Influence of keratometric readings on comparative intraocular pressure measurements with Goldmann, Tono-Pen, and noncontact tonometers.

PURPOSE: To evaluate the influence of keratometric measurements on the concordance of intraocular pressure (IOP) readings with three applanation tonometers. PATIENTS AND METHODS: The IOPs of 404 eyes of 202 patients from a general eye clinic were measured by Goldmann, Tono-Pen XL, and noncontact Nidek NT 2000 tonometers. Differences in the IOP measurements between Goldmann and the other two tonometers (deltaIOPG-TP and deltaIOPG-NCT) were analyzed in the overall group and within three subgroups based on keratometry measures: flatter, intermediate, and steeper corneas (quartiles as cut-off points). Regression analysis of deltaIOP and keratometry measures was also performed. Right and left eyes were analyzed separately. RESULTS: The IOP readings taken with the Goldmann tonometer were significantly higher than those taken with either of the other two tonometers within the overall study population. The deltaIOP within the three keratometric subgroups was not statistically significant except for deltaIOPG-TP in the right eyes. Regression analysis showed that keratometry and deltaIOPG-TP and deltaIOPG-NCT had a significant but very weak coefficient of correlation in the right eye, but not in the left. CONCLUSION: Corneal curvature within the normal range does not have a clinically significant influence on the concordance of IOP readings obtained with Goldmann and Tono-Pen or noncontact tonometers.

Pattern reversal visual evoked response in retinitis pigmentosa.

PURPOSE: To determine if the pattern reversal visual evoked response (PVER) can objectively evaluate visual function in retinitis pigmentosa (RP). METHODS: We retrospectively reviewed the medical records of 29 patients (29 eyes) with RP, a visual acuity (VA) better than 20/100, and for whom an electroretinogram (ERG) and a PVER had been recorded. A steady-state PVER was measured using five check sizes: 160, 80, 40, 20 and 10 min of arc. The best-corrected VA was measured using the ETDRS chart. Visual fields (VFs) were measured using standard Goldmann perimetry. To quantify the VFs, we measured the field size (isopter IV-2) in four meridians and averaged them. Twenty-five eyes of 25 normal subjects served as controls. RESULTS: The mean and median VAs were 20/40 (logMAR = 0.30 +/- 0.20). The average VF (isopter IV-2 ) was 20 degrees (median, 9 degrees: range. 2 degrees to 62 degrees). All patients had a recordable PVER. Only 12 (41 %) patients had a recordable ERGs, all subnormal. The PVER amplitudes showed a relatively good correlation with VA in the intermediate check sizes (40 min of arc, r = 0.611. P = 0.0004: 20 min of arc, r = 0.596. P = 0.0007). The PVER amplitude-check size function had a flattened inverted V shape in the RP patients and an inverted U shape in the normal subjects, with the mean amplitudes for the RP patients significantly smaller than the normals at all check sizes. CONCLUSION: The PVER is a useful method for objectively evaluating the visual function in RP patients whose central vision is still preserved.

Comparison of Snellen acuity and objective assessment using the spatial frequency sweep PVER.

BACKGROUND: We compared the vision objectively assessed by spatial frequency sweep pattern-reversal visual-evoked response (SPVER) with the Snellen acuity in patients. METHODS: SPVER acuity and Snellen acuity were measured in 100 patients with various ocular pathologies, including macular diseases, diffuse retinal degeneration, optic nerve diseases, glaucoma, and high myopia. For SPVER, 10 sinusoidally modulated vertical gratings were presented as stimuli. The responses were averaged and displayed through the discrete Fourier transform on the monitor display. The PVER acuity was determined by extrapolating the SPVER amplitude-spatial frequency function to baseline. RESULTS: Vision ranged from 20/15 to 20/400 with Snellen acuity, and from 20/25 to 20/190 with SPVER. The overall correlation between the two acuities was r = 0.666. The correlation varied from r = 0.895 in eyes with glaucoma to r = 0.436 in eyes with optic nerve disease. Seventy-seven eyes (77%) had a visual acuity agreement of within 1.0 octave between the two measurements. CONCLUSION: The SPVER acuity and the Snellen acuity correlated to a certain degree. Discrepancies were found in certain diseases, with the highest disparity in patients with optic nerve disease. We conclude that the SPVER is effective in estimating vision objectively, particularly in patients in whom the standard Snellen test is impossible to perform or yields unreliable results.

Spatial tuning loss of pattern reversal visual evoked response in optic nerve disease.

