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Thermography by Specialty
Published in James Stewart Campbell, M. Nathaniel Mead, Human Medical Thermography, 2023
James Stewart Campbell, M. Nathaniel Mead
Dry eye syndrome presents with significantly lower central corneal temperatures. Corneal temperatures in these conditions may range from 0.55°C (1°F) to 0.95°C (1.7°F) below normal.74 This decrease may be due to increased evaporation by the more aqueous tears found in dry eye. Dry eye caused by meibomian gland dysfunction (MGD) may also be detected by thermography, but special measurements may be required for this analysis. Upper eyelid margin temperature as measured by thermography increases normally from the lateral lid to the medial lid (Figure 11.23). This increase in temperature is significantly higher in cases of MGD. To normalize this difference to an individual's body temperature, the lid margin measurements can be divided by the reference temperature (REF) taken over the main portion of the upper lid. At Area 1, this ratio is less than 1.0 in both MGD and control subjects, becoming greater than 1.0 at Area 4 in MGD cases, and Area 6 in normals. In normal individuals, the ratio remains less than 1.2 at Area 8, while in MGD, that ratio is between 1.2 and 1.5, increasing with the severity of the condition.75 Further investigations into these measurements should be undertaken.
Microfluidic Contact Lenses for Ocular Diagnostics
Published in Raju Khan, Chetna Dhand, S. K. Sanghi, Shabi Thankaraj Salammal, A. B. P. Mishra, Advanced Microfluidics-Based Point-of-Care Diagnostics, 2022
Antonysamy Dennyson Savariraj, Ammar Ahmed Khan, Mohamed Elsherif, Fahad Alam, Bader AlQattan, Aysha. A. S. J. Alghailani, Ali K. Yetisen, Haider Butt
Continuous monitoring of ocular surface temperature (OST) is helpful to review ocular conditions such as glaucoma, vascular neuritis, diabetic retinopathy, carotid artery stenosis, and dry eye disease (DED). The positive correlation observed between body temperature and ocular temperature (Purslow and Wolffsohn 2005) and between ocular temperature difference values (TDVs) and dry eye parameters suggest that OST monitoring is important to obtain POC ocular diagnostics. OST increase observed in patients with meibomian gland dysfunction (MGD) (Terada et al. 2004), phakic and pseudophakic (Sniegowski et al. 2015) psychiatric disorders (Monge-Roffarello et al. 2014, Tan et al. 2009) in post-corneal transplant undergoing inflammation (Sniegowski et al. 2018), and dogs with keratoconjunctivitis sicca (Biondi et al. 2015) further evidences for the necessity for the measurement of OST to monitor disease progression in personalized diagnostics (Moreddu et al. 2019).
Theory of the Liquid and Solid Films Rupture
Published in Eli Ruckenstein, Gersh Berim, Wetting Theory, 2018
The outermost layer of the tear film (located at the tear—air interface) is made up of low polarity waxy and cholesteryl esters (24). This superficial lipid layer is about 1000 Å thick in a normal eye (7a). The amount of high polarity lipids like triglycerides, free fatty acids and phospholipids is negligible in a normal eye (25). The following two distinct types of lipid abnormalities are identified to affect the BUT adversely: A complete absence of the lipid layer may occur if either the lipid-secreting meibomian gland openings are absent or these glands are destroyed. The occurrence of this condition is, however, very rare (7a).An alteration in the chemical composition and the consequent high surface activity of the eye lipids, such as that seen in the case of chronic blepharitis and facial skin infections like acne rosacea, leads to a marked decrease in BUT (26,27). A significant amount of polar lipids, viz., free fatty acids and triglycerides, are present in such instances.
Lenstar LS900 vs EchoScan US-800: comparison between optical and ultrasound biometry with and without contact lenses and its relationship with other biometric parameters
Published in Expert Review of Medical Devices, 2023
Veronica Noya-Padin, Jacobo Garcia-Queiruga, Maria Iacubitchii, Maria J. Giraldez, Eva Yebra-Pimentel, Hugo Pena-Verdeal
A total of 51 participants (13 men and 38 women) with a mean age of 22.2 ± 2.25 years (range from 18 to 28 years) were randomly recruited among university students. Participants were included if they had an auto-refracted sphere of − 10.00 to + 4.00D, astigmatism up to − 3.00D, anterior chamber angle ≥ 30º and a compensated intraocular pressure (IOP) ≤ 20.85 mmHg [2,18,19]. Patients were excluded if they had ever been diagnosed with an ocular infection, trauma disorders, diseases at the time of the study (glaucoma, scleral or corneal anomalies, dry eye disease, meibomian gland dysfunction, etc.), undergone ocular surgery, diagnosed with systemic disorders that could affect the measurements (diabetes mellitus, rheumatoid arthritis, etc.), or had a history of hypersensitivity or allergy to anesthesia [2,10,20]. No participant was under any type of topical, systemic treatment or used artificial tears at the time of the study. All participants gave their written informed consent to be included in the study. The study protocol followed the tenets of the Declaration of Helsinki and was approved by the Ethics Committee of the university (Approval number: USC 04/2022).
Meibomian gland cyst detection and classification using hyperspectral imaging
Published in Cogent Engineering, 2021
Wessam Shehieb, Maher Assaad, Ayman Tawfik, nor Ashidi Mat Isa
Meibomian gland cyst (MGC), usually referred to as eye bump, is a common disease that blocks the eyelid gland. Topical ophthalmic ointments and eyelid heat massages can treat early diagnosed MGC; otherwise, surgical operation is required. The current techniques of diagnosing MGC are usually uncomfortable or invasive, such as examining the tarsal plate after everting the eyelid or by biopsy procedures. The purpose of this work is to propose a non-invasive MGC evaluation and classification technique using hyperspectral imaging and image processing. The proposed work built the threshold of the complete system, where early diagnosis of an MGC is possible before it becomes visible to the eye; hence reducing the treatment duration and avoiding any further complications that requires clinical lancing. Also, the system can be used as a postoperative check postsurgery to make sure the eyelid went back to normal.
Assessment of ocular surface response to tinted soft contact lenses with different characteristics and pigment location
Published in International Journal of Optomechatronics, 2020
Min-Yen Hsu, Pei-Yu Hong, Jyh-Cheng Liou, Yu-Ping Wang, Connie Chen
There was a significant difference in Meibomian gland dysfunction level between the four groups on day 3 (p = 0.003) (Table 2). There was also a significant difference in Meibomian gland dysfunction level between group B and group C (p = 0.012) on day 3. The results of Meibomian gland dysfunction level are shown in Figure 4. There was a significant difference in Meibomian gland dysfunction between baseline and day 3 (p = 0.030) in group B.