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Background: Keratoconus is a contraindication for photorefractive keratectomy (PRK). In the recent decade, some efforts have been made to perform PRK in patients with keratoconus whose corneas are stable naturally or by doing corneal collagen crosslinking. These studies have suggested residual central corneal thickness (CCT) ≥450 μm. Aims: The aim was to evaluate the long-term outcomes of PRK in patients with mild to moderate keratoconus in patients older than 40 with residual CCT ≥ 400 μm. Settings and Design: This prospective study was conducted in our Cornea Research Center, Mashhad, Iran. Materials and Methods: Patients over 40 years old, with a grade I/II keratoconus without progression in the last 2 years were recruited. Patients with a predicted postoperative CCT < 400 μm were excluded. PRK with tissue saving protocol was performed with Tecnolas 217 Z. Mitomycin-C was applied after ablation. The final endpoints were refraction parameters the last follow-up visit (mean: 35 months). Paired t-test and Chi-square were used for analysis. Results: A total of 38 eyes of 21 patients were studied; 20 eyes (52.6%) with a grade I and 18 eyes (47.4%) with grade II keratoconus. The mean uncorrected visual acuity, best corrected visual acuity (BCVA), spherical equivalent, cylindrical power and keratometric readings were significantly improved at the final endpoint compared to preoperation measurements (P < 0.001). Two eyes (5%) lost two lines of BCVA at the final visit. No case of ectasia occurred during the follow-up course. Conclusions: PRK did not induce keratoconus progression in patients older than 40 with a grade I/II keratoconus. Residual CCT ≥ 450 μm seems to be sufficient to prevent the ectasia.

We report a case of ocular tuberculosis (TB) which initially presented with disc edema and was mistaken for optic neuritis. With no definite pathology being identified, the patient was treated on the lines of optic neuritis with intravenous (IV) steroid with beneficial effect. Ocular TB was suspected when he presented later with a subretinal abscess. Based on positive Mantoux, QuantiFERON TB gold results and radiographic findings, a diagnosis of subretinal abscess of presumed tubercular etiology was made. The patient was successfully treated with anti-tubercular therapy. To the best of our knowledge, this is the first case report of ocular TB presenting as disc edema followed by subretinal abscess.

A 13-year-old male patient came with diminution of vision in right eye for last 10 days. His best-corrected visual acuity (BCVA) was 20/120 OD and 20/30 OS. Anterior segment OU was normal. Dilated fundus OU showed multiple serous retinal detachments, elevation of the peripapillary retinochoroidal layer and hyperemia of optic nerve head [Fig. 1]. Spectral domain optical coherence tomography (SD-OCT) and combined fluorescein-indocyanine green angiography (FA-ICGA) confirmed the diagnosis of Vogt–Koyanagi–Harada (VKH). SD-OCT showed multilobular serous retinal detachment, subretinal septas, and hyperreflective dot reflexes in subretinal fluid [Fig. 2]. Early-phase FA showed multiple points of dye leakage at the level of the retinal pigment epithelium (RPE), and late-phase FA showed pooling of dye [Fig. 3]. ICGA revealed multiple hypofluorescent dark spots during the early and late phase [Fig. 3]. Following the course of intravenous pulse therapy and oral steroids, BCVA improved to 20/20 OU with resolution on OCT after 1-month [Fig. 4]. Figure 1 Fundus photograph of OD (a) and OS (b) showing multiple serous retinal detachments, elevation of the peripapillary retinochoroidal layer, and hyperemia of optic nerve head Figure 2 Spectral domain optical coherence tomography of OD (a) and OS (b) showing multilobular serous retinal detachment in OU, subretinal septas (1) (c) and hyper-reflective dot reflexes (2) (d) seen in OD Figure 3 Fluorescein angiogram early phase of OD (a) and OS (c) showing multiple pinpoint leakage and late phase of OD (e) and OS (g) showing pooling of dye. Indocyanine green angiography OU (b, d, f, h) showing hypofluorescent dark spots in both early (b and ... Figure 4 Spectral domain optical coherence tomography 1-month post steroid treatment of OD (a) and OS (b) showing resolution

In the early visual system, regarding the detection of a visual event, local motion information is pre-processed in the Magnocellular pathway, while it has been shown that the Koniocellular pathway also plays an important role, providing a global a-priori estimation about such a kind of information processing. However, the functional interplay between these two parallel pathways remains partially understood. To fill this gap, we investigate, through simulations, the impact of the multi-scale characteristics of the Konio pathway in the Magno-driven thalamocortical system of the mammal. We propose a systemic retino-thalamo-cortico-collicular model, including feedforward, feedback and inhibitory connections. In order to provide a discriminative framework, the model implements minimal algorithms, such as spatio-temporal filters and dynamic neural fields, and is fed with a sequence of images. Our results show that the multi-scale interactions between both pathways, integrating local and larger image cues, account for target discrimination, selection and tracking in the presence of threats or targets. This approach proposes an innovative answer to the interplay issues between these pathways, and it is generalizable to other visuo-motor functions.

