Sauvageot, P.; Julio, G.; Alvarez, J.; Charoenrook, V.; Barraquer, R. Journal of cataract and refractive surgery Vol. 43, num. 2, p. 167-173 DOI: 10.1016/j.jcrs.2016.12.019 Data de publicació: 2017-02-01 Article en revista
Purpose: To compare ocular surface characteristics in eyes after femtosecond laser-assisted laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK).
Setting: Centro de Oftalmologia Barraquer, Barcelona, Spain.
Design: Prospective comparative observational study.
Methods: Patients with myopia who had femtosecond laser assisted LASIK or PRK were included. Tear osmolarity, the Ocular Surface Disease Index questionnaire, Schirmer I, corneal sensitivity, tear breakup time (TBUT), and corneal fluorescein staining were evaluated preoperatively and 3, 6, and 12 months postoperatively. The Wilcoxon signed-rank test was used for temporal intragroup analysis, and the Mann-Whitney U test was used for intergroup comparisons.
Results: The study comprised 44 patients (44 eyes) with myopia. Comparison of the parameters between the femtosecond laser-assisted LASIK group (22 eyes) and the PRK group (22 eyes) showed a similar temporal progression postoperatively. Compared with the preoperative evaluation, corneal sensitivity decreased after 3 months (P = .002 and P = .02, respectively) and 6 months (P = .03 and P = .04, respectively). The TBUT reached the highest mean value after 12 months (P = .01 and P = .04, respectively), and tear osmolarity was slightly increased after 1 year, although the mean values remained within the normal range (P = .01 and P = .04, respectively). The only difference between the 2 groups was lower corneal sensitivity in the femtosecond laser-assisted LASIK group after 3 months (P = .02). The ocular surface condition could be considered clinically unaltered after 1 year in both groups.
Conclusion: Femtosecond laser-assisted LASIK and PRK techniques seemed to be safe for the ocular surface condition and to have a similar effect on it.
Purpose: To establish determining factors for fast corneal sensitivity (CS) recovery after pterygium excision.
Methods: Thirty-two eyes of 14 males and 18 females with primary nasal pterygium were recruited. Differences in CS (in the 4 quadrants and the center using a Cochet–Bonnet esthesiometer), pterygium corneal area (PCA), tear osmolarity, tear break-up time, Schirmer test, and ocular symptoms were analyzed before and 1 month after lesion excision. The relationship between CS recovery (difference between the 2 time points; CS1 – CS0) and the other features was assessed.
Results: All the studied locations exhibited normal (6 cm) or near-normal mean CS at the 2 time points, except a tendency for moderate hypoesthesia in nasal CS0 (median 4.5; range: 1.5–6.0 cm). Point by point comparison revealed significant postoperative improvements in nasal location (P = 0.008; Wilcoxon signed-rank test) with normal values in 17 eyes (53%) and a median CS1 = 5.0 cm (2.5–5.5 cm) in 15 eyes with no complete recovery. No significant correlation was found between CS0 and the studied variables, and CS1 was only significantly correlated with PCA (rho: -0.441; P < 0.05). CS recovery also showed significant correlation with PCA (rho = -0.516; P < 0.01).
Conclusions: CS recovery after pterygium excision showed important variability, and the only studied factor that seems to be determinant could be PCA. It would be advisable to operate when the lesion is relatively small, with lower surgical injury and faster and complete recovery, thus protecting ocular surface homeostasis.
Purpose: The purpose of this study was to compare inflammatory events and graft characteristics 1 month and 6 months after conjunctival limbal autograft (CLAU) with and without intraoperative mitomycin C (MMC).
Methods: This study included 69 eyes of 69 patient’s eyes with pterygium. Clinical data concerning patient demography, preoperative examination including pterygium morphology, recurrence clinical assessment, and complications after CLAU with (MMC+) and without (MMC-) intraoperative MMC were all registered at 1 month and 6 months after surgery.
Results: Thirty-five eyes were included in MMC+ and 34 in MMC-. Preoperative data were similar in both groups (Student’s t test and Fisher’s exact test; p > 0.05).
