Clinical evaluation of meibomian gland dysfunction in patients with keratoconus.

PURPOSE: To investigate the association of keratoconus (KC) with meibomian gland dysfunction (MGD) and to describe the epidemiological characteristics of MGD in this disease. METHODS: In this observational study, 120 KC patients seen in the Department of Ophthalmology of the Complexo Hospitalario Universitario de Santiago de Compostela and 87 controls were analyzed. The Ocular surface disease index (OSDI) questionnaire was administered and several DED tests and an evaluation of the meibomian glands and lid margin were performed. MGD signs and DED tests were compared between the groups. Symptoms were further analyzed in patients and controls with and without MGD. RESULTS: KC was significantly associated with MGD after adjusting for age and sex [adjusted odds ratio (ORa), 2.40]. The frequency of MGD in KC patients [59 (49.2%) KC patients and 25 (28.7%) controls had MGD] correlated with the severity of KC (r = 0.206) (P = 0.020). Mean OSDI score in KC patients with and without MGD was 31.1 ± 24.1 and 35.2 ± 26.0 (P = 0.326), and 17.2 ± 22.7 and 13.3 ± 14.1 in controls with and without it (P = 0.366). The most common MGD signs coincided in both groups. Staining with fluorescein (P = 0.000) and lissamine green (P = 0.019) was higher in KC patients, but no differences were detected with TBUT (P = 0.116) or the Schirmer test (P = 0.637). Hypersecretory MGD was the most prevalent variant in both groups. CONCLUSIONS: MGD and DED are common in KC patients. MGD correlates with the severity of KC and is indistinguishable from MGD in patients without KC. No association was found with symptoms. Patients with KC should be screened for MGD because of its possible clinical implications. Further research is needed to clarify the role of MGD in KC patients.

Recent Research in Ocular Cystinosis: Drug Delivery Systems, Cysteamine Detection Methods and Future Perspectives.

Cystinosis is a rare genetic disorder characterized by the accumulation of cystine crystals in different tissues and organs. Although renal damage prevails during initial stages, the deposition of cystine crystals in the cornea causes severe ocular manifestations. At present, cysteamine is the only topical effective treatment for ocular cystinosis. The lack of investment by the pharmaceutical industry, together with the limited stability of cysteamine, make it available only as two marketed presentations (Cystaran® and Cystadrops®) and as compounding formulations prepared in pharmacy departments. Even so, new drug delivery systems (DDSs) need to be developed, allowing more comfortable dosage schedules that favor patient adherence. In the last decades, different research groups have focused on the development of hydrogels, nanowafers and contact lenses, allowing a sustained cysteamine release. In parallel, different determination methods and strategies to increase the stability of the formulations have also been developed. This comprehensive review aims to compile all the challenges and advances related to new cysteamine DDSs, analytical determination methods, and possible future therapeutic alternatives for treating cystinosis.

Incidence and Risk Factors of Dry Eye in a Spanish Adult Population: 11-Year Follow-Up From the Salnés Eye Study.

PURPOSE: To estimate the incidence of dry eye (DE) and to evaluate risk factors in an adult cohort in Spain. METHODS: The Salnés Eye Study (SES) was a cross-sectional population-based study of 654 subjects conducted from 2005 to 2006. After 11 years, 264 individuals (65.8% response rate) participated in SES 2. The incidence cohort consisted of 209 subjects not diagnosed with DE in SES 1 [mean age (SD) 67.6 years (±10.1), range: 51-92, women 69.4%]. DE was defined as the simultaneous presence of symptoms and at least 1 sign. A Schirmer test score ≤5 mm, tear film breakup time ≤10 seconds, rose bengal staining ≥3, and fluorescein staining ≥1 were considered indicative of signs. Poisson regression models were performed to evaluate risk factors. RESULTS: The 11-year incidence of DE was 25.4% (95% confidence interval, 19.5-31.3) and that of symptoms was 31.6% (confidence interval, 25.4-37.8). DE incidence was significantly associated with age (P < 0.05). After adjusting for age, secondary or university studies were protective factors for DE; taking anxiolytics or antidepressants and angiotensin-converting enzyme inhibitors increased the risk of symptoms; a history of hypertension, chronic obstructive pulmonary disease, or autoimmune diseases increased the risk of signs. CONCLUSIONS: The annual incidence of DE, symptoms, and signs, was found to be 2.3 per 100 person-years. The incidence of symptoms was higher than that reported in similar studies. This study suggests that some factors may increase the risk of symptoms, whereas other factors may increase the risk of signs.

