Analysis of Choroidal Vascularity Index in Keratoconus Patients Using Swept-Source Optical Coherence Tomography-Based Binarization Techniques

Detecting early changes in choroidal vascularity and thickness using optical coherence tomography in patients with corneal crosslinking for keratoconus

AIM

To investigate changes in choroidal thickness and vascularity in keratoconus patients treated with corneal crosslinking.

METHODS

This study evaluated 28 eyes of 22 patients with keratoconus who underwent corneal crosslinking. The choroidal thicknesses were evaluated on enhanced depth imaging optical coherence tomography at the preoperative and postoperative 3d, 1, and 3mo. Choroidal thickness in the four cardinal quadrants and the fovea were evaluated. The choroidal vascularity index was also calculated.

RESULTS

There was no significant difference in central choroidal thickness between the preoperative and postoperative 3d, 1mo (P>0.05). There was a significant increase in the 3mo (P=0.034) and a significant decrease in the horizontal choroidal vascularity index on the postoperative 3d (P=0.014), there was no statistically significant change in vertical axes and other visits in horizontal sections (P>0.05).

CONCLUSION

This study sheds light on choroidal changes in postoperative corneal crosslinking for keratoconus. While it suggests the procedure's relative safety for submacular choroid, more extensive research is necessary to confirm these findings and their clinical significance.

Subfoveal and Parafoveal Choroidal Thickening in Patients with Keratoconus Using the ETDRS Grid on Swept-Source OCT

INTRODUCTION

There is growing evidence that confirms morphological changes in the posterior structures in patients with keratoconus (KC); however, isolated alterations could have been missed. This study assesses choroidal thickness (CT) in the fovea and beyond in KC eyes.

METHODS

This prospective case-control and non-randomized study enrolled 107 eyes, 62 eyes of 62 patients with KC, and 45 age-matched eyes of 45 control subjects with axial length in the range of 22-26 mm. Swept-source optical coherence tomography (SS-OCT) was performed to manually measure the subfoveal choroidal thickness (SCT) using a single-line scan. CT was obtained automatically from the Early Treatment Diabetic Retinopathy Study (ETDRS) grid using the 12-lines radial scan pattern. A two-way repeated-measures analysis of variance (ANOVA) was conducted to evaluate CT variations among macular eccentricity, parafoveal area, and the interaction between both factors. CT was compared in all parafoveal areas between groups and subgroups of KC.

RESULTS

SCT was significantly thicker in KC eyes (357 ± 57 µm) than in healthy eyes (325 ± 63 µm) (p < 0.001). Significant choroidal thickening was observed in the central ring and outer and inner rings of the temporal, superior, and inferior parafoveal macular areas (p < 0.001), except in the outer ring of the nasal macular zone (p > 0.05) of KC compared to healthy eyes. The CT significantly decreased from the center to the outer ring regardless of the presence of KC (p < 0.001). The choroid in the nasal macular zone was significantly thinner than that in the temporal, superior, and inferior parafoveal areas (p < 0.001).

CONCLUSIONS

The choroidal structure increased its thickness not only in the subfoveal area, but also in eight parafoveal areas of the ETDRS grid encompassing a wider area of macular examination. These findings demonstrate and corroborate that keratoconus is not a purely corneal disease. Furthermore, it confirms the role that the choroidal structure has in the pathophysiology of keratoconus.

Association of torpedo maculopathy and keratoconus in a young patient: A multimodal imaging study

PURPOSE

To report and document a case of torpedo maculopathy found in a patient affected by keratoconus.Case report: An healthy 16-year-old male patient, affected by keratoconus in both eyes, was referred to the cornea service of our hospital for a follow-up visit.During the dilated fundus examination of the left eye, an oval, well-demarcated, hypopigmented lesion was observed in the juxtafoveal temporal region, pointing towards the center of the macula. Multimodal imaging of the lesion was performed, and the diagnosis of Torpedo Maculopathy was established based on the clinical picture.

CONCLUSION

This is the first case of torpedo maculopathy described in a patient affected by keratoconus. This association may be merely fortuitous or the result of developmental abnormalities affecting both corneal and retinal structures.