Thirty-four (49.6%) eyes in the whole sample showed at least one inflammatory complication at 1 month after surgery. MMC- group showed a significantly higher number of cases with complications (p < 0.001; Chi2 test) (MMC+ 28.5%; MMC- 70.5%). No patients presented clinical recurrence at 1 month after surgery. The examination revealed a higher incidence of clinical hyperemia surrounding the surgical site and graft contraction on the host site on the MMC- group, both with statistical signification (p < 0.001; Chi2 test). Although the hemorrhages were less frequent in the MMC- group, there were no significant differences between the two groups (p > 0.05; Chi2 test). Pyogenic granuloma developed at the surgical site in three eyes (4.37%), two of those granulomas were at the MMC- group (p > 0.05).
Tendency for recurrences was significantly different between both groups (p = 0.0001; Fisher’s exact test) at the end of 6 months. Thirteen (38%) eyes showed recurrence in MMC- and no cases were displayed in MMC+. Presence of at least 1 inflammatory event was only seen in 16 (23%) cases, all of them in MMC-. Specifically, 15 (44%) eyes showed hyperemia and one (3%) eye presented conjunctival hemorrhages. No new cases of pyogenic granuloma or graft contraction were seen at this time point in both groups. Hyperemia was the only specific event with significant differences between MMC- and MMC+ (p = 0.0001; Fisher’s exact test) at 6 months after surgery.
Conclusion: The eyes receiving intraoperative MMC after CLAU seem to present less hyperemia and graft contraction after surgery than those that did not receive MMC as an adjuvant factor. Intraoperative MMC could be associated with a lower recurrence rates.
Lluch, S.; Julio, G.; Pujol, P.; Merindano, M. Graefe's archive for clinical and experimental ophthalmology Vol. 254, num. 1, p. 143-148 DOI: 10.1007/s00417-015-3186-9 Data de publicació: 2016-01-01 Article en revista
Background Optical coherence tomography (OCT) has become
a very useful tool to study in vivo different ocular structures
and to improve differential diagnosis and management of
many ocular pathologies. This study aims to identify pterygium
alterations that trigger characteristic OCT images, and
analyze if this pattern correctly demarcates lesion boundary.
Methods Thirty-two patients, 22 men, and ten women, aged
between 26 and 56 (mean age 40.5±6.9) with symptomatic
primary pterygium were recruited. After excision, lesion images
were obtained by high-definition OCT. Specimens were
stained with hematoxylin–eosin (H&E), antivimentin for all
mesenchymal origin cells and altered limbal basal cells, CD45
for lymphocyte and macrophage cells, CD1a for Langerhans
cells, and S100 for melanocyte and Langerhans cells.
Results The typical OCT wedge-shape hyperreflective mass
was evident only by vimentin antibody and included, mainly,
fibroblasts but also immune cells (verified by CD45) in a rich
network of collagen fibers. The mass apex, often extended
centripetally as a thin subepithelial line, hyperreflective by
OCT, was formed by a row of fibroblasts under an apparently
intact Bowman’s layer, as vimentin samples revealed.
Hyperreflective epithelium overlying the mass showed a great
number of vimentin-positive infiltrated cells such as melanocytes,
Langerhans cells, and lymphocytes (identified by the
other biomarkers). H&E staining revealed the presence of
goblet cells. Nevertheless, only vimentin staining revealed
the presence of altered basal cells above partially dissolved
or apparently intact Bowman’s layer, coinciding in this last
case with the fibroblast subepithelial line. In most of the cases
(72 %), the altered cells occupied a basal segment shorter than
the fibroblast subepithelial line but in some specimens, these
cells exceeded the fibroblast line length.
Conclusions This study demonstrated the great visual accordance
between pterygium OCT images and vimentin staining.
Alteration in collagen arrangement, infiltration of inflammatory
cells, and fibroblast subepithelial line in the lesion apex
were the main histological changes responsible for the anomalous
hyperreflectivity of the OCT pattern. By contrast, altered
basal cells located in the basal epithelial layer of the
pterygium head could not be detected by OCT, which might
generate lesion size underestimation.
Full-thickness macular hole (FTMH) is probably caused by tissue tangential separation but mechanism remains controversial. This study aims to compare the inner retinal complex thickness (IRCT) adjacent to FTMH with the contralateral healthy eye. Changes may help to clarify FTMH formation.
Seventeen eyes of 17 patients, 9 males and 12 females; mean age 66 ± 6 (51-74), with idiopathic stage 2 FTMH were enrolled. Contralateral eyes were the controls. Measurements of IRCT (from nerve fibre layer to inner nuclear layer) were made at 1000 (IRCT1) and 2000 µm (IRCT2) from the centre of the fovea using optical coherence tomography images in nasal and temporal side. Wilcoxon rang test was applied in comparison assessments.
