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M J Maldonado

Publications and source records attributed to M J Maldonado.

At least 19 recordsLinked to original sources
PubMed2006

Optical coherence tomography to monitor photodynamic therapy in pathological myopia.

AIM: To evaluate the role of optical coherence tomography (OCT) in determining choroidal neovascularisation (CNV) activity before and after photodynamic therapy (PDT) in patients with pathological myopia. METHODS: 33 patients (33 eyes) with pathological myopia and being treated with PDT were included. Every 3 months all patients were evaluated and presence or absence of leakage on fluorescein angiography, presence of intraretinal or subretinal fluid on OCT, and macular and choroidal neovascular complex thickness on OCT, were determined at each examination. RESULTS: The macular thickness decreased significantly after PDT at 6 months (p = 0.001) and at 12 months follow up (p = 0.01). However, no significant changes in CNV thickness were measured after PDT at 6 months of follow up (p = 0.418) and at 12 months of follow up (p = 0.521). Once the diagnosis of CNV associated with pathological myopia was established, before treatment, OCT had a sensitivity of 96.96% for detecting CNV activity. After treatment, OCT had a good sensitivity (95.23%) and a moderate specificity (69,69%) in determining CNV activity, which resulted in a diagnostic efficiency (proportion of correct results) of 79.62%. CONCLUSIONS: OCT appears to be useful for indicating CNV activity. Therefore, it may serve as a complementary technique for deciding the need for PDT and re-treatment in patients with pathological myopia.

Adult↗
PubMed2001

Cataract surgery in a patient with Brown-McLean syndrome.

The Brown-McLean syndrome is defined by corneal edema that involves the peripheral 2.0 to 3.0 mm of cornea, sparing the central cornea. This syndrome is usually associated with previous cataract surgery but has been reported rarely in patients with other predisposing factors such as angle-closure glaucoma or spontaneous lens absorption with iridodonesis. We describe the clinical course of a 50-year-old man with myotonic dystrophy who had Brown-McLean syndrome with no identifiable predisposition for peripheral corneal edema. Although this syndrome appears to be the result of peripheral endothelial dysfunction, this patient was able to tolerate cataract extraction without developing central corneal edema.

Cataract↗
PubMed2001

[Ultrastructural changes of the retinal pigment epithelium in pigs fed with a fat rich diet].

PURPOSE: To determine if the intake of a rich diet is related to ultraestructural changes and with an increase in lipofuscin accumulation in porcine retinal pigment epithelium (RPE). METHODS: The animals were divided into two groups of 6 pigs each. In the first group (control), a restricted diet of chow mix was supplied. The second group (fat-fed group) was fed with the same type of nutritional diet, however one third of the food was replaced by saturated fatty acid. Total cholesterol, HDL, LDL, and triglycerides were determined at the beginning and at the end of the experiment. After 12 weeks, the eyes were enucleated and the RPE structure was examined by electron microscopy. RESULTS: No significant differences were observed in the RPE lipofuscin accumulation between the control group and the fat-fed group (p=0.3). However, morphological disorders such as nuclear pyknosis, accumulation of electron dense particles in Bruch's membrane, and the accumulation of empty and lipid-like vacuoles in the cytoplasm were observed in the RPE of the fat-fed group but not in the control animals. CONCLUSIONS: The ultrastructural changes observed in the porcine RPE can be related to a high fat diet to the increase in lipid plasma levels.

Animals↗
PubMed2001

[Mitral flow propagation velocity assessed with M-mode color Doppler in patients with dilated cardiomyopathy].

