according to the Amsler-Krumeich classification) might alter the scattering of the light entering the eye.

Analysis of corneal topographic and densitometric properties in patients receiving systemic isotretinoin therapy

PURPOSE

To evaluate dry eye parameters, corneal topographic features, corneal densitometric changes, and anterior segment parameters in patients receiving systemic isotretinoin treatment.

METHODS

This prospective cross-sectional study included 66 eyes of 33 patients who were started on oral isotretinoin therapy for severe acne vulgaris. All patients were evaluated in terms of ocular surface tests such as tear break-up time (TBUT) and Schirmer-1 and were asked to fill in the ocular surface disease index (OSDI) questionnaire. Corneal densitometric and topographic measurements were obtained using the Scheimpflug imaging system.

RESULTS

The mean age of the patients was 19.9 ± 1.6 years, and 21 (63.6%) of the participants were female. The mean OSDI score was significantly higher in the third month than before treatment (20.05 ± 19.38, vs. 26.96 ± 22.94, p = 0.00, respectively). The mean values of the TBUT test were significantly lower in the third month than before treatment (9.06 ± 4.40 sec, vs. 10.71 ± 4.61 sec, p = 0.02, respectively). Mean scores of the Schirmer 1 test showed no statistically significant difference between before treatment and the third month (16.08 ± 8.40 mm, vs. 16.08 ± 8.50 mm, p = 1, respectively). There was no statistically significant difference between before treatment and the third month in the majority of the densitometry measurements in concentric zones. However, the difference tended to be significant between the groups concerning posterior zone 0-2 mm (11.01 ± 0.85 GSU vs. 10.62 ± 0.89 GSU, p = 0.006). The RMS LOAs (front), RMS Total (Total), RMS LOAs Total (Total), RMS HOAs Total (Total), K_max, CCT, and CoV values were significantly higher in the third month than before treatment (p < 0.05 for all).

CONCLUSIONS

The dermatology specialists should be aware of the ocular complications of systemic isotretinoin therapy. Therefore, a complete ophthalmologic examination for the prompt apprehension and management of ocular involvement is essential in patients under isotretinoin therapy to increase ocular comfort and adherence to the therapy.

Corneal Optical Densitometry in the Evaluation of 2-Year Graft Function Following Endothelial Keratoplasty

This study aimed to assess clinical application of the Scheimpflug corneal tomography for objective evaluation of corneal optical density in eyes undergoing Descemet's stripping endothelial keratoplasty (DSEK). In this prospective study, 39 pseudophakic eyes with bullous keratopathy were enrolled. All eyes underwent primary DSEK. Ophthalmic examination included best corrected visual acuity (BCVA) measurement, biomicroscopy, Scheimpflug tomography, pachymetry, and endothelial cell count. All measurements were taken preoperatively and within a 2-year follow-up period. Gradual BCVA improvement was observed in all patients. After two years, the mean and median BCVA values were 0.18 logMAR. A decrease in central corneal thickness was noted only during the first 3 months postoperatively and was followed by a gradual increase. Corneal densitometry decreased constantly and most significantly in the first 3 months postoperatively. The consecutive decrease in endothelial cell count of the transplanted cornea was most significant during the first 6 months postoperatively. Six months postoperatively, the strongest correlation (Spearman's r = -0.41) with BCVA was found for densitometry. This tendency was maintained throughout the entire follow-up period. Corneal densitometry is applicable for objective monitoring of early and late outcomes of endothelial keratoplasty, showing a higher correlation with visual acuity than pachymetry and endothelial cell density.

Subjective and objective evaluation of corneal haze after accelerated corneal crosslinking for corneal ectasias

PURPOSE

To evaluate the relationship between subjective (slit lamp examination [SLE]) and objective (densitometry) measurements of corneal haze after accelerated corneal crosslinking (aCXL), assess the relationship between densitometry and corrected distance visual acuity (CDVA), and determine the effect of baseline characteristics on densitometry after aCXL in eyes with progressive keratoconus and other ectasias.