We compared the pattern reversal visual evoked response (PVER) amplitude-check size functions from 25 eyes (25 normal subjects; visual acuities > or = 20/20) with those from 32 eyes (22 patients; visual acuities 20/15 to 20/50; mean, 20/25.5) with mild optic nerve disease to determine if spatial tuning loss of the PVER occurs in the presence of optic nerve dysfunction. The steady-state PVER was recorded with five check sizes (range, 160 to 10 minutes of arc). To analyze the PVER amplitude-check size function, we calculated the difference between the maximum and minimum PVER amplitudes and then calculated the area of spatial tuning (the area under the function). Values were significantly smaller in patients than in normal subjects (1.81 +/- 1.27 microV versus 5.73 +/- 3.27 microV; F = 41.24, p = 0.0001; 3.87 +/- 2.70 area units versus 12.57 +/- 7.60 area units; F = 38.62, p = 0.0001). There was no shift in the distribution of peak check sizes. Results suggest that a spatial tuning loss occurs in optic nerve disease. The shape of the function, including the area of spatial tuning, appears to be a sensitive indicator of early or mild optic nerve dysfunction.

Pós-graduaçäo médica: critérios de seleçäo vs. produçäo científica / Graduation in medicine: admission criteria vs. scientific production

Apresenta-se um estudo comparativo entre a produçao científica de dois diferentes serviços de pós-graduaçao (PG) stricto sensu na área médica, correlacionando-a com os critérios de seleçao para entrada em cada curso, se determinante, ou nao, de elevada proporçao endogênica (pós-graduandos selecionados entre os próprios residentes do serviço). Editais e informaçao das secretarias foram a fonte para os critérios de seleçao e proporçao endogênica. Na avaliaçao da produçao científica utilizou-se o método de Ellwein et al. (l989), modificado: número de publicaçoes em periódicos nacionais da especialidade, com a participaçao de pelo menos um pós-graduando, assim como sua posiçao no byline (se primeiro ou co-autor). Período considerado: 1983-1992. Os serviços foram denominados, por questoes éticas, "beta" e "gama" (beta e gama). "Beta"seleciona principalmente pelo currículo, teve uma proporçao endogênica total de 29,4 por cento (34/116), uma produçao média de 8,6 + 4,3 e uma produçao proporcional (ao número de pós-graduandos) total de 0,74 (74 por cento). "Gama" prioriza uma prova de conhecimentos sobre a especialidade (elaborada a partir das aulas proferidas durante o curso de residência) e apresentou os respectivos resultados: 93,5 por cento (56/60), 1,5 + 1,4 e 0,25 (75 por cento). Tais diferenças entre os serviços sao estatisticamente significativas (p<0,001). Conclui-se que elevada endogenia é prejudicial a um serviço de PG estricto sensu. Discute-se, ainda, maneiras para selecionar, na busca da ideal.

[Graduation in Medicine: admission criteria vs. scientific production]. / Pós-graduação médica: critérios de seleção vs. produção científica.

Medical postgraduation in Brazil is divided into two categories: lato sensu (residency and fellowship) and stricto sensu (MSc, PhD), being the former a prerequisite to the latter. The author presents a study comparing two postgraduation courses in which both lato and stricto sensu are available, in order to determine if their selection criteria for the MSc/PhD courses are protective for their own residents (endogenic) and the consequences to their scientific production. The information concerning selection criteria and endogenic proportion was obtained directly from the courses' offices. To evaluate the scientific production, the Ellwein et al. (1989) method, modified, was used: number of papers published in the two major Brazilian journals of the specialty, in which there was, at least, one post-graduation student and the position in the byline as well. Period considered: 1983-1992. For ethical reasons the courses were named by greek letters "beta" and "gamma". "Beta" selects mainly by the curriculum vitae. It had an endogenic proportion of 29.4% (34/116), a mean scientific production of 8.6 +/- 4.3 papers/year that, when considered proportionally (total number of papers/total number postgraduate students) gives us the value of 0.74 (74%). "Gamma" prefers a test in the specialty and the questions come from lectures given in its residency course. Respectively, the "gamma" results were: 93.5% (56/60), 15 +/- 14 and 0.25 (25%). The differences between "beta" and "gamma" were statistically significant (p < 0.001). The author concludes that a high endogenic proportion acts negatively in the scientific production of a stricto sensu (Master and PhD) Brazilian course. Different ways to select are also discussed.

Controlled production of cirrhosis in the rat liver.

In the present study we propose a standardization of the method for the induction of fibrosis of the liver in rats by weekly administration of CCl4 by the intragastric route. The present method is a variation of that described by Proctor and Chatamra. The initial CCl4 dose is 0.04 ml (X dose) but the subsequent doses are calibrated using a 5% variation in animal weight as a reference point. For a weight gain of 5% or more, the successive doses are progressively increased by 50 to 150% (1.5X, 2X, 2.5X). When there is no variation in weight or loss in less than 5%, the previous dose is maintained. For a weight loss of more than 5%, the CCl4 dose is decreased by 50%. Consistent fibrosis if obtained as early as during the 8th week. Collagen content increases progressively from the 8th to the 12th week, reaching on average a level eight-fold higher than that observed in the control.