The mean nasal IRCT1 and IRCT2 in FTMH were 235 ± 43 and 194 ± 39 µm, respectively. At temporal side mean IRCT1= 211 ± 44 and IRCT2= 160 ± 22 µm. Control eye mean nasal IRCT1 and IRCT2 were 202 ± 21 and 184 ± 19 µm, respectively. Temporal data of IRCT1= 171 ± 27 and IRCT2= 157 ± 17 µm.
Significantly higher IRCT values were found in FTMH than in control eyes at the same locations (p=0.004 for nasal IRCT1; p= 0.004 for temporal IRCT1 and p=0.036 for temporal IRCT2), except for nasal IRCT2 that displayed similar results. IRCT1 were always higher than IRCT2 in both FTMH and control eyes (p= 0.001 in FTMH and temporal control comparisons and p=0.006 in nasal control comparison). Nasal were significantly higher than temporal values (p=0.001 or lower in all the analyses) and differences tended to be similar between FTMH and control eyes (p>0.05).
FTMH eyes seem to show a higher IRCT beyond the lesion. This abnormality could be longer in temporal side and vitreomacular traction could be a plausible cause.
Macular oedema (MO) is the main cause of vision impairment after retinal vein occlusion (RVO). Dexamethasone implant is used to reduce MO and improve patient’s vision. This study aims to assess early response to the therapy according to outer retinal layer status.
Method Twenty-nine eyes of 16 males and 13 females, mean age 65 ± 13 (36-91), with MO after RVO were prospectively enrolled, receiving a single dose of dexamethasone implant (0.7 mg). Exclusion criteria were uncontrolled glaucoma and history of intraocular surgery within 6 months.
Best corrected visual acuity (BCVA; in decimal scale) and central foveal thickness (CFT) were performed at baseline and 1 day after drug administration. The eyes were grouped, according to initial optical coherence tomography images, in G2 (visible external limiting membrane and inner/outer segment junction), G1 (only visible one of these layers) and G0 (no visible layers). Wilcoxon rang test and Student t test were used to compare, VA and CFT intragroup changes, respectively.
Eleven eyes were included in G0, 8 eyes in G1 and 10 eyes in G2. G0 showed a mean change from VA = 0.04±0.06 to 0.09±0.08 and CFT from 689±171 to 521±168 µm. G1 displayed a mean change from VA = 0.18±0.16 to 0.30±0.27 and CFT from 529±147 to 419±85 µm.
G2 disclosed a mean change from VA = 0.35±0.08 to 0.32±0.09 and CFT from 472±160 µm to 410±99 µm. VA showed a weak but significant improvement in G0 and G1 (p=0.027 and 0.028, respectively) while CFT decreased in both groups (p= 0.002 and 0.043, respectively). No significant changes were found in G2.
Early effect of dexamethasone implant depends on outer retinal layer status. The drug seems to produce faster significant changes in more altered tissues.
Retinal vein occlusion is the second most common retinal vascular disease and macular oedema (MO) is one of its complications. Global visual benefits after dexamethasone implant, compared to sham group, has been widely described. Nevertheless, pattern of visual response showed a high variability, depending on diverse factors, and frequently displays a temporal effect.
The aim of this study was to describe the early visual response to dexamethasone implant and the factors that condition its variability. A comprehensively study of this initial stage could help to understand the drug benefits and the visual prognosis in each patient.
Acute specialist care Department of Ophthalmology at Hospital de Terrassa-Consorci Sanitary de Terrassa (Barcelona, Spain).
Thirty eyes of 30 patients with MO due to central (CRVO) or branch (BRVO) retinal vein occlusion were prospectively enrolled in this study and received a single treatment of dexamethasone implant (0.7mg). Exclusion criteria were uncontrolled glaucoma, loss of vision as a result of other causes, and history of intraocular surgery within 6 months.
Best corrected visual acuity (VA), expressed as the logarithm of the minimum angle of resolution (LogMAR); central foveal thickness (CFT), and categorical evaluation of outer foveal layers by Optical Coherence Tomography were performed at baseline, and 1 day after drug administration. The external limiting membrane (ELM) and the inner segment/outer segment (IS/OS) junction were qualitatively assessed as distinct and continuous line, present but disrupted line, or absent line. The presence/absence of foveal detachment (FD), the cone outer segment tips (COST), and the dome shape of the IS/OS layer, called foveal bulge (FB), were also analyzed.
