Correlation between Blood Flow and Temperature of the Ocular Anterior Segment in Normal Subjects

Association between dryness sensation and ocular surface temperature and conjunctival blood flow in soft contact lens wearers

PURPOSE

To investigate the association between dryness, ocular surface temperature (OST), and conjunctival blood flow (CBF) in soft contact lens (SCL) wearers after airflow stimulation.

METHODS

After recruiting 21 SCL wearers (mean age, 25.3 ± 4.2 years), subjects used two different daily disposable silicone hydrogel SCLs (narafilcon A and delefilcon A lenses). On three of four measurement days, excluding the first, OST, CBF, tear meniscus height (TMH), and non-invasive tear break-up time (NIBUT) were measured after airflow stimulation at a rate of 3 m/s for 10 min. The measurements were conducted without SCLs on the first and second days, and with different SCLs on the third and fourth days. Dryness was evaluated using the visual analogue scale (VAS). These parameters were compared between the two types of SCLs, and their association with the dryness sensation was then investigated.

RESULTS

Dryness was significantly weakly correlated with OST (r = -0.375, p < 0.05) and CBF (r = 0.339, p < 0.05). TMH, NIBUT, and VAS scores for dryness with the delefilcon A lens (0.15 ± 0.05 mm, 3.7 ± 01.7 s and 29.4 ± 16.9) were significantly higher, longer, and lower, respectively, than those with the narafilcon A lens (0.12 ± 0.05 mm, 2.3 ± 1.7 s and 35.9 ± 17.0; p < 0.05, p < 0.01 and p < 0.01). The changes in the OST and CBF between with and without the delefilcon A lens (-0.36 ± 0.35 °C and 0.99 ± 0.19) were significantly small compared to the narafilcon A lens (-0.60 ± 0.42 °C and 1.11 ± 0.21; p < 0.01 for both comparisons).

CONCLUSION

Dryness was correlated with OST and CBF, which indicates that when dryness was high, OST was low and CBF was high. These results suggest that OST and CBF assessments are effective for evaluating dryness sensation.

Clinical characteristics of the well-defined upper eyelid vascular network pattern in patients with rosacea

BACKGROUND

Rosacea is a chronic inflammatory skin disease. The diagnosis is based on the symptoms and physical signs, which still lacks objective laboratory tests or imaging tests.

OBJECTIVES

To propose and evaluate the upper eyelid network pattern in rosacea.

METHODS

Participants included patients diagnosed with rosacea, other facial erythematous skin diseases, and normal controls, all of whom underwent full-face imaging utilizing the VISIA® system software. According to these images, researchers evaluated the condition of the upper eyelid vascular network, developed the grading scale and then compared the difference of distribution in the three groups.

RESULTS

The occurrence rate of upper eyelid vascular network in rosacea was significantly higher than that in other facial erythematous skin diseases (84.3 vs. 32.0%, P < 0.001) and normal controls (84.3 vs. 28.0%, P < 0.001). The upper eyelid vascular network pattern was proposed (none [no clearly reticular vessels], mild [10-50% area of reticular vessels], moderate-to-severe [>50% area of reticular vessels]). Moderate-to-severe grade was defined as well-defined upper eyelid vascular network pattern, which was specific to patients with rosacea (rosacea vs. other facial erythematous skin diseases, adjusted odds ratio [aOR] = 5.814, 95% confidence interval [CI]: 3.899-8.670) (rosacea vs. heathy controls, aOR = 12.628, 95% CI: 8.334-19.112). The severity of the well-defined pattern had no significant association with age, duration, and phenotypes of rosacea (P > 0.05).

CONCLUSION

The well-defined upper eyelid vascular network pattern specifically appeared in patients with rosacea, which could be a possible clue to the diagnosis of rosacea.

Applications of Infrared Thermography in Ophthalmology

Body temperature is one of the key vital signs for determining a disease’s severity, as it reflects the thermal energy generated by an individual’s metabolism. Since the first study on the relationship between body temperature and diseases by Carl Reinhold August Wunderlich at the end of the 19th century, various forms of thermometers have been developed to measure body temperature. Traditionally, methods for measuring temperature can be invasive, semi-invasive, and non-invasive. In recent years, great technological advances have reduced the cost of thermographic cameras, which allowed extending their use. Thermal cameras capture the infrared radiation of the electromagnetic spectrum and process the images to represent the temperature of the object under study through a range of colors, where each color and its hue indicate a previously established temperature. Currently, cameras have a sensitivity that allows them to detect changes in temperature as small as 0.01 °C. Along with its use in other areas of medicine, thermography has been used at the ocular level for more than 50 years. In healthy subjects, the literature reports that the average corneal temperature ranges from 32.9 to 36 °C. One of the possible sources of variability in normal values is age, and other possible sources of variation are gender and external temperature. In addition to the evaluation of healthy subjects, thermography has been used to evaluate its usefulness in various eye diseases, such as Graves’ orbitopathy, and tear duct obstruction for orbital diseases. The ocular surface is the most studied area. Ocular surface temperature is influenced by multiple conditions, one of the most studied being dry eye; other diseases studied include allergic conjunctivitis and pterygium as well as systemic diseases such as carotid artery stenosis. Among the corneal diseases studied are keratoconus, infectious keratitis, corneal graft rejection, the use of scleral or soft contact lenses, and the response to refractive or cataract surgery. Other diseases where thermographic features have been reported are glaucoma, diabetic retinopathy, age-related macular degeneration, retinal vascular occlusions, intraocular tumors as well as scleritis, and other inflammatory eye diseases.

