Study Of IOP Diurnal Variation Curves After Trabeculectomy In Patient With Primary Open-angle Glaucoma

Background and PurposeGlaucoma is a progressive optic neuropathy characterized by the change of structure of optic disc, it is usually accompanied by a corresponding visual field change. The level of intraocular pressure is one of the most determined factor for glaucoma, which is a easily measured and treatment factor. Significant proportion of patients whose IOP is down to satisfied level, but still have progressive visual field. Studies have shown that peak and diurnal IOP is an important risk factor for glaucomatous damage. But the fluctuation of IOP as risk factors for optic nerve injury can not get by a single measurement, Twenty-four-hour IOP monitoring is the best way to access to the real situation in patients with IOP. The purpose of this research is to characterize the of IOP before and after filtering surgery in patients with primary open angle glaucoma, and to compare the differences of diurnal variation curves between POAG patients and healthy controls and define the distribution of the peak of IOP. MethodsA prospective study.60 (60 eyes) patients with POAG and 75 (75 eyes) normal subjects were selected in the study. IOP were measured with Non-contact tonometer within 24 hours, Measurements were taken every 3 hours in each eye (8 times in 24 hours) from the early morning 7:00 to 4:00 early morning of the next day. All patients with glaucoma were performed with trabeculectomy. IOP was measured at 3d,2w,1m,6m after trabeculectomy. Both the 24h IOP and the visual field were measured at 6m after trabeculectomy. The peak IOP and the range of IOP fluctuation were evaluated the diurnal IOP. Mean defect reflected the changes of visual field. Then, comparising the pattern of IOP fluctuations between preoperative and postoperative POAG and the normals.All results are expressed as the Mean±SD. Statistical analyses were performed with SPSS 13.0 software. A less than 0.05 was considered as statistical significance.Results1. In the normal control group, the peak IOP value occurres in the daytime in 24 people (32%), and 51 persons (68%) in night; the amplitude of 24-hour IOP is 4.53±2.46 mmHg; the total of IOP fluctuation less then 6 mmHg is 41 people (54.6 %), the total of IOP fluctuation more then 8 mmHg is 10 people (13.4%).2. In the preoperative POAG group, the peak IOP value occurres in the daytime in 25 people (41.7%), and 35 persons (58.3%) in the night; The amplitude of 24-hour IOP is 8.31±2.50 mmHg; The total of IOP fluctuation less then 6 mmHg is 4 (6.6%), the total of IOP fluctuation more then 8mmHg is 28 people (46.7%); The mean defect of the visual field is 9.87±3.57 dB.3. In the postoperative POAG group, the peak IOP value occurres in the daytime in 35 people (58.3%), and 25 persons (41.7%) in the night; The amplitude of 24-hour IOP is 3.93±2.74 mmHg; The total of IOP fluctuation less then 6 mmHg is 32 (53.3%), the total of IOP fluctuation more then 8 mmHg is 6 people (10%); The mean defect of the visual field is 9.94±3.65 dB.4. Peak IOP, the range of IOP fluctuation, the number of the eye and the percentage of different range of IOP as indicators. Significant differences exist between preoperative and postoperative POAG (P< 0.001).The differences are significant between preoperative POAG with normal controls. The differences are not statistically significant between postoperative POAG with normal controls (P> 0.05)There are not significant changes in visual field between preoperative and postoperative POAG.Conclusions1. Peak IOP value occurs outside normal clinical hours in 68% of normal controls and in 58.3% of POAG patients. So measure IOP in office-time may miss the dynamic information of IOP.2. The IOP peak can occur at the night in 58.3% of POAG patients. Nocturnal intraocular of the patients with POAG pressure should be paid more attention.3. The peak IOP and IOP fluctuation were significantly decreased in the postoperative POAG; The IOP fluctuation of 90% patients is less than 8 mmHg.4. POAG patients and normal controls have asymmetric IOP diurnal variation. There is not significant difference in IOP diurnal variation between the postoperative POAG and normal controls.5. Trabeculectomy can significantly reduce intraocular pressure and control the IOP fluctuation effectively, and it has a protective effect on visual field.