The data were clustered in three groups, according to VA response at 24h (improvement, loss or no change with respect to baseline) and statistical analysis was performed to assess differences among the groups.
Twenty-seven eyes with MO of 16 males and 11 females, mean age 65 ± 13 (range 36-85), were included in the study. Thirteen eyes (52%) presented CRVO and 14 (48%) BRVO.
Global tendency of the group showed significant improvement in VA (Wilcoxon signed rang test; p=0.035) and CFT reduction (Student’s t test; p=0.0001) at 1 day. Twelve eyes (41%) increased VA respect to baseline (mean change of 0.40 ± 0.30 LogMAR units; range 0.12-1.00), 5 eyes (17%) lost VA (mean change of 0.16 ± 0.06 LogMAR units; range 0.06-0.22) and 10 eyes (35%) showed no changes. CFT revealed reduction in 22 eyes (82%) with a mean decrease of 137 ± 87 µm (range 29-348) and increase in the remaining 5 cases (18%) with a mean value of 63 ± 34 µm (range 22-105).
Significantly worse condition of ELM, IS/OS and FB was found with the eyes that underwent improvement or no changes in VA (Kruskal-Wallis test; p=0.005, p=0.0001, p=0.001; respectively) than those with VA loss. No significant differences were disclosed in age and CFT (ANOVA: p>0.05), or in etiology (CRVO or BRVO), FD and COST values (Kruskal-Wallis test; p>0.05).
Dexamethasone implant seems to be able to act as early as 24h, generating a global MO reduction and VA improvement. Baseline characteristics of the outer foveal microstructures seem to determine visual response in this initial stage. They would explain much of the variability in the foveal functionality of these patients despite the great number of cases with CFT reduction. An individual evaluation of the anatomical conditions prior to treatment may help ophthalmologists to predict visual benefits of dexamethasone implant in patients with MO secondary to retinal vein occlusion.
Retinitis pigmentosa (RP) is a slow and progressive inherited retinal disease. The patients experience reduced visual function caused by degeneration of photoreceptors and retinal pigment epithelium. At the end stage of the disease, the loss of central cones leads to blindness.
The aim of this study was to describe the process of impairment of the external layers of the fovea in patients with RP and assess the relationship between the anatomical deterioration of these subcelular structures and the functionality of the tissue.
Specialist care Department of Ophthalmology at Hospital de Terrassa-Consorci Sanitary de Terrassa (Barcelona, Spain).
Thirty eyes of 30 patients with RP were enrolled in this study. High definition Optical Coherence Tomography (OCT) was used to prospectively characterize photoreceptor impairment in the fovea. Cases with atypical or unilateral RP, epiretinal membrane, macular oedema, poor fixation because of extremely low visual acuity (VA < 0.01 in a decimal scale), myopic eyes with posterior staphyloma, and eyes with media opacities that affected VA were excluded. In each OCT 6mm-images of the fovea, external limiting membrane (ELM), photoreceptor inner and outer segment junctions (IS/OS), and cone outer segment tips (COST) were classified in 4 categories (0=absent; 1=abnormally structured; 2= short highly reflective line; 3=reflective line with normal length). Presence of the domelike appearance of the IS/OS layer, called foveal bulge (FB), was also recorded. To assess tissue functionality best corrected (BCVA) was performed using standard Snellen eye charts.
Twenty-seven eyes of 7 males and 20 females, mean age 58 ± 15 (range 18-71) were included in this study. The mean BCVA was 0.56 ± 0.31 (range 0.01-1in decimal scale). The most frequent category in ELM was category 2, in 16 eyes (59%). In case of IS/OS was category 1, in 12 eyes (44%) and COST most frequent result was category 0, in 23 eyes (85%). No eyes showed category 3 for any of these layers. FB was present in 9 eyes (33%). Statistical differences between the three layers of each eye were confirmed (Wilcoxon rank test; p=0.001 in the case of ELM vs IS/OS; p=0.0001for the other pair comparisons).