BACKGROUND: The role of diastolic disfunction in the setting of severe left ventricular (LV) disfunction is usually forgotten due to difficulties in quantification and interpretation. The propagation velocity (PV) of mitral inflow into the left ventricle has been proposed as a load independent indicator of LV diastolic function. Our aim was to correlate PV with age, body surface, chambers dimensions, wall thickness and with classic parameters of systolic and diastolic function. We had in mind the validation of this index in the quantification of LV filling and in risk stratification of patients with dilated cardiomyopathy (DC). MATERIAL AND METHODS: We prospectively studied 32 consecutive patients, mean age 56.1 +/- 15.7 years, 22 (68.75%) male, mean ejection fraction 28.1 +/- 7.5%. All of them were in NYHA class < or = II and on ACE inhibitors. Eight (25%) were on beta-blockers. Patients without sinus rhythm, paced or with significant hypertensive, congenital or valvular heart disease were previously excluded. The following parameters of LV systolic function were assessed by echocardiography: fractional shortening, ejection fraction and cardiac output. LV filling was assessed by transmitral flow pulsed Doppler analysis: isovolumic relaxation time (IVRT), peak E and A wave velocities, E wave deceleration time (DT). We also evaluated a new Doppler index of combined systolic and diastolic myocardial performance (Tei index). PV (cm/s) was calculated by Color M-mode. Univariate regression analysis was performed (PV as dependent variable). RESULTS: We detected a high prevalence of diastolic function disturbances: 25 (78.1%) patients with a delayed relaxation pattern and only 3 (9.4%) with a restrictive pattern. PV did not correlate with age, body surface and LV geometry. There was a significant correlation between PV and E/A ratio (r = 0.61; p < 0.0001), IVRT (r = -0.50; p = 0.006), DT (r = -0.41; p = 0.01) and Tei index (r = -0.36; p = 0.04). CONCLUSIONS: Our results indicate that, in patients with a predominance of delayed relaxation, there is a strong relationship between PV and the classic parameters of LV filling. For similar levels of systolic impairment, PV could be an easy, fast and reproducible quantitative indicator of severity on DC.

Cardiomyopathy, Dilated↗
PubMed2000

Optical coherence tomography evaluation of the corneal cap and stromal bed features after laser in situ keratomileusis for high myopia and astigmatism.

OBJECTIVE: To study the corneal microstructure by optical coherence tomography (OCT) after laser in situ keratomileusis (LASIK) for high myopia with and without astigmatism. DESIGN: Nonrandomized self-controlled comparative trial. PARTICIPANTS: Sixty-three consecutive LASIK eyes with spherical equivalent refraction between -6.0 and -17.0 diopters (D) and astigmatism between 0.0 and -5.0 D were prospectively recruited for examination. INTERVENTION: LASIK was performed with the Chiron Hansatome microkeratome (160-microm fixed plate) and Summit Apex Plus excimer laser using a 5.5/6.0/6.5-mm multizone pattern. Proper preoperative calculations were performed to ensure stromal beds thicker than 250 microm. MAIN OUTCOME MEASURES: OCT imaging and measurement of corneal thickness was performed preoperatively. In addition, corneal cap and stromal bed thickness measurements were performed 1 day, 1 month, and 3 months postoperatively. RESULTS: The average central corneal pachymetry was 538.9 +/- 26.2 microm preoperatively. Mean corneal cap thickness measured 124.8 +/- 18.5 microm 1-day postoperatively. Mean stromal bed thickness was 295.2 +/- 37.1 microm on the first postoperative day. Compared with the 1-day postoperative examination, the average stromal bed thickness increased significantly by 5.9 microm (P = 0.001) and 7.2 microm (P = 0.001) at the 1-month and 3-month postoperative examinations, respectively. Mean difference between actual (118.7 +/- 27.8 microm) and predicted (104.1 +/- 20.8 microm) central ablation depths was 14.6 +/- 16.7 microm (P = 0.0001). A weak but statistically significant positive association was found between preoperative refraction and the difference between expected and real ablation depth values (R = 0.26; P = 0.042). Posterior stromal beds were more than 250-microm thick in 58 eyes (89.9%) 1 day postoperatively. This safety requirement improved at the 1-month postoperative examination, when the partial regression accounted for slightly thicker stromal beds and only two cases (3.2%) exhibited posterior stromal tissue thinner than 250 microm. These two cases were seen only for corrections exceeding 12 D (P = 0.04). CONCLUSIONS: OCT appears to be a useful tool for the evaluation of both the qualitative and quantitative anatomic outcome of LASIK. Corrections of higher degrees of ametropia run a higher risk of producing a thinner than expected central cornea. Particularly, corrections greater than 12 D may lead eventually to stromal beds thinner than 250 microm, despite proper preoperative calculations. Because corneal flaps are usually thinner than expected with the microkeratome used herein, adequate posterior corneal stroma is preserved in most instances.

Adolescent↗
PubMed2000

Repolarization abnormalities after catheter ablation of differently located overt accessory pathways.