Serum inflammatory biomarkers are associated with increased choroidal thickness in keratoconus

Inflammation may play a significant role in Keratoconus (KC), but the relationship between inflammatory markers and choroidal thickness (CT) is unknown. The purpose of this study was to evaluate serum inflammatory markers and correlate them with the choroidal profile of KC patients and control subjects. Forty patients with KC and 26 age-matched control subjects were enrolled in a cross-sectional case-control study. Choroidal profile was studied with a Spectralis Heidelberg apparatus and venous blood samples were collected. Neutrophil/lymphocyte ratio (NLR), monocyte/HDL ratio (MHR), platelet/lymphocyte ratio (PLR) and systemic immune inflammation index (SII) were calculated. Serum inflammatory biomarkers IL-1, IL-6 and TNF-alfa were also analyzed. KC group presented thicker choroids in each evaluated point when compared to the control group (subfoveal CT 417.38 ± 79.79 vs 299.61 ± 76.13, p < 0.001 for all measured locations). Mean values of NLR, PLR and SII were significantly higher in patients with KC (NLR p = 0.001; PLR p = 0.042; SII p = 0.007). Although KC patients presented higher mean levels of MHR, IL-1, IL-6 and TNF-α than control group, no significant differences were achieved. Positive correlations were found between subfoveal CT and NLR and SII (0.408, p = 0.001 and 0.288, p = 0.019 respectively). The results presented are in favor of a relationship between the increased CT and inflammatory mechanisms in KC patients. The elevated serum inflammatory indices NLR, SII and PLR provide additional evidence of a role for systemic inflammation in the pathophysiology of KC.

Choroidal Vascularity Index versus Choroidal Thickness as Biomarkers of Acute Central Serous Chorioretinopathy

INTRODUCTION

The aim of this study was to analyze the choroidal vascularity index (CVI) versus choroidal thickness (CT) as biomarkers in acute central serous chorioretinopathy (CSCR).

METHODS

In this multicenter retrospective, cross-sectional, noninterventional study carried out at Puerta de Hierro-Majadahonda University Hospital, Madrid, Spain; Jules-Gonin, Lausanne, Switzerland; and Pittsburg University, USA. 40 eyes from 40 patients with acute CSCR, 40 eyes from 40 patients with keratoconus (KC), and 40 eyes from 40 healthy patients were included. The variables analyzed were age, CT, CVI, and the presence of neurosensory retinal detachment. CT and the CVI were obtained from a 12-mm horizontal single-line B-scan (Triton SS-OCT, Topcon Co., Japan). Blinded measurements of the subfoveal CT were performed manually by two independent investigators. The images of the choroid were automatically binarized using a validated algorithm, and a percentage of vascularity was calculated.

RESULTS

There were no significant differences in age between the three groups (ANOVA, p = 0.092). There were statistically significant differences in CT and the CVI (ANOVA, p < 0.001). After Bonferroni correction, pairwise analysis between CSCR group against the KC group showed no significant differences in age and CT (p = 0.10 and p = 0.27, respectively). CVI was statistically greater among CSCR patients (p = 0.03).

CONCLUSION

CT does not meet the criteria to be considered a biomarker of acute CSCR, while CVI may prove to be a more specific and reliable biomarker. Further studies with larger sample sizes, standardized procedures, and a wider representation of all CSCR stages are necessary to confirm the validity of CVI as biomarker in this disease. Further studies with larger samples are required in order to validate the use of CVI/CT correlation as a new biomarker.

New Findings in Early-Stage Keratoconus: Lamina Cribrosa Curvature, Retinal Nerve Fiber Layer Thickness, and Vascular Perfusion

PURPOSE

Our aim was to investigate the involvement of posterior pole structures in eyes affected by keratoconus (KC). Optical coherence tomography (OCT) and OCT angiography (OCTA) were used to determine the status of lamina cribrosa (LC), peripapillary retinal nerve fiber layer (RNFL), macular and peripapillary microvasculature.

DESIGN

Observational, cross-sectional, case-control analysis.

METHODS

Single-center investigation involving patients with KC and healthy control subjects. Enrolled subjects underwent anterior segment OCT combined with Placido-disk topography, macular and optic nerve head swept-source OCT and swept-source OCTA scans, and 3D wide glaucoma module for peripapillary RNFL thickness measurement. The LC curvature index was used to express the degree of LC posterior bowing. We calculated the vessel density and vessel length density at the macular superficial capillary plexus, deep capillary plexus, choriocapillaris, and nerve radial peripapillary capillary plexus.