SETTING

Kensington Eye Institute and Bochner Eye Institute, Toronto, Canada.

DESIGN

Retrospective analysis of a prospective interventional cohort study.

METHODS

Scheimpflug-derived corneal densitometry, CDVA, maximum keratometry (K_max ), and central corneal thickness were measured preoperatively and up to 1 year after aCXL, and post-operative haze was estimated with SLE (n = 483 eyes). A random effect model was used to examine the relationship between post-operative subjective haze with SLE and densitometry. Linear mixed models were used to examine the relationship between densitometry, pre-operative baseline characteristics, and CDVA.

RESULTS

There was a significant association between subjective haze with SLE and densitometry (p < 0.001). There was a significant relationship between CDVA and densitometry: for every 10 GSUs of increased densitometry in the 0-2 mm zone, CDVA worsened by approximately half a Snellen line (p < 0.001). Age and pre-operative K_max were significant predictors of densitometry. For every 10 years of age, densitometry increased by 0.68 GSUs (95% CI [0.27 to 1.07], p < 0.001). For every 10 D of increased preoperative K_max , densitometry increased by 0.69 GSUs (95% CI [0.41 to 0.98], p < 0.001).

CONCLUSIONS

Subjective haze after aCXL estimated with SLE, is significantly associated with densitometry. Increased densitometry after aCXL is associated with a reduction in CDVA.

Evaluating the topographical measurements and tear function status in patients with hemifacial spasm: A comparative fellow eye study

OBJECTIVE

To investigate the effect of eyelid spasm on corneal and tear film characteristics in patients with hemifacial spasm (HFS) and compare these data with those of the contralateral eyes of the same patients.

METHODS

This prospective study is comprised of 64 eyes of 32 HFS patients, 32 eyes on the spasm side (Group 1) and 32 contralateral eyes (Group 2). Corneal tomographic analyses were performed; corneal power of flat axis (K1) and steep axis (K2), astigmatism and thinnest pachymetry; anterior, posterior and total corneal aberrometry [spherical aberration (SA), vertical coma (vcoma), horizontal coma (hcoma), total higher order aberration (THOA) and total RMS], and corneal densitometry values were evaluated and compared between groups. Tear meniscus height and depth (TMH, TMD) were measured using anterior segment optic coherence tomography. Tear function tests including TMH and TMD, the Schirmer I test, and tear break-up time (TBUT) were compared between the groups.

RESULTS

K1, K2, astigmatism and corneal densitometry values were similar between groups (p > 0.05). Thinnest pachymetry values were significantly thinner on the spasm side (p = 0.040). Anterior and total corneal SA and RMS were significantly higher on the spasm side (p = 0.032, p = 0.005; p = 0.015, p = 0.006, respectively). TMH, TMD and TBUT were significantly lower in Group 1 (p = 0.01, p = 0.02 and p = 0.03, respectively). Schirmer I test values were similar between groups (p > 0.05).

CONCLUSION

In HFS patients, there are changes in corneal parameters and tear film in the eye on the spasm side compared to unaffected eye.

Corneal tissue changes following short-term soft contact lens wear of different materials

PURPOSE

To study the effect of different soft contact lens (CL) materials during short-term wear on corneal tissue.

METHODS

Twenty-two healthy participants wore both silicone hydrogel (MyDay, CooperVision) and hydrogel soft CLs (Biomedics 1 day extra, CooperVision) for 8 h per lens. In each session, Scheimpflug images were captured before and immediately after CL removal. Images were analysed using the densitometry distribution analysis, a technique from which two parameters, α (corneal transparency) and β (corneal homogeneity), were estimated. In addition, the central corneal thickness changes after CL wear and the influence of the CL material on corneal transparency were evaluated.

