#31
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Вопрос: это ваше предположение - про то, что размер отпечатка действительно зависит от кривизны роговицы? Не настолько она крута даже в самых крутых случаях, чтобы влиять на её упругость. Разве не так?
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#32
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Цитата:
Результаты измерения ВГД тонометром Маклакова должны коррелировать с данными тонометрии по Гольдману, но для исключения вопросов необходимо провести сходное исследование. Все-таки есть различие в степени давлении на роговицу. |
#33
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Азиатское глаукомное общество в своем гайдлайне четко пишет, что тонометр Маклакова не является достаточно точным, по сравнению с Гольдманом и не может быть рекомендован для минимального оснащения кабинета. Действительно ли коррелируют результаты измерения ВГД двумя методами по такому утверждению еще не ясно.
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#34
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Цитата:
Другая крайность - кривизна 7,0 (порядка 47-48 D) ну вот сколько было пациентов ну минимум 23 - 24 - 25 -26 в зависимости от толщины роговицы. Не получается на крутой роговице давление 20 И ответ: изначально это не мое предположение, а старших коллег с которыми я работаю, но я думаю что в этом есть рациональное "зерно" и на это стоит обращать внимание. опять таки же IMHO. |
#35
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Цитата:
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#36
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Каждый тонометр имеет свои достоинства и свои недостатки.
Неплохо это показано в нашей отечественной работе Ю. С. Астахов и соавт. Аппланационная и динамическая контурная тонометрия: сравнительный анализ. Офтальмологические ведомости. Том I № 1 2008 |
#37
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#38
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Центральная кривизна роговицы влияет на разультат аппланационной тонометрии по ГольдмаННу.
"Optom Vis Sci. 2011 Jan;88(1):E102-12. Multiparameter correction equation for Goldmann applanation tonometry. Elsheikh A, Alhasso D, Gunvant P, Garway-Heath D. Source Division of Civil Engineering, University of Dundee, Dundee, United Kingdom. Abstract PURPOSE: To develop a correction factor to improve the accuracy of intraocular pressure (IOP) measurements made by the Goldmann applanation tonometer (GAT), which considers the combined effects of variations in central corneal thickness (CCT), central anterior curvature (R), age, and the IOP level itself. METHODS: Nonlinear numerical simulations based on the finite element method were used to represent corneal behavior under the effect of IOP and external tonometric pressure. The simulations considered various biomechanical corneal properties including the cornea's nonuniform thickness, elliptical topography, weak stromal interlamellar cohesion, low epithelial and endothelial stiffness, and hyperelastic and hysteretic material behavior. The simulations were used to model the GAT procedure on corneas to obtain a correction equation based on the values of CCT, R, age, and IOP measured using GAT (IOPG). The efficiency of the equation in reducing the effects of corneal parameters on IOPG measurements was also assessed using an independent clinical database. RESULTS: The individual effects of variations in CCT, R, and age were estimated at 1.66 mm Hg/100 μ of CCT, 0.89 mm Hg/1 mm of R, and 0.12 mm Hg/decade of age. The correction equation reduced the association between clinical IOP measurements and corneal parameters with r2 reducing from 11.8 to 0.02%. CONCLUSIONS: The GAT correction factor can consider the combined effect of variations in corneal thickness, curvature, age, and IOP. The factor could significantly reduce the reliance of IOPG measurements on corneal stiffness parameters." |
#39
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Zhonghua Yan Ke Za Zhi. 2009 Aug;45(8):713-8.
[Effects of central corneal thickness and corneal curvature on measurement of intraocular pressure with Goldmann applanation tonometer and non-contact tonometer]. [Article in Chinese] Zhang Y, Zhao JL, Bian AL, Liu XL, Jin YM. Source Department of Ophthalmology, Peking Union Medical College Hospital, Peking Union Medical College, Eye Research Center of Chinese Academy of Medical Sciences, Beijing 100730, China. [Ссылки доступны только зарегистрированным пользователям ] Abstract OBJECTIVE: To investigate the effects of central corneal thickness (CCT) and corneal curvature (CC) on intraocular pressure (IOP) measurements by the Goldmann applanation tonometer (GAT) and the non-contact tonometer (NCT). METHODS: One hundred and twenty patients were recruited from the clinic of Peking Union Medical College Hospital. The CCT was measured by ultrasound pachymetry and the mean radius of CC by using Canon PK-5 refractometer. The IOP of each eye was measured by both GAT and NCT. Linear regression was used to compare the measurements of GAT and NCT; multi regression was used to analyze the relationships between CCT, CC and the measurements of GAT and NCT. Bland-Altman method was used to compare the effect of NCT and GAT on the IOP measurements. RESULTS: The results of the right eyes were reported in this paper. The mean and standard deviation of IOP measured by GAT and NCT was (18.4 + or - 4.0) mm Hg (1 mm Hg = 0.133 kPa) and (17.0 + or - 4.6) mm Hg, respectively, the difference was statistically significant (r = 0.835, P = 0.000). IOP measured using GAT increased by 0.039 mm Hg per microm increase in CCT. IOP measured using NCT increased by 0.064 mm Hg per microm increase in CCT. For an increase of 1 mm of mean corneal curvature there was decrease in IOP of 2.648 mm Hg measured by the GAT and of 3.190 mm Hg measured by the NCT. Compared to the GAT, NCT underestimated at low IOP level and overestimated at higher IOP level. CONCLUSIONS: The IOP measurement obtained with both GAT and NCT varied with CCT and CC. CCT affected IOP measurements by NCT more than that by GAT. |
#40
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А тут по другому.
