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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).
Development of Ophthalmic Formulations
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Paramita Sarkar, Martin Coffey, Mohannad Shawer
Dry eye disease is a common medical condition affecting nearly 20 million people in the United States. The Dry Eye WorkShop or DEWS report [56] classifies dry eye into two major categories: Aqueous deficient dry eye due to abnormal tear productionEvaporative dry eye caused by excessive water loss due to compromised lipid layer as a result of meibomian gland dysfunction, disorders of lid aperture, and low blink rates as well as extrinsic factors such as contact lens wear, side effects from systemic drugs, and vitamin A deficiency.
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).
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.
The tear turnover and tear clearance tests – a review
Published in Expert Review of Medical Devices, 2018
Izabela K. Garaszczuk, Robert Montes Mico, D. Robert Iskander, Alejandro Cerviño Expósito
TTR was shown to be an indirect measure of dry eye-associated ocular surface irritation regardless of normal or reduced aqueous tear production [13–16] and found to be reduced in symptomatic dry eye subjects [1,12,17–19]. The value of TTR allows to distinguish between aqueous deficient and evaporative dry eye [20]. TTR correlates with the severity of ocular epithelial disease assessed with corneal fluorescein staining [15,16,21] rather than with reduced aqueous tear production, often assessed with the Schirmer test [21]. Delay of tear clearance is also associated with Meibomian gland dysfunction [15,16] and decreased ocular surface sensitivity [3,14–16,22–25]. In a mouse model of dry eye, reduced tear clearance showed greater correlation with the severity of ocular surface disease than reduced tear production [25]. Also, age and factors associated with age, like conjunctivochalasis, lid laxity, functional obstruction to tear flow, and blink abnormalities contribute to development of delayed tear turnover [14,15,26–28]. On the contrary, some studies showed no relation with aging [29–31]. Reduced tear clearance promotes ocular surface inflammation [14], as it leads to accumulation of cytokine interleukin-1α and the activity of matrix metalloproteinase (MMP-9) and gelatinase B in tear film [14–16,22,23,32] and was proved to improve with topical methylprednisolone, together with decrease in symptoms of ocular irritation, conjunctival redness, and surface epithelial disease [14,15]. However, the exact mechanism by which reduced clearance leads to corneal epithelial disease and ocular irritation has not been established. It is suggested that the increase in MMP-9 activity may lead to corneal epithelial disease. Tear clearance is also reduced in subjects with contact lens-associated papillary conjunctivitis [33]. Delayed tear clearance may be the best measure for identifying patients with tear film disorders, who may respond to anti-inflammatory therapy [3]. Delay in tear clearance can lead to prolonged exposure to topical medications and their preservatives (e.g. benzalkonium chloride) on the ocular surface compared with normal clearance subjects, thus affected individuals have higher chance to develop ocular surface medication toxicity [12,14,15,34]. Decreased tear clearance is also associated with untreated [35] and timolol-treated open-angle glaucoma [36].