Pressure-Induced Stromal Keratopathy after Surface Ablation Surgery.

Introduction: The purpose of this clinical report was to describe an unprecedented case of bilateral pressure-induced stromal keratopathy (PISK) following corneal photorefractive keratectomy, associated with presumed herpetic keratitis, and to present tomographic and biomechanical findings before and after appropriate treatment. Case Presentation: A 33-year-old male patient was referred to our clinic with suspected delayed corneal epithelial healing 3 weeks after an uncomplicated PRK. A central layer of corneal opacity with a presumed fluid-filled interface area was observed upon slit lamp biomicroscopy. Scheimpflug images from the Pentacam® revealed a hyperreflective area beneath the central cornea. Scheimpflug-based corneal tomography, biomechanical assessment using the Pentacam® AXL Wave, and the Corvis ST® were conducted. Goldmann applanation tonometry measured 23/13 mm Hg, while noncontact tonometry intraocular pressure measured with the Corvis ST® (Corvis ST IOPnct) was 40.5/43.5 mm Hg. Treatment with oral valacyclovir, combined with ocular hypotensive therapy, led to a significant reduction in IOP and improved corneal deformation parameters after 1 month. Conclusion: Surgeons should be aware of the inaccuracy of Goldmann applanation tonometry in PISK, which can occur after LASIK or surface ablation.

A Morphometric Study of the Pars Plana of the Ciliary Body in Human Cadaver Eyes.

This study aimed to determine the pars plana length in postmortem human eyes using advanced morphometric techniques and correlate demographics to ocular metrics such as age, sex, ethnicity, and axial length. Between February and July 2005, we conducted a cross-sectional observational study on 46 human cadaver eyes deemed unsuitable for transplant by the SBO Eye Bank. The morphometric analysis was performed on projected images using a surgical microscope and a video-microscopy system with a 20.5:1 correction factor. The pars plana length was measured three times per quadrant, with the final value being the mean of these measurements. Of the 46 eyes collected, 9 were unsuitable for the study due to technical constraints in conducting intraocular measurements. Overall, the average axial length was 25.20 mm. The average pars plana length was 3.8 mm in all quadrants, with no measurements below 2.8 mm or above 4.9 mm. There were no statistically significant variations across quadrants or with age, sex, axial length, or laterality. Accurately defining the pars plana dimensions is crucial for safely accessing the posterior segment of the eye and minimizing complications during intraocular procedures, such as intravitreal injections and vitreoretinal surgeries.

Ocular Biomechanics and Glaucoma.

Biomechanics is a branch of biophysics that deals with mechanics applied to biology. Corneal biomechanics have an important role in managing patients with glaucoma. While evidence suggests that patients with thin and stiffer corneas have a higher risk of developing glaucoma, it also influences the accurate measurement of intraocular pressure. We reviewed the pertinent literature to help increase our understanding of the biomechanics of the cornea and other ocular structures and how they can help optimize clinical and surgical treatments, taking into consideration individual variabilities, improve the diagnosis of suspected patients, and help monitor the response to treatment.

Corneal biomechanics and glaucoma beyond the bidirectional impact of intraocular pressure and corneal deformation response / Biomecânica corneana e glaucoma além do impacto bididirecional da pressão intraocular e da resposta da deformação corneana

ABSTRACT The purpose of this study was to highlight the impact of biomechanical corneal response in available in vivo tonometry methods for glaucoma management. Systematic review of non-contact air-puff tonometers that analyzes the corneal deformation response, with special focus on the investigation of the correlation of derived parameters with intraocular pressure measurements. The two actual and commercially available in vivo corneal tonometers provide promising information about biomechanical characteristics of the cornea and its relation to glaucoma, allowing the development of new protocols to evaluate, diagnose, and manage this disease.

RESUMO O objetivo deste estudo é destacar o impacto da resposta biomecânica corneana em métodos de tonometria in vivo disponíveis para o manejo do glaucoma. Trata-se de revisão sistemática de tonômetros de ar que analisa a resposta à deformação corneana, com foco especial na investigação da correlação dos parâmetros derivados com as medições da pressão intraocular. Os dois tonômetros mais recentes e comercialmente disponíveis fornecem informações promissoras sobre as características biomecânicas da córnea e sua relação com o glaucoma, permitindo o desenvolvimento de novos protocolos para avaliar, diagnosticar e controlar a doença.

Ocular pulse amplitude in patients with asymmetric primary open-angle glaucoma.

AIM: To evaluate ocular pulse amplitude (OPA) using the dynamic contour tonometer (DCT) in patients with asymmetric primary open-angle glaucoma (POAG) and asymmetric intra-ocular pressure (IOP). METHODS: The participants consisted of 48 patients (96 eyes) with asymmetric POAG. Three measurements of IOP and OPA were taken using DCT. The diagnosis of asymmetry required a difference of glaucomatous visual field loss greater than 6 dB in the global index MD and a difference of 5 mmHg in IOP measured by Goldmann tonometry between the more affected and the contra-lateral eye. All participants underwent full ophthalmologic clinical assessment including ultrasonic pachymetry and biometric measurements. Exclusion criteria were corneal diseases or scars, topical or systemic glaucomatous medications, and previous ocular surgery. RESULTS: No difference (p = 0.142) was found between the axial length measurements of the better eyes group (22.95 ± 0.91 mm) and worse eyes group (22.85 ± 0.97 mm). There was a statistically significant difference (p = 0.011) between the central corneal thickness values of the better eyes group (537.08 ± 29.54 µm) and worse eyes group (534.40 ± 29.87 µm). The OPA values of the better eyes group (3.32 ± 1.14 mmHg) were significantly lower (p = 0.001) than those obtained in the worse eyes group (3.83 ± 1.27 mmHg). When correcting the OPA readings by the IOP there was no statistical difference between groups (p = 0.996). CONCLUSION: Higher OPA values were found in eyes with higher IOP levels and advanced glaucoma's lesions in asymmetric hypertensive POAG patients. However, after the OPA correction by the IOP levels there was no more statistical difference between eyes.