Choroidal thickness in keratoconus

Pachychoroid pigment epitheliopathy in keratoconic eyes

PURPOSE

To report the association between keratoconus (KC) and pachychoroid pigment epitheliopathy (PPE). As secondary outcome, we explored the relation between subfoveal choroidal thickness (SFCT) and topometric indexes.

METHODS

Retrospective, observational, cross-sectional, case-control study. Multicentric study including patients with KC and healthy controls. Each subject underwent a complete ophthalmological visit, Placido-based corneal topography, Scheimpflug corneal tomography and spectral-domain OCT (SD-OCT) with the enhanced depth imaging (EDI) mode on. Linear mixed models (LMM) were employed for comparison between groups, and to examine the impact of different topometric factors on SFCT. KC stages were defined according to Belin grading.

RESULTS

Overall, 56 eyes from 35 KC patients and 52 eyes from 27 healthy, age- and axial length-matched control subjects were included in the study. PPE was found in 10 (17.9%) eyes from 8 KC patients, whereas was absent in all healthy controls. SFCT was statistically significantly higher in keratoconic eyes (median: 390 µm; interquartile range (IQR): 339 - 425 µm) compared to healthy eyes (median: 240 µm; IQR: 200 - 288 µm) (p < 0.001). SFCT did not differ across different KC stages and between keratoconic eyes with and without PPE.

CONCLUSIONS

PPE is a relatively frequent finding in eyes with KC, being present in about 1 out of 6 cases, regardless of disease stage.

KEY MESSAGES

What is known: Keratoconus (KC) is a corneal disorder commonly associated with other chorioretinal abnormalities. It is well known that keratoconic eyes display increased choroidal thickness, and the rare association between KC and central serous chorioretinopathy (CSC) has already been reported in the literature.

WHAT IS NEW

We identified an association between KC and pachychoroid pigment epitheliopathy (PPE), a precursor or forme fruste of pachychoroid diseases, such as CSC. PPE presence is independent from corneal parameters and is observed in about 1 out 6 KC eyes.

Macular choroidal thickness in keratoconus

CLINICAL RELEVANCE

Expanding practitioner knowledge regarding potential changes in ocular structure of keratoconic eyes will improve the eye care practice and patient management.

BACKGROUND

This study aimed to compare the difference in choroidal thickness between keratoconus patients and two control groups of myopic-astigmatism and emmetropic subjects.

METHODS

A case-control study was undertaken which included 50 patients with keratoconus, 50 with myopic-astigmatism, 30 with emmetropia aged between 18 and 39 years. Choroidal thickness was measured at three different locations, including the subfoveal, nasal, and temporal (750 micrometres) to the fovea, using a spectral-domain optical coherence tomography with an enhanced depth imaging technique.

RESULTS

The mean spherical equivalents were 0.03 ± 0.05, -3.00 ± 0.2, and -3.00 ± 0.3 dioptre in emmetropic, myopic-astigmatism and keratoconus subjects, respectively. The choroid was significantly thicker in keratoconus patients than in myopic-astigmatism and emmetropic subjects in the subfoveal (396 ± 14, 314 ± 12, and 320 ± 18 μm, respectively, p < 0.001), temporal (405 ± 14, 317 ± 12, and 328 ± 19 μm, respectively, p < 0.001) and nasal (376 ± 14, 285 ± 12, and 311 ± 18 μm, respectively; p < 0.001).

CONCLUSION

Choroidal thickness is increased in keratoconus. The exact mechanism for choroidal thickening in individuals with keratoconus is unknown, but inflammatory responses could be the reason.

