A technique called optical coherence tomography (OCT) has been developed for noninvasive cross-sectional imaging in biological systems. OCT uses low-coherence interferometry to produce a two-dimensional image of optical scattering from internal tissue microstructures in a way that is analogous to ultrasonic pulse-echo imaging. OCT has longitudinal and lateral spatial resolutions of a few micrometers and can detect reflected signals as small as approximately 10(-10) of the incident optical power. Tomographic imaging is demonstrated in vitro in the peripapillary area of the retina and in the coronary artery, two clinically relevant examples that are representative of transparent and turbid media, respectively.

/pdf/optical-coherence-tomography-3zqbp7mpwb.pdf

Optical coherence tomography

Aim: To estimate the number of people with open angle (OAG) and angle closure glaucoma (ACG) in 2010 and 2020. Methods: A review of published data with use of prevalence models. Data from population based studies of age specific prevalence of OAG and ACG that satisfied standard definitions were used to construct prevalence models for OAG and ACG by age, sex, and ethnicity, weighting data proportional to sample size of each study. Models were combined with UN world population projections for 2010 and 2020 to derive the estimated number with glaucoma. Results: There will be 60.5 million people with OAG and ACG in 2010, increasing to 79.6 million by 2020, and of these, 74% will have OAG. Women will comprise 55% of OAG, 70% of ACG, and 59% of all glaucoma in 2010. Asians will represent 47% of those with glaucoma and 87% of those with ACG. Bilateral blindness will be present in 4.5 million people with OAG and 3.9 million people with ACG in 2010, rising to 5.9 and 5.3 million people in 2020, respectively. Conclusions: Glaucoma is the second leading cause of blindness worldwide, disproportionately affecting women and Asians.

The number of people with glaucoma worldwide in 2010 and 2020

Optical coherence tomography (OCT) has developed rapidly since its first realisation in medicine and is currently an emerging technology in the diagnosis of skin disease. OCT is an interferometric technique that detects reflected and backscattered light from tissue and is often described as the optical analogue to ultrasound. The inherent safety of the technology allows for in vivo use of OCT in patients. The main strength of OCT is the depth resolution. In dermatology, most OCT research has turned on non-melanoma skin cancer (NMSC) and non-invasive monitoring of morphological changes in a number of skin diseases based on pattern recognition, and studies have found good agreement between OCT images and histopathological architecture. OCT has shown high accuracy in distinguishing lesions from normal skin, which is of great importance in identifying tumour borders or residual neoplastic tissue after therapy. The OCT images provide an advantageous combination of resolution and penetration depth, but specific studies of diagnostic sensitivity and specificity in dermatology are sparse. In order to improve OCT image quality and expand the potential of OCT, technical developments are necessary. It is suggested that the technology will be of particular interest to the routine follow-up of patients undergoing non-invasive therapy of malignant or premalignant keratinocyte tumours. It is speculated that the continued technological development can propel the method to a greater level of dermatological use.

https://link.springer.com/content/pdf/bfm%3A978-3-319-06419-2%2F1.pdf

Optical Coherence Tomography

AIM: To estimate the prevalence of glaucoma among people worldwide. METHODS: Available published data on glaucoma prevalence were reviewed to determine the relation of open angle and angle closure glaucoma with age in people of European, African, and Asian origin. A comparison was made with estimated world population data for the year 2000. RESULTS: The number of people with primary glaucoma in the world by the year 2000 is estimated at nearly 66.8 million, with 6.7 million suffering from bilateral blindness. In developed countries, fewer than 50% of those with glaucoma are aware of their disease. In the developing world, the rate of known disease is even lower. CONCLUSIONS: Glaucoma is the second leading cause of vision loss in the world. Improved methods of screening and therapy for glaucoma are urgently needed.

https://bjo.bmj.com/content/bjophthalmol/80/5/389.full.pdf

Number of people with glaucoma worldwide.

Global prevalence of glaucoma and projections of glaucoma burden through 2040: a systematic review and meta-analysis.

Cataract after glaucoma filtration surgery.

Incidence of acute angle-closure glaucoma after pharmacologic mydriasis.

SummaryPurposeThe objective of this research was to compare the loss of retinal ganglion cells subserving the fovea to that of the ganglion cells in the surrounding perifoveal region in eyes with experimental glaucoma.MethodsGanglion cell nucleoli were counted using light microscopy from vertically

Study of central retinal ganglion cell loss in experimental glaucoma in monkey eyes.

Purpose of reviewTo discuss issues that affect development of new glaucoma treatments known as neuroprotection.Recent findingsThere are barriers to neuroprotection trials for glaucoma.SummaryWith design features discussed in the review, neuroprotection trials can be effectively carried out.

Clinical trials for glaucoma neuroprotection are not impossible.

• β-Adrenergic antagonists taken orally adversely alter plasma lipid profiles. This study was designed to determine whether 0.5% topical timolol maleate has a similar effect. Forty volunteers who were not using medications known to alter plasma lipid levels were recruited for an unmasked study in which each subject served as his or her own control. Twelve subjects did not complete the study because of ocular and systemic side effects or extraneous factors. Twenty-eight subjects used topical timolol for an average of 76 days, with two 12-hour fasting plasma specimens obtained at the beginning and end of the period. Mean total cholesterol and low-density lipoprotein cholesterol levels did not change significantly with treatment. Triglyceride values increased 12%; high-density lipoprotein cholesterol levels decreased 9%; and the total cholesterol-high-density lipoprotein cholesterol ratio increased 8%. Higher baseline high-density lipoprotein cholesterol levels were associated with larger reductions in high-density lipoprotein cholesterol levels. Changes in high-density lipoprotein cholesterol levels of this magnitude have been estimated to increase the risk of coronary artery disease by 21%.

Harry A. Quigley

Papers

Cataract after glaucoma filtration surgery.

Incidence of acute angle-closure glaucoma after pharmacologic mydriasis.

Study of central retinal ganglion cell loss in experimental glaucoma in monkey eyes.

Clinical trials for glaucoma neuroprotection are not impossible.

Topical timolol decreases plasma high-density lipoprotein cholesterol level.