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

Corneal crosslinking effects on macular microvasculature in progressive keratoconus cases: A prospective single-arm study

OBJECTIVE

To evaluate the macular microvascular changes after corneal collagen crosslinking (CXL) in progressive keratoconus (KCN) cases DESIGN: Single-arm prospective interventional study PARTICIPANTS: Thirty eyes of 25 cases with progressive KCN are included in this study to undergo a corneal epi‑off CXL procedure.

METHODS

All included eyes underwent an epi‑off CXL procedure with Dresden protocol and were followed up for 6 months. All patients were examined at four visits: before the CXL procedure, one week, one month, and 6 months after the CXL procedure. Patients underwent a macular optical coherence tomography angiography (OCTA) before, 1 month, and 6 months after the CXL procedure.

MAIN OUTCOME MEASURES

The vessel density (VD) in the foveal, parafoveal, perifoveal, whole image, superior-Hemi, and inferior-Hemi regions was evaluated in both superficial and deep capillary plexus (SCP and DCP).

RESULTS

The study enrolled 12 Males and 13 Females with a median age of 24.0 (IQR:21.0-26.5). Foveal VD in DCP was lower than the baseline at 1 and 5-6 months after the procedure. The mean difference (MD) between the baseline and the follow-ups was 4.34 % (95 %CI:0.25-8.42) and 6.21 % (95 %CI:2.20-10.35), respectively. The SCP VD showed a significant decrease in the superior segment of the macular OCTA 5-6 months after CXL (MD: 3.44 % (95 %CI:1.28-5.60)). Other macular SCP and DCP parameters showed no statistically significant change 5-6 months after CXL, although numerically, they seem lower at the last follow-up compared to the baseline.

CONCLUSION

The corneal CXL procedure may alter the macular microvasculature, lasting even 6 months after the procedure, despite its overall presumed safety regarding the patients' vision and retinal function.

Retinal thickness and vascular density changes in Keratoconus: A systematic review and meta-analysis

Purpose

This systematic review and meta-analysis aimed to assess the changes in retinal layer thickness and vascular density in patients diagnosed with keratoconus (KC).

Methods

We conducted a thorough search in PubMed, Scopus, Embase, and Web of Science, encompassing all observational studies from January 1990 to February 2024. We analyzed the data using STATA software 17 and the random effects model with the restricted maximum likelihood (REML) or maximum likelihood (ML) method to pool the standardized mean difference (SMD) and the weighted mean difference (WMD) of retinal thickness and vascular density compared to non-KC eyes.

Results

From 4608 records, 16 primary studies met our inclusion criteria, involving 1932 eyes in two groups. The meta-analysis revealed a significant reduction in retinal nerve fiber layer (RNFL) thickness (SMD: -0.30 [-0.52, -0.08]), perifoveal macular thickness in the nasal region (SMD: -0.32 [-0.55, -0.09]) and superior region (SMD: -0.24 [-0.47, -0.02]), and superior capillary plexus (SCP) density (SMD: -1.52 [-2.27, -0.77]) of KC eyes. Additionally, there was a mildly to moderately significant increase in the optic nerve head (ONH) disk area (SMD: 0.40 [0.06, 0.75]). However, there were no significant changes in foveal macular thickness, parafoveal macular thickness, or deep capillary plexus (DCP) density.

Conclusion

In KC patients, significant alterations in retinal structure and vascular density have been observed. Although these changes do not currently influence treatment strategies, they offer valuable insights into the relationship between the retina and the cornea. Understanding these changes may be essential for future research focused on early detection, potential prognosis markers, and further exploration of the retina-corneal connection in KC.

Retinal neurovascular assessment and choroidal vascularity index in patients with keratoconus

