This study explored the anatomical characteristics and occurrence mechanisms of acute primary angle closure (APAC) by comparing the quantitative data of ultrasound biomicroscopic data (UBM) images of the APAC and fellow eyes. A total of 131 patients (262 eyes) were studied over five years by retrospective analysis. The quantitative data from UBM images including angle opening distance at 500 μm (AOD500), trabecular-iris angle (TIA), iris convexity (IC), iris span (IS), iris-lens angle (ILA), iris-lens contact distance (ILCD), iris-ciliary process angle (ICPA) and limbus-ciliary body angle (LCBA) were retrospectively recorded; comparative analysis of the APAC and fellow eyes was performed.

The superior, inferior, nasal, temporal and mean AOD500, TIA, IC and LCBA were significantly smaller in APAC than in fellow eyes. Values of the lens thickness (LT), lens/axial length factor (LAF), lens position (LP) and relative lens position (RLP) were lower in APAC than in fellow eyes. In APAC eyes, AOD500 was significantly positively correlated with IC, ILCD and LCBA; TIA was significantly positively correlated with IC, ILCD and LCBA. In fellow eyes, AOD500 was significantly negatively correlated with ILA, and significantly positively correlated with ILCD, ICPA, LCBA, axial length (AL), central anterior chamber depth (CACD) and LP; TIA was significantly negatively correlated with ILA, and significantly positively correlated with IS, ILCD, ICPA, LCBA, AL, CACD, LP and RLP.

Multiple non-pupillary block factors (plateau iris, anterior attachment and insertion of the iris root, anterior shift of the lens and anterior rotation of the ciliary body) promote the occurrence of APAC, and abnormal positional relationships of the iris, ciliary body and lens may contribute to APAC.

To investigate the prevalence of dry eye among all adult age categories and to discover independent risk factors by investigating a wide range of etiological categories, a cross-sectional association study was conducted, including 79,866 voluntary participants, ages 20 to 94 years, from the population-based Lifelines Cohort Study in the Netherlands.

Overall, 9.1% of participants had dry eye disease as measured by the Women's Health Study dry eye questionnaire. Dry eye symptoms were particularly prevalent in 20 to 30-year-old individuals. Dry eye was associated with comorbidities in almost all body systems, including musculoskeletal, gastrointestinal, ophthalmic, autoimmune, psychiatric, pain, functional, dermatological and atopic disorders. Numerous independent risk factors were discovered or confirmed, with strong associations for female sex, contact lens use, irritable bowel syndrome, fibromyalgia, chronic fatigue syndrome, eye surgery including cataract and laser refractive, keratoconus, osteoarthritis, connective tissue diseases, atherosclerosis, Graves' disease, autistic disorder, depression, “burnout,” Crohn's disease, sarcoid, lichen planus, rosacea, liver cirrhosis, sleep apnea, sinusitis, thyroid function and air pollution (NO2). High blood pressure and high BMI were strongly associated with less dry eye, as was current smoking, while ex-smokers had more dry eye. No clear link between dry eye, and lipid or blood glucose levels was found.

This study on dry eye confirmed but also refuted many risk factors from smaller epidemiological studies, and discovered numerous new risk factors in multiple etiological categories. Researchers concluded that the finding that dry eye symptoms are particularly common in young adults is concerning and warrants further study.

The purpose of this study was to characterize the central epithelial thickness (CET) of penetrating keratoplasty corneal specimens obtained from patients with keratoconus (KC) and correlate the histological patterns with their clinical history. Ex vivo histological imaging was performed to measure CET and total corneal thickness (TCT) in 56 patients with KC. Microscopic slides from penetrating keratoplasty corneal specimens, stained with hematoxylin and eosin, were evaluated using brightfield microscopy. CET and TCT were measured, and morphological features were studied. Clinical history regarding duration of KC prior to surgery, and length of and tolerance to contact lens wear were compared and analyzed.

The microscopic slides of all patients available for follow up (n=48) were analyzed, and CET and TCT were measured. The histological evaluation revealed three distinctive epithelial patterns. Pattern 1 with central hypertrophic and hydropic changes (n=19) measured 70.89±25.88μm in CET and 308.63±100.74μm in TCT; pattern 2 (n=14) had not changed, similar to normal epithelium CET and TCT measuring 36.5±7.02μm and 260.14±87.93μm, respectively. Pattern 3 (n=15) demonstrated thinner central epithelium characterized by atrophy and focal hydropic changes measuring 19.93±4.60μm and 268.00±79.39μm in CET and TCT, respectively. The presence of pattern 2 characterized by similar to normal CET was correlated with the duration of the condition. There was a significant difference in the length of CL wear comparing those with patterns 1 and 2 vs. 3 (least number of CL years).

Patients with advanced disease had various central corneal epithelial changes detected with histology. Although each central epithelial pattern type was distinctive comparing the three patterns, no correlation was found with years of CL wear, but only with the duration of the condition.