Preclinical characterization and clinical evaluation of tacrolimus eye drops.

Severe allergic ocular diseases as atopic keratoconjunctivitis can induce corneal damage due to inflammatory substances released from giant papillae. Tacrolimus eye drops are one of the current therapeutic alternatives for its treatment. This work is aimed at developing and characterizing a 0.03% tacrolimus ophthalmic formulation, which was introduced in three types of vehicles (BBS, PVA and Hyaluronic Acid). For this, we have performed in vitro (stability studies) and in vivo assays (corneal permanence time measured directly by Positron Emission Tomography) of three potential formulations. Next, the best formulation was selected, and its toxicological profile and clinical effectiveness have been evaluated. The biopermanence studies (direct measurements and PET/CT) showed that the formulations with PVA and Hyaluronic Acid present more retention time on the ocular surface of rats than PBS. From the stability study, we have determined that tacrolimus with PVA in cold storage is the best option. Tacrolimus with PVA has shown lower cytotoxicity than cyclosporine at early times. On the other hand, the pilot study performed has shown significant improvements in patients, with no noticeable adverse reactions. Based on stability, biopermanence, safety and clinical effectiveness studies, we concluded that tacrolimus-PVA eye drops are a suitable candidate for its clinical application in inflammatory ophthalmology diseases.

Hidrogel oftálmico de cisteamina para el tratamiento de la cistinosis ocular / Cysteamine ophthalmic hydrogel for the treatment of ocular cystinosis

La cistinosis ocular es una enfermedad rara que se caracteriza por el depósito de cristales de cistina a nivel corneal, los cuales dificultan la visión de los pacientes. La cisteamina oral se administra en forma de cisteamina, pero esta no alcanza la córnea debido a la falta de vascularización corneal, por lo que es necesaria la aplicación tópica ocular. El objetivo del presente trabajo es determinar la estabilidad de un hidrogel oftálmico de cisteamina, potencialmente formulable en servicios de farmacia hospitalaria, conservado este bajo diferentes condiciones de almacenamiento durante un periodo de 30 días. Los parámetros físicos y químicos evaluados han sido la osmolalidad, el pH y la concentración de cisteamina, siendo esta última valorada mediante un método de cromatografía líquida de ultra alta presión, empleando un detector de masas en tándem (UPLC-MS/MS). Los ensayos descriptivos se han basado en la medición de la transparencia y los ensayos microbiológicos en la realización de pruebas de esterilidad. Los resultados obtenidos permiten concluir que el hidrogel de cisteamina es estable durante un periodo de 30 días, recomendándose que su conservación sea en nevera (AU)

Ocular cystinosis is a rare disease characterised by the deposit of cystine crystals on the corneal surface, which hinder patients' eyesight. Oral cysteamine is given as cysteamine; however, it does not reach the cornea due to the lack of corneal vascularization making necessary its administration by the topical ocular route. The aim of the present study is to determine the stability of an ophthalmic hydrogel of cysteamine, which can be potentially prepared at hospital pharmacy departments, under different preservation conditions during a follow-up of 30 days. Different physical and chemical parameters were evaluated: osmolality, pH and cysteamine concentration, which has been measured by a method of ultra performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS). Descriptive assays were also performed, such as transparency measurement and microbiological assays in order to verify its sterility. The obtained results allow us to conclude that the cysteamine hydrogel is stable during 30 days, being recommendable its preservation in refrigerated conditions (AU)

[Cysteamine ophthalmic hydrogel for the treatment of ocular cystinosis]. / Hidrogel oftálmico de cisteamina para el tratamiento de la cistinosis ocular.

