Keratoplasty for keratoconus: advantages and disadvantages

Keratoconus is a progressive bilateral corneal ectasia, accompanied by loss of vision due to high irregular astigmatism, which is the leading indication for corneal transplantation. The review presents a variety of surgical corneal transplantation techniques for keratoconus available today and discussed their advantages and disadvantages.

Optimum | Tangible Hydra-PEG™ – Gaining Momentum in the Industry

The issue of hydrophilicity of the surface of gas permeable contact lenses remains one of the persistent problems. Tangible Hydra-PEG™ surface coating is applied to gas permeable contact lenses to significantly improve wettability and wearing comfort. Although it is mainly used to alleviate dry eye symptoms in scleral and corneal lens users, particularly for those patients with corneal ectasia and/or Ocular Surface Disease (OSD), it can be used in other modalities. This article describes the development of the product and describes the benefits of its use in a clinical case.

A Clinical Case of Fitting Scleral Lens for Correction of Pellucid Marginal Degeneration

Background. Pellucid Marginal Degeneration (PMD) is a rare bilateral degenerative corneal disease. It causes corneal ectasia with bilateral, clear, inferior (typically 4 o’clock to 8 o’clock), peripheral corneal thinning. It usually affects about 80% of corneal stroma, which leads to the corneal ectasia above the thinning area as well as provokes the irregular astigmatism and visual impairment that are difficult to correct. Purpose. To study the possibilities of correction and social rehabilitation in a patient with PMD wearing scleral lenses. Materials and methods. The study included a patient with PMD, signs of corneal dysfunction and narrow-angle subcompensated glaucoma in the right eye, and PMD of the cornea resulted in a corneal leukoma – terminal glaucoma in the left eye. In addition to standard ophthalmic methods, we performed corneal topography and optical coherence tomography (OCT). For intraocular pressure measurement, ICARE IOP tonometer was used in several areas of the intact peripheral cornea. Results. Prior to lens fitting, UCVA in the right eye amounted to 0.06. Scleral lens helped achieve a high visual acuity of 0.9–1.0. The lens was well-tolerated by the patient. Conclusion. Scleral lenses may be a good choice for patients with irregular cornea caused by corneal dystrophy. Not only they are easy to use and have a good visual effect, but they also help patients with social rehabilitation.

Bilateral Differential Topography—A Novel Topographic Algorithm for Keratoconus and Ectatic Disease Screening

Purpose: The purpose of this study was to establish a novel bilateral differential topographic algorithm and assess its efficacy for screening of keratoconus and corneal ectasia before corneal refractive surgery.Methods: One hundred and sixty-one consecutive patients (115 men and 46 women, aged 22.8 ± 6.8 years) with keratoconus, including clinical keratoconus, subclinical keratoconus, forme fruste keratoconus (FFK), and corneal ectasia (KC group) and one hundred and seventy-four consecutive patients (97 men and 77 women, aged 25.1 ± 6.7 years) with ametropia (control group) visiting the Eye and ENT hospital of Fudan University from June 2018 to April 2021 were included. Bilateral differential keratometry, elevation, and pachymetry topographies were composed based on raw topographic data obtained by a Scheimpflug imaging anterior segment analyzer. Key bilateral differential characteristic parameters were calculated. SPSS 20 (SPSS Inc., IBM) was used for statistical analyses and the receiver operating characteristic (ROC) curves were used to determine the diagnostic efficacies.Results: Mann-Whitney tests detected that the front keratometry, front elevation, corneal pachymetry, and back elevation maximal, mean, and standard deviation values within a 1.5-mm radius of the bilateral differential topography were all significantly higher in the KC group than in the control group (all p-values <0.001). The front keratometry mean (ΔFKmean) and standard deviation (ΔFKsd) and the front elevation standard deviation (ΔFEsd) and maximal (ΔFEmax) values within a 1.5-mm radius of the bilateral differential topography yielded the four highest accuracies (area under the ROC curve = 0.985, 0.985, 0.984, and 0.983, respectively) for discriminating KC cases (including FFK cases) from normal cases. Cut-off values of 0.75 diopters (D) for the ΔFKmean, 0.67 D for the ΔFKsd, 2.9 μm for the ΔFEsd, and 14.6 μm for the ΔFEmax had the highest sensitivities (95.7, 95.0, 96.9, and 95.0%, respectively) and specificities (96.0, 97.7, 94.8, and 95.4%, respectively).Conclusion: Bilateral differential topographic parameters may be efficient for the early detection of keratoconus and corneal ectasia secondary to corneal refractive surgery. This bilateral differential topographic algorithm may complement conventional diagnostic models by improving the sensitivity and specificity of screening for early keratoconus and ectasia before corneal refractive surgeries.

Current and new indications for corneal cross-linking in the therapy of corneal diseases

Corneal collagen cross-linking, a technique used in ophthalmology, involves the creation of new bonds between collagen fibers, thus leading to stabilization and corneal stiffening. The most common indication for corneal collagen cross-linking procedures is to prevent the progression of corneal ectasia,\ i.e., keratoconus, pellucid marginal degeneration, and ectasia after corneal refractive surgery. Clinical data also indicate that it is effective in the treatment of bacterial corneal infections and bullous keratopathy. Corneal collagen cross-linking was shown to inhibit the progression of corneal ectasia, and the treatment commonly leads to the improvement in visual acuity, decreases the maximum keratometry values, and improves the corneal topography image. In addition, it is possible to avoid or postpone the need for more complex and invasive surgery.

Simultaneous transepithelial topographic-guided laser and cross-linking to correct irregular astigmatism in a pediatric patient

Purpose: To evaluate an original approach for treating corneal ectasia and irregular astigmatism secondary to penetrating trauma in a pediatric patient. Case report: An 11 year old patient had a penetrating trauma in right eye when he was two and the refractive error was +1.50 diopters sphere −6.00 diopters cylinder axis 95°. To correct irregular astigmatism, the patient underwent simultaneous transepithelial topographic-guided laser Central Corneal Remodeling (CCR) and Corneal Cross-linking (CXL) in the attempt to regularize corneal ectasia and to improve the quality of vision. Uncorrected and Corrected Distance Visual Acuity were measured using Efficacy and Safety indexes; objective and subjective qualities of vision were evaluated using respectively corneal morphological irregularity index and National Eye Institute Visual Function questionnaires. Conclusions: Twelve month follow up suggests that simultaneous CCR and CXL could be effective to improve the quality of vision and to halt the progression of post-traumatic ectasia in pediatric patients.