[Corneal wound healing-Pharmacological treatment]. / Wundheilung der Kornea ­ Pharmakologische Therapie.

Physiological wound healing of the cornea is a complex process and involves numerous multifactorial tissue processes. A proper wound healing, especially without the formation of light-scattering scars, is essential to preserve the integrity and function of the cornea. Misdirected wound healing is of vast clinical relevance as it can lead to corneal fibrosis and the loss of optical transparency with subsequent reduction of visual acuity, up to blindness. In addition to the understanding of the pathophysiological mechanisms, the knowledge of therapeutic concepts and options for treating corneal wound healing disorders and fibrosis is essential to counteract a permanent damage of the cornea as early as possible. Nowadays, various pharmacological and surgical options are available for treatment. The decision, appropriate selection and indication for the optimal treatment depend primarily on the genesis and clinical appearance of the corneal wound, fibrosis or scar. The treatment of wound healing disorders ranges from the use of topical therapy and supportive measures up to tissue replacement procedures. As long as the mechanical stability of the cornea is intact and wound healing processes are still ongoing, a pharmacological modulation is reasonable, which is discussed in this article.

Anatomical and functional results after vitrectomy with conventional ILM peeling versus inverted ILM flap technique in large full-thickness macular holes.

BACKGROUND: Aim of the study was to compare success rate and functional outcome following pars plana vitrectomy (PPV) with conventional internal limiting membrane (ILM) peeling versus ILM flap technique for full-thickness idiopathic macular holes (FTMH). METHODS: Retrospective analysis of consecutive eyes with FTMH having undergone vitrectomy with sulfur hexafluoride (SF6) endotamponade 25% at the University Medical Center Rostock, Germany (2009-2020). Eyes were divided according to applied surgical technique (ILM peeling [group P] versus ILM flap [group F]). Inclusion criteria were macular hole base diameters (MH-BD) ≥ 400 µm plus axial length ≤ 26.0 mm. Each group was divided into two subgroups based on macular hole minimum linear diameter (MH-MLD): ≤ 400 µm and > 400 µm. Exclusion criteria were FTMH with MH-BD < 400 µm, trauma, myopia with axial length > 26.0 mm or macular schisis. Demographic, functional, and anatomical data were obtained pre- and postoperatively. Preoperative MH-BD and MH-MLD were measured using optical coherence tomography (OCT; Spectralis®, Heidelberg Engineering GmbH, Heidelberg, Germany). Main outcome parameter were: primary closure rate, best-corrected visual acuity (BCVA), and re-surgery rate. RESULTS: Overall 117 eyes of 117 patients with FTMH could be included, thereof 52 eyes underwent conventional ILM peeling (group P) and 65 additional ILM flap (group F) technique. Macular hole closure was achieved in 31 eyes (59.6%) in group P and in 59 eyes (90.8%) in group F (p < 0.001). Secondary PPV was required in 21 eyes (40.4%) in group P and in 6 eyes (9.2%) in group F. Postoperative BCVA at first follow-up in eyes with surgical closure showed no significant difference for both groups (MH-MLD ≤ 400 µm: p = 0.740); MH-MLD > 400 µm: p = 0.241). CONCLUSION: Anatomical results and surgical closure rate following ILM flap technique seems to be superior to conventional ILM peeling for treatment of FTMH.

Impact of implementation of polymerase chain reaction on diagnosis, treatment, and clinical course of Acanthamoeba keratitis.

PURPOSE: Acanthamoeba keratitis (AK) is a painful and possibly sight-threatening ocular infection. While the correct diagnosis and specific treatment in the early stages significantly improve the prognosis, the disease is often misdiagnosed and in clinical examination confused with other forms of keratitis. Polymerase chain reaction (PCR) for the detection of AK was first introduced in our institution in December 2013 to improve the timely diagnosis of AK. The aim of this study was to assess the impact of implementation of Acanthamoeba PCR on the diagnosis and treatment of the disease in a German tertiary referral center. PATIENTS AND METHODS: Patients treated for Acanthamoeba keratitis between 1st of January 1993 and 31st of December 2021 in the Department of Ophthalmology of the University Hospital Duesseldorf were identified retrospectively via in-house registries. Evaluated parameters include age, sex, initial diagnosis, method of correct diagnosis, duration of symptoms until correct diagnosis, contact lens use, visual acuity, and clinical findings as well as medical and surgical therapy by keratoplasty (pKP). In order to assess the impact of implementation of Acanthamoeba PCR, the cases were divided into two groups (before (pre-PCR group) and after PCR implementation (PCR group). RESULTS: Seventy-five patients with Acanthamoeba keratitis were included (69.3% female, median age 37 years). Eighty-four percent (63/75) of all patients were contact lens wearers. Until PCR was available, 58 patients with Acanthamoeba keratitis were diagnosed either clinically (n = 28), by histology (n = 21), culture (n = 6), or confocal microscopy (n = 2) with a median duration until diagnosis of 68 (18; 109) days. After PCR implementation, in 17 patients, the diagnosis was established with PCR in 94% (n = 16) and median duration until diagnosis was significantly shorter with 15 (10; 30.5) days. A longer duration until correct diagnosis correlated with a worse initial visual acuity (p = 0.0019, r = 0.363). The number of pKP performed was significantly lower in the PCR group (5/17; 29.4%) than in the pre-PCR group (35/58; 60.3%) (p = 0.025). CONCLUSIONS: The choice of diagnostic method and especially the application of PCR have a significant impact on the time to diagnosis and on the clinical findings at the time of confirmation of diagnosis and the need for penetrating keratoplasty. In contact lens-associated keratitis, the first crucial step is to take AK into consideration and perform a PCR test as timely confirmation of diagnosis of AK is imperative to prevent long-term ocular morbidity.