Ocular cystinosis is a rare disease characterised by the deposit of cystine crystals on the corneal surface, which hinder patients' eyesight. Oral cysteamine is given as cysteamine; however, it does not reach the cornea due to the lack of corneal vascularization making necessary its  administration by the topical ocular route. The aim of the present study is to  determine the stability of an ophthalmic hydrogel of cysteamine, which can be  potentially prepared at hospital pharmacy departments, under different preservation conditions during a follow-up of 30 days. Different physical  and chemical parameters were evaluated: osmolality, pH and  cysteamine concentration, which has been measured by a method of ultra  performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS).  Descriptive assays were also performed, such as transparency measurement and  microbiological assays in order to verify its sterility. The obtained results  allow us to conclude that the cysteamine hydrogel is stable during 30 days,  being recommendable its preservation in refrigerated conditions.

La cistinosis ocular es una enfermedad rara que se caracteriza por el depósito de  cristales de cistina a nivel corneal, los cuales dificultan la visión de  los pacientes. La cisteamina oral se administra en forma de cisteamina, pero  esta no alcanza la córnea debido a la falta de vascularización corneal, por lo que  es necesaria la aplicación tópica ocular. El objetivo del presente trabajo es  determinar la estabilidad de un hidrogel oftálmico de cisteamina, potencialmente  formulable en servicios de farmacia hospitalaria, conservado  este bajo diferentes condiciones de almacenamiento durante un periodo de 30  días. Los parámetros físicos y químicos evaluados han sido la osmolalidad, el pH  y la concentración de cisteamina, siendo esta última valorada mediante un  método de cromatografía líquida de ultra alta presión, empleando un detector de  masas en tándem (UPLC-MS/MS). Los ensayos descriptivos se han basado  en la medición de la transparencia y los ensayos microbiológicos en la realización  de pruebas de esterilidad. Los resultados obtenidos permiten  concluir que el hidrogel de cisteamina es estable durante un periodo de 30 días,  recomendándose que su conservación sea en nevera.

Cysteamine polysaccharide hydrogels: Study of extended ocular delivery and biopermanence time by PET imaging.

Cystinosis is a rare autosomal recessive disorder in which cystine crystals accumulate within the lysosomes of various organs, including the cornea. Ocular treatment is based on the administration of cysteamine eye drops, requiring its instillation several times per day. We have introduced the cysteamine in two types of previously developed ocular hydrogels (ion sensitive hydrogel with the polymers gellan gum and kappa-carrageenan and another one composed of hyaluronic acid), aiming at increasing the ocular retention in order to extend the dosing interval. The biopermanence studies (direct measurements and PET/CT) show that these formulations present a high retention time on the ocular surface of rats. From the in vitro release study we determined that both hydrogels can control the release of cysteamine over time, showing a zero order kinetics during four hours. At the same time, these hydrogels could act as corneal absorption promoters, as they allow a higher permeation of cysteamine through bovine cornea compared to a solution. HET-CAM test and cytotoxicity assays show no irritation on the ocular surface. These results demonstrate that the developed formulations present a high potential as vehicles for the topical ocular administration of cysteamine.

In Vitro Evaluation of the Ophthalmic Toxicity Profile of Chlorhexidine and Propamidine Isethionate Eye Drops.

PURPOSE: Acanthamoeba keratitis causes frequent epithelial lesions that fully expose the corneal stroma. The aim of this study was to determine the toxic profile of chlorhexidine and propamidine eye drops. METHODS: We used primary human keratocytes in cell culture in combination with a novel technology that evaluates dynamic real-time cytotoxicity through impedance analysis. Additional studies such as a classic cell viability test (WST-1®), a bovine corneal opacity and permeability assay, and an irritation eye study (Hen's Egg Test [HET]) have been made. RESULTS: Both eye drop formulations showed a time- and concentration-dependent toxicity profile, in which long periods and high concentrations were more detrimental to cells. In prolonged times of exposure, propamidine is more harmful to cells than chlorhexidine. On the contrary, no irritation has been detected in using the HET-chorioallantoic membrane test and no alterations in the corneal transparency nor permeability was produced by the treatment with both eye drops. CONCLUSIONS: In culture assay, chlorhexidine eye drops have proven to be less cytotoxic than Brolene® for a long contact period of time, but no signs of irritation or alterations in transparency or permeability have been observed in the cornea after both treatments.

