Danson V Muttuvelu

Hypoxia is a key regulator of limbal epithelial stem cell growth and differentiation

The aim of this study was to determine whether the growth and differentiation of limbal epithelial stem cell cultures could be controlled through manipulation of the oxygen tension. Limbal epithelial cells were isolated from corneoscleral disks, and cultured using either feeder cells in a growth medium supplemented with serum (3T3 system) or without feeder cells in a dedicated serum-free medium (EpiLife). During the culture, the cells were maintained either at ambient oxygen tension (20%) or at different levels of hypoxia (15, 10, 5, and 2% oxygen). The effect of oxygen on cell growth, progression through cell cycle, colony forming efficiency (CFE), and expression of stem cell (ABCG2 and p63α) and differentiation (CK3) markers was determined throughout the culture period of up to 18 days. Low oxygen levels favored a stem cell phenotype with a lower proliferative rate, high CFE, and a relatively higher expression of ABCG2 and p63α, while higher levels of oxygen led not only to decreased CFE but also to increased proportion of differentiated cells positive for CK3. Hypoxic cultures may thus potentially improve stem cell grafts for cultured limbal epithelial transplantation (CLET).

Transcriptional dissection of human limbal niche compartments by massive parallel sequencing.

Corneal epithelium is maintained throughout life by well-orchestrated proliferation of limbal epithelial stem cells (LESCs), followed by migration and maturation centripetally towards the ocular surface. Disturbance of LESCs can potentially lead to a blinding condition, which can be reversed by reconstitution of a functional LESC pool. The current clinical procedures are effective to some degree, however, deeper knowledge of the molecular interplay within the limbal niche is necessary to achieve a fully satisfactory patient outcome. The present study was thus undertaken to carry out a comprehensive transcriptome analysis of four distinct human limbal compartments, including basal limbal crypts (BLCs), superficial limbal crypts (SLCs), cornea, and the supporting stroma, with the aid of laser capture microdissection and deep RNA sequencing. The tissue harvest pipeline was rigorously optimized so that the exposure to cold ischemia would be less than five minutes. The global gene ontology analysis confirmed existence of primitive cells in BLCs, migratory and activated cells in SLCs, and differentiated cells in cornea. Interestingly, many significantly upregulated genes in SLCs mapped to processes involved in regulation of vasculature, such as sFLT1. In contrast, BLCs exhibited many genes mapping to neurogenic processes and processes related to cell development. The primitive nature of BLCs was, furthermore, confirmed by the KEGG pathway analysis, and some potential regulators of LESCs were revealed, such as Lrig1 and SOX9. The analysis also yielded comprehensive lists of uniquely expressed genes in both BLCs and cornea, which may be useful to identify possible biomarkers. In conclusion, the current investigation provides new insight into the relationship between distinct cell populations within the limbal niche, identifies candidates to be verified for novel biological functions, and yields a wealth of information for prospective data mining.

Cataract surgery education in member countries of the European Board of Ophthalmology

PURPOSE To address the use of and knowledge about skills assessment and competency-based training in cataract surgery in European Board of Ophthalmology (EBO) member countries. METHODS A survey was emailed directly to all directors of the European societies in ophthalmology. The survey included queries about criteria to undergo training in cataract surgery, regulation of education in cataract surgery, and skills assessment and training methods. In addition, all Danish Eye Departments were further asked to what extent they find assessment tools useful, if competency-based training in cataract surgery would be an improvement, and if an assessment tool would be considered for use in future training of cataract surgeons. RESULTS Training in cataract surgery in EBO countries is very diverse; although some EBO countries consider it mandatory in residency, most do not. In EBO countries where training is mandatory and regulated by the local health authority, the use of skills assessment tools and competency-based education are more prevalent (e.g., U.K., Ireland, Switzerland, and the Netherlands). In Denmark, training in cataract surgery is not mandatory, and none of the eye departments used assessment scores to evaluate their trainees; 63% did not believe that using assessment tools would improve the outcome of surgical training, and less than one-third would consider frequent use of assessment tools in the future. CONCLUSION General unawareness and scepticism toward objective structured assessment of technical skills and a considerable heterogeneity in concept and organization of training in cataract surgery across EBO countries is an issue to address.

Decreased retinal sensitivity in depressive disorder: a controlled study

To compare pupil responses in depressed patients with a seasonal pattern, depressed patients without a seasonal pattern and healthy controls as a function of daylight hours on the testing day.

Paraneoplastic retinopathy associated with occult bladder cancer

The aim was to report the first case of cancer-associated retinopathy (CAR) presenting before bladder cancer diagnosis. A 71-year-old woman with a history of bilateral vision loss underwent subsequent complete ophthalmic examination include a fluorescein angiography, full-field electroretinogram (ERG), serology including serum antibodies for CAR, and positron emission tomography-computed tomography (PET-CT) scan. The patient was diagnosed with bladder carcinoma revealed by PET-CT. Timely recognition of this entity may be crucial for an increased patient survival thus adult onset progressive photoreceptor dysfunction, confirmed by ERG, should alert to a possible remote effect of known or occult malignancy. In the latter, PET-CT may be exploited as a powerful diagnostic tool.

Correlation between retinal vein occlusion and cancer - a nationwide Danish cohort study

To explore the association between retinal vein occlusion (RVO) and incident cancer.

Inconsistent distortion in ultra-widefield fundus image

Editor, W hile the advantages of modern ultra-widefield imaging based on ellipsoidal-mirror-SLO-techniques are evident, these images emphasize the need for raising awareness in Optos image interpretation, particularly when precision and reproducibility of the content is critical, for example, in choroidal naevus follow-up. It is well known from cartography that projecting the surface of a 3D globe to a 2D image causes stretching of the projected image, for example, Greenland and Canada appear larger on the world maps. Similar findings may be assumed in ultra-widefield fundus imaging. There is only one study regarding this entity, and it demonstrates horizontal stretching in Optos images compared to conventional images (Nicholson et al. 2016). However, in their study, the stretching of the image appears to be in the horizontal plane and evenly distributed. We here report a case that demonstrates a nonlinear distortion within the Optos image. A 74-year-old woman presents for choroidal naevus follow-up. It appeared as the choroidal naevus was shrunken at the Optos Image (Fig. 1A) compared to the previous visit (Fig. 1B). Subsequently, traditional fundus colour image (Zeiss FF450plus, Zeiss, Germany) and OCT-image (Heidelberg Spectralis OCT: Heidelberg Engineering, Heidelberg, Germany) were taken. Size and location of the choroidal naevus in the images were compared. In contrast to Optos images, traditional fundus image andOCT scans showed no change in naevus size or location. More detailed examination of the Optos images 1A/1B showed similar optic disk diameters (ODD) (ODDA/ ODDB = 1.00). Image 1A and 1B were further compared by calculating the index-ratio between the distance from the optic disk in image 1A and 1B (ODA and ODB) to the point of venous branching (PVB A–A, B– B), respectively, in image 1A/1B and by calculating the index-ratio between the PVB (A–A, B–B) in image 1A/ 1B. This revealed a highly inconsistent distortion pattern with indexing varying from 1.00 (no difference) to 0.74 (upto 26% difference in|AA?|/| BB?|). The index-ratio is presented in Table 1. These Optos Images (1A and 1B) highlight there is no simple correction factor, as the distortion is inconsistent within the image. This warrants a need for further evaluation and a better understanding of the algorithm in the ultra-widefield imaging system converting the 3-D globe as a 2D image. Finally, we recommend that Optos ultra-wide imaging is not used as the only imaging modality in evaluation and follow-up of intraocular tumours.