This study aims to evaluate the macular and the optic nerve head thickness and vascular profiles in KC patients and compare them with two groups of healthy emmetrope and subjects with myopic-astigmatism. This cross-sectional study was conducted at Khatam-Al-Anbia Eye Hospital between 2022 and 2023. Subjects aged 18 to 40 were prone to be included in the study. The participants in this study were grouped into three categories: emmetrope (E), myopic-astigmatic (MA), and keratoconus (KC). All participants underwent a comprehensive ocular examination, as well as macular and optic nerve head (ONH) optical coherence tomography angiography (OCTA). In this study, 143 subjects, 50 cases in the KCN group, 46 cases in the E group, and 47 cases in the MA group, enrolled. There was no difference between the three groups regarding age (p = 0.123) and gender (p = 0.632). The superficial and deep capillary densities at the fovea, parafovea, and perifovea were significantly lower in KC patients than in the control groups (p < 0.01). The radial peripapillary capillary (RPC)- all vessels' density is significantly lower in the KC group (p < 0.001). Besides, the choroidal vascularity index (CVI) and choroidal luminal area (CLA) were considerably higher in KC patients (p < 0.001). The macular and ONH vascular profile in KC patients significantly differs from the vascular profile of healthy controls. Further scientific evidence regarding the systemic implications of keratoconus on the vascular system would be desirable to understand the connections between KC and vascular disease.

Assessment of OCT and Angio-OCT Parameters in Keratoconus Patients with and without Penetrating Keratoplasty

Background/Objectives: Keratoconus (KC) is a bilateral eye disease characterized by corneal thinning and cone-like deformation, leading to visual impairment. This study evaluated the radial peripapillary capillaries (RPCs) in keratoconus patients with and without penetrating keratoplasty (PKP) using OCT and angio-OCT, comparing the results to a control group. Methods: This retrospective study included 149 eyes, 97 from patients who underwent PKP between January 2018 and February 2023 and 52 from patients who did not undergo PKP. The control group comprised 72 patients (144 eyes) who were healthy volunteers. Measurements included the best corrected visual acuity (BCVA), the intraocular pressure (IOP), slit-lamp biomicroscopy, a fundus examination, and corneal topography, as well as OCT and angio-OCT assessments of the RPCs, retinal nerve fiber layer (RNFL), ganglion cell complex (GCC), and central retinal thickness (CRT). Statistical analyses were performed using Student's t-test and Pearson's correlation coefficient. Results: The RNFL was significantly thinner in KC eyes after PKP compared to control eyes (p < 0.001), and the CRT was significantly thicker in KC eyes after PKP compared to control eyes (p = 0.003). However, the GCC was similar across the groups (p = 0.0885). Additionally, RPCs inside the disc were significantly reduced in KC eyes after PKP compared to control eyes (p < 0.0001). A significant positive correlation was found between RPC whole vessel density and RNFL thickness as measured via angio-OCT (r = 0.308, p < 0.0001). Conclusions: This study found that the RPC density inside the disc is significantly reduced in keratoconus patients after penetrating keratoplasty, highlighting RPCs inside the disc as a potential diagnostic tool for further assessment of keratoconus.

Reduced Retinal Blood Vessel Densities Measured by Optical Coherence Tomography Angiography in Keratoconus Patients Are Negatively Correlated with Keratoconus Severity

Keratoconus (KC) is the most common corneal ectasia. Optical coherence tomography angiography (OCT-A) is a relatively new non-invasive imaging technique that allows the visualization and quantification of retinal and choriocapillary blood vessels. The aim of this study is to assess retinal and choriocapillary vessel density (VD) differences between KC patients and healthy controls and to investigate correlations between VD and KC severity. Fifty-two eyes were included in this exploratory study: twenty-six eyes from 26 KC patients and twenty-six eyes from 26 age- and gender-matched healthy controls. All patients underwent Scheimpflug corneal topography with Pentacam, axis lengths measurement and optical coherence tomography angiography (OCT-A). The thinnest spot in corneal pachymetry, maximum K (Kmax) and KC severity indices from the Belin/Ambrósio enhanced ectasia display (BAD) were also assessed. There was a distinct reduction particularly in the retinal VD of the superficial capillary plexus (SCP). Correlation analyses showed strong and moderate negative correlations between the VD in the macular SCP and BAD KC scores and between the SCP VD and Kmax. There was no difference in retinal thickness between the KC and healthy controls. With this study, further evidence for altered VD measurements by OCT-A in KC patients is given. For the first time, we demonstrated negative correlations between BAD KC scores and retinal blood vessel alterations. A major limitation of the study is the relatively small sample size. Since an artefactual reduction of the quantitative OCT-A measurements due to irregular corneal topography in KC must be assumed, it remains to be investigated whether there are also actual changes in the retinal microcirculation in KC.

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.