Age-Related Changes in Corneal Epithelial Thickness Measured with an Ultrasound Pachymeter

Corneal Epithelial Remodeling After Hyperopic SMILE: A 4-Year Study

PURPOSE

The purpose of this study was to investigate dynamic changes in corneal epithelial thickness (ET) after hyperopic small incision lenticule extraction (SMILE).

METHODS

This observational study included 18 eyes of 16 patients who were scheduled for hyperopic SMILE. High-resolution spectral-domain optical coherence tomography and a custom image segmentation algorithm were applied to measure corneal dynamic ET over a central 6 mm area. ET was analyzed among different corneal sectors (central, pericentral, and peripheral) at baseline and multiple postoperative time points (1 day, 1 month, 6 months, 2 years, and 4 years). Correlation analysis was performed between ET changes and preoperative and intraoperative parameters.

RESULTS

The mean spherical equivalent of hyperopia correction was +2.64 ± 1.00 D, and the average age of enrolled 16 patients was 32.4 ± 10.8 years. At the last follow-up, 72% of eyes kept or improved corrected distance visual acuity, with 2 eyes that lost 2 lines. 72% of eyes were within ±1.0 D of target refraction, and 56% were within ±0.5 D. Average ET decreased by 11.0% (5.9 ± 2.3 μm) from 53.2 ± 3.5 μm to 47.4 ± 4.2 μm 4 years postoperatively (P<0.001). The ET at center 2 mm decreased most significantly by 14.5% (7.9 ± 2.9 μm), followed by the pericentral area by 10.5% (5.6 ± 2.3 μm). ET and front corneal curvature stabilized 1 month after surgery. No correlation was found between refraction regression and ET changes.

CONCLUSIONS

Hyperopic SMILE induced significant central ET thinning. ET remodeling in the 6 mm area stabilized after 1 month and did not underlie refractive changes.

Retinal and Corneal OCT Results of Patients Hospitalized and Treated in the Acute Phase of COVID-19

Objective: This study aimed to assess changes in the morphology of the retina and cornea in patients treated and hospitalized during the acute active phase of SARS-CoV-2 infection. Methods: A total of 24 patients with symptomatic early COVID-19 disease and 38 healthy participants from a control group were enrolled in our study. Among them, 20 received oxygen therapy at flow rates ranging from 1-10 L, while four received high-flow intranasal oxygen therapy (HFNOT). Some patients were treated with other types of therapy, such as Remdesivir, COVID-19 convalescent plasma therapy, or Tocilizumab. In the study, we focused on the analysis of optical coherence tomography (OCT) images of the cornea and retina including corneal thickness, central retinal thickness, retinal nerve fiber layer (RNFL), and optic disc parameters. The measurements were acquired using Spectral-domain OCT REVO FC 130. Results: The analysis did not show significant changes between the examined ophthalmological parameters before and after therapy. Furthermore, there were no detected significant differences between the tested parameters of the retina and cornea in COVID-19-positive patients compared to the control group. Conclusions: No ophthalmological manifestations of COVID-19 disease were observed during the study. Taking into account the results of other publications, the lack of an unambiguous position on this topic requires further research.

Mimicking TGFBI Hot-Spot Mutation Did Not Result in Any Deposit Formation in the Zebrafish Cornea

PURPOSE

Mutations in transforming growth factor beta-induced (TGFBI) protein are associated with a group of corneal dystrophies (CDs), classified as TGFBI-associated CDs, characterized by deposits in the cornea. Mouse models were not proper in several aspects for modelling human disease. The goal of this study was to generate zebrafish mutants to investigate the corneal phenotype and to decide whether zebrafish could be a potential model for TGFBI-associated CDs.

METHODS

The conserved arginine residue, codon 117, in zebrafish tgfbi gene was targeted with Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 method. Cas9 VQR variant was used with two target-specific sgRNAs to generate mutations. The presence of mutations was evaluated by T7 Endonuclease Enzyme (T7EI) assay and the type of the mutations were evaluated by Sanger sequencing. The mutant zebrafish at 3 months and 1 year of age were investigated under the microscope for corneal opacity and eye sections were evaluated histopathologically with hematoxylin-eosin, masson-trichrome and congo red stains for corneal deposits.

RESULTS

We achieved indel variation at the target sequence that resulted in p.Ser115_Arg117delinsLeu (c. 347_353delinsT) by nonhomology mediated repair in F1. This zebrafish mutation had the potential to mimic two disease-causing mutations reported in human cases previously: R124L and R124L + del125-126. Mutant zebrafish did not show any corneal opacity or corneal deposits at 3 months and 1 year of age.

CONCLUSION

This study generated the first zebrafish model mimicking the R124 hot spot mutation in TGFBI-associated CDs. However, evaluations even at 1 year of age did not reveal any deposits in the cornea histopathologically. This study increased the cautions for modelling TGFBI-associated CDs in zebrafish in addition to differences in the corneal structure between zebrafish and humans.

Association between Thyroid Function and Ocular Parameters

During development, thyroid hormones play an important role in eye development, while in adults, some pathological thyroid conditions can affect the normal functioning of the eyes. Thyroid eye disease is the most well-known eye pathology caused by a pathological thyroid condition. Few studies have investigated the association between ocular parameters and thyroid function. Thus, in this study, we aimed to examine whether thyroid activity affects ocular parameters. This cross-sectional study included 4633 healthy adults recruited within the 10,001 Dalmatians project of the Croatian Biobank. The plasma levels of thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), thyroglobulin (Tg), thyroglobulin antibodies (TgAb), and thyroid peroxidase antibodies (TPOAb) were measured by an immunoassay. We determined 20 ocular parameters for each participant (10 for each eye, including corneal radius, corneal thickness, anterior chamber depth, anterior chamber angle, lens thickness, posterior chamber length, axial length, intraocular lens power (IOL), spherical power, and cylinder power). Patients with hyperthyroidism had thicker corneas compared to euthyroid individuals. Corneal thickness was also negatively associated with plasma TSH levels. Intra-ocular lens power was higher in patients with clinical hypothyroidism, while spherical power was higher in euthyroid individuals with positive antibodies compared to euthyroid individuals. Intra-ocular lens power negatively correlated with fT4 levels, while spherical power positively correlated with TgAb, TPOAb, and Tg levels and negatively correlated with TSH levels. The anterior chamber angle was positively associated with plasma TSH levels and TPOAb levels and negatively associated with plasma fT4 levels. These findings suggest an interesting interplay between ophthalmic measures and thyroid status, detectable even in the general adult population.