Biomedical subjects

L E Pablo

Publications and source records attributed to L E Pablo.

13 recordsLinked to original sources

PubMed2001

Functional and structural measurements in a multifactorial glaucoma risk model.

PURPOSE: To evaluate the relationship between a multifactorial probability risk model of developing glaucomatous visual field defects and the assessment of the retinal nerve fiber layer (RNFL) and short-wavelength automated perimetry (SWAP) in glaucoma suspects. METHODS: 157 eyes of 157 glaucoma suspects were included in the study. The risk of developing glaucomatous defects was assessed by applying a multifactorial model that included intraocular pressure, vertical cup-to-disk ratio, age and family history. Photographs of the RNFL and SWAP were performed. RESULTS: The SWAP was abnormal in 54 cases (34.3%); 21% of abnormal perimetries were obtained in the low-risk group, 37% in the moderate risk group and 56% in the high risk group. The nerve fiber layer evaluation in the different risk stages showed a pattern similar to the results obtained with SWAP. Multiple regression analyses, performed with the four variables included in the model with SWAP and RNFL evaluation, showed the relationship between the risk factors and the presence of glaucomatous damage--evaluated by RNFL and SWAP (p<0001). CONCLUSIONS: The probability model showed a good correlation between the risk scale and the RNFL and SWAP assessment.

Adult↗

PubMed2001

[Ciliary ablation with diode laser. Long-term study].

PURPOSE: The effects of contact transscleral cyclophotocoagulation with diode laser for refractory glaucoma have been analyzed. METHODS: A diode laser system was used to treat twenty one eyes with refractory glaucoma. The mean follow-up was 22.24+/-9.89 months. All the eyes were treated with 15 laser spots placed over 270 degrees, 1 mm posterior to the limbus, using 3.0 J (1.0 W X 3.0 sg). RESULTS: The mean preoperative intraocular pressure was 40.95+/-11.76 mmHg and the mean intraocular pressure at the end of the follow-up was 24.28+/-7.80 mmHg (p<0.5). An intraocular pressure below 21 mmHg was obtained in 10 out the 13 eyes (76.92%). Six of the 8 painful eyes had pain relief (75.00%). The principal complications included a decreased visual acuity in 5 eyes and chronic uveitis in 2 patients. CONCLUSIONS: These results suggest that semiconductor diode transscleral cyclophotocoagulation can be used successfully to reduce intraocular pressure in the treatment of refractory glaucoma.

Adult↗

PubMed2000

[Reproducibility of planimetric optic nerve head analysis with scanning laser ophthalmoscope].

PURPOSE: To determine the variability of disc and cup area measurements in digital images obtained with scanning laser ophthalmoscope. METHODS: 10 sets of images of 4 optic discs (normal, myopic, ocular hypertensive and glaucomatous) were obtained with the Rodenstock scanning laser ophthalmoscope. Images focused at different depths were used by 2 operators (with and without experience in planimetry) to determine the disc and cup areas by means of an image analysis program (Visilog). This study was performed in 10 images obtained from the same optic nerve (inter-image analysis) and 10 times in the same image of each optic nerve (intra-image analysis). RESULTS: The variability of all the measurements was under 5%. Disc area measurements were lower than cup area determination. The experienced operator obtained lower variability. The myopic optic disc images were less reproducible than the other groups of images. CONCLUSIONS: The planimetric analysis of optic nerve head digital images obtained with scanning laser ophthalmoscope is reproducible and allows quantification of optic disc areas.

Humans↗

PubMed1999

Quantification of intraoperative administration of mitomycin-C in filtering surgery with surgical sponge material.

