Gemma Julio

Effects of tear hyperosmolarity on conjunctival cells in mild to moderate dry eye

Citation information: Julio G, Lluch S, Pujol P & Merindano MD. Effects of tear hyperosmolarity on conjunctival cells in mild to moderate dry eye. Ophthalmic Physiol Opt 2012, 32, 317–323. doi: 10.1111/j.1475‐1313.2012.00915.x

Tear osmolarity and ocular changes in pterygium.

Purpose: To determine abnormalities in tear osmolarity (TO), tear function, and impression cytology in patients with pterygium and to assess the relationship between the variables. Methods: Thirty eyes from 30 patients with primary nasal pterygium and 30 eyes from 30 volunteers without ocular pathologies or dry eye symptoms were enrolled in the present study. TO test, tear ferning test, fluorescein tear breakup time, Schirmer test, and impression cytology of the conjunctiva were performed. Analysis of variance was applied for intergroup comparisons, and Pearson correlation was used to calculate the strength of relationships between the variables. A statistical significance level of P <0.05 was considered. Results: Pterygium patients had significantly higher TO, lower crystallization percentage, and lower goblet cell density (GCD) than control patients. A weak but significant negative correlation seems to exist between TO and crystallization percentage (r = −0.425, P < 0.01) and between TO and GCD (r = −0.295, P < 0.05). Conclusion: There is evidence to suggest that pterygium appears to induce unfavorable conditions of increasing TO that could trigger alterations in tear crystallization and GCD. Being aware of TO changes seems essential to understand the complex relationship among pterygium, tear film functions, and ocular surface changes.

Item by item analysis strategy of the relationship between symptoms and signs in early dry eye

Purpose: The present study aimed at analyzing the relationship between several particular symptoms, risk factors or global questionnaire scores and some tear clinical signs in early dry eye patients. Material and methods: A total of 77 volunteers were enrolled in the study without any prior classification, although patients with severe dry eye were excluded. Two questionnaires were used to assess ocular symptoms and risk factors, and clinical tear signs were evaluated with four tests (osmolarity, ferning, break-up time and the phenol red thread test). Multiple linear regression analysis was performed to determine the relative predictive value of each particular ocular symptom and risk factor, for each clinical sign. This analysis was repeated using symptoms and risk factors global scores. Results: The symptom “eyes stuck shut in the morning” was the only predictor variable for the sign “ferning crystallization” (R = 0.228, p < 0.05) and “dryness” for “break-up time” (R = –0.315, p < 0.01). “Burning sensation” and “computer use for more than 3 h” were predictor variables for “tear osmolarity” (R = 0.342, p < 0.01), while “itching” and “female gender” were found to predict the outcomes of the “phenol red thread test” (R = –0.462, p < 0.05). Global questionnaire scores were not found to predict any tear clinical sign. Conclusions: The present findings support the informative value of exploring the associations between clinical signs, ocular symptoms and risk factors by following an item by item strategy rather than opting for global questionnaire scores.

Image processing techniques to quantify microprojections on outer corneal epithelial cells

It is widely accepted that cellular microprojections (microvilli and/or microplicae) of the corneal surface are essential to maintain the functionality of the tissue. To date, the characterization of these vital structures has been made by analysing scanning or transmission electron microscopy images of the cornea by methods that are intrinsically subjective and imprecise (qualitative or semiquantitative methods). In the present study, numerical data concerning three microprojection features were obtained by an automated method and analysed to establish which of them showed less variability. We propose that the most stable microprojection characteristic would be a useful sign in early detection of epithelial damage or disease. With this aim, the scanning electron microscopy images of 220 corneal epithelial cells of nine rabbits were subjected to several image processing techniques to quantify microprojection density, microprojection average size and surface covered by microprojections (SCM). We then assessed the reliability of the methods used and performed a statistical analysis of the data. Our results show that the thresholding process, the basis of all image processing techniques used in this work, is highly reliable in separating microprojections from the rest of the cell membrane. Assessment of histogram information from thresholded images is a good method to quantify SCM. Amongst the three studied variables, SCM was the most stable (with a coefficient of variation of 15.24%), as 89.09% of the sample cells had SCM values ≥ 40%. We also found that the variability of SCM was mainly due to intercellular differences (the cell factor contribution represented 88.78% of the total variation in the analysed cell areas). Further studies are required to elucidate how healthy corneas maintain high SCM values.