Spearman’s rank correlation found significant correlations between BCVA and all the anatomical variables. The strongest relationship was disclosed between BCVA and IS/OS (rho = 0.717; p<0.01) and FB (rho=0.644; p<0.01) followed by ELM (rho=0.632; p<0.01) and, finally COST (rho=0.458; p<0.05).
Anatomical analysis by OCT showed a higher tendency for deterioration in COST and FB while the most preserved layer was ELM. These results indicated that the first healthy features to be altered in the fovea of RP patients were COST and FB. In fact, COST has been described as the first retinal layer that becomes disorganized but, sometimes, is difficult to identify. In healthy retina, FB is due to the higher number of membranous discs of most central cones. This clearly identifiable feature could indicate early damage of central photoreceptors, in an easy and more reliable manner, and seems to be relatively well correlated with functionality of the tissue in RP patients.
Julio, G.; Lluch, S.; Pujol, P.; Merindano, M.; Marques, M.S. Optometry and vision science Vol. 92, num. 7, p. 790-795 DOI: 10.1097/OPX.0000000000000622 Data de publicació: 2015-07-01 Article en revista
Purpose To analyze conjunctival cytological features 1 month after pterygium excision using limbo-conjunctival autograft (LCA) with and without intraoperative mitomycin C and to assess tissue short-term evolution in both situations.; Methods Fifty-nine primary nasal pterygia from 59 patients were excised with LCA. Twenty-nine were treated with intraoperative mitomycin C 0.02% (MMC+) and 30 were treated without it (MMC-). Impression cytology was performed in nasal and temporal conjunctiva before and 1 month after the excision. Goblet cell density (GCD) and nucleus-to-cytoplasm nongoblet epithelial cell ratio were quantified.; Results Surgical strategy comparisons (intergroup comparisons): All the preoperative data were, in mean, within the reference range, except for a slight goblet cell hyperplasia in the area of the lesion in MMC+ but no significant differences were found between the groups (p = 0.079 for GCD and p = 0.245 for nucleus-to-cytoplasm ratio; analysis of variance). Clinically relevant differences after surgery were only shown in nasal GCD that was significantly lower in MMC+ than in MMC- (p = 0.000; analysis of variance), with the mean value in MMC+ slightly below normal values whereas that in MMC- remained normal. Tissue evolution (intragroup comparisons): No clinically relevant changes were found in MMC-. Data from MMC+ displayed no changes 1 month after surgery, except for nasal GCD that showed a significant reduction (p = 0.000; paired t test). Nevertheless, this GCD decrease was more modest than that previously described using mitomycin C without autograft, because in the present study, nasal GCD was not lower but similar to postoperative temporal data of the same eye (p = 0.164; paired t test).; Conclusions Limbo-conjunctival autograft is a good technique for conjunctiva early recovery. When mitomycin C was added, the GCD reduction was lower than described using other surgical techniques. Mitomycin C, in optimal concentration and exposure, associated with LCA could be a good clinical option to minimize pterygium recurrence.
PurposeTo establish the sequence of tomographic changes in the tissue recovery process after pterygium excision and to propose healing indicators.; MethodsOptical coherence tomography (OCT) images were taken at 1week, 1, 3 and 6months after lesion excision in 73 eyes of 73 patients (33 male, 40 female; mean age 50, S.D. 5.0, range 40-70years) with primary nasal pterygium. Biomicroscopy was performed at each visit and at 12months, to diagnose clinical healing or lesion recurrence. The presence of well demarcated corneal epithelium, conjunctival epithelium, limbal demarcation area, and graft thickening were analysed. Comparisons between tomographic data of both clinical situations were made at each time point using contingency tables.; ResultsEleven eyes displayed lesion recurrence (R group) and 62 eyes showed no recurrence (NR group). Normal anatomical structures, corneal and conjunctival epithelium and limbal demarcation area, were identified by OCT images in a higher percentage of NR cases over time, compared to the R group where most of the cases presented without these markers of tissue recovery. In contrast, the variable graft thickening, which analysed a pathological event, revealed similar results in both groups (p>0.05; Fisher's exact statistic), with a clear decrease of cases which showed graft thickening over time. Differences between groups started at 1month, when no eye had yet presented clinical recurrence, with greater identification of corneal epithelium in the NR group (p=0.04; Fisher's exact statistic). At 3months, corneal and conjunctival epithelium identification tended to be more frequent in the NR than in the R group (in both cases, p=0.0001; Fisher's exact statistic). Finally, at 6months these different patterns consolidated, with a significantly higher number of limbal demarcation areas being identified in the NR group (p=0.001; Fisher's exact statistic). In fact, this landmark of a normally structured limbus was never found in the R group.; ConclusionsThe sequence of tissue restoration, according to OCT images, seems to start in the cornea and end in the limbal area, similar to the process of pterygium injury in reverse. Although the visualisation of corneal epithelium could be an early indicator of successful surgery, identification of the limbal demarcation area, as a normal limbal pattern in OCT images, seems to be a better positive predictive value in diagnosing healing.