Ocular safety comparison of non-steroidal anti-inflammatory eye drops used in pseudophakic cystoid macular edema prevention.

Non-steroidal anti-inflammatory drug (NSAID) eye drops are widely used to treat ocular inflammatory conditions related to ophthalmic surgical procedures, such as pseudophakic cystoid macular edema, and they have been used for off-label treatments. The most commonly used NSAIDs are diclofenac and ketorolac and the new molecules bromfenac and nepafenac have also been used. We used primary human keratocytes in cell culture in combination with a novel technology that evaluates dynamic real-time cytotoxicity through impedance analysis. This study also included classic cell viability tests (WST-1(®) and AlamarBlue(®)), wound healing assay, Hen's Egg Test and an ex vivo histopathological assay. NSAIDs were shown to have important cytotoxicities and to retard the healing response. Furthermore, the new eye drops containing bromfenac and nepafenac were more cytotoxic than the more classical eye drops. Nevertheless, no immuno-histochemical changes or acute irritation processes were observed after the administration of any eye drops tested. Due to cytotoxicity and the total absence of discomfort and observable injuries after the administration of these drugs, significant corneal alterations, such as corneal melts, can develop without any previous warning signs of toxicity.

Tear film inflammatory mediators during continuous wear of contact lenses and corneal refractive therapy.

OBJECTIVES: To study changes in tear film inflammatory mediators following continuous wear of silicone-hydrogel lenses and corneal refractive therapy with reverse geometry contact lenses. DESIGN: A prospective, case-control study. METHODS: Twenty-eight subjects had worn silicone-hydrogel lenses on a 30-night continuous wear basis. Thirty-two subjects had worn corneal refractive therapy lenses on an overnight basis. Thirty-two matched control subjects were also recruited. Tear samples were obtained 12 months after initial fitting and assayed using ELISA for cytokines (interleukin (IL)-6 and IL-8), matrix metalloproteinase 9 (MMP-9) and epidermal growth factor (EGF). RESULTS: EGF was significantly increased 12 months after both interventions. IL-6, IL-8 and MMP-9 were significantly increased only after corneal refractive therapy. The inflammatory response for the corneal refractive therapy patients was found to be associated with the degree of myopia corrected and the presence of corneal staining. Moreover, an increased level of MMP-9 and EGF was found to be associated with the presence of corneal-pigmented arc in the corneal refractive therapy group. CONCLUSIONS: This research showed long-term increased tear levels of inflammatory markers in subjects wearing corneal refractive therapy lenses when compared with continuous wear of silicone-hydrogel lenses or no lens wear.

Prevalence of asymptomatic and symptomatic meibomian gland dysfunction in the general population of Spain.