PURPOSE: To determine the absorption and release of mitomycin-C 0.4 and 0.2 mg/mL from sponge-like specimens of Spongostan film (Ferrosan, Copenhagen, Denmark) and the scleral and conjunctival impregnation in an experimental model of filtering surgery. METHODS: The maximum amount of mitomycin per volume unit that Spongostan is able to absorb was determined physically as the difference between dry weight and soaked weight. Mitomycin-C activity in known volumes of Spongostan after mitomycin-C release in vitro also was determined at 0, 1, 10, and 30 seconds and 1, 3, 5, 10, 15, and 30 minutes. Antibiotic activity of the specimens was evaluated by means of bioassay. Millimeters of inhibition of bacterial growth were related to microg of mitomycin activity according to a reference curve obtained from known amounts of mitomycin-C. Finally, 10 eyes of 10 rabbits underwent filtering surgery with intraoperative application of mitomycin by means of the Spongostan film. The Spongostan implants then were removed and tested for mitomycin activity. Scleral and conjunctival specimens were obtained for bioassay. RESULTS: The maximum capacity of 25 mm2 x 0.5 mm thick Spongostan films saturated in 0.4 and 0.2 mg/mL solutions of mitomycin-C were 8.49 microg and 4.23 microg, respectively. Biologic activity (bioassay determination) was 8.24 microg and 4.19 microg of mitomycin-C, respectively. In vitro release of mitomycin was gradual until 30 minutes. In vivo mitomycin release from Spongostan after 5 minutes was 6.91 microg. Impregnation with the antimitotic was better in conjunctiva than sclera. CONCLUSION: Bioassay permits quantification of mitomycin-C activity. The release from sponge specimens is gradual, and impregnation was better in conjunctiva than sclera.

Absorption↗

PubMed1999

Correlation of functional and structural measurements in eyes suspected of having glaucoma.

PURPOSE: This study was conducted to determine the correlation between structural changes in the retinal nerve fiber layer (RNFL) and functional loss detected on short-wavelength automated perimetry (SWAP) in a population of patients with suspected glaucoma. METHODS: With a selection criteria of intraocular pressure (IOP) more than 21 mmHg and normal results of conventional automated perimetry, 49 eyes of 49 patients with ocular hypertension were enrolled in the study. The SWAP was performed with a modified Humphrey field analyzer, and visual field indexes (mean deviation [MD], corrected pattern standard deviation [CPSD]) were calculated. Semiquantitative RNFL scores were given separately to diffuse and localized defects of the RNFL. RESULTS: The MD increased significantly with higher diffuse and total RNFL scores, with good correlation coefficients. A weak correlation was found between CPSD and diffuse, total, and localized RNFL scores. CONCLUSION: Diffuse RNFL loss are associated with abnormalities in visual field indexes (MD), whereas focal structural damage showed no correlation with visual field loss.

Adult↗

PubMed1998

Short-wavelength automated perimetry and retinal nerve fiber layer evaluation in suspected cases of glaucoma.

OBJECTIVES: To determine if short-wavelength automated perimetry (SWAP) provides evidence that indicates early functional losses in ocular hypertensive subjects and to establish a direct comparison with early structural abnormalities in the retinal nerve fiber layer (RNFL). METHODS: A total of 160 eyes belonging to 83 patients with ocular hypertension (intraocular pressure >21 mm Hg and normal results on standard automated perimetry evaluation), on which a SWAP and RNFL study were performed, were examined. One hundred twenty-eight age-matched subjects without ocular hypertension were evaluated to establish the 95% and 99% confidence intervals at each of the 76 exploration points of the SWAP test. RESULTS: The RNFL study results were normal in 83 cases (51.8%) and pathologic in 77 cases (48.1%). The SWAP results were pathologic in 57 cases (35.6%). Significant differences (P<.001) were observed when comparing the distribution of normal and pathologic SWAP results among the types of defects in the RNFL (focal wedge, diffuse atrophy, and mixed atrophy). CONCLUSIONS: Short-wavelength automated perimetry is a useful test for the early detection of visual field losses. It is more sensitive than standard automated perimetry and provides a high association with RNFL assessment, which has proved capable of detecting signs of glaucomatous damage several years before the onset of the typical visual field defects.

Adult↗

PubMedDate not supplied

Assessment of the ocular media absorption index.

