ตรวจสุขภาพตาก่อนสาย เพราะ “ต้อหิน” ตัวร้าย...ไม่มีอาการแสดง

Glaucoma is a condition characterized by continuous degeneration or loss of the optic nerve at the optic disc, often caused by high intraocular pressure. The normal function of the optic nerve is to transmit and process images to the brain. Therefore, as the optic nerve gradually deteriorates, it stops sending signals to the brain, causing the patient to slowly lose peripheral vision, which narrows progressively toward the center&#8230; until complete vision loss occurs.
<h2 style="color: #008080;">How does “Glaucoma” occur? 
</h2>
The cause of glaucoma lies in the anterior part of the eye, where the aqueous humor circulates. This fluid is produced by an internal eye structure called the Ciliary Body, which maintains a balance between production and absorption. The aqueous humor flows through the lens and pupil and is absorbed through the drainage system located at the anterior chamber angle, which has a mesh-like structure called the Trabecular Meshwork. In glaucoma, this balance of aqueous humor circulation is disrupted, leading to increased intraocular pressure and subsequent compression and damage to the optic nerve.
<h2 style="color: #008080;">Why does high intraocular pressure damage the optic nerve? 
</h2>
Normal intraocular pressure is usually not more than 21 millimeters of mercury. Imbalance and elevated intraocular pressure above 21 mmHg can occur in two cases:
<ul>
<li>The aqueous humor is produced excessively, causing the drainage system at the anterior chamber angle to be unable to absorb the fluid quickly enough.</li>
<li>The aqueous humor production is normal, but the drainage meshwork at the anterior chamber angle is blocked or structurally abnormal, causing fluid buildup. Most glaucoma cases arise from this second scenario rather than the first. When intraocular pressure rises, the eye, which cannot expand, presses the excess pressure against the soft tissues inside, including the optic nerve, leading to glaucoma.</li>
</ul>
In another case, patients with normal intraocular pressure but continuous optic nerve damage suffer from insufficient blood supply to the optic nerve. This is often seen in patients with chronic diseases that impair oxygen delivery to the optic nerve, such as diabetes, hypertension, migraine, and sleep apnea.
<h2 style="color: #008080;">What are the risk factors for glaucoma?</h2>
<ul>
<li>Intraocular pressure higher than 21 millimeters of mercury</li>
<li>Genetics: family history of glaucoma increases the likelihood of abnormalities in the balance of aqueous humor production and absorption</li>
<li>Older age, as nerve cells die more easily than in younger individuals</li>
<li>Severe nearsightedness or farsightedness, which may cause structural abnormalities in the eye affecting aqueous humor balance</li>
<li>Long-term use of steroids, which affects aqueous humor absorption</li>
<li>Eye surgery or trauma, which may alter normal internal structures and disrupt the balance</li>
</ul>
<h2 style="color: #008080;">Types of glaucoma are as follows:</h2>
<ul>
<li>Primary open-angle glaucoma is the most common type, caused by blockage of the trabecular meshwork at the anterior chamber angle, preventing normal aqueous humor outflow. This leads to increased intraocular pressure and glaucoma. This type usually has no symptoms and is often found incidentally during routine health or pre-LASIK eye exams.</li>
<li>Angle-closure glaucoma occurs when the anterior chamber angle is blocked by the iris, preventing normal aqueous humor outflow. This type presents with symptoms such as eye pain, redness, blurred vision, tearing, headache, nausea, and vomiting.</li>
</ul>
<h2 style="color: #008080;">Glaucoma treatment methods 
</h2>
Glaucoma treatment is mostly supportive. Early detection benefits the patient because dead optic nerve cells cannot be restored. Treatment aims to prevent further vision loss and preserve the remaining healthy optic nerve. The treatment approach depends on the severity of the disease.
<ul>
<li>Treatment with eye drops to reduce intraocular pressure and prevent further optic nerve damage</li>
<li>Laser treatment to alter the trabecular meshwork structure in open-angle glaucoma or to open blocked angles in angle-closure glaucoma, restoring balanced aqueous humor absorption</li>
<li>Surgical treatment
<ul>
<li>The standard surgery, called Trabeculectomy, creates a drainage pathway by making an opening in the eye wall when pressure cannot be controlled by medication and/or laser, and vision loss continues</li>
<li>For severe or uncontrolled glaucoma, surgery with Glaucoma Drainage Device (GDD) implantation involves inserting a tube to help drain aqueous humor, significantly lowering and stabilizing intraocular pressure</li>
</ul>
</li>
<li>Currently, minimally invasive glaucoma surgery (MIGS) uses small devices inserted to aid fluid drainage. This method involves fewer steps, smaller wounds, and faster recovery but is generally suitable only for mild to moderate glaucoma. Severe glaucoma requires larger incisions for more effective and stable drainage.</li>
</ul>
<h2 style="color: #008080;">Glaucoma can be prevented&#8230; just take care of your eyes 
</h2>
People aged 40 and above should have regular eye check-ups with an ophthalmologist using Slit-lamp Microscopy to examine the optic disc, measure intraocular pressure, and assess the anterior chamber angle in detail. If suspected, visual field tests and optic nerve scans are performed for accurate diagnosis. Since glaucoma shows no symptoms, do not neglect your eye health&#8230; before it is too late to treat.
&nbsp;
Dr. Kanokwan Yuttitham
Glaucoma Specialist Ophthalmologist
Phayathai 2 Hospital Eye Center

Glaucoma is a condition characterized by continuous degeneration or loss of the nerves at the optic nerve head, with high intraocular pressure being a significant factor. As the optic nerves gradually deteriorate one by one, vision is eventually lost.

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