RESULTS

The β parameter (homogeneity) increased by 5% after wearing both CL materials (paired t-test, p < 0.001). However, the α parameter (transparency) only increased in half of the participants. No material was found to be more determinant in causing the corneal densitometry changes. Statistically significant but not clinically relevant changes in corneal thickness were observed.

CONCLUSIONS

Biomarkers of corneal tissue integrity (α and β) were affected by short-term soft contact lens wear. The observed changes in corneal transparency and homogeneity were not clinically relevant but support the importance of participant-material biocompatibility.

3D Visualization System in Descemet Membrane Endothelial Keratoplasty (DMEK): A Six-Month Comparison with Conventional Microscope

Background: To compare the efficacy and safety of Descemet membrane endothelial keratoplasty (DMEK) surgery using the three-dimensional (3D) display system NGENUITY to DMEK surgery performed with the traditional microscope (TM) in patients affected by Fuchs Endothelial Corneal Disease (FECD). Methods: Retrospective comparative study of 40 pseudophakic eyes of 40 patients affected by FECD who underwent DMEK surgery. Twenty patients (3D group) were operated on using the 3D display system and 20 patients (TM group) were operated on using the traditional microscope. Best spectacle corrected visual acuity (BSCVA), central corneal thickness (CCT), endothelial cell density (ECD) and corneal densitometry (CD) values were documented before and at 1, 3 and 6 months after DMEK. Intra- and postoperative complications were recorded. Results: The baseline assessments did not differ between the two groups (p > 0.05). Global surgical time and time to perform descemetorhexis were significantly lower in the TM group (p = 0.04 and p = 0.02, respectively). BSCVA, CCT, ECD and CD values did not differ significantly in the two groups at all follow-ups (p > 0.05). Complication rate was similar between the two groups. Conclusion: Three-dimensional display systems can be securely employed in DMEK surgery considering the satisfactory clinical outcomes, including Scheimpflug CD. Nevertheless, the slightly longer surgical time of the 3D DMEKs may lead to surgeons’ hesitancy. The main advantages of the heads-up approach may be the improved ergonomic comfort during surgery and the utility of assistants in surgical training.

Scheimpflug Corneal Densitometry Values and Severity of Guttae in Relation to Visual Acuity in Fuchs Endothelial Corneal Dystrophy

PURPOSE

The purpose of this study was to investigate the association between corneal densitometry (CD) values from Scheimpflug tomography imaging, severity of guttae, and visual acuity in eyes with Fuchs endothelial corneal dystrophy (FECD).

METHODS

This was a retrospective, cross-sectional study. Patients with FECD were examined at the Bascom Palmer Eye Institute from January 2015 to September 2019. We extracted CD values at central annuli of 0-2, 2-6, 6-10 and 10-12 mm from Scheimpflug tomography images. We investigated the association of corrected distance visual acuity (CDVA) with CD values, severity of guttae, central corneal thickness (CCT), cataract grade, refractive error, corneal edema grade, age, and gender using multivariate generalized estimating equation regression models.

RESULTS

One hundred ninety-two eyes from 110 patients were included in this study. Increase in central CD values at the 0 to 2 mm zone (P < 0.001), severity of guttae (P = 0.046), age (P < 0.001), cataract grade (P < 0.001), corneal edema grade (P < 0.001), and type of refractive error (P = 0.008) were significantly associated with decreased CDVA. Central corneal thickness, sex, and the peripheral CD values (2-6, 6-10, and 10-12 mm) were not significantly associated with CDVA (P > 0.05) in the final multivariate regression model.

CONCLUSIONS

Our study demonstrates that central CD values at 0 to 2 mm and severity of guttae are each associated with decreased CDVA in FECD. These findings carry implications for patients with FECD considering surgical intervention for phacoemulsification alone, Descemet stripping only, or endothelial cell transplantation and provide a multifactorial perspective on vision loss in FECD.

Corneal densitometry in patients with arcus senilis and its correlation with serum lipid levels

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.

