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Introducción. la alergia a la leche de vaca (aplv) es un problema sanitario global. Su diagnóstico adecuado y su seguimiento son esenciales ya que la leche de vaca es un alimento importante en la dieta de muchos lactantes. los desafíos orales doble ciego controlados por placebo (ddcpc) son la herramienta ideal para el diagnóstico y seguimiento de las alergias alimentarias. este estudio describe las características evolutivas de pacientes con aplv y las posibles variables que la pudieran modificar. material y métodos. Se estudiaron pacientes con diagnóstico de aplv previo con desafíos abiertos. Se catalogaron las reacciones de acuerdo a la normativa dracma. positivas fueron las pruebas en las que se presentaron alteraciones clínicas o variaciones hemodinámicas. negativas fueron aquellas en las que el paciente toleró la leche. Se consideraron edades de inicio y de realización del ddcpc, sexo y patología de aplv. resultados. Se estudiaron 106 pacientes (50 masculinos, 56 femeninos), promedio edad de inicio de síntomas 5,31 m (rango: 1-48 meses) y al procedimiento 23,14 m (5 meses - 5 años), y 13 pruebas positivas. un conjunto se refirió al mecanismo fisiopatológico y se dividió en ige mediadas (n=55) con 8 pruebas positivas y mixtas/celulares (n=51) con 5 pruebas positivas. otro conjunto fueron no gastrointestinales (n=61) con 7 pruebas positivas y gastrointestinales (n=45) con 6 pruebas positivas. todos los grupos fueron similares en cuanto a las variables demográficas. el sexo masculino y el diagnóstico de anafilaxia fueron factores de riesgo para no resolver su aplv (p=0,0125 y p=0,002 respectivamente). conclusiones. el momento de resolución de la aplv es independiente del mecanismo fisiopatológico subyacente o la edad de inicio de los síntomas. en general resuelven el problema de manera espontánea hacia los dos años de vida en más de un 87% de los casos. el sexo masculino (en ige mediadas) y el antecedente de anafilaxia podrían ser factores de riesgo para tener menos probabilidades de resolver la APLV. (AU)

Introduction: cow´s milk allergy (cma) is a global health issue. a proper diagnosis and follow up become essential. double blind placebo controlled challenges (dbpcc) is the gold standard for this purpose. this paper describes clinical evolution and characteristics of cma, as well as variables that may modify the affection course. methods & material: a group of patients, with a previous diagnosis of cma by open challenges, has been studied and its results cataloged according to dracma guidelines. tests with hemodynamic changes or clinical symptoms were considered as positives, while those with no clinical reaction were considered as negatives. variables involved were: age of symptoms starting, age of dbpcc performing, gender and cma clinical manifestations. results: 106 patients has been studied (50 male, 56 female), with a median age of 5,31 mo (range 5 ­ 48 mo) at the starting symptoms, and a median age of 23,14 mo (range 5 mo ­ 5 y) at the performing of dbpcc. 13 tests were negative. as regards to the different immune mechanisms, 55 were ige dependent (8 negative), and 51 were mediated by mixed/cellular (5 negative). patients were divided into two groups: with gastrointestinal symptoms (n=45) and with no gastrointestinal symptoms (n=61). they showed 6 and 7 negative results, respectively. all groups were similar. male gender, and anaphylaxis diagnosis turned out to be risk factors not to resolve cma (p=0,0125 and p=0,002 respectively). conclusions: cma resolution is independent of the immune mechanisms involved or the age of its symptoms starting. cma is solved spontaneously towards the age of two in 87% of the cases. male gender, and anaphylaxis may become risk factors not to resolve cma.(AU)

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PURPOSE: To describe 7 patients who developed ectasia following laser in situ kerato-mileusis (LASIK). SETTING: Instituto de la Visión, Buenos Aires, Argentina. METHODS: In this retrospective study of 7 patients, visual acuity, refraction, pachymetry, and corneal topography were examined before and after the refractive procedure and the occurrence of ectasia. RESULTS: Two of the 7 patients required penetrating keratoplasty. Ectasia developed within a mean of 1.02 years +/- 0.31 (SD). The clinical evolution of ectasia and the potential physiopathogenic causes of ectasia are described. CONCLUSION: Ectasia should be considered a potential complication of LASIK that is closely related to corneal thickness, but another variable, the optical zone diameter, should also be considered.

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PURPOSE: To evaluate laser in situ keratomileusis (LASIK) cases in which a customized ablation assisted by corneal topography was performed. SETTING: Instituto de la Visión, Buenos Aires, Argentina. METHODS: The study group comprised 23 cases with asymmetrical corneas; 17 had myopia and 6, hyperopia. Visual acuity, spherical equivalent (SE), and cylinder vectorial change measurements, along with keratometry and corneal topography, were performed in all cases preoperatively and postoperatively. RESULTS: In the myopic cases, the mean preoperative SE was -4.92 diopters (D) +/- 2.46 (SD); it was -0.38 +/- 0.66 D after a mean follow-up of 4.41 +/- 2.32 months. In the hyperopic cases, the preoperative SE was +3.54 +/- 1.57 D; it was +0.33 +/- 0.50 D after a mean follow-up of 3.42 +/- 3.23 months. Cylinder vectorial change, visual acuity, and the number of visual acuity lines gained or lost were also evaluated in both groups. CONCLUSION: Although some features of our algorithm for corneal-topography-assisted customized ablations should be modified, the results of our treatment of cases with asymmetrical astigmatism were encouraging.