PURPOSE: Electrical repolarization abnormalities are usually seen after radiofrequency catheter ablation in overt accessory atrio-ventricular pathways. These abnormalities have been recognised as "cardiac memory". The aim of this study was to assess the relationships between electrical repolarization abnormalities and the location of the accessory atrioventricular pathway in the atrio-ventricular junction. We also assessed the relationship between electrical repolarization abnormalities and the degree of ventricular preexcitation. MATERIAL AND METHODS: Our group consisted of 45 patients with overt and persistent preexcitation who were successfully submitted to radiofrequency catheter ablation. Mean age was 38.9 +/- 14.9 years (14 to 64), 28 of whom (62.2%) were male and 17 (37.8%) female. The location of accessory pathways the was left lateral in 14 patients, right posteroseptal in 14 patients, right mesoseptal in eight patients, right anteroseptal in four patients and other locations in the remaining four. Surface electrocardiograms were performed immediately following ablation, 24 hours later and three or more months after the procedure. RESULTS: T wave abnormalities (flattened, inverted or peaked) were detected on the first day in 51% of patients, being more frequent after right accessory pathway ablation (86.9% versus 13.1% in left accessory pathways). These electrocardiographic changes were particularly frequent in patients with right mesoseptal (5/8, 62.5%) and posteroseptal (13/14, 93.3%) pathways, of which 62.5% and 71.5%, respectively, showed marked preexcitation before ablation. These findings were significantly different from those observed in patients with left lateral pathways--only 35.7% showed marked preexcitation and only two of fourteen patients (14.3%) presented T wave abnormalities after ablation. After the third month, most of the patients that had undergone successful ablation presented completed electrocardiographic normalization. CONCLUSIONS: Patients undergoing radiofrequency catheter ablation for right accessory pathways show more frequently repolarization abnormalities than those submitted to ablation of the left lateral accessory pathways. The occurrence of these changes after preexcitation resolution may depend on the degree of previous preexcitation.

Adolescent↗
PubMed2000

Permanent pacing in patients with congenital atrio-ventricular block--experience of 33 cases.

OBJECTIVES: The authors review permanent pacing in patients with congenital atrioventricular block (CAVB) and present their experience in permanent pacing in this pathology. STUDY POPULATION AND METHODS: In a population of 4,355 patients submitted to implantation of permanent pacing between January 1980 and January 1998, 33 (0.75%) had CAVB. The mean age of the patient population with CAVB was 16.7 years (aged from eleven days to 35 years); 33% were below 10 years of age; 16 patients were male. The majority of the patients had symptoms of brain hypoperfusion; two patients had concomitant malignant ventricular tachyarrythmias (one of these with Torsade de Pointes due to congenital long QT syndrome). Transvenous (endocardial) pacing was used in 32 patients (two with previous epicardial pacing and exit block) and epicardial pacing in one. The mode of stimulation used was VVI in three patients, DDD in eight patients, VVIR in 14 patients, DDDR in four patients and VDD in four. Smaller pulse generators were used in children of lower weight. In recent years single lead VDD systems have been preferred whenever technically possible. Vascular access was the left cephalic vein in 17 patients; the left subclavian vein in 14 patients and the right jugular vein in one patient. During a mean follow-up of 6.9 years, two patients with ventricular stimulation systems developed "Pacemaker Syndrome" and required a change of mode of stimulation. Lead fracture and posterior cutaneous necroses were observed in two other patients, who were accordingly submitted to surgical revision. It was deemed necessary, one year later, to increase the lead loop in a child with a permanent pacemaker implanted at eleven days of age. No other complications occurred with the other patients; replacement of the pulse generators was performed in an elective manner. CONCLUSIONS: CAVB is a rare indication for the implantation of a permanent pacemaker. In children, in the majority of cases, endocardial stimulation is possible in spite of the obvious technical difficulties due to low weight. Sequential, more physiological, stimulation systems should be preferred. However, VVIR stimulation systems of smaller dimensions can be the first choice of mode of stimulation in smaller children, mainly due to anatomical and technical limitations.

Adolescent↗
PubMed1999

Final clear corneal incision size for AcrySof intraocular lenses.

PURPOSE: To evaluate clear corneal incision size variation in phacoemulsification surgery after the implantation of 2 models of AcrySof intraocular lenses (IOLs). SETTING: Departamento de Oftalmología, Clínica Universitaria de Navarra, Universidad de Navarra, Pamplona, Spain. METHODS: This prospective study comprised 108 eyes that had phacoemulsification and implantation of an Acrysof IOL model MA60BM (56 eyes) or MA30BA (52 eyes). Wound incision size was quantified using the Nordan incision size measurer. The incision size for each IOL model was evaluated before and after implantation and its relationship with the complications during implantation analyzed. RESULTS: Mean incision size varied from 3.7 mm +/- 0.14 (SD) before implantation to 3.9 +/- 0.11 mm after implantation for the MA60BM model (P = .001) and from 3.3 +/- 0.15 mm to 3.4 +/- 0.13 mm for the MA30BA model (P = .001). Intraoperative complications occurred in 14 eyes, and difficulty during IOL implantation, in 23 eyes. There was no association between final incision size and complications. CONCLUSIONS: Incision size increased after the implantation of the 2 AcrySof IOL models used in this study. Modifications to model MA30BA have led to an average decrease in wound size of 0.5 mm with respect to the MA60BM model. Most difficulties encountered were attributable to improper IOL unfolding.