Safety of EVO ICL Implantation With an Ophthalmic Viscosurgical Device-Free Technique in the Early 24 h After Surgery

Purpose: To compare the safety of the non-ophthalmic viscosurgical device (OVD) technique with that of the minimum OVD technique in EVO Implantable Collamer Lens (EVO-ICL) implantation.

Methods: A total of 180 eyes of 90 consecutive patients were enrolled in the study, of which 100 eyes of 50 patients were treated with non-OVD technique, with a 55% success rate. The remaining 80 eyes of 40 patients were treated with min-OVD technique, so they were classified into the min-OVD group. Preoperative and postoperative intraocular pressure (IOP) measurements were collected and analyzed at 1, 2, 3, and 24 h. Visual acuity, corneal endothelial cell density (ECD), and corneal densitometry 24 h postoperatively were evaluated.

Results: No significant difference was found in visual outcomes (P = 0.54) or ECD (P = 0.78) between the two groups. The operation time was significantly shorter in the non-OVD group (P < 0.0001). The IOP was significantly higher at 1 h (P < 0.0001), 2 h (P < 0.0001) and 3 h (P = 0.0045) postoperatively in the min-OVD group. The non-OVD group had significantly lower IOP than the min-OVD group at 1 h (P = 0.01) and 2 h (P = 0.013) postoperatively. The temporal corneal densitometry in the non-OVD group were significantly lower than those in the minimum group (P = 0.0063) 1 day after surgery.

Conclusion: The non-OVD technique is safe and efficient for ICL implantation. It can be a safer method of ICL implantation in that it completely eliminates ophthalmic viscoelastic devices related complications without causing additional complications in short term.

One-step viscoelastic agent technique for ICL V4c implantation for myopia

AIM

To investigate the safety and efficacy of using a one-step viscoelastic agent technique for posterior chamber phakic implantable collamer lens with a central hole (ICL V4c) implantation for myopia correction.

METHODS

The one-step viscoelastic agent technique for ICL V4c implantation was used in 100 eyes of 52 patients. Refractive outcomes, intraocular pressure (IOP), corneal endothelial cell, and corneal densitometry values were evaluated at 1d, 1wk, 1 and 3mo postoperatively.

RESULTS

All the surgeries were uneventful. No corrected distance visual acuity was lost after 3mo. IOP was 16.12±3.18 mm Hg before surgery, and 14.74±3.08 mm Hg at 1d and 14.50±2.56 mm Hg at 3mo after surgery (P<0.05). Corneal endothelial cell density was 2580±242 cell/mm², the coefficient of variation in cell size was 42.11%±7.92%, and the percentage of hexagonal cells was 40.98%±9.46% before surgery. No significant difference was found when these outcomes were compared between the studied time points (P>0.05). The corneal densitometry values of the central 2 mm and 2 to 6 mm areas showed similar regularities. After surgery, the values significantly increased at 1d, then decreased to the preoperative values at 1wk, and then continued to decrease at 3mo (P<0.05).

CONCLUSION

The one-step viscoelastic agent technique for ICL V4c implantation is found to be safe and effective for myopia correction and causes little disturbance to the cornea.

Evaluation of corneal densitometry changes in patients with lichen planus

PURPOSE

To investigate the corneal topography and densitometry changes in patients with lichen planus (LP).

METHODS

Anterior segment parameters and corneal densitometry of patients with LP and age- and gender-matched individuals with healthy eyes were evaluated using Scheimpflug corneal topography. A 12 mm corneal area was divided into 4 annular zones and 3 regions-in-depth anterior, central and posterior-for densitometry evaluation.