Subfoveal choroidal thickness increases after excimer laser-assisted penetrating keratoplasty but not after excimer laser-assisted deep anterior lamellar keratoplasty

To evaluate the impact of excimer laser-assisted deep anterior lamellar keratoplasty (Exc-DALK) and excimer laser-assisted penetrating keratoplasty (Exc-PKP) on subfoveal choroidal thickness (SFCT) in eyes with advanced keratoconus. A retrospective comparative clinical study, which compares the outcomes of 24 eyes treated with Exc-DALK (G1) against matched group of 43 eyes treated with Exc-PKP (G2) at both 2 months (T1) and 2 years (T2) postoperatively. Main outcomes included best-corrected visual acuity (BCVA), central macular thickness (CMT), and SFCT. Preoperatively, there were no significant differences between both groups regarding BCVA, CMT or SFCT (p > 0.05). There were no significant differences between both groups regarding BCVA at both follow-ups (p > 0.05). There were no significant differences between both groups regarding CMT at both follow-ups (p > 0.05). SFCT was higher in G2 than G1 at both follow-ups (p < 0.01). Compared to preoperative SFCT, there were no significant changes in SFCT in G1 at both follow-ups (p > 0.05). In G2, SFCT increased significantly at T1 (p < 0.01) and did not differ significantly at T2 (p = 0.17). SFCT increased significantly after Exc-PKP but not after Exc-DALK, which might indicate that Exc-DALK affects the choroid less and thus could represent a less traumatic approach to ocular tissue than Exc-PKP.

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.

Effect of Nasal Septum Deviation on the Choroidal Thickness

INTRODUCTION

Nasal cavity blood circulation and ocular blood circulation have common pathways for both arterial blood supply and venous drainage. Therefore, nasal pathologies can affect ocular blood circulation. This study aimed to evaluate the relationship between nasal obstruction and choroidal thickness.

METHODS

A prospective study was planned by forming a group of 144 patients diagnosed with nasal septum deviation at the otorhinolaryngology clinic and 100 healthy voluntary individuals. Of the total, 69 patients with nasal right septum deviation were evaluated as Group 1, 75 patients with nasal left septum deviation as Group 2, and 100 healthy volunteers as the control group. Detailed ophthalmological examinations of all the participants were performed, and choroidal thickness was measured using spectral domain optical coherence tomography. The relationship between choroidal thickness and ocular parameters was evaluated and compared between the patient groups with nasal septum deviation and the control group.

RESULTS

When the choroidal thickness measurements of the patients in Group 1 were examined, the choroidal thickness increased in all the regions in the eye contralateral to the deviation side (left), and intraocular pressure (IOP) was higher compared to the eye on the deviation side (right) and the control group at a statistically significant level. In Group 2, the choroidal thickness measurements increased in all the regions in the eye contralateral to the deviation side (right), and IOP was higher compared to the deviation side (left) and the control group.

CONCLUSIONS

We found that the patients with nasal septum deviation had higher choroidal thickness and IOP values in the eye contralateral to deviation.

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."

Alterations in the choroidal thickness and retinal vascular caliber in keratoconus

PURPOSE

To compare the choroidal thickness (CT) and retinal vascular caliber in the differentiation of patients who have keratoconus (KC) from those of astigmatic and normal patients.

METHODS

This was a prospective, cross-sectional study. A total of 72 patients who had KC, 70 who had astigmatism, and 83 healthy control subjects were enrolled in this study. All the patients were examined using the Sirius topography system and spectral domain optical coherence tomography with enhanced depth imaging. Using the digital fundus photographs, the retinal vascular calibers were calculated. The measurements were also analyzed between the KC stages according to the Amsler-Krumeich classification.

RESULTS

The CT measurements were significantly higher in the KC group, when compared with the other 2 groups, in each location (P < 0.05). No statistically significant difference was observed with regards to the central retinal artery equivalent (CRAE) values (P = 0.959), while significant differences were noted in the central retinal vein equivalent (CRVE) among the groups (P = 0.011). Significant increases were noted in the CT as the stage of KC progressed, except at temporal 3000 µm (P = 0.603). No statistically significant difference was observed with regards to the CRAE among the stages (P = 0.901). However, the CRVE changes increased remarkably as the stages advanced (P < 0.001).

CONCLUSION

The patients who had KC seemed to have a thicker CT and higher CRVE values than the healthy individuals, and these differences were progressively increased as the stages of KC advanced. Reflecting the vascular effects of inflammation, the high CRVE supported theories based on the inflammatory component of KC.