PURPOSE: To describe epidemiologic characteristics of asymptomatic and symptomatic meibomian gland dysfunction (MGD) in a general adult population in northwestern Spain. METHODS: A total of 1155 subjects aged 40 years and older were selected by an age-stratified random sample procedure in O Salnés, Spain. A standardized symptoms questionnaire was administered and a comprehensive ophthalmic evaluation, which included ocular surface tests, was carried out. Absent, viscous, or waxy white secretion upon digital expression, lid margin telangiectasia or plugging of the meibomian gland orifices was considered evidence of MGD. The prevalence and associations of asymptomatic and symptomatic MGD, and their effects on the ocular surface, were investigated. RESULTS: From 937 eligible subjects, 619 (66.1%) participated (mean age [SD], 63.4 [14.5] years; range, 40-96; 37.0% males). The prevalence of asymptomatic MGD was 21.9% (95% confidence interval [CI], 18.8-25.3). This prevalence increased with age (P = 0.000) and was higher in males than in females (P = 0.003). The prevalence of symptomatic MGD was 8.6% (95% CI, 6.7-10.9). This prevalence also increased with age (P = 0.000) but was not associated with sex. Abnormal tear breakup time and fluorescein staining prevalence estimates were higher among asymptomatic subjects. After controlling for age and sex, asymptomatic MGD was associated with diabetes (adjusted odds ratio [OR(a)] 2.23) and cardiovascular disease (OR(a) 1.80), and symptomatic MGD with rosacea (OR(a) 3.50) and rheumatoid arthritis (OR(a) 16.50). CONCLUSIONS: Asymptomatic MGD is more common than symptomatic MGD. Symptomatology is not associated with secondary damage to the ocular surface. Some systemic diseases may lower whereas others may raise the risk of developing symptoms. Symptom-based approaches do not seem appropriate for MGD estimation.

Activation of MAPK signaling pathway and NF-kappaB activation in pterygium and ipsilateral pterygium-free conjunctival specimens.

PURPOSE: To evaluate mitogen-activated protein kinases (MAPKs) and nuclear factor-κB (NF-κB) signaling pathways in pterygium and pterygium-free conjunctivas. METHODS: Primary pterygia (n = 21), ipsilateral superior-temporal bulbar conjunctivas (n = 8), and healthy conjunctival (n = 5) biopsy specimens were analyzed. Total and phosphorylated (phospho) levels of extracellular-regulated 1/2 (ERK1/2), p38, and c-jun N-terminal (JNK) MAPKs and NF-κB inhibitor-alpha (IκΒ-α) were analyzed by immunobead-based assay. Tissue phospho-, total protein, and activation values determined by phospho/total ratios were compared. Correlation among those values and clinical parameters were determined. Average-linkage hierarchical cluster analysis identified patients with similar protein activation values. The k-nearest neighbor classifier predicted the origin of specimens based on protein levels. RESULTS: Pterygium samples had significantly lower total JNK and IκΒ-α levels than did healthy conjunctivas. Decreased total JNK and IκΒ-α and increased phospho-IκΒ-α levels and phospho/total ratio of JNK and IκΒ-α were present in ipsilateral conjunctivas compared with healthy conjunctivas. Protein levels were correlated among them in pterygium, ipsilateral, and healthy conjunctivas and with sun exposure, pterygium grade, and pterygium measurements. Cluster analysis of activation values and ratios in pterygium and ipsilateral-conjunctiva revealed different groups of patients with similar values. Prediction accuracy was 70% to 80% for the classifiers phospho- and total protein levels and phospho/total ratio. CONCLUSIONS: Pterygium and pterygium-free ipsilateral conjunctivas had alterations in MAPK and NF-κB pathways not present in healthy conjunctivas. The high prediction accuracy based on phospho- and total protein levels and phospho/total ratio of ERK1/2, p38, JNK, and IκB-α suggests these molecules as potential biomarkers of inflammation in pterygia.

Central corneal thickness measured with three optical devices and ultrasound pachometry.

PURPOSE: To evaluate the reliability of three noninvasive pachometry methods against the ultrasound pachometer considered the gold standard. METHODS: Central corneal thickness (CCT) was measured using a Paxis ultrasound (US) pachometer, Orbscan II, Pentacam, and Topcon SP-3000 specular microscope in 22 right eyes of 22 healthy adults (7 men, 15 women). Three repeated measures were obtained and then compared to obtain the repeatability of each instrument and the agreement between pachometers. RESULTS: Pentacam is the optical system that renders values of CCT closer to those obtained with US pachometry. Conversely, a specular microscope shows a poorer agreement with US measures, and differences depend on the thickness being measured. The Orbscan system shows a consistent trend toward underestimation of CCT compared with US and Pentacam irrespective of the value measured. CONCLUSION: Different optical methods used to measure CCT showed significantly different results compared with US pachometry except for the Pentacam system. Clinicians should take into account the fact that specular microscopy might either underestimate or overestimate values of CCT, whereas Orbscan systematically overestimates CCT compared with US and Pentacam.

