Blog

Glaucoma is a symptomatic condition where the functional integrity of the eye is disturbed , resulting in characteristics irreversible loss of visual field due to persistent raised IOP . Glaucoma is a multifactorial optic neuropathy in which there is a characteristics loss of retinal ganglion cells and atrophy of the optic nerve . Though controversial , this definition of American Academy of Ophthalmology excludes IOP as a criterion and says this is a risk factor .

Symptoms – 

1. Marked photophobia 
2. Blepharospasm 
3. Watering 
4. Headaches 
5. Low vision 
6. Vision loss 
7. Nausea and vomiting. 

Signs – 

1. Eyeball – it becomes enlarged , if the IOP becomes elevated prior to age of 3 years . This enlarged eyeball due to glaucoma , is known as bupthalmos .
2. Sclera – bluish discoloration 
3. Cornea – it is enlarged , globular and steamy . Horizontal curvilinear lines are seen on the back of the cornea , known as Haab’s striae and they represent healed breaks of Descemets membrane . Corneal sensation is diminished.  
4. AAnterior chamber – deep 
5. Lens – flattened and displaced backward . There may be subluxation . 
6. Fundus – shows cupping of the disc , but it may regress when the IOP is normalized quickly.  
7. Refractive error – the patient becomes myopic. But the amount of myopia is less than anticipated from the increased axial length , owing to flattening and backward displacement of the crystalline lens . 

Types – 

1. Open angle glaucoma 
2. Angle- closure glaucoma 
3. Congenital glaucoma 
4. Secondary glaucoma 

Diagnosis- 

1. Measurements of corneal diameter- 

In infant , the mean horizontal corneal diameter is 10.0 mm . If a corneal diameter is more than 12mm within first year , it is always pathological . 

1. Dilated eye exam to widen pupils and view your optic nerve at the back of your eyes.
2. Gonioscopy to examine the angle where your iris and corneglaucoma
3. Optical coherence tomography (OCT) to look for changes in your optic nerve that may indicate glaucoma.
4. Ocular pressure test (tonometry) to measure eye pressure.
5. Pachymetry to measure corneal thickness.
6. Slit-lamp exam to examine the inside of your eye with a special microscope called a slit lamp.

Visual acuity test (eye charts) to check for vision loss.

1. Intraocular tension – it is preferably measured with Parkins applanation tonometer , as the scleral rigidity is very low in children . 

Management – 

1. Medical – 
   1. Miotic therapy – instillation of pilocarpine 2% every 5 minutes, is usually effective in pulling the iris from the angle and aborting the attack . The fellow eye should be treated with 2% pilocarpine , 3 times daily . 
   2. Tablet acetazolamide (250gm ) 2 tabs Stat and then followed by 1 tablet 4 times daily , with potassium supplement .
   3. Hyperosmotic agents – 

1. Intravascular injection of mannitol (20%)- the dose is 1-2 g/kg body weight . 300-500 ml is given intravenously over a period of 30-45 minutes . 
2. Oral glycerol (50% solution)- 30ml of pure glycerol with equal amount of fruit juice stat, and then 3 times daily . Cannot be used in diabetics. 
3. Isosorbide – it is used orally , and it doesn’t cause nausea. It can be used safely in diabetic patients. 

1.  Beta blocker – 

1. Timolol maleate eye drops , at 12 hourly interval ( twice daily ) . It is a nonselective beta blocker . It lowers the IOP by reducing the aqueous secretion , as a result of direct action on the secretory, as a result of direct action on the secretory epithelium of the cilliary body.  
2. Betaxolol eye drops twice daily . It is cardioselective beta 1 blocker and is almost as effective as timolol. 
3. Levabunolol eye drops twice daily . It is as effective as timolol with less ocular side effects . 

1. Prostaglandin analogs (PGAs) – act by increasing the uveoscleral outflow by over 100 % of physiological levels . It lowers IOP by 25-35% from baseline  The once daily dosing and minimal ocular side effects are advantageous . But there are expensive drugs . Exmp- Latanoprost (0.005%) eye drop , Travoprost (0.004%).

1. Surgical – 
   1. Goniotomy – an accurate incision is made with a special knife , halfway between the iris and the Schwalbe’s line. 
   2. Goniopuncture – a puncture is made through the whole thickness of the trabecular region into the Subconjunctival space . 
   3. Trabeculectomy – a fine metal probe is passed into the schlemm’s canal , and is then swept into the anterior chamber , thus exposing the Schlemm’s canal directly to the aqueous humor . 
2. Rehabilitation – It is extremely important to detect and treat any refractive error and amblyopia . Corneal opacity may be treated by penetrating keratoplasty .