Photic maculopathy: A review of the literature (I). / Maculopatía fótica: revisión de la literatura (I).

The human retina, as transducer of light energy, is especially exposed to light toxicity. Solar maculopathy has been the only form of photic maculopathy for millennia, often secondary to the observation of an eclipse. During the last century, technological advances have led to the appearance of new forms of photic maculopathy, related to the exposure to new forms of artificial light, such as welding devices and lasers. In recent years, the general use of laser pointers has led to an upturn in interest in this pathology. The aim of this review is to offer an integrated view of the different types of photic maculopathy. Due to the extension of this topic, the review is presented divided into two parts. In this first part solar maculopathy and welding arc maculopathy are presented.

Photic maculopathy: A review of the literature (ii). / Maculopatía fótica: revisión de la literatura (ii).

The human retina, as transducer of light energy, is especially exposed to light toxicity. Solar maculopathy has been the only form of photic maculopathy for millennia, often secondary to the observation of an eclipse. During the last century, technological advances have led to the appearance of new forms of photic maculopathy, related to the exposure to new forms of artificial light, such as welding devices and lasers. In recent years the general use of laser pointers has led to an upturn in interest in this pathology. The aim of this review is to offer an integrated view of the different types of photic maculopathy. Due to the extension of the topic, the review is presented divided into 2 parts. In this second part, atomic bomb maculopathy, laser maculopathy, iatrogenic forms of photic maculopathy, and foveomacular retinitis are presented.

The visual system of diurnal raptors: updated review. / El sistema visual de las rapaces diurnas: revisión actualizada.

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 acuity¼ OR eye OR macula OR retina OR fovea OR «nictitating membrane¼ OR «chromatic vision¼ OR ultraviolet). The search was restricted to the «Title¼ and «Abstract¼ 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 2foveas. 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.

Nonsurgical Procedures for Keratoconus Management.

OBJECTIVES: To describe the past 20 years' correction modalities for keratoconus and their visual outcomes and possible complications. METHODS: A review of the published literature related to the visual outcomes and possible complications in the context of keratoconus management using nonsurgical procedures for the last 20 years (glasses and contact lenses) was performed. Original articles that reported the outcome of any correction modalities of keratoconus management were reviewed. RESULTS: The most nonsurgical procedure used on keratoconus management is the contact lens fitting. Soft contact lenses and soft toric contact lenses, rigid gas-permeable contact lenses, piggyback contact lens system, hybrid contact lenses, and scleral and corneoscleral contact lenses form the contemporary range of available lens types for keratoconus management with contact lenses. All of them try to restore the vision, improve the quality of life, and delay surgical procedures in patients with this disease. Complications are derived from the intolerance of using contact lens, and the use of each depends on keratoconus severity. CONCLUSIONS: In the context of nonsurgical procedures, the use of contact lenses for the management of keratoconic patients represents a good alternative to restore vision and improve the quality of live in this population.

Surprising characteristics of visual systems of invertebrates. / Curiosidades sobre el sistema visual de los invertebrados.

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 stabilising the image during flight, the potential advantages related to the extreme refractive error that characterises the ocelli of many insects, as well as the ability to detect polarised 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.

Ocular residual astigmatism's effect on high myopic astigmatism LASIK surgery.

PURPOSE: To analyze the effect of ocular residual astigmatism (ORA) on the effectiveness of LASIK for treating high myopic astigmatism. METHODS: This is an observational, cross-sectional study. We studied 116 consecutive myopic eyes with -3 diopters (D) or more of astigmatism that underwent LASIK surgery. The magnitude of uncorrected residual refractive astigmatism 3 months postoperatively was measured. RESULTS: The mean preoperative cylinder was -4.0±0.83 D (range, -7.5 to -3 D) and the mean preoperative ORA was 0.82±0.5 D. The mean residual refractive cylinder 3 months postoperatively was -0.78±0.83 D (range, -3 to 0 D). No correlation was found between ORA and the refractive cylinder 3 months postoperatively (P=0.6). CONCLUSION: In eyes with high myopic astigmatism undergoing LASIK, ORA was not correlated with the residual postoperative cylinder.

[An experimental model to measure real intraocular pressure (IOP) during LASIK]. / Modelo experimental para medir la presión intraocular (PIO) durante LASIK.

PURPOSE: To design a model to measure real IOP during lasik in pig eyes. METHODS: A reusable blood pressure transducer was used. Each eye was placed on a stand with sufficient support for the surgical procedure. The globes were inflated with 5% glucosated solution through the optic nerve to attain an IOP of 10-20 mmHg. A 27-gauge catheter was then inserted from the pars plana to the anterior chamber cavity. Real IOP was transmitted via the catheter liquid column to an external sensor. A suction ring was applied and a flap was created. During the procedure, IOP was registered with the ML110 Bridge Amplifier connected to a baro transducer. RESULTS: Values of real IOP were measured in freshly enucleated pig eyes during the lasik procedure. The model was able to instantaneously register the changes in IOP induced by the application of a suction ring and the creation of a flap in the pig eyes with good reproducibility. At the end of the procedure the IOP values remained stable. CONCLUSIONS: We have developed an experimental model to observe the course of suctioning and changes in IOP simultaneously. This model seems to be accurate in obtaining IOP values from the anterior chamber cavity during LASIK.