RESULTS

The study included 45 patients with LP and 50 individuals with healthy eyes. The two groups were similar in age and gender, and they showed no significant differences in anterior segment corneal topography parameters. Schirmer's I test results were significantly lower in the patients with LP than in the control group (P ˂ .001). The total corneal densitometry was higher in patients with LP than in the control group (P = .030). The anterior, central and posterior corneal densitometry in the 0-2 mm and 2-6 mm annular zones was higher in the LP group than in the control group. Correlation analysis between disease duration and corneal densitometry values showed a strong positive correlation in the anterior segment and a moderate positive correlation in the central and posterior segments (r = 0.632, P ˂ .001; r = 0.572, P ˂ .001; and r = 0.562, P ˂ .001, respectively).

CONCLUSIONS

Corneal densitometry values were higher in patients with LP than in individuals with healthy eyes, even if the patients had a clinically transparent cornea. More studies are needed to evaluate the changes that may occur in corneal transparency in patients with LP and other autoimmune dermatologic diseases that may affect the eye.

The effect of smoking on corneal densitometry and endothelial cell morphology

PURPOSE

We investigated corneal endothelial morphology and corneal densitometry in smokers and compared our results with findings observed in non-smokers.

MATERIALS AND METHODS

This cross-sectional observational study included 100 participants (50 smokers, 50 non-smokers) aged 18-80 years in whom corneal endothelial morphology was analysed using a non-contact Tomey EM-4000 specular microscope (Tomey Corporation, Japan). The Pentacam HR system was used to measure corneal densitometry spatially in three concentric zones (from the centre to the periphery) and at three different corneal depths (from the anterior to the posterior aspects). Endothelial morphology findings and corneal densitometry values were recorded in all participants, and these results were compared between smokers and non-smokers.

RESULTS

Endothelial morphology and corneal densitometry analysis showed significantly lower endothelial cell counts (Num) in smokers (228 cells/mm² vs. 246 cells/mm², p = 0.02) in addition to increased maximum cell area (Max) values (986.5 µm² vs. 935 µm², p = 0.04). We observed no statistically significant intergroup difference in corneal densitometry values (p > 0.05 for each zone); however, we observed a moderately positive correlation between densitometry values in the 6-10 mm concentric zone and between the all total corneal zones and number of pack-years in smokers.

CONCLUSIONS

Our study highlights that among the morphometric corneal endothelial variables analysed in this study, only the Num value was significantly correlated with smoking. We observed no statistically significant intergroup difference in corneal densitometry values in this study; however, a positive correlation was observed between the number of pack-years and corneal densitometry findings. Therefore, as the pack-years increase, the increase in corneal densitometry values may indicate a decrease in corneal clarity, considering the possible contribution of secondary factors such as age.

Densitometry marks delineating the affected area in keratoconus: clinical suitability of a new descriptive system based on its repeatability and reproducibility

PURPOSE

To present a descriptive system for the elliptic demarcation area seen in keratoconus densitometry maps (obtained with a Scheimpflug tomographer) and to evaluate its suitability for clinical practice.

METHODS

The subjects were 30 keratoconus patients at different stages and 20 healthy subjects. The averaged densitometry maps ('two-layers' scan, with fixed layers 120 µm and endothelium) were analysed using a system of four categories (termed 'Brightness', 'Contrast', 'Decentration' and 'Octants surrounded by a dark line') that we created to characterise the demarcation area. Four examiners (three corneal specialists and one junior resident) used the system to classify the maps. The inter-rater agreement was calculated for two subgroups: (1) clinical keratoconus patients and (2) both healthy patients and forme fruste keratoconus patients. Intra-rater agreement was also determined.

RESULTS

Inter-rater agreement on classification was higher when analysing clinical keratoconus, reaching levels of substantial agreement. Despite this, only low levels of agreement were found in 'Decentration', penalized due to the skewness in the distribution of this descriptor. Almost perfect intra-rater agreement was obtained for all descriptors in the first subgroup of clinical keratoconus, whereas the agreement was generally moderate within the second subgroup of normal and forme fruste eyes. Agreement was slightly lower with the less experienced observer. At least three observers agreed on four forme fruste keratoconus eyes presenting abnormalities in the images. The observers reported that the 'Brightness' descriptor was subjective and redundant with 'Contrast'.