Acrylic Resins↗
PubMed1998

Analysis of the promoter region of the murine complement factor H gene.

We have used the luciferase system to assay basal promoter activity of the murine factor H gene. Based on the results from luciferase assays with clones of 13 nested deletions, a 242-bp region that appeared to contain an enhancer element was subcloned upstream of a heterologous promoter and was shown to enhance transcription. A 26-bp fragment from this region was shifted in electrophoretic mobility assays, and this fragment contains a consensus sequence for the adenovirus major late transcription factor/upstream stimulatory factor (MLTF/USF). This fragment had enhancing activity in a minimal factor H promoter construct, demonstrating that it is a major enhancer of the factor H gene in murine liver cells.

Animals↗
PubMed1998

Corneal epithelial alterations resulting from use of chlorine-disinfected contact tonometer after myopic photorefractive keratectomy.

OBJECTIVE: This study aimed to describe a previously unreported complication associated with the use of chlorine-disinfected applanation tonometer heads for intraocular pressure measurement after excimer laser photorefractive keratectomy. DESIGN: Two retrospective case reports. PARTICIPANTS: Two patients underwent, respectively, a 7-diopter and a 4-diopter myopic excimer laser correction in their first eye 2 weeks apart. Complete epithelial closure of the ablated area was observed by biomicroscopy in the first-week examination. INTERVENTION: Four weeks after photorefractive keratectomy, a complete ophthalmic examination was performed. Goldmann applanation tonometry was performed bilaterally after thoroughly rinsing and drying the tonometer biprism, which had been immersed regularly in a chlorine 5000-parts per million solution. MAIN OUTCOME MEASURES: Slit-lamp examination and corneal topographic surface regularity were measured. RESULTS: A few minutes after applanation tonometry, both patients reported ocular discomfort in the excimer laser-treated eyes, whereas the untreated fellow eyes were painless. Punctate corneal lesions and superficial epithelial cell clumping were present in the first patient's treated eye, predominantly in the inferior aspect of the applanated cornea. Visual inspection showed a normal tonometer tip. In the second patient's treated cornea, a focal epithelial defect was identified biomicroscopically, which corresponded to the steeper region within the ablation zone on the videokeratograph. In this case, crystal deposits were found on the tonometer tip. The epithelial alterations resolved without sequelae in both cases. CONCLUSIONS: Disinfecting solutions of chlorine can cause crystal deposit formation on the tonometer head. Applanation tonometry after repeated disinfection with chlorine solutions appears to have the potential for disrupting the epithelial layer of the healing cornea. Covered contact tonometry or noncontact tonometry should be evaluated as alternative methods to chemically disinfected contact tonometry for intraocular pressure measurement after excimer laser surgery, especially during the first postoperative month.

Adult↗
PubMed1997

Reproducibility of digital image analysis for measuring corneal haze after myopic photorefractive keratectomy.

PURPOSE: To evaluate the usefulness of digital image analysis for quantifying corneal haze by determining the reproducibility of its measurements at the corneal plane. METHODS: In a prospective study, 20 randomly selected eyes that had undergone myopic photorefractive keratectomy were photographed focusing the slit beam on their anterior corneal surface. Each photograph was examined using computer image analysis techniques that detect the edge of the reticular pattern of the image. Quantification of the difference between two areas, treated and adjacent untreated cornea, each containing 3,750 pixels with a resolution of 256 gray levels, was performed. Intra-analyzer variation was determined by evaluating the photographs obtained by two analyzers under standard conditions on four separate visits. Interanalyzer variation was calculated using one measurement and the mean of the four measurements. RESULTS: The pooled standard deviation of the measurements for the analyzers was 0.63 and 0.62 gray levels (coefficient of variation, 4.1% and 3.3%). An association between less severe haze measurements and higher reproducibility scores was found (r = .42; P = .007). The mean interanalyzer variation was smaller for the average of four measurements, 0.55 +/- 0.37 gray levels, than for one measurement, 0.94 +/- 0.73 gray levels (P = .014). CONCLUSIONS: Good reproducibility for haze measurements by digital image analysis of the differences between the treated and adjacent untreated corneal areas was obtained. When the average of four measurements was used instead of a single measurement, interanalyzer reproducibility increased significantly. This new technique may be used to quantify and analyze corneal haze after myopic photorefractive keratectomy.