Survival is one of the evolutionary priorities for every species on Earth. It is strongly linked to making good decisions, even if these are unconsciously made. In the visual system, interactions between conscious and unconscious processing have been discussed, depending on the main two information ows originating from the retina: the Parvo and Magno pathways. We consider here a possible role of the Konio pathway; less studied and with di erent characteristics, such as large receptive elds for global complex event detection, and di use projections which may allow to quickly inform several areas in the brain of something im- portant present in the visual world. To test these hypotheses, we developed a computational systemic model of the early visual system proposing one type of Konio cells, which respond to certain spectral patterns and change the dynamics of the rest of the system accordingly. When examining the model's responses to static inputs, we observe that the system exhibits desirable reactions, together with time cost and e ciency characteristics. We also discuss the implications of the hypotheses for more complete survival and decision making processes, as the Konio pathway may only be a foundation stone for them in terms of evolution., La survie est l'une des priorités évolutives pour toutes les espèces sur la Terre. il est fortement liée à prendre les bonnes décisions, même si elles sont inconsciemment fait. Dans le système visuel, les interactions entre traitement conscient et inconscient ont été discutés, selon les deux principales informations ux en provenance de la rétine: les voies Parvo et Magno. Nous considérons ici un possible rôle de la voie Konio;? moins étudiées et avec di érentes caractéristiques, telles que grands champs récepteurs pour la détection événement mondial complexe et di? utiliser des projections ce qui peut permettre d'informer rapidement plusieurs zones dans le cerveau de quelque chose im- présente important dans le monde visuel. Pour tester ces hypothèses, nous avons développé un calcul modèle systémique du système visuel au début de proposer un type de Konio cellules qui répondent à certains modèles spectraux et changer la dynamique du reste du système en conséquence. Lors de l'examen des réponses du modèle à entrées statiques, nous observons que le système présente des réactions souhaitables, ainsi que avec des caractéristiques de coût et de temps e cacité?. Nous avons également discuter des implications des hypothèses de survie plus complet et le processus décisionnel, comme la voie Konio ne peut être qu'une première pierre pour eux en termes d'évolution.

Context: Sunglasses should follow minimum requirements to sufficiently protect eyes. It is not known whether all items obtainable from the market are appropriately designed. Aims: To compare ultraviolet (UV)-protective properties of commercially available sunglasses obtained from authorized and unauthorized Iranian sellers. Settings and Study Design: An analytic-descriptive study performed in a metropolitan area (Tehran). Materials and Methods: Using a UV-visible standard spectrophotometer, the percentage transmittance was scanned between 280 and 400 nm in 348 pairs of nonprescription sunglasses (price range: 20–80 US$) obtained anonymously and randomly from authorized (permitted by the Ministry of Health, 189 pairs) and unauthorized (159 pairs) sellers in the Iranian capital city, Tehran. The Australian/New Zealand Standard (AS/NZS) and the American National Standards Institute [ANSI] standards were followed. Statistical Analysis: Chi-square test, independent samples t-test or Mann–Whitney U-test. Results: UV-protective properties of the sunglasses obtained from authorized sellers complied with AS/NZS and ANSI guidelines in 92.6% and 95.2% of items, respectively. The corresponding rates for sunglasses obtained from unauthorized sellers were 0% and 8.2%, respectively (P < 0.001 for both). The rate of defective polarizing capability of lenses was 27.4% in sunglasses obtained from authorized sellers versus 90.4% in sunglasses obtained from unauthorized sellers (P < 0.001). Neither brand nor price played significant contributions to UV protection/lens polarizing capability of sunglasses obtained from authorized sellers. Conclusions: Sunglasses provided by unauthorized sellers are alarmingly unreliable and could be potentially hazardous for the eye. Brand and price do not guarantee optimal protection against UV radiation or polarizing performance of the lens.

The information generated by cone photoreceptors in the retina is compressed and transferred to higher processing centers through three distinct types of ganglion cells known as magno, parvo and konio cells. These ganglion cells, which travel from the retina to the lateral geniculate nucleus (LGN) and then to the primary visual cortex, have different structural and functional characteristics, and are organized in distinct layers in the LGN and the primary visual cortex. Magno cells are large, have thick axons and usually collect input from many retinal cells. Parvo cells are smaller, with fine axons and less myelin than mango cells. Konio cells are diverse small cells with wide fields of input consisting of different cells types. The three cellular pathways also differ in function. Magno cells respond rapidly to changing stimuli, while parvo cells need time to respond. The distinct patterns of structure and function in these cells have provided an opportunity for clinical assessment of their function. Functional assessment of these cells is currently used in the field of ophthalmology where frequency-doubling technology perimetry selectively assesses the function of magno cells. Evidence has accrued that the three pathways show characteristic patterns of malfunctions in multiple sclerosis, schizophrenia, Parkinson's and Alzheimer's diseases, and several other disorders. The combination of behavioral assessment with other techniques, such as event related potentials and functional magnetic resonance imaging, seems to bear promising future clinical applications.