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PURPOSE: There are many different excimer laser devices available for photoablative refractive surgery. Smoothness of ablation may vary with different excimer lasers systems. METHODS: Ablations were performed on polymethylmethacrylate (PMMA) plates of 8 x 4 x 0.5 cm, with four different excimer lasers: VISX-Star, Coherent Schwind Keratom I/II, Chiron Technolas Keracor 117C (Plano Scan), and the Nidek EC-5000, to determine and compare the homogeneity and smoothness of the surface. Ten -3.00 D samples, ten -6.00 D samples, and ten -9.00 D samples were ablated with each laser. The PMMA discs were examined with optical microscopy, documented by photographs, and each sample was measured quantitatively using a Hommel-Werkel rugosimeter. We used the same PMMA material throughout. RESULTS: Statistically significant differences in smoothness were found between the Chiron Technolas 117C and the VISX-Star, Nidek and VISX-Star, and Coherent Schwind and VISX-Star in the homogeneities achieved by ablating -3.00 D. Ablations of -6.00 D resulted in homogeneities that were statistically significantly different: Chiron Technolas 117C with the other three devices, the Nidek EC-5000 with the VISX-Star, and the Coherent-Schwind with the VISX-Star. In the ablations for -9.00 D, statistically significant differences in homogeneity were found between the Chiron Technolas 117C and Nidek, between the Chiron and VISX-Star, between the Coherent Schwind and VISX-Star, and between the Nidek and VISX-Star. The laser with the scanning spot system was smoother. CONCLUSION: Scanning spot technology produced smooth ablations even up to -9.00 D.

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PURPOSE: To compare the results of hyperopic laser in situ keratomileusis (LASIK) with a 5.9 mm optical zone (OZ) with those with smaller zones (4.4 to 5.5 mm). SETTING: Instituto de la Visión, Buenos Aires, Argentina. METHODS: The results of LASIK with a 5.9 mm OZ (147 cases) were compared with those in a previously reported group treated with OZs of 4.4 to 5.5 mm (679 cases). In the 5.9 mm group, 31.3% (46 eyes) had low hyperopia, 46.9% (69 eyes) had moderate hyperopia, and 21.8% (32 eyes) had high hyperopia. In the smaller OZ group, follow-up was 1 month in 79.4% (539 eyes), 3 months in 75.5% (501 eyes), 6 months in 68.5% (465 eyes), and 1 year in 38.3% (260 eyes). The hyperopic population studied was divided into 3 subgroups based on the preoperative spherical equivalents of the manifest refraction: subgroup A, low hyperopia: < or = +2.0 diopters (D); subgroup B, moderate hyperopia: +2.0 to +3.0 D; and subgroup C, high hyperopia: > +3.0 D. The following parameters were measured postoperatively: uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refraction (evolution and distribution), and visual acuity lines gained and lost. RESULTS: The preoperative mean spherical equivalents in the 5.9 mm OZ group were +1.47 +/- 0.41 (SD) (subgroup A); +2.98 +/- 0.41 (subgroup B); and +5.13 +/- 0.61 (subgroup C). In the smaller OZ group, they were +1.31 +/- 0.74, +2.56 +/- 0.28, and +5.28 +/- 0. 69, respectively. At 12 months, the distribution of eyes in the 5.9 mm OZ group with refractions within +/-1.0 D were as follows: subgroup A, 100%; subgroup B, 100%; and subgroup C, 94.2%. In the smaller OZ group, the distributions were 100%, 95.3%, and 71.4%. In the 5.9 mm and the smaller OZ groups, the UCVA was 20/40 or better in 92.0% and 81.8% of eyes, respectively, in subgroup A; 94.6% and 100%, respectively, in subgroup B; and 76.5% and 77.9%, respectively, in subgroup C. The percentage of eyes with 0 +/- 1 line of BCVA 12 months after the procedure was also determined in the 5.9 mm OZ group and compared with the percentages in the smaller OZ group. CONCLUSION: Results of hyperopic LASIK with a 5.9 mm OZ in eyes with low, moderate, and high hyperopia are more stable, predictable, and safe than those in eyes with OZs smaller than 5.9 mm.

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The visual performance tester (VPT), a device that uses patient response time as a variable to assess visual power, is described. Results in 126 emmetropic eyes that had not had surgery are presented. The VPT provides more complete and accurate information about visual performance than the standard visual acuity examination because the device considers all variables involved in visual function results.