[Corneal wound healing-Pathophysiology and principles]. / Wundheilung der Kornea ­ Pathophysiologie und Grundlagen.

The cornea forms the anterior border of the eye and significantly contributes to a sharp optical image quality on the retina through its transparency, avascular nature and curvature. Because of its anatomical structure and as a barrier to the environment, the cornea is particularly exposed to various external factors, such as injuries and pathogens. A correct wound healing without the formation of light diverging scarring is therefore essential to preserve the integrity and function of the cornea. Misguided wound healing is of outstanding clinical relevance and can lead to corneal fibrogenesis. Corneal fibrosis results in scarring with a loss of optical transparency, which significantly reduces eyesight and can lead to blindness. Understanding the pathophysiological mechanisms of wound healing and fibrogenesis is of great importance for the diagnostics, treatment and evaluation of the subsequent healing process in order to prevent permanent damage as far as possible.

Collagen Remodeling Plays a Pivotal Role in Endothelial Corneal Dystrophies.

Purpose: To elucidate the collagen structure in the Descemet membrane (DM) of the human cornea and to characterize its rearrangement in patients with endothelial corneal dystrophies. Methods: Corneas from nine human donors and dystrophic DMs removed from 16 affected eyes of 13 patients by endothelial keratoplasty (DMEK) were investigated using a correlative RT-qPCR and label-free two-channel multiphoton microscopy (MPM) setup. Although collagen formation was visualized by second harmonic generation, the cellular structure was determined by autofluorescence. Results: The DM of the human donor cornea was characterized by a consistent pattern of fine hexagonal collagen structures that form a supportive scaffold for the endothelial cells. Accordingly, network-forming collagens (8A1 and 8A2) but less fibrillar collagens (only 1A2) were expressed. DMEK resulted in significant (P < 0.0001) improvement of best-corrected visual acuity. In the removed dystrophic DMs, MPM analyses revealed collagen rearrangement in addition to loss of endothelial cells and the development of guttae. MPM analyses of the whole patient's DM demonstrated this collagen remodeling in its entirety and facilitated correlation to Scheimpflug corneal tomography. In most DMs a unique honeycomb collagen network was identified, with distinct bundles surrounding the guttae and correlating with expression of fibrillar collagens (1A1). Conversely, some DMs showed either reduced collagen on MPM and RT-qPCR analysis or diffuse thickening and storage of extracellular matrix. Conclusions: The collagen structure of the DM and its adaptive remodeling in endothelial corneal dystrophies has been characterized for the first time here and will facilitate individual therapeutic approaches.

3D confocal laser-scanning microscopy for large-area imaging of the corneal subbasal nerve plexus.

The capability of corneal confocal microscopy (CCM) to acquire high-resolution in vivo images of the densely innervated human cornea has gained considerable interest in using this non-invasive technique as an objective diagnostic tool for staging peripheral neuropathies. Morphological alterations of the corneal subbasal nerve plexus (SNP) assessed by CCM have been shown to correlate well with the progression of neuropathic diseases and even predict future-incident neuropathy. Since the field of view of single CCM images is insufficient for reliable characterisation of nerve morphology, several image mosaicking techniques have been developed to facilitate the assessment of the SNP in large-area visualisations. Due to the limited depth of field of confocal microscopy, these approaches are highly sensitive to small deviations of the focus plane from the SNP layer. Our contribution proposes a new automated solution, combining guided eye movements for rapid expansion of the acquired SNP area and axial focus plane oscillations to guarantee complete imaging of the SNP. We present results of a feasibility study using the proposed setup to evaluate different oscillation settings. By comparing different image selection approaches, we show that automatic tissue classification algorithms are essential to create high-quality mosaic images from the acquired 3D datasets.