Retinitis pigmentosa is a slow and progressive inherited retinal disease. The patients experience reduced visual function caused by degeneration of photoreceptors and retinal pigment epithelium. At the end stage of the disease, the loss of central cones leads to blindness.
High definition optical coherence tomography (HD-OCT Cirrus Carl Zeiss Meditec, Dublin, CA, USA) was used to characterize photoreceptor impairment in central retina of 42 eyes of 21 patients with non syndromic retinitis pigmentosa (NSRP) without retinal oedema or hemorrhage. External limiting membrane (ELM), photoreceptor inner and outer segment junctions (IS/OS), and cone outer segment tips (COST) were identified and classified in 4 categories (0=absent; 1=abnormally structured; 2= short highly reflective line; 3=reflective line with normal length). Presence of foveal bulge (FB) was also assessed.
Abnormal patterns were always disclosed in the three studied layers. ELM showed grade 2 in 28 (66.67%), and grade 1in 11 (26.19%) been absent in 3 eyes (7.14%). IS/OS displayed grade 2 in 26 (61.90%), grade 1 in 12 (28.57%) and grade 0 in 4 eyes (9.53%). COST was absent in 33 (78.57%) revealing grade 2 only in 3 eyes (7.14%), and grade 1 in 6 eyes (14.29%). FB was inexistent in 38 eyes (90.48%).
COST has been described as the first retinal layer that becomes disorganized but sometimes is difficult to identify. FB indicates a domelike appearance of the IS/OS junction in healthy central retina due to the higher number of membranous discs of central cones. This clearly identifiable feature was the most frequently altered in NSRP and could indicate early damage of central photoreceptors in an easy and reliable manner. (COI/financial disclosure: none)
Pterygium is a common ocular surface lesion originates from altered limbal stem cells, which proliferate into the cornea, accompanied by degradation of Bowman’s layer and elastosis. Corneo-conjunctival changes could trigger tear film alterations that, in some conditions, reduce corneal sensitivity. The purpose of this study was to compare corneal sensitivity on affected and unaffected zone, thus assessing a relative loss of sensitivity.
Thirty-nine eyes of 39 patients with primary nasal pterygium were included in this study. Cochet-Bonnet aesthesiometer were used to evaluate corneal sensitivity of 3 points on pterygium lesion (delimiting a triangle) and 4 points on unaffected cornea (central, temporal, upper and lower). All the measurements were made for the same practitioner and in similar conditions of humidity and temperature. Results on one zone were added to calculate the sensitivity of this zone.