CONCLUSIONS

The description of the area was repeatable and reproducible, and may be a valuable supplement when documenting clinical keratoconus stage and progression in daily practice. However, a minor learning curve was noticed and agreement was higher among the more experienced observers. Since the descriptor 'Brightness' was found to be subjective and redundant, it was excluded from the final proposed classification.

Corneal Densitometry After Small Incision Lenticule Extraction (SMILE) and Femtosecond Laser-Assisted LASIK (FS-LASIK): 5-Year Prospective Comparative Study

Purpose: To investigate long-term changes in corneal densitometry (CD) following small incision lenticule extraction (SMILE) vs. femtosecond laser-assisted LASIK (FS-LASIK) in patients with myopia or myopic astigmatism.

Methods: Prospective analysis was performed in 66 eyes of 38 patients (13 males) who underwent SMILE and 54 eyes of 29 patients (5 males) who underwent FS-LASIK. In all patients, an ocular examination was performed preoperatively, and at 6–12 months and 5 years postoperatively. CD was obtained with the Pentacam Scheimpflug imaging system at the 0–2-mm, 2–6-mm, and 6–10-mm zones of the cornea at depth of anterior 120 μm, midcornea, and posterior 60 μm. Correlation analysis was performed between postoperative change in CD and other variables such as age, type of surgery, central corneal thickness, spherical equivalent, lenticule thickness/ablation depth, and changes in wavefront aberrations.

Results: At postoperative 6–12 months, a significant reduction at several corneal zones in the FS-LASIK cohort (P < 0.05) was observed. In the SMILE cohort, no significant change in CD relative to baseline was observed. However, at 5 years postoperatively, in both groups, a significant decrease in CD was observed in three zones of three layers (all P < 0.001). The change in CD was similar between groups at postoperative 6–12 months, but at 5 years the magnitude of change was significantly smaller in SMILE than FS-LASIK in the anterior and central layers (all P < 0.05).

Conclusion: CD with the Scheimpflug imaging system showed a significant decrease at 5 years after SMILE or FS-LASIK, and the change was significantly less pronounced after SMILE.

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.

Evaluation of corneal structures in myopic eyes more than twenty-two years after photorefractive keratectomy

The aim of this study is to evaluate corneal epithelial thickness (CET), corneal densitometry (CD) in 84 myopic eyes (57 patients) more than 22 years after photorefractive keratectomy, using anterior segment-optical coherence tomography (AS-OCT) and Scheimpflug imaging system. The CET was significantly higher in all operated eyes than in unoperated eyes in central sector. A statistically significant increase in CD in corneal anterior layer of central sector was shown in groups of operated eyes with greater ablation depth respect to unoperated eyes. While there was no significant difference in CD between the operated eyes groups with lower ablation depth and unoperated eyes. A significant trend toward higher values in anterior CD with deeper ablations in central sector was found. These noninvasive imaging techniques allow to better understand the corneal remodeling process after photoablation and to monitor the patients over time.

Corneal and lens densitometry with Pentacam HR in children with vernal keratoconjunctivitis

CLINICAL RELEVANCE

Corneal and lens densitometry measurements provide clinically important information for the evaluation and monitoring of corneal and lens health in patients with vernal keratoconjunctivitis.

BACKGROUND

To compare the corneal and lens densitometry values between paediatric patients with vernal keratoconjunctivitis (VKC) and healthy individuals.

METHODS

This study included 72 eyes of 72 patients with VKC (25 with mild VKC [Group 1], 22 with moderate VKC [Group 2], and 25 with severe VKC [Group 3]), and 25 eyes of 25 healthy subjects (Group 4). Corneal and lens densitometry values were measured using Pentacam HR as follows: for corneal densitometry in two different corneal zones (0-2 and 2-6-mm) and four different corneal depths (at the total thickness, anterior, central, and posterior layers), and lens densitometry in three different lens zones (Zone 1: 2.0-mm, Zone 2: 4.0-mm, and Zone 3: 6.0-mm).