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PURPOSE: To analyze the effectiveness of laser in situ keratomileusis (LASIK) and arcuate keratotomy (AK) to treat simple myopic, compound myopic, and mixed astigmatism. SETTING: Instituto de la Visión, Buenos Aires, Argentina. METHODS: This retrospective nonrandomized study comprised 821 cases treated with LASIK and 46 cases treated with AK. Patients were divided into 4 groups, which had the following preoperative cylinder corrections: simple myopic astigmatism (Group 1) (LASIK: n = 76, -3.91 diopters [D] +/- 1.29 [SD]; AK: n = 5, -3.85 +/- 0.65 D); compound myopic astigmatism up to 2.00 D (Group 2) (LASIK: n = 401, -1.69 +/- 0.76 D; AK: n = 14, -1.48 +/- 0.41 D); compound myopic astigmatism over 2.00 D (Group 3) (LASIK: n = 253, -3.61 +/- 0.89 D; AK: n = 16, -3.09 +/- 0.84 D); mixed astigmatism (Group 4) (LASIK: n = 91, +3.65 +/- 1.62 D; AK: n = 11, 4.39 +/- 0.92 D). RESULTS: Six months postoperatively, the cylinder's vector-corrected change was as follows: Group 1, LASIK 3.75 +/- 1.08 D, AK 3.16 +/- 0.84 D; Group 2, LASIK 1.55 +/- 1.12 D, AK 1.34 +/- 0.44 D; Group 3, LASIK 3.39 +/- 0.98 D, AK 2.70 +/- 1.21 D; Group 4, LASIK 3.77 +/- 1.43 D, AK 3.75 +/- 0.89 D. Respective mean uncorrected visual acuities in each group were as follows: Group 1, 0.71 +/- 0.12 and 0.60 +/- 0.12; Group 2, 0.83 +/- 0.12 and 0.78 +/- 0.24; Group 3, 0.78 +/- 0.18 and 0.48 +/- 0.24; Group 4, 0.69 +/- 0.21 and 0.55 +/- 0.18. CONCLUSIONS: The vector-corrected change and visual acuity achieved with LASIK were better, although not significantly, than those attained with AK except for the UCVA obtained with LASIK in eyes with compound myopic astigmatism over 2.00 D. Both methods proved to be safe.

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PURPOSE: To evaluate the results of laser in situ keratomileusis (LASIK) to treat hyperopia. SETTING: Instituto de la Vision, Buenos Aires, Argentina. METHODS: This nonrandomized study comprised 679 eyes of 321 patients having LASIK. Patients were divided into three groups based on preoperative spherical equivalent: Group A (low hyperopia, 2.00 diopters [D] or less); Group B (moderate hyperopia, between 2.00 and 3.00 D); Group C (high hyperopia, more than 3.00 D). The following were measured postoperatively: uncorrected visual acuity (UCVA); best spectacle-corrected visual acuity (BSCVA); refraction (evolution and distribution); lines of visual acuity gained and lost. Follow-up was 1 month in 79.4% of cases, 3 months in 75.5%, 6 months in 68.5% and 1 year in 38.3%. RESULTS: Six months after LASIK. 100% of cases in Group A, 95.3% in Group B, and 71.4% in Group C were within +/- 1.00 D of emmetropia; UCVA was 20/40 or better in 94.1, 100, and 87.8%, respectively. The percentage losing or gaining 0 +/- 1 line of BSCVA was 100, 97.6, and 100, respectively. CONCLUSIONS: Laser in situ keratomileusis was predictable and safe in the treatment of low and moderate hyperopia.

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PURPOSE: To analyze the results after laser-assisted in situ keratomileusis (LASIK) treatment for positive cylinder at the flattest meridian. SETTING: Instituto de la Visión, Buenos Aires, Argentina. METHODS: A prospective, nonrandomized study was conducted. Patients were divided into three groups: (1) simple hyperopic astigmatism (SHA); 15 eyes with a mean preoperative cylinder of +3.37 diopters (D) +/- 1.62 (SD); compound hyperopic astigmatism (CHA); 75 eyes with a mean preoperative cylinder of +3.34 +/- 1.39 D; (3) mixed astigmatism (MA); 73 eyes with a mean preoperative cylinder of +3.45 +/- 2.15 D. In all eyes, treatment of the cylinder was performed at the flattest meridian by LASIK using the Chiron-Technolas Keracor 116/117 laser. The following parameters were analyzed over time: uncorrected visual acuity; best corrected visual acuity; correction of the spherical equivalent and the cylinder; lines of visual acuity gained and lost. RESULTS: Six months after the procedure, refractive cylinder was reduced to +0.58 +/- 1.22 D in the SHA group, +0.12 +/- 1.23 D in the CHA group, and -0.11 +/- 1.28 D in the MA group. Uncorrected visual acuities were 20/20 or 20/25 in 66.7, 60.4, and 76.5% of the groups, respectively. CONCLUSIONS: Use of the LASIK technique with the Keracor laser to treat positive cylinder at the flattest meridian corrected simple and compound hyperopic astigmatism and mixed astigmatism with good predictability and safety. This treatment has not produced a hyperopic refractive change at the opposite meridian.

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