Ophthalmology. 2007 Jan;114(1):20-6. Epub 2006 Oct 27. Effects of corneal thickness, corneal curvature, and intraocular pressure level on Goldmann applanation tonometry and dynamic contour tonometry. Francis BA, Hsieh A, Lai MY, Chopra V, Pena F, Azen S, Varma R; Los Angeles Latino Eye Study Group. Source Doheny Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA. Abstract PURPOSE: To compare the measurements of intraocular pressure (IOP) with Goldmann applanation tonometry (GAT) and dynamic contour tonometry (DCT) and the effects of central corneal thickness (CCT), corneal curvature, and level of IOP on these methods. DESIGN: Cross-sectional population-based study. PARTICIPANTS: From the Los Angeles Latino Eye Study, 2157 participants of primarily Mexican ancestry. METHODS: Average GAT measurements were compared to DCT, and both were examined with respect to CCT (< or =500, 501-550, 551-600, >600 microns), corneal curvature (<42, 42-46, >46 diopters), and level of IOP (0-10, 11-20, >20 mmHg). MAIN OUTCOME MEASURES: Mean GAT and DCT IOP levels were compared for the entire population, and then trends for the CCT, curvature, and IOP groupings were analyzed. The magnitude of the difference of GAT minus DCT was compared for these different strata, with special attention to a difference of +/- 3 mmHg or greater, which was defined as clinically significant. RESULTS: Mean IOP for the entire population by GAT was significantly lower (14.4+/-3.2 mmHg) compared with DCT (16.0+/-3.6; P<0.0001). Both GAT and DCT IOP levels were lowest for thin CCT and increased stepwise with increasing CCT, but this difference was more pronounced with GAT than DCT (P<0.0001 and P = 0.0012, respectively). The difference between GAT and DCT was largest for thin CCT and decreased for thicker CCT (P<0.0001). After adjusting for CCT, the corneal curvature affected IOP measured by DCT (P = 0.02) but not GAT (P = 0.3) such that mean DCT IOP increased with increasing corneal curvature. After adjusting for the CCT effect on IOP and stratifying by DCT IOP groups, the greatest difference between GAT and DCT was seen in the lowest IOP group (3.55+/-3.1), became negative in the intermediate group (-1.86+/-2.60), and was most negative in the highest IOP group (-3.88+/-3.3; P<0.0001). CONCLUSIONS: Intraocular pressure measured by GAT was consistently lower when compared with DCT, and this difference was greatest with thinner CCT. Dynamic contour tonometry was also less affected by variations in CCT. Corneal curvature affected IOP measurements with DCT but not GAT, but this effect was less than the CCT effect on GAT. Goldmann applanation tonometry tended to underestimate IOP at higher levels and overestimate it at lower IOP levels when compared to DCT. |
#41
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Прошу прощения, может быть не к месту, но где выставляется диагноз глаукома? В условиях стационара или поликлиники?
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#42
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Практически не имеет значения при одинаковой доступности оборудования.
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#43
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У Гольдмана есть корректор астигматизма-это с кривизной связано?
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#44
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Теоретически - да.
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#45
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Хорошо, можно спорить долго о влиянии разных факторов, но вопрос несколько иной. А что мы именно меряем? Измеряется не "внутриглазное давление" ведь, и даже не давление в п/к глаза, а ригидность роговицы, по которой косвенно судим о давлении в п/камере. Но реально для глаукомного процесса имеет значение давление перед диском зрительного нерва, которое измерить пока невозможно.
ИМХО, важно измерять одним методом для того, чтобы знать на сколько удалось понизить ВГД, а за динамикой процесса будут уже отвечать острота зрения, периметрия, состояние дисков и т. д. |