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Objective Diurnal birds of prey (raptors) are considered the group of animals with highest visual acuity (VA). The purpose of this work is to review all the information recently published about the visual system of this group of animals. Material and methods A bibliographic search was performed in PubMed. The algorithm used was (raptor OR falcon OR kestrel OR hawk OR eagle) AND (vision OR “visual acuity” OR eye OR macula OR retina OR fovea OR “nictitating membrane” OR “chromatic vision” OR ultraviolet). The search was restricted to the “Title” and “Abstract” fields, and to non-human species, without time restriction. Results The proposed algorithm located 97 articles. Conclusions Birds of prey are endowed with the highest VA of the animal kingdom. However most of the works study one individual or a small group of individuals, and the methodology is heterogeneous. The most studied bird is the Peregrine falcon (Falco peregrinus), with an estimated VA of 140 cycles/degree. Some eagles are endowed with similar VA. The tubular shape of the eye, the large pupil, and a high density of photoreceptors make this extraordinary VA possible. In some species, histology and optic coherence tomography demonstrate the presence of 2 foveas. The nasal fovea (deep fovea) has higher VA. Nevertheless, the exact function of each fovea is unknown. The vitreous contained in the deep fovea could behave as a third lens, adding some magnification to the optic system. pre-print 778 KB

Objective To communicate relevant and striking aspects about the visual system of some close invertebrates. Material and methods Review of the related literature. Results The capacity of snails to regenerate a complete eye, the benefit of the oval shape of the compound eye of many flying insects as a way of stabilizing the image during flight, the potential advantages related to the extreme refractive error that characterizes the ocelli of many insects, as well as the ability to detect polarized light as a navigation system, are some of the surprising capabilities present in the small invertebrate eyes that are described in this work. Conclusions The invertebrate eyes have capabilities and sensorial modalities that are not present in the human eye. The study of the eyes of these animals can help us to improve our understanding of our visual system, and inspire the development of optical devices.

Purpose To evaluate the evolution of visual acuity after enhacement after LASIK performed either with a mechanical microkeratome (MM) or femtosecond laser (FS), up to the third month post-op. Methods Retrospective analysis of 148 consecutive eyes who had LASIK, 125 with femtosecond laser (intralase) and 123 with a mechanical microkeratome (Moria M2), had an enhacement performed between the third and the sixth month post-op. All the surgeries were performed by the same surgeon. All the patients were examined preoperatively, 24 hours, 7 days, one month and three months after the enhancement. Results Both groups had good visual outcomes with no significant differences in visual acuity at the third month. The uncorrected visual acuity (UCVA) was 1.02±0.2 in both groups (p=0.9), the best corrected visual acuity (BCVA) was 1.07±0.1 and 1.09±0.1 for the FS and the MM groups respectively. The safety (1.02±0.1 in the FS group, 1.03±0.1 in the MM group, p=0.7) and efficacy (0.97±0.1 and 0.95±0.1 for the FS and MM respectively, p=0.4) were similar in both groups. Neverthelerss we found a statistically significant difference on UCVA on the first week (0.93±0.1 femtosecond vs 0.98±0.1 microkeratome, p=0.01). Conclusion Visual acuity recovery is slower after enhacement on FS flaps only on the early postoperative period. Probably, there is an increased epithelial damage or a superior inflammatory response due to a more difficult flap-lifting in FS vs a MM cases.

Purpose To compare real-time intraocular pressure (IOP) in LASIK versus Epi-LASIK in porcine eyes during flap creation using the Moria 2 microkeratome and the Moria Epi-KTM epikeratome. Methods Interventional, prospective study of two keratomes: Moria Group (M2) and epipolis laser in situ keratomileusis Group (MEpi-K). These devices were used to create a lamellar corneal or epithelial flap respectively in freshly enucleated porcine eyes. The IOP changes induced by the procedures were recorded using manometry by direct cannulation with a reusable blood pressure transducer connected to the anterior chamber. Results 7 eyes were included for M2 Group and 10 for the MEpi-K Group. In the M2 Group the IOP increased during suction phase to a mean value of 122.53±30.40 mm Hg and to 160.52±22.73 mm Hg during cutting phase (mean time: 21.42±7.48 and 15.71±1.88 secs respectively). In the MEpi-K Group, mean IOP increase was 100.66±18.60 mm Hg during suction phase, 91.38±17.79 mm Hg during cutting phase and 74,37±12.70 during low-back phase (mean time: 25.79±3.44, 33.68±2.81 and 29.74± 3.11 secs respectively). IOP values in both groups showed statistical significant difference in all comparison (p

Purpose: To evaluate corneal structure in keratoconus eyes using “in vivo” laser confocal microscopy. Methods: In this prospective study we evaluated 23 eyes of 12 consecutive patients with keratoconus [6 men and 6 women, mean aged 37,30 ± 9,93; range: 23-52 years]. 23 eyes of normal patient were the control group. Keratoconus were classified in mild ( 55D).We evaluated using laser confocal microscopy the corneal epithelium, Bowman layer and anterior, intermediate and posterior stroma. We quantified the mean density per mm2 of basal epithelial cells, anterior stromal keratocites (50 μm down Bowman layer), intermediate and posterior (50 μm up endothelial cells). All measurements were done by the same masked examiner. Results: Of the 23 eyes, 16 had mid keratoconus , 5 moderate keratoconus and 2 severe keratoconus. Basal epithelial cells density was 5600,22 cel./mm2 ± 975,13. Keratocite density was 391,04 cel./mm2 ± 105,39 in anterior stroma, 353,83 cel./mm2 ± 53,28 in intermediate stroma and 349,43 cel./ mm2 ± 61,34 in posterior stroma. We found a reduction of cellular density in all measurements with a p

Purpose: To analyze corneal aberrometry and visual outcome after implantation of intracorneal ring segments (INTACS) in keratoconus patients. Methods: Corneal aberration was measured in 15 keratoconus eyes pre and post implantation of INTACS. Root Mean Square values (RMS), (Total, RMS for corneal astigmatism and RMS for coma) where recorded for 5, 6 and 7 pupil diameters, and where divided into two groups due to their previous levels of coma and total RMS. Comatic aberration was divided in vertical (Z3-1) an horizontal (Z3+1) Zernicke Coeficcients. All data was recorded pre-op and three months after surgery. Best corrected visual acuity (BCVA), uncorrected visual acuity (UCVA), spherical equivalent and astigmatism where also analyzed. Results: We found statistically significant decrease in spherical equivalent (p