| Glaucoma is the leading cause of irreversible blindness worldwide and it is harmful for its stealthiness and irreversibility of optic nerve damage. Primary open angle glaucoma (POAG) is a chronic and progressive optic neuropathy. Pathological increase of intraocular pressure (IOP) is the main risk factor for glaucomatous optic nerve damage. IOP used to play an important role in the diagnostic process of POAG, however, it has not been a necessary indicator of the diagnosis of POAG any more with many cases reports about normal tension glaucoma (NTG) and ocular hypertension (OH). Once the characteristic damage of optic nerve and visual field which occurred without any other causes, as well as an open angle is observed, it can be diagnosed as POAG. However, it is globally recognized that reducing IOP is the only effective treatment of glaucoma, which makes it a rather embarrassing situation that the diagnosis and treatment principle of glaucoma deviate from each other. Some researchers regard glaucoma as a neurodegenerative disease and has numerous similarities with neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases. Why the glaucomatous optic nerve damage still happens when the IOP is normal and why the glaucomatous optic nerve damage doesn’t happen in 90.5% of the patient with OH after a 5-year follow-up when no treatment was given to the patient. The trans-lamina cribrosa pressure difference (TLCPD) theory offers us a new understanding about the questions and reminds us that glaucoma is still a disease that closely related to IOP and at the same time influenced by many other factors such as intracranial pressure (ICP). Whether more attention should still be paid to IOP during the diagnostic process of POAG is to be demonstrated by many clinical studies.POAG was divided into high tension glaucoma (HTG) and NTG according to the different level of IOP. Ophthalmologic epidemiology study abroad showed that Asia is the high-incidence area of NTG with a proportion as high as 52%-92%, while the proportion was about 30%～38.9% in the white people and about 57.1% in the African people. Ophthalmologic epidemiology study inland also shows that NTG is the chief component of POAG and the proportion is as high as 60%-90%. However, some clinical institutions abroad shows that HTG is more common in clinical practice. Gyasi found that there were only 32 NTG patients (about 7%) among 455 POAG patients in Emmanuel Eye Clinic. The clinical proportion of NTG and HTG was rarely reported in China. Like blood pressure, IOP also has complicated changes and fluctuations and is easily affected by different factors, such as age, body position, illumination and so on. Single or few times daytime IOP measurement can’t provide sufficient basis to determine the type of POAG. What is the IOP level before treatment of the POAG patients? What is the percentage of NTG in POAG patients in clinic? Whether the proportion is influenced by central corneal thickness (CCT) or 24-hour IOP changes? These problems remain to be discussed. The difference in the proportion of the NTG between the ophthalmic epidemiology research and clinical ophthalmic research remain to be thought.Closed and complicated connections exist between IOP and the development and progression of glaucomatous optic nerve damage or visual field defect. Previous studies show that pathological increase of IOP is the main risk factor for glaucomatous optic nerve damage or visual field defect, and topical IOP-lowering medication can effectively delay or prevent the occurrence of glaucomatous optic nerve damage in patients with elevated IOP. IOP is a very important index to determine the treatment goals as well as evaluate the effect of the treatment. The visual field defect degree at the time of diagnosis of POAG is related to the treatment and progression of the disease. Ren found that glaucomatous visual field defect was positively related to IOP with a correlation coefficient of 0.57. However, what is the relationship between IOP and visual field defect at the time of diagnosis of POAG patients? what is the visual field defect degree at the time of diagnosis and its relevant factors? Those were rarely reported in China.In light of the above, we conducted a clinical observation on the outpatients of POAG in glaucoma specialist clinic of our hospital for more than a year, in order to know about the IOP level of POAG patients before treatment and the relationship between IOP and the visual field defect degree at the time of diagnosis. This research consists of two parts:in the first part, we aims at knowing about the IOP level before treatment of the outpatients with POAG and analysis the proportion of HTG and NTG as well as the influence of CCT and 24h IOP to the proportion result through observation on IOP and 24 hour IOP of the outpatients of POAG; in the second part, we concentrate on analyzing the defect degree of visual field at the time of diagnosis of POAG and its relationship with IOP and other factors by observing the visual field and IOP.Part One Analysis of intraocular pressure before treatment of the outpatients with primary open angle glaucomaObjectiveTo know about the IOP level before treatment of the outpatients with POAG and analysis the proportion of HTG and NTG as well as the influence of CCT and 24h IOP to the proportion result.MethodsOutpatients with definite POAG in glaucoma specialist clinic of Wuhan General Hospital were collected from May 2014 to April 2015. Analysis the IOP level before treatment of outpatients with POAG. Three classification