vol. 10 núm. 2 (2012)

<em><strong>Objective:</strong></em> To compare the physiological and geometrical parameters of the Snellen E and Landolt C optotypes, through calculations and conceptual arguments, to formulate the Guerrero’s Arorradial Stimulus (GAS), based on the angular principle of the former and Landolt’s concentric arrangement. <em><strong>Methodology:</strong></em> It was based on a literature review of visual acuity, physiological basis, geometric-trigonometric calculation and anatomical principles applicable to the design of stimuli. The analysis revealed common elements and differences of the printed area and the perimeter area of the compared stimuli and made it possible to formulate a EAG matrix with homogeneous patterns of foveolar stimulation. <em><strong>Results:</strong></em> Common elements of angular configuration of the stimuli and differences in their morphological perimeter and geometric parameters were found. This suggests the reliability of the concentric matrix, which stimulates in a manner consistent with the anatomical distribution of photoreceptors and presumably provides greater reliability of visual responses. Conclusions: Perimeter and geometric differences found between alphanumeric stimuli of the same trial suggest that directional concentric tests gather the conditions of stimulation of homogeneous retinal areas to promote answers based on optical discrimination rather than readability. The GAS could become a modified alternative of the Landolt stimuli, which, by including radial elements that confer directionality to the stimulus and distractors, make it possible to conduct a qualitative study of refractive astigmatism and simulation.

Pituitary adenoma is a tumor with a diameter greater than 10 mm located in the pituitary gland, with a prevalence of 0.20 % in unselected living population. Clinical manifestations include visual disturbances such as visual field defects due to displacement of the optic chiasm from its normal position. The prevalence of visual field defects varies from 32% to 96%, and bitemporal hemianopsia is typically found. These lesions rarely have a full recovery, and so these patients are categorized as low vision patients according to the World Health Organization; hence the importance of knowing what the optometrist intervention and management are in such cases.

Morphological and physiological changes induced by contact lens (CL) are mainly due to hypoxia, mechanical trauma and toxicity associated with time of use of CL. <em><strong>Objective:</strong></em> To determine changes in the ocular surface and tear film during 30 days of daily use of hydrogel and silicone hydrogel CL. Materials and <em><strong>Methods:</strong></em> 20 individuals, novices in the use of CL signed an informed consent and were adapted with Lotrafilcon A and Vasurfilcon A. Conjunctival hyperemia, Schirmer I, TBUT, corneal staining and comfort were assessed before adaptation and during each check-up (4 and 8 hours, day 3, 7, 11, 15, 19, 23, 27 and 30). The Wilcoxon rank test (IC 95 %), the Mann/Whitney test (IC 95 %) and the Spearman correlation were used. <em><strong>Results:</strong></em> Alterations were evident in all tests studied after 4 hours of use of the two lenses. The greatest decrease (p < 0.05) in the tear film quality was on day 3 of use of Lotrafilcon A and Vasurfilcon A (4.5 s and 5.5 s, respectively) and in the quantity of the tear film was on day 30 (12 min/5 min and 9 min/5 min, respectively). There was a gradual increase in the percentage of patients with corneal staining and with conjunctival hyperemia during the 30 days. There were no statistical differences (p > 0.05) or clinically significant differences between the two groups of lenses. Conclusions: Soft CL with high and low Dk/t during 30 days of daily use cause significant changes in the ocular surface and tear film, without showing any differences among the changes generated by the two types of lenses.

The stereopsis test reports on the quality of the patient’s binocular vision and provides guidance on the existence and severity of binocular suppressions. <em><strong>Objective:</strong></em> To determine the sensitivity and specificity of the Random Dot test with Lea symbols in preschool children from the city of Bucaramanga, between August 2009 and April 2010. Methodology: The tests were applied to 349 children. The Randot® Preschool stereoscopic test was used as reference, confronted with the new Random Dot test with Lea symbols. Two clinical observers were responsible for performing a different test each. <em><strong>Results:</strong></em> A sensitivity of 79.31 % and a specificity of 80 % were observed for the Random Dot Test with Lea Symbols. Positive Predictive Value (PPV): 26.44 %; Negative Predictive Value (NPV): 97.7 %. Conclusions: The Random Dot test with Lea symbols does not represent a reliable value to use as single visual screening test for the detection of binocular vision disturbances. The low prevalence (8.31 %) of the condition in this study increases its NPV. This, together with its high specificity, makes the test very efficient when it comes to confirming the likelihood of not having the disorder when a different test has already classified it with normal results.

This paper reviews the market of biotechnological drugs that show a higher collection to the General Social Security System in Health, according to the demographic and epidemiological profile of the Colombian population. It also highlights the importance of competition in the pharmaceutical biotechnology industry by granting greater access to the population, reducing the prices of these products and, consequently, favoring the health sector finances.