Abnormal sensitivity in the three point of the lesion was found in 35 eyes (89.74%) being the mean sensitive value of the affected zone 13.8 ± 2.8 cm (normal mean value of 18 cm, since the zone include 3 points and normal result is 6 cm in each point). Mean sensitivity in unaffected cornea was 23.5 ± 1.0 cm (normal mean values of 24 cm). Four eyes showed normal mean values in the two zones. A significant sensitivity reduction in the affected zone was found when results of the two zones were compared (p < 0.001; Wilcoxon test) (data were normalized to avoid influence of the different number of points analyzed in each zone). Pterygium changes seem to induce corneal sensitivity loss, regardless changes in tear film. (COI/financial disclosure: none)
Pujol, P.; Julio, G.; de Carvalho, A.M.; Kostov, B.; Martí , T. Optometry and vision science Vol. 91, num. 7, p. 747-751 DOI: 10.1097/OPX.0000000000000307 Data de publicació: 2014-07-01 Article en revista
Purpose. To compare corneal astigmatism after pterygium excision, using limbal-conjunctival autograft (LCA) with and without mitomycin C (MMC) and to establish a threshold for postoperative astigmatism reduction.; Methods. Sixty-eight eyes with primary pterygium were consecutively sampled and assigned to LCA with MMC (MMC+) or LCA without MMC (MMC-). Corneal lesion length, corneal lesion area, preoperative corneal astigmatism (PRCA), and postoperative corneal astigmatism (POCA) at 1, 3, and 6 months were assessed.; Results. Thirty-six men and 24 women (60 eyes), aged between 24 and 65 years (mean +/- SD, 41 +/- 8.2 years), completed the study. Thirty-one eyes were included in the MMC+ group and 29 were in the MMC- group. Both groups showed astigmatism reduction (p < 0.05; paired, two-tailed t test) 1 month after the surgery and remained stable. No differences were found between groups in corneal lesion length, corneal lesion area, or astigmatism results at the four time points (p 9 0.05, independent t test). Preoperative corneal astigmatism showed a significant correlation with POCA at 6 months (r = 0.529; p < 0.01). According to receiver operating characteristic curve analysis, the better threshold for astigmatism reduction with the surgery was 1.05 diopters of PRCA, with 82.5% sensitivity and 80.5% specificity.; Conclusions. Both surgical procedures could have similar astigmatism results. Pterygium patients with more than 1.05 diopters of PRCA could reduce it after the surgery. Direct relationship between PRCA and POCA revealed that postoperative astigmatism reduction was partial. Therefore, for minimizing final astigmatism, preoperative values should be slightly above the threshold.
Rodriguez, A.; Canal, C.; Calafell, M.; Ginebra, M.P.; Julio, G.; Marques, M.S. European polymer journal Vol. 49, num. 11, p. 3501-3511 DOI: 10.1016/j.eurpolymj.2013.08.010 Data de publicació: 2013-11 Article en revista
Natural and synthetic biodegradable polymers have been investigated for controlled drug release. Poly(3-hydroxybutyrate) can be produced by bacteria and is remarkable for this application due to its excellent biocompatibility and biodegradability. The objective of this work was to study different drug-entrapment and emulsification methods for the obtaining of doxycycline-loaded PHB micro- and nano-spheres. The micro-/nano-particles were prepared by polymer precipitation via dialysis, simple emulsion (O/W) or multiple emulsion (W1/O/W2) applying solvent evaporation in the last two cases. This was carried out either by ultrasonication, dripping and/or high speed stirring. Different processing conditions were varied in order to evaluate their influence on morphology, size, and drug entrapment capabilities. The highest drug loading was obtained by single emulsion with high speed stirring. In the case of multiple emulsion, the combination of ultrasound with high speed stirring resulted in the most elevate process yield and drug loading capability.
PURPOSE: To evaluate the effect of pterygium size and excision on corneal astigmatism before, after surgery.
METHODS: Thirty two eyes with pterygium, were operated using the limbal-conjunctival autograft technique. Corneal topography was performed preoperatively, one, and 3 months after the intervention.
RESULTS: A significant correlation (p < 0.05) was obtained berween pterygium length and preoperative astigmatism, but no correlation was observed berween length and astigmatism at any timepoint. A statistically significant reduction was found berween pre-surgical astigmatism and astigmatism at one and three months. No differences were observed berween one and 3 months. No significant differences were found when comparing the presurgical and postsurgical astigmatism axis.
CONCLUSIONS: Pterygium surgery with limbal-conjunctival autograft moderarely reduces corneal astigmatism. Preoperative astigmatism is associated with the size of the
Julio, G.; Merindano, M.; Lluch, S.; Caum, C. International Conference on the Tear Film & Ocular Surface: Basic Science and Clinical Relevance p. 77 Data de presentació: 2010-09-23 Presentació treball a congrés
Julio, G.; Merindano, M.; Lluch, S.; Caum, C. International Conference on the Tear Film & Ocular Surface: Basic Science and Clinical Relevance p. 76-77 Data de presentació: 2010-09-23 Presentació treball a congrés
Premi extraordinari doctorat curs 2007-2008, àmbit d’Enginyeria Civil
La descripción del flujo de fluidos involucra la solución de las ecuaciones de Navier-Stokes compresible, un problema muy complejo cuya estructura matemática no es del todo comprendida. Por lo tanto, mediante análisis asintótico, se pueden derivar modelos simplificados bajo ciertas hipótesis sobre el problema hechas en términos de parámetros adimensionales que miden la importancia relativa de los diferentes procesos físicos. Los flujos a baja velocidad se pueden describir por diferentes modelos que incluyen las ecuaciones de Navier Stokes incompresible cuya matemática es mucho mas conocida. Sin embargo, algunos flujos importantes no se pueden considerar incompresibles debido a la presencia de efectos térmicos. En esta clase de problemas se pueden derivar otra clase de ecuaciones simplificadas: las ecuaciones de Boussinesq y las ecuaciones de bajo numero de Mach.