The association of meibomian gland dysfunction and other common ocular diseases with dry eye: a population-based study in Spain.

PURPOSE: To investigate the relationship of meibomian gland dysfunction (MGD) and other prevalent ocular diseases with dry eye (DE) in a general adult population. METHODS: An age-stratified random sample of 1155 subjects aged ≥40 years was selected in O Salnés, Spain. From 937 eligible subjects, 654 (69.8%) participated (mean age (SD): 63.6 (14.4) years; range: 40-96; and 37.2% males). A standardized DE questionnaire was administered. Objective evaluation included the Schirmer test, tear film breakup time (TBUT), fluorescein staining, and rose bengal staining. DE was defined as the simultaneous presence of symptoms and at least one sign. The relationship of MGD and other ocular diseases with DE was investigated. A design-based analysis was performed, and all calculations were weighted to give unbiased estimates. RESULTS: DE and MGD prevalence were 11.0% [95% confidence interval (CI), 8.6-13.3] and 30.5% (95% CI, 26.9-34.1), respectively. MGD was present in 45.8% (95% CI, 34.8-57.2) of subjects with DE and was associated, after controlling for age and sex, with DE [adjusted odds ratios (ORa), 1.81]; with symptoms (ORa, 2.26); and with TBUT (ORa, 1.97), fluorescein staining (ORa, 2.09) and rose bengal staining (ORa, 3.25). The remaining ocular diseases were not associated with symptoms. However, pterygium was significantly associated with fluorescein staining (ORa, 1.89); cataract surgery with TBUT (ORa, 2.79); trauma and pseudoexfoliation with rose bengal staining (ORa, 2.75 and ORa, 4.04); and glaucoma with TBUT (ORa, 3.26), fluorescein staining (ORa, 3.40), and rose bengal staining (ORa, 3.46). CONCLUSIONS: DE and MGD are common diseases in this population. MGD is strongly associated with symptoms and signs of DE. Nearly half of the subjects with DE have MGD. Pterygium, trauma, cataract surgery, pseudoexfoliation, and glaucoma are associated with signs of DE.

Prevalence of pseudoexfoliation syndrome among adult Spanish in the Salnés eye Study.

PURPOSE: To estimate the prevalence of Pseudoexfoliation syndrome (PXF) and to investigate its relationship with systemic and ocular diseases and lifestyle factors in a general adult population in north-western Spain. METHODS: An age-stratified random sample of 1155 subjects was drawn from the population aged 40 years and over of O Salnés (Spain). From 937 eligible subjects, 619 (66.1%) participated (mean age (Standard Deviation [SD]): 63.4 (14.5) years, range: 40-96, 37.0% males). An interview to collect past history of ocular and systemic diseases and lifestyle details, and a comprehensive ophthalmic evaluation were performed. Study subjects with typical pseudoexfoliative material on the anterior capsule or in the pupil margin were labelled as having PXF. A design based analysis was performed and all calculations were weighted to give unbiased estimates. RESULTS: The prevalence of PXF was 6.5% (95% confidence interval [CI]:4.9-8.1). PXF rates increased significantly with age (P = 0.000). No cases of PXF were detected in subjects between 40 and 60 years. Prevalence of PXF was 8.0% (95% C I5.4-11.6) in men and 5.4% (95% CI 3.8-7.6) in women (P = ns). The prevalence of glaucoma in subjects with PXF was 19.6% (95% CI 8.2-40.0). After controlling for age and sex, glaucoma, cataract surgery, rose bengal staining and diabetes were associated with PXF but only glaucoma and rose bengal staining associations remained significant in a multivariate model. CONCLUSIONS: PXF is common among older individuals in north-western Spain. Subjects with pseudoexfoliation have a significantly higher prevalence of glaucoma than subjects without. An abnormal ocular surface detected by rose bengal staining is highly prevalent among subjects with pseudoexfoliation.