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.

PURPOSE To determine the effect of taxol and etoposide, hydrophobic drugs with antifibrosis activity, on the outcome of filtration surgery in glaucomatous monkeys. METHODS Elevated intraocular pressure was produced bilaterally in eight cynomolgus monkeys by laser treatment of the trabecular meshwork. Four animals subconjunctivally received a polyanhydride disk containing 1 mg etoposide at the time of posterior lip sclerectomy in one eye; the other eye received an identical disk without drug. Similarly, four animals received a disk containing 50 micrograms of taxol in one eye and a blank disk in the other. RESULTS Eyes treated with taxol had lower intraocular pressures than control eyes from 20 days after surgery until death. Eyes with satisfactory filtration bleb appearance and patent fistulae on histologic examination had lower intraocular pressures. The intraocular pressure was lower and the duration of success longer in the etoposide-treated eyes (mean, 16 days) compared to that of the fellow eyes (mean, 10 days), but the difference was not statistically significant. CONCLUSIONS Use of polyanhydride disks containing taxol, but not etoposide, had a marked beneficial effect on intraocular pressure and bleb appearance after experimental filtration surgery in monkeys. The difference between the two agents may result from the greater antiproliferative potency of taxol and its greater duration of release from the polymer.

Glaucoma filtration surgery in nonhuman primates using taxol and etoposide in polyanhydride carriers.

Long-term outcomes in fellow eyes after acute primary angle closure in the contralateral eye.

munication between doctor and patient, cost of therapy in time and money, patient attitudes towards health and disease, side-effects of treatment and a host of other risk factors. Some are inherent to OAG and others are similar to those relevant to all disease management. We can learn much from studies of these issues in other chronic diseases. One disturbing finding is the failure of women with OAG to fill prescriptions at the same rate as men do. The cited study detected behaviour from pharmacy data, so it is not clear whether women were being offered fewer prescriptions than men by their doctors, or whether women were not filling prescriptions as often as men were. Either explanation requires our attention. Gender bias was suspected in the application of cardiac surgery, but clinical variation and patient choice may partly explain the conclusion. If women cannot or will not start and continue OAG treatment as often as men, we should learn why this is the case and intervene effectively. We need to develop electronic monitoring systems that are incorporated into eyedrop bottles to study who is cooperating with treatment. These could be used covertly in a research mode, or overtly to assist patients to improve cooperation with treatment. Research is needed to monitor actual behaviour by doctors and patients. In doing so, we will learn what works, so that preferred practice patterns of the future will be evidence-based.

Dirty little secrets.

Outcomes of Surgical Bleb Revision for Complications of Trabeculectomy

Purpose: To evaluate nerve fiber layer photography as a method for glaucoma screening in a general medical clinic setting. Methods: One hundred seventy-one persons who attended an academic hospital medical clinic were administered a questionnaire and underwent a complete eye examination, including automated perimetry and photography of the optic disc and nerve fiber layer. Results: Eighteen patients were diagnosed as having primary glaucoma; one, secondary glaucoma; and 21 were suspected of having glaucoma. Nerve fiber layer photographs were taken on 145 persons (85%) and were readable in 136 (80%) of the sample of 171 subjects. Nerve fiber layer atrophy was detected on masked evaluation in 64% of those with glaucoma, in 28% of those suspected of having glaucoma, and in 16% of persons who did not meet the criteria for glaucoma. Conclusions: Nerve fiber layer photography can be carried out as a screening method and can identify a substantial proportion of those with glaucoma. It compares favorably with tonometry, cup-disc ratio estimation, or screening visual field examination for glaucoma detection.

https://jamanetwork.com/journals/ophth/articlepdf/640723/archopht_112_6_042.pdf

Harry A. Quigley

Papers

Glaucoma filtration surgery in nonhuman primates using taxol and etoposide in polyanhydride carriers.

Long-term outcomes in fellow eyes after acute primary angle closure in the contralateral eye.

Dirty little secrets.

Outcomes of Surgical Bleb Revision for Complications of Trabeculectomy

Screening for Glaucoma in a Medical Clinic With Photographs of the Nerve Fiber Layer