La complejidad de estos problemas matemáticos hace que su solución numérica sea muy difícil. En estos problemas el método de los elementos finitos es inestable, lo que en la práctica implica soluciones numéricas que presentan oscilaciones nodo a nodo de naturaleza no física. En las ecuaciones de Navier Stokes incompresible, dos fuentes bien conocidas de inestabilidad son la condición de incompresibilidad y la presencia del término convectivo. Muchas técnicas de estabilización utilizadas hoy en día se basan en la separación de escalas, descomponiendo la incógnita en una parte gruesa inducida por la discretización del domino y una parte fina de subescala. Modelar la subescala y su influencia conduce a un problema modificado para la escala gruesa que resulta estable.
Aunque las técnicas de estabilización son ampliamente utilizadas hoy en día, importantes problemas permanecen abiertos. Contribuyendo a su comprensión, en este trabajo se analizan varios aspectos del modelado de las subescalas. Para problemas escalares de segundo orden, se encuentra la dependencia de la subescala con el tamaño de la malla en el caso general de mallas anisótropas. Estas ideas son extendidas a sistemas de ecuaciones para considerar el problema de Oseen. También se analiza el modelado de las subescalas en problemas transitorios, obteniendo un mejor esquema de integración temporal para el problema de escala gruesa. Para considerar flujos a baja velocidad, se presenta la extensión de estas técnicas a problemas no lineales acoplados, lo que esta íntimamente relacionado con el problema del modelado de la turbulencia, que es un tema en si mismo.
Los flujos acoplados térmicamente, aparte del interés intrínseco que merecen, son importantes desde un punto de vista ingenieril. Una solución precisa del problema de flujo es necesaria para definir las cargas térmicas sobre las estructuras, que en muchos casos responden fuertemente, haciendo el problema acoplado. Esta clase de problemas, que motivaron este trabajo, incluyen la respuesta estructural en el caso de un incendio.
A general description of a fluid flow involves the solution of the compressible Navier-Stokes equations, a very complex problem whose mathematical structure is not well understood. Therefore, simplified models can be derived by asymptotic analysis under some assumptions on the problem, made in terms of dimensionless parameters that measure the relative importance of different physical processes. Low speed flows can be described by several models including the incompressible Navier Stokes equations whose mathematical structure is much better understood. However many important flows cannot be considered as incompressible, even at low speed, due to the presence of thermal effects. In such kind of problems another class of simplified equations can be derived: the Boussinesq equations and the Low Mach number equations. The complexity of these mathematical problems makes their numerical solution very difficult. For these problems the standard finite element method is unstable, what in practice means that node to node oscillations of non physical nature may appear in the numerical solution. In the incompressible Navier Stokes equations, two well known sources of numerical instabilities are the incompressibility constraint and the presence of the convective terms. Many stabilization techniques used nowadays are based on scale separation, splitting the unknown into a coarse part induced by the discretization of the domain and a fine subgrid part. The modelling of the subgrid scale and its influence leads to a modified coarse scale problem that now can be shown to be stable. Although stabilization techniques are nowadays widely used, important problems remain open. Contributing to their understanding, several aspects of the subgrid scale modelling are analyzed in this work. For second order scalar problems, the dependence of the subgrid scale on the mesh size, in the general anisotropic case, is clarified. These ideas are extended to systems of equations to consider the Oseen problem. The modelling of the subgrid scales in transient problems is also analyzed, leading to an improved time discretization scheme for the coarse scale problem. To consider low speed flow models, the extension of these techniques to nonlinear and coupled problems is presented, something that is intimately related to the problem of turbulence modelling, which a entire subject on its own right. Thermally coupled flow problems, despite the intrinsic interest they deserve, are important from an engineering point of view. An accurate solution of a flow problem is needed to define thermal loads on structures which, in many cases have a strong response, making the problem coupled. This kind of problems, that motivated this work, include the problem of a structural response in the case of fires.