RESULTS

Overall, 32 eyes with KC and an equal number of age- and axial length-matched control eyes were included in the analysis. Almost all (97%) of eyes with KC were classified as early stage. KC displayed a reduction in peripapillary RNFL thickness (104.8 ± 11.9 µm vs 110.7 ± 10.5 µm; P = .039) and nerve radial peripapillary capillary plexus vessel density (46.31% ± 3% vs 43.82% ± 4%; P = .006) when compared with control subjects; these differences were more evident in the temporal sector and were associated with a higher LC curvature index (9.9% ± 2.6% vs 8.48% ± 1.7%; P = .012). Mean macular superficial capillary plexus vessel density was 3 percentage points lower in eyes with KC than in healthy controls (P < .001).

CONCLUSION

Early-stage KC may be characterized by a posterior bowing of the LC along with a subtle peripapillary RNFL thinning and vascular impairment. These findings support the hypothesis that KC may be a corneal manifestation of a more generalized "eye collagen disease."

Evaluation of Choroidal Vascularity Index in Keratoconus Patients: Does Choroidal Vascularity Change in Keratoconus?

Purpose

To investigate the choroidal structure in keratoconic patients with different severity using the choroidal vascularity index (CVI) derived from image binarization on enhanced depth imaging optical coherence tomography scans (EDI-OCT).

Methods

Sixty-eight eyes from 34 keratoconus (KCN) patients and 72 eyes from 36 healthy subjects were recruited in this prospective, noninterventional, comparative cross-sectional study. EDI-OCT was employed to measure choroidal parameters, including choroidal thickness (CT), total choroidal area (TCA), luminal area, stromal area, and CVI.

Results

Subfoveal CT was 354.6 ± 66.8 μm in the control group and 371 ± 64.5 μm in the KCN group (P = 0.86). There was no significant difference between control and KCN groups in terms of TCA (0.66 ± 0.14 mm2 vs. 0.7 ± 0.12 mm2; P = 0.70), luminal area (0.49 ± 0.10 mm2 vs. 0.53 ± 0.08 mm2; P = 0.67), and stromal area (0.16 ± 0.05 mm2 vs. 0.17 ± 0.05 mm2; P = 0.84). CVI was also comparable in the control group (75.4% ±3.4%) and the KCN group (75.6% ±4.5%; P = 0.43). There was also no significant correlation between other choroidal parameters and KCN severity indices.

Conclusion

It seems that CVI as well as other choroidal biomarkers were not significantly different between patients with KCN and healthy subjects.

Optic disc and retinal vessel densities assessment by optical coherence tomography angiography in patients with keratoconus

BACKGROUND

This study aimed to evaluate retinal and optic disc vascular changes in patients with keratoconus (KC) using optical coherence tomography angiography (OCTA).

METHODS

Thirty-two eyes of 22 patients with KC and 24 eyes of 24 age- and sex-matched healthy controls were included in this study. Corneal topography and OCTA were performed. Quantitative vessel density of the macular superficial capillary plexus (SCP), macular deep capillary plexus (DCP), and radial peripapillary capillaries (RPC); choriocapillaris flow area; and choroidal thickness were compared between the KC and control groups.

RESULTS

SCP and DCP vessel densities showed a significant reduction in the KC group compared to that in the control group (p < 0.001 and p < 0.001 in the whole image and parafovea, respectively). Choriocapillaris flow area was significantly higher in patients with KC than in the control group (p = 0.003). The foveal avascular zone area did not significantly differ between the two groups (p = 0.949). RPC inside disc vessel density was significantly decreased in the KC group compared to that in the control group (p < 0.001).

CONCLUSION

This study revealed important macular, choroidal, and optic disc vessel densities changes in patients with KC. Macular whole vessel density and parafoveal vessel density of the SCP and DCP decreased, while choriocapillaris flow area increased in patients with KC.

Choroidal thickness assessment in keratoconus patients treated with cross-linking compared to healthy population

PURPOSE

To analyze the choroidal thickness between patients with keratoconus undergoing cross-linking treatment and a healthy population, as well as to determine the factors that influence choroidal thickness.