Adult↗
PubMed1996

Direct objective quantification of corneal haze after excimer laser photorefractive keratectomy for high myopia.

PURPOSE: The purpose of the study is to measure regional distribution differences in corneal haze after excimer laser photorefractive keratectomy for high myopia. METHODS: The authors developed computerized gradient edge detectors with which were analyzed digitized anterior slit-lamp photographs of 40 eyes, an average of 21.0 plus or minus 14.5 weeks after photorefractive keratectomy for high myopia (-6 to -22 diopters). A treated area an adjacent untreated area on the anterior corneal surface, each containing six regions, were quantified, and the difference was correlated with various parameters. RESULTS: Mean differences between scarred and clear areas for haze grade 0.5, 1.0, 2.0, 3.0, and 4.0 were 16.9, 26.6, 42.6, 60.4, and 76.4 gray levels, respectively (rs = 0.96; P = 0.0001). A low but statistically significant correlation between the intended correction and postoperative corneal haze was found (r = 0.33; P = 0.037). The mean coefficient of variation of the amount of opacification within each treated area was 9.4%. This coefficient of variation increased with a longer follow-up time (r = 0.88; P = 0.0001). The difference in the intensity of haze between the center and more peripheral regions over the entrance pupil did not correlate with the attempted correction. However, a strong association between a relatively less severe central corneal haze with respect to more peripheral haze and longer follow-up time was found (r = -0.96; P = 0.0001). CONCLUSION: The amount of corneal haze showed a weak positive association with the attempted correction in excimer laser photorefractive keratectomy for high myopia. Corneal haze appeared fairly uniformly distributed within the ablation zone, but a more heterogeneous distribution was found with a longer follow-up time. Furthermore, later postoperative examinations disclosed a clear trend toward diminishing central opacification relative to peripheral regions over the entrance pupil.

Adult↗
PubMed1996

Goldmann applanation tonometry using sterile disposable silicone tonometer shields.

PURPOSE: Placement of a sterile single-use cover over the tonometer tip may be a convenient and safe alternative method to repeated chemical disinfection. This study was undertaken to evaluate the accuracy and performance of Goldmann applanation tonometry using a sterile disposable silicone tonometer shield over the biprism tip. METHODS: The same investigator measured intraocular pressure in 120 eyes with and without the shield. The eyes were tested randomly first with either the uncovered or the covered tonometer to control for the possible effects of repeated tonometry influencing measurement differences. Readings were recorded independently in a masked fashion. RESULTS: The intraocular pressure measurements evaluated with the silicone shield caused an average overestimation of the true intraocular pressure of 1.9 +/- 1.9 mmHg (P = 0.0001). Covered and uncovered readings correlated well (r = 0.91, P = 0.0001). The sensitivity and specificity of the covered tonometry in detection intraocular pressures of 21 mmHg or higher (as measured without the shield) were 96.3% and 68.8%, respectively. Minor distortions of the normal-appearing fluorescein bands were seen in 5% of the tonometries, and the shield had to be replaced because of bubbles or wrinkles on the applanating surface in 3.3% of the measurements, which means that care must be taken when fitting the shield. CONCLUSIONS: Although covered and uncovered tonometry readings correlated well, an overall trend for a slightly increased measured intraocular pressure as a result of using the silicone shield over the Goldmann tonometer tip was found. The outstanding sensitivity of this procedure in detecting increased intraocular pressure suggests that it can be useful in screening for ocular hypertension and glaucoma.

Adolescent↗
PubMed1996

Anterior chamber contamination following uncomplicated cataract surgery: comparative results using intravenous imipenem.

BACKGROUND AND OBJECTIVE: An attempt was made to establish the effect of an intravenous antibiotic on anterior chamber (AC) fluid contamination when administered before surgery. PATIENTS AND METHODS: A prospective study of AC contamination was conducted in 60 patients undergoing extracapsular cataract extraction (ECCE)/intraocular lens (IOL) implantation. The final 20 patients received 1 g of intravenous imipenem 1 hour before surgery. RESULTS: There were 4 positive AC cultures from the 20 patients in the imipenem group, and 13 positive AC cultures from the 40 control patients (P = .4, chi-square test). Of the 60 eyes, 17 had positive AC aspirate cultures and 23 had positive conjunctival smears. Only in one instance was the microorganism isolated from each case the same (1.7%). CONCLUSIONS: An insignificant decrease in AC contamination was observed when intravenous imipenem was used before surgery. The results also suggest that conjunctiva might not be the main source of contamination during surgery.

Anterior Chamber↗