PURPOSE: To determine a practical method for quantifying in vivo lens absorption by human crystalline, obtaining an index of lens density in our population. METHOD: 62 normal subjects were evaluated in this study (ages ranging from 20 to 71 years). TESTING PROCEDURE: Measurements of dark-adapted scotopic thresholds for 450 nm and 656 nm stimuli were obtained (Tubinger perimeter) in order to determine ocular media absorption. Van Norren and Vos's procedure was used to calculate ocular media absorption transmission loss. Least-squares linear regressions were used to correlate lens density to age. RESULTS: A gradual and approximately linear increase in average lens absorbance was found under 55 years of age. Elder subjects showed a higher increase in this absorbance with higher variability. A correction factor for age-related ocular media absorption was obtained from the calculated curve. The range was approximately 1 to 5 dB. CONCLUSION: Determination of the transmission characteristics of the preretinal media is essential for interpreting threshold sensitivity values. Increase in lens absorption has been shown to be selective for short wavelengths. Due to this fact, a correction factor for the age-related ocular media absorption should be applied to avoid misinterpretation of the Blue-on-Yellow perimetry absolute results. That factor may discriminate sensitivity losses due to changes in the lens from those due to retinal or neuronal dysfunction.

Absorption↗

PubMedDate not supplied

Semiconductor diode laser transscleral cyclophotocoagulation versus filtering surgery with Mitomycin-C.

Both filtering surgery with Mitomycin-C and diode laser cyclophotocoagulation have proved to be effective alternatives in cases of glaucoma with poor surgical prognosis. The right eyes of 40 pigmented rabbits were randomly divided into 2 groups: Mitomycin-C group underwent filtering surgery with application of 0.4 mg/ml of Mitomycin-C whereas the diode laser (DL) group received 15 applications of 1.8 J (1800 mW. 1000 ms) distributed in 270 degrees. Mean IOP showed statistical differences in two periods between days 3-13 and 45-60-Mann-Whitney U test -with a higher IOP lowering in the DL group. The comparison of IOP survival curves (Log-Rank test) was not significant p = 0.070809. Ocular hypertension, hyphema and inflammatory signs were higher in the DL group, both in short and long term, but in terms of statistical significance only ocular hypertension showed differences p = 0.00011717-Fisher exact test. Microscopic examination revealed patent sclerostomies in 60% of the MMC group eyes with different grades of fibroblastic proliferation. In the DL group we observed necrosis of the scleral stroma and of the pigmented and unpigmented ciliary epithelium, with signs of thermal coagulation of the ciliary stroma and of the stromal vasculature. We must point out that the treatment with laser has proved to be more effective although both treatments showed very acceptable IOP lowering until 2 months after the surgery.

Administration, Topical↗

PubMedDate not supplied

Assessment of diurnal tensional curve in early glaucoma damage.

We know very little about the relationship between the diurnal intraocular pressure variations and the progression of visual field loss. A prospective study of 149 eyes of 149 patients suffering from intraocular hypertension has been carried out through a minimum period of five years. At least 4 years before the appearance of field defects, we detected significant oscillations of IOP in the 64% of the cases prone to develop visual field loss. Likewise, we have found a statistically significant relationship between the presence of defects in the RNFL (retinal nerve fiber layer) and the existence of significant oscillations of IOP.

Circadian Rhythm↗

PubMedDate not supplied

Histological toxicity of grepafloxacin after intravitreal injection.

PURPOSE: To determine the intravitreal levels of grepafloxacin after intravitreal injection of 80 microg and to evaluate the retinal toxicity after intravitreal injection of different doses of grepafloxacin in rabbit eyes. METHODS: Fifteen female New Zealand white rabbits and 15 female pigmented 'Gigantes de España' rabbits were injected with 80 microg of grepafloxacin into the vitreous cavity. The grepafloxacin concentration was determined with HPLC after 2, 4, 8, 12 and 24 h. Eighteen female rabbits (9 New Zealand white rabbits and 9 pigmented 'Gigantes de España' rabbits) were used for a study of toxicity. The rabbits were divided into 6 treatment groups: group 1 (3 pigmented rabbits) received an intravitreal injection of 80 microg of grepafloxacin in 0.1 ml of saline solution, group 2 (3 white rabbits) 80 microg of grepafloxacin in 0.1 ml, group 3 (3 pigmented rabbits) 800 microg of grepafloxacin, group 4 (3 white rabbits) 800 microg of grepafloxacin, group 5 (3 pigmented rabbits) and group 6 (3 white rabbits) 0.1 ml of saline solution. Clinical examination was performed prior to injection and 24 h and 10 days after surgery. The animals were sacrificed 10 days after the injection, and the eyes were enucleated and fixed for histopathology. The specimens were stained with hematoxylin-eosin and toluidine blue. RESULTS: No relevant complications were found during the clinical follow-up. All the eyes showed no abnormalities in the histologic evaluation. CONCLUSION: Grepafloxacin can be considered as a safe alternative for intravitreal injection for the treatment of intraocular infections.