Image processing techniques in a preliminary morphometric characterization of corneal epithelium by scanning electron microscopy

Several processing techniques of digital images allowed us to quantify the percentage of cell surface covered by microprojections (microvilli or microplicae) (SCM), the adhesion between epithelial cells by the parameter intercellular junctions (IJ), the size (cell area), shape (cell shape) and shade (cell shade) of cells on the corneal epithelium of nine rabbits. The data were analyzed and the epithelial cells were classified into three groups by cluster analysis. Assuming the representativeness of the sample, our findings suggest that for a normal corneal epithelium, 80% of the cells could show SCM >41%, and IJ >0.98 (being one a cell to cell junction without disruptions). Standard deviations of cell shade lower than 21 gray levels could indicate a tendency to lose the cell shade mosaic. Normal corneas could show a majority of cells (54–69%) included in group 2 with smaller mean size (80% of cells with cell area <242 μm2), higher SCM (80% of cells with SCM >44.83%), polygonal mean shape and brighter shade. Group 1 (15–30% of cells) could show a larger mean size (80% of cells with cell area >494 μm2), lower SCM (although 80% of cells with SCM >32.61%), circular mean shape and darker electron reflex. Group 3 could display a medium mean size, higher SCM (similar to group 2), circular mean shape (similar to group 1), and brighter shade. These analyses could possibly be used to further assess the corneal response to ocular drugs, contact lens, and surgical procedures or to discriminate between pathology stages. Microsc. Res. Tech. 73:1059–1066, 2010.

Ocular discomfort in pterygium patients.

Purpose To evaluate the relationship between ocular discomfort and pterygium clinical characteristics. Methods The Ocular Comfort Index test was self-completed by 25 men and 15 women (age [mean ± SD], 43 ± 11 years) with primary pterygium. Pterygium corneal area (PCA) and limbal perimeter, course and bilaterality of the lesion, visibility of episcleral vessels, conjunctival hyperemia, and exposure to dry or dusty environments were assessed. Spearman correlation and multiple linear regression were performed to evaluate the relationship between ocular discomfort and pterygium clinical characteristics. Results Ocular discomfort was inversely correlated with PCA (&rgr; = −0.447, p < 0.01) and directly correlated with the exposure to dry or dusty environments (&rgr; = 0.324, p < 0.05). The other studied factors did not show any significant relationship with discomfort symptoms. The linear regression analysis identified PCA as the only factor that significantly influenced ocular discomfort (R = −0.404, p < 0.01). Conclusions The findings confirm an inverse linear relationship between ocular discomfort and PCA, providing evidence of corneal sensitivity loss in these patients.

Indicators of progressive corneal exposure to dry eye conditions.

Purpose. To establish the main indicator of progressive corneal exposure to dry eye conditions in an animal model. Methods. Cell surface covered by microvilli (SCM), intercellular junctions (IJs), cell area, cell shape, and cell shade were measured in 988 epithelial corneal cells from rabbit eyes that were kept open for different drying times (DT) between 0 and 3 h. Two multivariate logistic regressions were used to model the relationship between these morphometric cell characteristics and DT. To corroborate the results, terminal differentiation was assessed by cluster analysis. Results. Scanning electron microscopy images of the epithelial cells showed typical desiccation changes that increased in frequency and intensity as DT were prolonged. Binomial logistic regression, to distinguish cells exposed to desiccation from the control cells, displayed SCM, IJ, and cell shade as significant indicators (p < 0.01) of desiccation exposure. Multinomial logistic regression analysis showed SCM, IJ, cell shade, and cell area as significant indicators (p < 0.01) differentiating the four levels of desiccation exposure, and SCM was the variable that showed elevated odds ratio in all the analysis. In addition, the cells were grouped in three groups (G1, G2, and G3) by cluster analysis. G2 cells increased in percentage as DT grew (p < 0.05, &khgr;2 test) in detriment of G1 cells, while the percentage of G3 cells remained stable. These changes were consistent with a terminal differentiation process from G1 cells to G2 cells, which was the group with the lowest values of SCM (p < 0.001, Mann-Whitney test). Conclusions. The variable SCM could be the best determining indicator of progressive corneal exposure to dry eye conditions. The development of clinical methods to analyze microvilli density could allow a more accurate assessment of the level of degradation of the corneal epithelium under evaporative conditions.

Determining Factors for Fast Corneal Sensitivity Recovery After Pterygium Excision.

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.

Conjunctival Short-term Evolution after Pterygium Excision

PurposeTo 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. MethodsFifty-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. ResultsSurgical 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). ConclusionsLimbo-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.

Healing indicators after pterygium excision by optical coherence tomography

To establish the sequence of tomographic changes in the tissue recovery process after pterygium excision and to propose healing indicators.