METHODS

This was an observational, analytical, case-control study that was conducted from February 2021 to June 2021. Choroidal thickness was measured at different locations, including the subfoveal, nasal (1000 μm), temporal (1000 μm), superior (1000 μm) and inferior (1000 μm) locations using a Spectral-domain optical coherence tomography with enhanced depth imaging, which allowed us to obtain horizontal and vertical B-scans centered on the fovea.

RESULTS

This study included 21 patients with keratoconus (mean age, 21.86 ± 5.28 years) and 28 healthy patients (mean age, 24.21 ± 4.71 years). Choroidal thickness was significantly greater in patients with keratoconus than in healthy patients in each of the following measured locations: subfoveal (P < 0.001); nasal (1000 μm) (P < 0.001), temporal (1000 μm) (P < 0.001), superior (1000 μm) (P < 0.001) and inferior (1000 μm) (P < 0.001) locations. Variables such as age (ρ = - 0.09; P = 0.50) and refraction (ρ = 0.14; P = 0.34) were not found to be associated with choroidal thickness. In a stepwise multiple linear regression, the group was the single variable correlated with choroidal thickness (β = 0.88; P < 0.001).

CONCLUSION

Choroidal thickness is thicker in keratoconus patients treated with cross-linking than in the healthy population. This finding could be associated with inflammatory choroidal mechanisms in keratoconus patients, but more studies are needed. Age and refractive error do not seem to influence choroidal thickness.

Assessment of the Retinal Vessels in Keratoconus: An OCT Angiography Study

This study investigated vascular density and foveal avascular zone (FAZ) parameters using optical coherence tomography angiography (OCT-A) in patients with keratoconus (KC). Participants with KC and healthy controls were included and underwent best-corrected visual acuity (BCVA), keratometry, anterior segment OCT, and macular OCT-A examinations. Of the 70 subjects (mean age 42.9 ± 15.31 years), 79 KC and 47 healthy eyes were included. Significant reductions in the KC group were recorded for the FAZ area, with a mean (±SD) of 0.19 ± 0.12 vs. 0.25 ± 0.09 mm2 p < 0.001. Central vascular density in KC patients was lower compared with the controls: 6.78 ± 4.74 vs. 8.44 ± 3.33 mm−1 p = 0.049; the inner density was also decreased in the study group (13.64 ± 5.13 vs. 16.54 ± 2.89 mm−1, p = 0.002), along with the outer density (14.71 ± 4.12 vs. 16.88 ± 2.42 mm−1, p = 0.004) and full density (14.25 ± 4.30 vs. 16.57 ± 2.48) p = 0.003. Furthermore, BCVA was positively correlated with central vascular density (R = 0.42 p = 0.004, total R = 0.40, p = 0.006) and inner density (R = 0.44, p = 0.002) in patients with KC but not in controls. Additionally, we found a correlation between K2 and inner vascular density (R = −0.30, p = 0.043) and central epithelium thickness and outer density (R = 0.03, p = 0.046). KC patients had lower macular vascular density and a smaller FAZ than healthy participants. The BCVA in KC patients was correlated with the vascular density.

[Results of optical coherence tomography of the retina and optic nerve in keratoconus]

The article reviews the results of optical coherence tomography (OCT) of the retina and optic nerve in patients with keratoconus (KC). This research direction is premised by the possibility that changes in the retina and optic nerve are associated with KC, as well as the potential influence of significant changes in axial eye length, disorders of corneal refraction and increased level of aberrations on the quality of visualization of these ocular structures. Results of the conducted studies were conflicting, but in all they indicated a possibility of OCT findings to be altered in KC patients. Therefore, the question of changing the parameters for OCT of the retina and optic nerve requires further investigation. The main problem that needs solving with evidence based medical research can be phrased as follows: are the changes in OCT findings observed in KC patients the consequence of changes in the retina and optic nerve associated with this disorder, or potential effect of aberrations and irregular astigmatism on the quality of visualization of the studied structures?

The Role of Atopy in the Choroidal Profile of Keratoconus Patients

Purpose

Although classically classified as a non-inflammatory condition, an inflammatory basis for keratoconus (KC) appears to be a growing evidence. Recently, it has been shown that KC patients have an increased choroidal thickness (CT). Among inflammatory disorders, atopy has been associated with KC development; therefore, the aim of this study was to evaluate if the increased CT in patients with KC is related to atopy.