RESULTS

In the 0-2-mm corneal zone for the total thickness and all three layers, corneal densitometry values in Group 3 were significantly higher than those in Groups 1, 2, and 4 (for all values p < 0.012). There was no significant difference in the mean corneal densitometry values between Groups 1 and 2 (for all values p > 0.05). In these groups, the mean corneal densitometry values were significantly higher than those in Group 4 for the anterior layer in the 0-2 and 2-6-mm corneal zones (for all values p < 0.012). The mean values for Zone 3 and average lens densitometry values in Groups 2 and 3 were significantly higher than those in Group 4 (p = 0.001 and p = 0.001, respectively).

CONCLUSION

The current study showed corneal clarity changes in patients with mild, moderate, and especially severe VKC. An increase in the lens densitometry values was also observed in patients with moderate and severe VKC than in healthy individuals.

Densitometric analysis of cornea in patients with neovascular age-related macular degeneration after intravitreal aflibercept loading dose

Purpose:

To evaluate the anatomic changes in the cornea and anterior segment following intravitreal aflibercept loading dose for neovascular age-related macular degeneration.

Methods:

The study included 40 eyes of 40 patients with neovascular age-related macular degeneration. Each patient underwent a loading dose of one injection per month for three consecutive doses of aflibercept (0.05 ml/2 mg). Before and after the loading dose, a record was made for each patient of corneal topography, anterior segment, corneal densitometry, and lens densitometry parameters with the Pentacam HR and specular microscopy parameters with a non-contact specular microscope. The data before and after the aflibercept loading dose were compared.

Results:

Corneal densitometry parameters in the 0- to 2-mm and 2- to 6-mm concentric zones of the posterior layer were significantly higher after the loading dose compared with baseline (p = 0.03, p = 0.04, respectively). Corneal densitometry parameters of the anterior, central, and total corneal layer in the 10- to 12-mm concentric zone were also significantly higher after the loading dose compared with baseline (p = 0.009, p = 0.02, and p = 0.007, respectively). No significant changes were determined in respect of corneal topography, anterior segment, lens densitometry, and specular microscopy parameters (p > 0.05 for all).

Conclusion:

The aflibercept loading dose caused slightly increased densitometric values in some corneal regions while it did not affect the corneal topography, anterior segment, lens densitometry, and specular microscopy parameters.

Topometric Indices And Corneal Densitometry Change After Corneal Refractive Surgery Combined With Simultaneous Collagen Crosslinking

Purpose

To show the alteration of tomography, topometric indices and corneal densitometry after corneal refractive surgery combined with collagen crosslinking.

Patients and methods

All medical records of patients undergoing corneal refractive surgery with simultaneous collagen crosslinking during April 2015 and August 2018 were retrospectively reviewed. Corneal tomography, higher-order aberrations (HOA), topographic indices and corneal densitometry were evaluated. All the data at 1 month, 3 months and 6 months were compared to baseline value. All complications were noted. P value less than 0.05 was considered statistically significant.

Results

Medical records of fourteen patients (twenty-five eyes) were reviewed. HOA increased at all time points (p < 0.05). Keratoconus index and central keratoconus index decreased, whereas index of surface variance, index of vertical asymmetry, index of height decentration and the minimum of radius of curvature increased at all time points (p < 0.05). Index of height asymmetry increased at 3 and 6 months (p < 0.05). Corneal densitometry at anterior layer of 0–10 mm zone and center layer of 0–6 mm zone increased at 1 and 3 months (p < 0.05). At 6 months, the densitometry at 0–6 mm zone returned to baseline level. However, at 6 months, at anterior and center layer of 6–10 mm zone, the densitometry values were still more than preoperative values (p < 0.05). There was one case of bacterial keratitis.

