Technique of corneal allogenic ring segment preparation using femtosecond laser: preclinical study on human corneal grafts.

PURPOSE: To describe a new technique for preparing corneal allogenic ring segments (CAIRSs) using femtosecond laser technology. SETTING: Hospital Foundation Adolphe de Rothschild-Noémie de Rothschild institute, Paris, France. DESIGN: Preclinical study conducted on human corneal grafts. METHODS: The corneal grafts were mounted on an artificial chamber pressurizer (ACP) with preset constant pressure, and the FSL was used to create a circular annulus with specific dimensions. The resulting CAIRSs were analyzed for their thickness and width after air drying. RESULTS: A total of 25 CAIRSs were prepared using the FSL. The mean width and thickness of the CAIRSs were 803 ± 77 µm and 83 ± 16 µm, respectively. Statistical analysis revealed no significant differences in width among the various quadrants of each CAIRS or between different CAIRSs. Significantly thicker CAIRSs were obtained with a higher ACP pressure. CONCLUSIONS: The technique of CAIRS preparation using FSL technology and controlled artificial anterior chamber pressure demonstrated reproducibility and precision. This approach holds the potential for customizing and personalizing CAIRSs based on individual corneal characteristics.

The Development of a Thick-Lens Post-Myopic Laser Vision Correction Intraocular Lens Calculation Formula.

PURPOSE: To describe the development of the post-myopic laser vision correction (LVC) version of the PEARL-DGS intraocular lens (IOL) calculation formula and to evaluate its outcomes on an independent test set. DESIGN: Retrospective, single-center case series. METHODS: A modified lens position prediction algorithm was designed along with methods to predict the posterior corneal curvature radius and correct the corneal power measurement error. A different set of previously operated eyes that underwent LVC was used to evaluate the prediction precision of the post-LVC formula. RESULTS: Post-LVC PEARL-DGS formula significantly reduced mean absolute error of prediction in comparison to Haigis-L, Shammas, and American Society of Cataract and Refractive Surgery (ASCRS) average formulas (P < .001). It exhibited similar postoperative refractive precision as the Barrett True-K No History formula (P = .61). CONCLUSION: The post-LVC formula development process described in this article performed as well as the state-of-the-art post-LVC formula on the present test set. Further studies are required to assess its efficacy in other independent sets.

Novel deep learning approach to estimate rigid gas permeable contact lens base curve for keratoconus fitting.

INTRODUCTION: Rigid gas permeable contact lenses (RGP) are the most efficient means of providing optimal vision in keratoconus. RGP fitting can be challenging and time-consuming for ophthalmologists and patients. Deep learning predictive models could simplify this process. OBJECTIVE: To develop a deep learning model to predict the base curve (R0) of rigid gas permeable contact lenses for keratoconus patients. METHODS: We conducted a retrospective study at the Rothschild Foundation Hospital between June 2012 and April 2021. We included all keratoconus patients fitted with Menicon Rose K2® lenses. The data was divided into a training set to develop the model and a test set to evaluate the model's performance. We used a U-net architecture. The raw matrix of anterior axial curvature in millimeters was extracted from Scheimpflug examinations for each patient and used as input for the model. The mean absolute error (MAE) between the prediction and the prescribed R0 was calculated. Univariate and multivariate analyses were conducted to assess the model's errors. RESULTS: Three hundred fifty-eight eyes from 202 patients were included: 287 eyes were included in the training dataset, and 71 were included in the testing dataset. Our model's Pearson coefficient of determination (R2) was calculated at 0.83, compared to 0.75 for the manufacturer's recommendation (mean keratometry, Km). The mean square error of our model was calculated at 0.04, compared to 0.11 for Km. The predicted R0 MAE (0.16 ± 0.13) was statistically significantly different from the Km MAE (0.23 ± 0.23) (p = 0.02). In multivariate analysis, an apex center outside the central 5 mm region was the only factor significantly increasing the prediction absolute error. CONCLUSION: Our deep learning approach demonstrated superior precision in predicting rigid gas permeable contact lens base curves for keratoconus patients compared to the manufacturer's recommendation. This approach has the potential to be particularly beneficial in complex fitting cases and can help reduce the time spent by ophthalmologists and patients during the process.

Six months' follow-up of combined phacoemulsification-kahook dual blade excisional goniotomy.