Methods

This is an analytical cross-sectional study of patients with KC. Patients were classified as atopic and non-atopic according to their atopy history (allergic rhinoconjunctivitis (AR), asthma (AA) and/or atopic dermatitis (AD)) and were also classified based on their eye rubbing habits. Choroidal profile of all subjects was evaluated using a Spectralis optical coherence tomography (OCT) device with enhanced depth imaging (EDI) mode. CT was measured and compared between groups at the center of the fovea and at 500 µm intervals along a horizontal section. A multivariable analysis, adjusted for sex, age, spherical equivalent, history of medication and atopy, was performed to assess the influence of atopy in CT.

Results

Of the 80 patients included, 51 were atopic and 29 non-atopic. Atopic patients showed a thicker choroid in every measured location than the non-atopic patients (mean subfoveal CT 391.53 µm vs 351.17 µm, respectively), although the differences were not statistically different. The multivariable analysis revealed that being atopic makes the choroid statistically thicker, on average, 55.14 µm, when compared to non-atopic patients (p=0.043). Furthermore, patients who are frequent eye rubbers have significantly thicker choroids than non-rubbers (p=0.004).

Conclusion

Although some results do not reach statistical significance, atopic KC patients seem to have thicker choroids compared with non-atopic KC patients, suggesting a possible role for atopy in the choroidal profile of KC. This constitutes a completely new sight in this field of research that needs further investigation.

Increased choroidal thickness is not a disease progression marker in keratoconus

The recent findings of increased Choroidal Thickness (CT) in Keratoconus (KC) patients raised the question of whether CT could be an indicator of progressive KC. To test this hypothesis, we evaluated and compared the choroidal profile in progressive and non-progressive KC. We ran a cross-sectional observational study in 76 patients diagnosed with KC, age 14–30, to assess KC progression. Progression was defined as when at least two of the studied variables confirmed progression (Kmax, Km, PachyMin, D-Index, Astig, K2, 3 mm PCR). Included patients performed a Spectralis Optical Coherence Tomography (OCT) with enhanced depth image (EDI) technology to evaluate choroidal profile. Choroidal measurements were taken subfoveally and at 500 µm intervals from the fovea, in 7 different locations, and compared between groups. Multivariate linear regression analyses were also performed to assess the influence of CT in KC progression. Thirty-six eyes (47.4%) were classified as KC progressors. The mean subfoveal CT observed in the total sample was 382.0 (± 97.0) μm. The comparison between groups (progressive and non-progressive KC) showed no differences in the locations evaluated (mean subfoveal CT difference between groups was 2.4 μm, p = 0.915). In the multivariate analysis CT seems not be influenced by KC progression (B = 6.72 μm, 95% CI − 40.09 to 53.53, p = 0.775). Assessment of choroidal profile does not appear to be a useful tool to differentiate progressive and non-progressive KC. Further research is needed in order to better understand the role of choroid in KC.

A review of imaging modalities for detecting early keratoconus

OBJECTIVES

Early identification of keratoconus is imperative for preventing iatrogenic corneal ectasia and allowing for early corneal collagen cross-linking treatments to potentially halt progression and decrease transplant burden. However, early diagnosis of keratoconus is currently a diagnostic challenge as there is no uniform screening criteria. We performed a review of the current literature to assess imaging modalities that can be used to help identify subclinical keratoconus.

METHODS

A Pubmed database search was conducted. We included primary and empirical studies for evaluating different modalities of screening for subclinical keratoconus.

RESULTS

A combination of multiple imaging tools, including corneal topography, tomography, Scheimpflug imaging, anterior segment optical coherence tomography, and in vivo confocal microscopy will allow for enhanced determination of subclinical keratoconus. In patients who are diagnostically borderline using a single screening criteria, use of additional imaging techniques can assist in diagnosis. Modalities that show promise but need further research include polarization-sensitive optical coherence tomography, Brillouin microscopy, and atomic force microscopy.

CONCLUSIONS

Recognition of early keratoconus can reduce risk of post-refractive ectasia and reduce transplantation burden. Though there are no current uniform screening criterion, multiple imaging modalities have shown promise in assisting with the early detection of keratoconus.