الفهرس 
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Abstract
Glaucoma is the second most prevalent eye condition, after cataracts, known to cause blindness worldwide. The actual etiology of the condition remains unknown, there is no known cure. Glaucoma consists of many eye disorders, such as congenital glaucoma, secondary glaucoma, primary angle closure glaucoma (PACG), normal tension glaucoma (NTG), pigmentary glaucoma, and primary open-angle glaucoma (POAG). These disorders destroy the optic nerve, which sends visual information to the brain, leading to blindness.
POAG accounts for around 70% of the total glaucoma cases worldwide, In POAG, there is a malfunction in the ocular drain¬age system, resulting in the accumulation of aqueous fluid. This increases the IOP which damages the optic nerves.
The main clinical features of primary open-angle glaucoma are an open iridocorneal angle and cupping of the optic disc, with corresponding loss of visual field. As there is no known curable treatment for glaucoma , Therefore, all current treatments of primary open-angle glaucoma are aimed at reducing intraocular pressure by medical or surgical means. Current treatment comprises incisional surgery, laser surgery, and medication. All these treatments aim to relieve the pressure on the optic nerve either by slowing the rate of aqueous humor production or by increasing the rate of excess aqueous humor drainage.
N.B: A glaucoma suspect is an individual with clinical findings and/or a constellation of risk factors that indicate an increased likelihood of developing primary open angle glaucoma(POAG). NTG is a subtype of POAG at which there is optic neuropathy and visual field affection but intraocular pressure still within normal limits.
Patients with NTG may be asymptomatic and present when they already have extensive visual field loss. The diagnosis of NTG is made only after a comprehensive assessment has been performed.
What is target IOP?
There are many definitions of target IOP, one of them is that introduced by the American Academy of Ophthalmology (AAO), which defines target IOP as ”a range of IOP adequate to stop progressive pressure induced injury”. The target IOP is assessed by taking into account the risk of future damage and should be reevaluated periodically. If the pressure goal cannot be reached medically or if the drug or combination of drugs have side effects surgical treatment should be considered. Above all it is important to estimate the slope of progression for each individual patient in order to minimize the risk of treatment. The goal of treatment is to maintain patient’s overall Quality of Life (QoL) by balancing the respective risks of treatment and disease, Given that the rate of progression of glaucomatous damage is different for each patient, glaucoma patients should not be thought of as being stable or progressing
but rather as progressing at varying rates.
There are variety of means to estimate and calculate target IOP, The target IOP is estimated for each patient based on initial intraocular pressure and degree of existing damage. It is important to be continuously reassessed and reset based on the clinical course. The less the initial pre-treatment, the more advanced the optic nerve damage; and the older the patient, the lower the target should be set.
Obviously the lowest possible pressure will be the safest for preventing further glaucomatous damage. But extreme low pressures may have drawbacks, and the medications necessary to obtain them have potential side effects, However there are limitations of target IOP approach.
In the present study we used mean deviation of the visual field to assess V.F. progression with treatment of POAG and the changes in visual field after achieving target IOP. In our study we depended on medical treatment and follow up period of six months. By the end of follow up we have two groups of patients ; group 1 patients achieved target IOP& group 2 patients didn’t achieve target IOP .
As regarding demographic data (age, sex) there was no statistically significant difference between the two groups. And by comparing P value of visual field MD difference. Between two groups we found that there is statistically significant difference between both groups as regard the group that achieved target IOP there was significant regression in visual field MD changes or at least no more changes than the initial one.