Animals↗

PubMedDate not supplied

Morphometric study of wound healing in a model of filtering surgery with mitomycin-C.

BACKGROUND: Failure of filtering surgery may be related to excessive wound healing in the surgical area. This effect diminishes with the use of antimetabolic agents. Mitomycin-C (MMC) has proved to be the most effective drug to reduce myofibroblastic proliferation in experimental in vivo and in vitro models. To our knowledge, the objective changes induced by mitomycin-C in the size of wound healing areas have not been investigated. METHODS: Filtering surgery was performed on both eyes of 40 pigmented rabbits. Preoperatively one of the eyes received MMC (0.5 mg/ml), and the fellow eye received balance salt solution as placebo. Animals were killed on days 6, 15, 30 and 58. Microscopic healing areas were measured by digital procedures. The areas of target and fellow control eyes were compared by the Wilcoxon test. RESULTS: This study showed significant differences (p < 0.05) between treated and untreated groups, the healing are a gradually becoming smaller. CONCLUSIONS: Objective methods to quantify the microscopic effects of MMC can be useful to improve our knowledge about the action on this antimetabolite and to enable us to adjust more accurately the timing and dosage when applying the drug in glaucoma filtering surgery.

Animals↗

PubMedDate not supplied

Long-term effects of postoperative subconjunctival injections of mitomycin-C in the rabbit eye.

AIM: Single or multiple subconjunctival injections of mitomycin-C (MMC) may offer one way of establishing the total dosage of MMC more accurately. The method also allows re-applications later postoperatively. In this experimental, randomized prospective study we compared the effects of a single intraoperative application of MMC at the filtering site and a single postoperative subconjunctival injection of the drug. METHODS: The left eyes of 32 pigmented rabbits were divided into two groups. In the first group we applied MMC intraoperatively (IO) with a 4 x 1 mm surgical sponge soaked in a MMC solution (0.5 mg/ml). In the second group we injected 0.4 ml of the same solution subconjunctivally (SC) immediately after (conjunctival) suture. Post-operative evaluation was carried out every day during the first week, then every three days until day 58. Survival analyses were done for intraocular pressure (IOP) and bleb failure. Log-rank tests were used to compare survival differences between the groups. RESULTS: The IO group showed longer survival parameters than the SC group (p < 0.05), both in the control of IOP and as regards blebs. The histological persistence of fistulas was similar. The IO group, however, had a higher incidence of undesirable side effects. CONCLUSIONS: Our findings suggest IO application of MMC is more effective in reducing fibroblast ingrowth. However, subconjunctival application offers certain advantages such as the possibility of repeating the treatment postoperatively and, therefore, using a smaller initial dose.

Animals↗

PubMedDate not supplied

Alpha-tocopherol derivatives and wound healing in an experimental model of filtering surgery.

OBJECTIVE: To describe the effect of alpha-tocopherol derivatives (acetate and acid-succinate) on the histopathological characteristics of the surgical fistula in an experimental model of filtering surgery. MATERIALS AND METHODS: Thirty pigmented rabbits were divided into 3 groups. Twenty-four hours before surgery the animals were injected subconjunctivally with 0.5 mL of solution that depended on the group of treatment: Group 1 (n = 10) 0.75% ethanol in balanced salt solution (BSS); Group 2 (n = 10) 100 microg alph-tocopherol-acetate in 0.75% ethanol in BSS; Group 3 (n = 10) 100 microg alpha-tocopheryl-acid-succinate in 0.75% ethanol in BSS. Histological findings were evaluated 30 days after surgery. RESULTS: The groups treated with alpha-tocopherol derivatives showed a higher percentage of persistence of the fistula and better intraocular pressure (IOP) control. CONCLUSIONS: Alpha-tocopherol derivatives showed antiproliferative properties in this experimental model of filtering surgery.

Animals↗