PURPOSE: This study reports on the combination of excisional goniotomy and cataract extraction in the management of glaucoma in terms of intraocular pressure (IOP) and glaucoma medication reduction. METHODS: This is a retrospective case series. Twenty-eight eyes of 22 patients with the diagnosis of cataract and ocular hypertension or glaucoma of any stage underwent combined phacoemulsification and Kahook Dual Blade (KDB) goniotomy, between March 2019 and September 2020. The parameters evaluated were postoperative best-corrected visual acuity, mean IOP reduction, number of IOP-lowering medications, and the surgical success rate defined as IOP reduction >20% and/or reduction in glaucoma medications >1. RESULTS: The mean IOP reduction at 6 months was 4.5 mmHg (P = 0.0007), which translates to 24.9% reduction from preoperative IOP. The mean preoperative number of glaucoma medications was 2.9 ± 1.0 (median of 3). It was reduced to 1.1 ± 1.1 (median of 1.5), 1.46 ± 1.17 (median of 2), 1.44 ± 1.28 (median of 2), and 1.56 ± 1.28 (median of 2) at 1 week, 1 month, 3 months, and 6 months, respectively. Twenty-nine percent (8/28) of the patients were off glaucoma medications at 6 months and 46% (13/28) had a reduction of more than 50% of their glaucoma medications. CONCLUSION: Combined phacoemulsification-KDB excisional goniotomy may be an effective and safe alternative to more invasive filtering surgery in glaucoma patients of any stage.

The role of funduscopy in severe thrombocytopenia: A prospective study.

PURPOSE: Platelet transfusions for patients suffering from severe thrombocytopenia are regulated by clinical bleedings and platelet counts. The aim of this study was to assess the prevalence of retinal hemorrhage in patients with hematologic and oncologic malignancies and severe thrombocytopenia, and to determine the benefit of systematic funduscopic examination in this setting. MATERIALS AND METHODS: Hospitalized patients with hematologic and oncologic malignancies having a platelet count less than 25,000 per µL underwent indirect ophthalmoscopy. The prevalence of retinal hemorrhage and its correlation with different patients' characteristics were determined. The decision to transfuse platelets or not following bedside indirect ophthalmoscopy was left at the discretion of the treating physician. RESULTS: A total of 34 severe thrombocytopenic patients were included in the study. The prevalence of retinal hemorrhage was detected in 10 patients (29.4%). No significant correlation was found between the occurrence of retinal hemorrhage and age, platelet count or thrombocytopenia etiology (P>0.05). No significant difference was found concerning the rate of transfusion between those with and without retinal hemorrhage. CONCLUSION: According to our statistical results, retinal hemorrhage is a frequent finding in severely thrombocytopenic patients. Early detection may lead to an increase in the platelet transfusion threshold from to 30,000 per µL offering additional protection against spontaneous bleedings. Funduscopy is a safe and easy exam to perform systematically in patients with severe thrombocytopenia.

Using the First-Eye Back-Calculated Effective Lens Position to Improve Refractive Outcome of the Second Eye.

The present study is a retrospective, monocentric case series that aims to compare the second-eye IOL power calculation precision using the back-calculated lens position (LP) as a lens position predictor versus using a predetermined correction factor (CF) for thin- and thick-lens IOL calculation formulas. A set of 878 eyes from 439 patients implanted with Finevision IOLs (BVI PhysIOL, Liège, Belgium) with both operated eyes was used as a training set to create Haigis-LP and PEARL-LP formulas, using the back-calculated lens position of the contralateral eye as an effective lens position (ELP) predictor. Haigis-CF, Barrett-CF, and PEARL-CF formulas using an optimized correction factor based on the prediction error of the first eye were also designed. A different set of 1500 eyes from 1500 patients operated in the same center was used to compare the basal and enhanced formula performances. The IOL power calculation for the second eye was significantly enhanced by adapting the formulas using the back-calculated ELP of the first eye or by using a correction factor based on the prediction error of the first eye, the latter giving slightly higher precision. A decrease in the mean absolute error of 0.043D was observed between the basal PEARL and the PEARL-CF formula (p < 0.001). The optimal correction factor was close to 60% of the first-eye prediction error for every formula. A fixed correction factor of 60% of the postoperative refractive error of the first operated eye improves the second-eye refractive outcome better than the methods based on the first eye's effective lens position back-calculation. A significant interocular biometric dissimilarity precludes the enhancement of the second-eye IOL power calculation according to the first-eye results.

Salvage of a cartilage framework exposure in total ear reconstruction using a retro-auricular fascia flap with double axial irrigation.

Cartilage framework exposure during total ear reconstruction requires an early salvage procedure and a secure coverage. We present a case that has been successfully covered by a retro-auricular fascia flap and a skin graft. Because we were dealing with a post-traumatic ear amputation with extensive scarring, the flap was designed to include both the retro-auricular artery and the occipital artery for an enhanced vascular security. This flap design may play a more important role especially in post-traumatic ear reconstruction.