Conclusion

After the corneal refractive surgery combined with collagen crosslinking, the HOA and corneal densitometry increased. Topographic indices showed conflicting results.

Management of recalcitrant epithelial ingrowth after laser in situ keratomileusis: A case report

RATIONALE

Surgically lifting and scraping, mitomycin C, fibrin glue, Nd:YAG laser, hydrogel ocular sealant, and amniotic membrane patch are the reported methods for treating epithelial ingrowth after laser in situ keratomileusis (LASIK). Here we report the management of a rare case of recalcitrant epithelial ingrowth using a combined scraping/laser ablation that occurred after LASIK.

PATIENT CONCERNS

A female patient underwent uncomplicated bilateral LASIK 10 years before incurring trauma to the right eye. Approximately 2.5 years later, she presented with a complaint of blurred vision and a foreign body sensation.

DIAGNOSES

The patient was diagnosed with epithelial ingrowth because of the presence of corneal melting, wrinkling, and scarring. Approximately 6 months after injury, the patient underwent corneal scraping to remove the epithelial ingrowth. Even after 2 more scraping procedures, the epithelial ingrowth recurred. Corneal densitometry was performed (Oculus Pentacam), which revealed a maximum corneal densitometry value of 87.4 gray scale units (GSUs) in the inferonasal quadrant. This reading highly elevated compared to readings from normal cornea (approximately 20 GSU).

INTERVENTIONS

We used a combination scraping/laser ablation procedure to correct astigmatism and eliminate any undetected residual corneal epithelial cells.

OUTCOMES

Two days following the procedure, the patient developed a mild corneal opacity in the area where the epithelial ingrowth had been located. At this time, visual acuity was 20/40, refractive error (manifest refraction) was -0.50 Diopter (D) sph, and the maximum corneal densitometry value was 79.2 GSU. After 2 months, the central cornea remained slightly blurred, but visual acuity was 20/25. No signs of recurrent epithelial ingrowth were present and the maximum corneal densitometry reading had decreased to 55.4 GSU.

LESSONS

This case demonstrates that epithelial ingrowth should be treated as soon as possible after trauma and that thorough scraping combined with laser ablation is effective for treating recalcitrant epithelial ingrowth. Additionally, corneal densitometry can be used to assess epithelial ingrowth severity and treatment efficacy.

The effect of corneal infiltrates on densitometry and higher-order aberrations

BACKGROUND

This study aimed to measure the effects of persistent corneal subepithelial infiltrates associated with epidemic keratoconjunctivitis on corneal densitometry and total corneal higher order aberrations (HOAs), and to compare these measurements with the data obtained from their fellow unaffected healthy eyes.

METHODS

This prospective cross-sectional study included those who had persistent subepithelial infiltrates in only the affected eyes for at least three months and clinically normal fellow unaffected eyes. Corneal densitometry was measured with the densitometry software of the Pentacam HR-Scheimpflug corneal topographer over a 12 mm diameter of cornea. Further, total corneal HOAs including coma (Z[1,3], Z[3,-1]), trefoil (Z[3], Z[3,-3]), spherical aberration, higher order root mean square (HO-RMS), and total RMS in the Zernike analysis were analysed by the same Pentacam HR device.

RESULTS

Forty-six eyes of 23 participants were analysed in this study. The mean corneal densitometry values were statistically significantly higher in all annular concentric areas (0-2, 2-6, 6-10, and 10-12 mm) of the anterior and central corneal layers in the eyes with subepithelial infiltrates when compared to normal fellow eyes (p < 0.05, for each one). Additionally, there were statistically significant differences between the eyes with subepithelial infiltrates and normal fellow eyes with regard to coma, trefoil, HO-RMS, and total RMS in the Zernike analysis (p < 0.05, for each one).

CONCLUSION

This study quantitatively demonstrated that persistent corneal subepithelial infiltrates associated with epidemic keratoconjunctivitis decrease corneal transparency and corneal optical quality in affected eyes.