bases were established to classify the outpatients into HTG (IOP>21mmHg) and NTG (IOP<21mmHg) according to three kinds of intraocular pressure (IOP), which includes maximum random IOP, maximum random IOP after corrected by CCT and peak of 24h IOP after corrected by CCT. The case numbers and proportions of the NTG and HTG by different classification bases were compared and analyzed. IOP between different age and gender was compared using independent-samples T test while the proportions of NTG and HTG were analyzed by x2 test.ResultsA total of 115outpatients with POAG were collected including 84 male (73.04%) and 31 female (26.96%). The ratio of male to female is 2.7:1.0 and the age was (47.68±15.74) years. Analyzing the IOP of the eye which had higher IOP between the two eyes, the maximum random IOP after corrected by CCT before treatment was as follows:23 eyes (20.00%)≤20mmHg,51 eyes (44.35%)>20-30mmHg,18 eyes (15.65%)>30-40mmHg,13 eyes (11.30%)>40-50mmHg,10 eyes (8.7%)>50mmHg. IOP of male was significantly higher than that of female ((32.34±13.49) vs. (25.86±9.99) mmHg). IOP of patients who were 40 years old or younger was significantly higher than that of patients who were over 40 years old ((36.03±13.62) vs. (27.22±11.32) mmHg). According to three different classification bases, the number of HTG and NTG are 95 and 20,89 and 26,109 and 6, while their proportions are 82.61% and 17.39%,77.39% and 22.61%,94.78% and 5.22%, respectively. There was no significant difference between the proportion of NTG and HTG acquired by the classification of maximum random IOP and that acquired by the classification of maximum random IOP after corrected by CCT (P>0.05). When compared these two results with the proportion of NTG and HTG acquired by the classification of the peak of 24h IOP after corrected by CCT respectively, the difference was significant and the latter one has significant low proportion of NTG (P<0.05).ConclusionFor outpatients with POAG in glaucoma specialist clinic of Wuhan General Hospital, different classification basis resulted in different NTG proportion. NTG was just accounted for a tiny part of POAG if the classification base was according to the peak of 24h IOP after corrected by CCT. CCT may not influence the proportion of NTG, but affected the discrimination of POAG types for individuals. During the process of the diagnosis of POAG, attention should be paid to the dynamic, comprehensive and systematic analysis of IOP.Part Two Relevant factor analysis of visual field defect degree at the time of diagnosis of primary open angle glaucomaObjectiveBy observing the visual field and IOP at the time of diagnosis of POAG, to analysis the defect degree of visual field at the time of diagnosis of POAG and its relevant factors.MethodsOutpatients with definite POAG in glaucoma specialist clinic of Wuhan General Hospital were collected from May 2014 to October 2015. Observe the visual field and IOP at the time of diagnosis of POAG. Analyzing the eye which had more serious visual field defect between the two eyes, patients were divided into early stage group (stage 0-1) and moderate-advanced stage group (stage 2-5) according to the stage of visual field defect. Clinical data including age at diagnosis, gender, body mass index(BMI), symptom related to POAG, family history of POAG, high myopia, CCT and IOP were analyzed between two groups. T test was used for measurement data and x2 test was used for categorical data and Spearman bivariate correlation analysis was used for correlation analysis.ResultsA total of 113outpatients with definite POAG were collected from May 2014 to October 2015, including 80 male (70.80%) and 33 female (29.20%). The age was 14～81 (48.73±17.02) years and the age at diagnose was 14～81(47.59±17.20).There were 31 cases (27.43%) in early stage group including 19 male (61.29%) and 12 female (38.71%), the age at diagnosis was (52.81±16.57) years and BMI was (22.00±4.72)kg/m2. Nine patients (29.03%) had symptom related to POAG,3 patients (9.68%) had family history of POAG and 3 patients (9.68%) had high myopia. The CCT was (533.12±29.79)μm and IOP was (23.67±11.44) mmHg. There were 82 cases (72.57%) in early stage group including 61 male (74.39%) and 21 female (25.61%), the age at diagnosis was (45.62±17.12) years and BMI was (23.24±3.08)kg/m2. Forty-four patients (53.66%) had symptom related to POAG,7 patients (8.54%) had family history of POAG and 24 patients (29.27%) had high myopia. The CCT was (536.93±35.02)μm and IOP was (30.58±12.13) mmHg. The IOP in early stage group was lower than that in moderate-advanced stage group while the age at diagnosis in early stage group was older than that in moderate-advanced stage group and the difference was statistically significant (P=0.047,0.007). The incidence of high myopia and symptom related to POAG in early stage group were significantly lower than those in moderate-advanced stage group (P=0.029,0.019). There was no statistically significant difference in gender, BMI, family history of POAG and CCT between two groups (all P>0.05). IOP was positively related to visual field defect at the time of diagnosis (r=0.411,P=0.000).ConclusionFor outpatients with POAG in glaucoma specialist clinic of Wuhan General Hospital, the majority of the patient had serious visual field defect at the time of diagnosis. High IOP, high myopia, symptom related to POAG and younger age at the time of diagnosis maybe risk factors for serious visual field defect at the time of diagnosis of POAG. |
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