As part of the Applicability of the Integrated Health Services Networks research Project, the concepts of territory, population and health are reviewed, as elements to be considered in the planning of health services. Territory is constituted in a dynamic and homogeneous unit in relation to the population that inhabits it and, as a result of interactions between people and their physical, economic and social environment, a culture is developed and different degrees of wellness are achieved. Population, understood as an organized cluster of human beings, conceptualizes health and expresses their needs and related expectations according the prevailing culture in a territory. This can be expressed from not being sick to considering it enforceable as a right related to decent living conditions. Formal and informal institutions in each region are also an expression of the culture of said population and the state’s ability to organize them in search of the highest standards of welfare for its inhabitants. In Colombia, regional differences are recognized as elements to be considered in the development plans and different territorial units from the traditional political-administrative divisions can be formed. In the case of the country’s health sector, the organization of the system independently from the territories achieves an improvement in health insurance; however, at the same time it causes difficulties in public health and access to some critical services such as perinatal health.

Retinitis pigmentosa refers to a heterogeneous group of genetic eye diseases where rods or cones are predominantly affected. Generally, the different forms of retinitis pigmentosa are based on a progressive degeneration of the neuronal photoreceptor, which is known for varied visual disabilities. Sometimes patient may not become visually limited or legally blind until their adult age, or they maintain a fairly acceptable vision for their entire lives. Other people become completely blind at an early age, during their middle childhood. Even though there are no efficient treatments for retinitis pigmentosa, we have several options for the future for this type of patients, which are currently under study. Nowadays a multidisciplinary approach is required that allows using the visual remnant and improvement in the daily activities of the patient.

Cigarette consumption is a risk factor for cardiovascular, pulmonary, skin and mucous diseases. <em><strong>Objective:</strong></em> To evaluate the quality and quantity alterations of the tear film and ocular surface in active smokers and non-smokers. Materials and <em><strong>Methods:</strong></em> Observational-transversal study. Thirty smoking individuals and 30 non-smokers between the ages of 18 and 40 were included. A background survey was applied, and those who met the inclusion criteria signed the informed consent, and they were submitted to BUT, Schirmer with anesthesia, fluorescein staining and impression cytology. The Mann-Whitney, Chi-squared and prevalence ratio (PR) tests were performed. <em><strong>Results:</strong></em> A statistically significant decrease in the quality of the tear film (p = 0.000) and significant increase in squamous metaplasia (p = 0.001) was found in the smokers’ group compared to the group of non-smokers. The prevalence of alterations in the tear film was 76.7 % in smokers (Quantity: 20 % and quality: 76.7 %). 60 % showed a change in the ocular surface (cornea: 10 % and squamous metaplasia: 56.7 %). A PR of 1.5 (95 % CI 0.94-2.0) was established between the habit of smoking and BUT, and a PR = 2.3 (95% CI 1.8-2.9) between the habit of smoking and degree of conjunctival squamous metaplasia. Conclusions: Cigarette consumption was associated with a decrease in the quality of the tear film and the increased conjunctival squamous metaplasia.

Mitochondrial diseases can affect patients in a systematic or organic way. A type of condition is Leber’s hereditary optic neuropathy, which causes atrophy of the optic nerve and causes a reduction of the visual field and visual acuity. On occasion, this disease does not show significant findings in the fundus and it is necessary to further explore it as completely as possible in order to find the problem. In this paper we will find the way in which the patient was handled from the time of the probable diagnosis until its corroboration and the latest information about the disease.

A case is presented of a patient who suffered an ocular chemical burn by alkalis (lime) in the right eye, treated for cornea service and external diseases with subconjunctival bevacizumab injection and subsequent autologous limbal cell transplant. The evaluation by contact lens service, 4 years later, revealed decreased visual acuity, high irregular astigmatism and high order corneal aberrations that could not be corrected with glasses; likewise, biomicroscopy showed conjunctivalization between 3 and 9 in the upper region with diffuse opacity of the cornea, as well as neovascularization and severe dysfunction of the lacrimal system. As a result, treatment was performed as an adaptation of a support scleral lens in the affected eye, which achieved a recovery in visual acuity, decreased corneal optical aberrations of higher order and forming of a moist chamber for lenscornea interface, which improved the optical regularization of the ocular surface. The patient was functionally and therapeutically rehabilitated through scleral lens adaptation, also called Boston keratoprosthesis of the ocular surface.

The association between the optical parameters and the axial length of the eyeball gives the refractive status in children at birth, which changes with the child’s development until emmetropization. <em><strong>Objective:</strong></em> To determine the corrected refractive status in premature infants of three to four months of age in the Madre Canguro Integral Program at Hospital San Ignacio. Materials and <em><strong>Methods:</strong></em> Medical records of 4908 patients seen between July 1, 2004 and June 31, 2009 were reviewed. <em><strong>Results:</strong></em> 1731 records met the inclusion criteria (52.3 % men, and 47.7 % women). The average gestational age was 34 weeks (Q 4); the average weight at birth was 1880 grams with (Q 570). The refractive state was of 67.26 % for hyperopic astigmatism, and when classified into 64 categories, this defect represented 8.55 % (category 14 with +3.00 to +3.75 spheres, with -1.00 to -1.75 cylinders). No statistically significant association was found between the refractive error and weight at birth (p = 0.08), gestational age (p = 0.582), Luchenco classification (p = 0.968) and oxygen delivery (p = 0.568). Conclusions: The most frequent refractive error in premature babies is hyperopic astigmatism, which coincides with the emmetropization process; there is no correlation between the child’s maturity at birth and the degree of hypermetropy and no correlation was found between oxygen level and degree of ametropia.