Evaluation of the optic nerve head and macular vessel density in keratoconus patients using optical coherence tomography angiography- a cross-sectional study

PURPOSE

Our study evaluated macular and optic disc vascular density (VD) changes in patients diagnosed with keratoconus, as compared with gender and age-matched healthy controls, in relation to the keratoconus stage.

METHODS

This comparative cross-sectional study included adult patients who received a diagnosis of keratoconus at the Cornea Clinic. All scans consisted of two 4.5 mm × 4.5 mm images of the optic disc area and 6 × 6 mm images of the macular area using optical coherence tomography angiography.

RESULTS

The study included 67 patients (26 women (38.8%) and 41 men (61.2%)) and 74 controls (31 women (41.9%) and 43 men (58.1%)). The mean ages of the keratoconus group and the control group were 30.0 ± 8.0 and 31.1 ± 7.5, respectively. Macular VD (whole, superficial, and deep) and peripapillary VD (whole) values were decreased statistically significant compared with the control group (p < 0.01 and p = 0.015, respectively). The keratoconus stage was negatively correlated with both the macular VD (p = 0.048, r = -0.314) and whole-peripapillary VD values (p = 0.03, r = -0.34).

CONCLUSION

Keratoconus might affect the posterior and anterior segments due to similar etiologies, including diminished collagen quality. Therefore, examination of the posterior segment should be performed thoroughly in keratoconus patients.

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.

The link between Keratoconus and posterior segment parameters: An updated, comprehensive review

Keratoconus (KCN) has been typically known as a disorder with effects limited to the cornea. Because of this viewpoint, less attention has been devoted to its effects on the posterior segment structures. We aimed to provide a comprehensive review of the literature to understand the potential link between KCN and posterior segment structures and their functions. It is clear from the extensive evidence in the literature that KCN can be associated with morphological and functional changes in different parts of the posterior segment. It is worth noting that anatomical changes have been not only noted in several layers of the retina but also in the optic nerve head and the choroid. Several mechanisms have been proposed to explain this observation, including incidents induced by oxidative stress in keratoconic corneas and retinal adaptions to the distorted image that lands on the retina. Consequently, when KCN has been diagnosed, it seems practical to consider assessing the retinal and choroidal profile using optical coherence tomography and potentially functional abnormalities through electrophysiology procedures.

[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.

The presence and progression of choroidal neurofibromas in a predominantly pediatric population with neurofibromatosis type-1

Background: Obtaining a definitive neurofibromatosis type-1 (NF1) diagnosis may take years. The natural history of choroidal neurofibromas in NF1 is unknown. This study evaluates a predominantly pediatric patient cohort for ocular features in NF1, including presence and progression of choroidal abnormalities, to determine their natural history, relationship to other NF1 features, and additive value in NF1 diagnosis.Methods: Retrospective analysis of 106 patients referred for Ophthalmic monitoring or diagnosis of NF1 between January 2012 and December 2018. Clinical records and Near-Infrared Reflectance (NIR) Optical Coherence Tomography imaging were analyzed for prevalence and progression of choroidal neurofibromas on NIR, and relation to other NF1 diagnostic criteria.Results: 54.7% of patients referred had a confirmed NF1 diagnosis, and 45.4% were NF1 suspects. First ophthalmic review resulted in an additional 6.6% patients meeting the diagnostic criteria, and 14.2% later developed sufficient features (total n = 80). Choroidal neurofibromas were present in 75.7% of patients that had NIR imaging and met diagnostic criteria, and detected in the absence of, or prior to Lisch nodules in 13.5%. Progression in the size and number of choroidal neurofibromas occurred in 26 eyes (32.5%) of 14 patients (35.0%), all under 16 years old. Patients without choroidal neurofibromas at first examination never developed them over the study period.Conclusion: Choroidal neurofibromas, detected by NIR imaging, are common in NF1, present early with frequent progression, and represent an additional tool to aid NF1 diagnosis in young children.

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.