Early warm compress treatment can promote recanalization of vascular embolisms and reduce tissue necrosis after polymethyl methacrylate injection

Injection of fillers for soft tissue augmentation can lead to a variety of complications, among which vascular occlusion caused by intravascular injection of filler will induce severe or permanent damage. The treatment strategies for intravascular embolization caused by injection include warm compress application, but the exact beneficial effects of this therapy have not been confirmed. The purpose of this study is to construct an intravascular injection embolism model and observe the effectiveness of warm and cold compress through a randomized, controlled trial. Thirty rabbit's sixty ears were randomly divided into warm compress group, cold compress group, and control group. Polymethyl methacrylate (PMMA) was slowly injected into the central ear artery (CEA) to cause vascular embolism. Warm compress and cold compress treatment were performed respectively. The vascular recanalization and other related indexes were observed at 30 min, 1 day, and 7 days after injection, and the tissue necrosis was analyzed at 7 days. In the early stage of vascular embolization, warm compress can immediately promote vascular dilatation, blood circulation and partial blood flow recovery. One day after intravascular injection, warm compress can reduce intravascular embolization and reduce the incidence of tissue necrosis. At 7 days after intravascular injection, the vessels in the cold compress and control groups were still embolized while the percentage of recanalization in the warm compress group was 47.4% (P < 0.000). Early-stage warm compress after intravascular PMMA injection is conducive to recanalization of vascular embolization and reducing tissue necrosis.

Association between mask-associated dry eye (MADE) and corneal sensations

To determine the risk of mask-associated dry eye (MADE), we investigated the fluorescein tear break-up time (FBUT), ocular surface temperature and blood flow, along with corneal sensitivity, in mask wearers. We enrolled 60 mask wearers (mean age, 27.1 ± 5.2 years) and then measured FBUT, corneal temperature and conjunctival blood flow without wearing masks (no mask), with masks, and with taped masks. We defined MADE as the condition in which dry eye symptoms appeared and the FBUT with mask was less than 5 s. The FBUT with a mask was significantly shorter compared to the no mask and taped mask groups (P < 0.01 and P < 0.05). The corneal temperature difference and conjunctival blood flow difference were significantly higher after wearing a mask than after wearing a taped mask (P < 0.01). Of the 60 subjects, 13 were diagnosed with MADE. Pain sensitivity and the Ocular Surface Disease Index (P < 0.05 and P < 0.01) were significantly higher in the MADE group, with the FBUT without masks (P < 0.05) significantly shorter than in the non-MADE group. MADE may be associated with corneal hypersensitivity. Wearing masks decreased FBUT and increased ocular surface temperature and blood flow. Taping the top edge of masks prevented these changes. Fitting masks properly may reduce MADE risk.

Ocular Surface Temperature: Characterization in a Large Cohort of Healthy Human Eyes and Correlations to Systemic Cardiovascular Risk Factors

Purpose: To characterize ocular surface temperature (OST) in healthy eyes and its association with systemic risk factors of cardiovascular and ischemic heart disease. Methods: This prospective cross-sectional study included consenting subjects who were examined at the Institute for Medical Screening in Sheba Medical Center. A Therm-App™ thermal imaging camera (Opgal LTD, Israel) was used for OST acquisition, and the mean OST of the medial canthal, lateral canthal, and central cornea regions were measured. Room and body temperatures were also recorded. Past medical and ocular history as well as data from various clinical examinations performed at the same visit were obtained. Results: Thermographic images were obtained from 186 subjects, 150 of which were included in the final analysis. OST was significantly higher in the medial canthal, central cornea, and lateral canthal regions in people with a history of ischemic heart disease (p = 0.02, p = 0.02, and p = 0.03, respectively). There were no significant OST differences (ANOVA test) associated with the presence of hypertension, diabetes mellitus, or active smoking status. Conclusions: OST correlated positively with the presence of ischemic heart disease. This correlation, its pathophysiological base, and its clinical application warrants further investigation.

Editorial of Special Issue "Differential Diagnosis for Dry Eye"

This editorial aims to summarize the scientific papers that contributed to the Special Issue "Differential Diagnosis for Dry Eye" [...].