Acute angle closure glaucoma (AACG) occurs when the outflow of aqueous is obstructed in its pathway resulting in significantly raised IOP. Pain, one of the important symptomatology in acute glaucoma may be falsely localised. Patient may have headache, which may be generalised and sometimes systemic symptoms and signs like nausea and vomiting and even abdominal pain may predominate which may lead to a false diagnosis of viral illness or even acute abdomen.1
The non ophthalmic origin of symptoms, coupled with a history of previous uncomplicated Argon laser PRP treatments may lead to the delay in the diagnosis as we see in our patient. Lack of ophthalmic cover, in district general hospitals may further delay proper management.
Argon laser PRP is a common ophthalmic procedure performed in eyes with vaso-proliferative retinopathy. Treatment is aimed at ablating peripheral retinal tissue in order to reduce the retinal oxygen supply to demand ratio. This in turn reduces the hypoxic vaso-proliferative drive which if left unchecked can result in a blind and painful eye.
The mechanism of IOP following PRP laser procedure is still unclear.
Blondeau et al2
observed angle closure in 44% of patients within hours after PRP. It is postulated to be due to anterior displacement of the iris caused by elevation of the cilliary body which is continuous with the iris root posteriorly. This results in narrowing of the drainage angle and obstruction of aqueous humour outflow. Ultrasound studies have shown the incidence of ciliochoroidal effusion following PRP to be as high as 90%.3
This effusion rotates the cilliary body and iris root anteriorly to trigger this cascade. Mensher et al4
have hypothesized that PRP damaged veins returning blood from the cilliary body to the choroidal venous system leading to oedema and hyperemia of the cilliary process. Another theory is that PRP caused a temporary breakdown in the blood retinal barrier leading to outpouring of fluid from the choroid into vitreous and an annular choroidal detachment.5
However, in the majority of cases, the angle closure and resultant IOP rise is transient and asymptomatic.
The hypermetropic refaction (+2.75D Sph both eyes) and age of our patient could have been significant contributory factors in our patient. Hypermetropes, have shorter axial lengths of the eye ball with narrow angle of the anterior chamber. With aging, the natural crystalline lens of the eye thickens leading to further compromise of the drainage angle. Furthermore, previous PRP applications may have already compromised his choroidal circulation, predisposing to ciliochoroidal effusion. Additionally choroidal effusions tend to occur more frequently in older patients due to stiffening of the sclera.
In summary, this case highlights important diagnostic aspects of AACG. Thorough, ocular examination is important in patients presenting with headache and vague systemic symptoms particularly of gastrointestinal origin in the elderly. A recent history of Argon laser PRP should increase the index of suspicion. Checking the refractive status, could further aid recognition of this rare, but serious complication of PRP. This will enable prompt treatment to alleviate patient discomfort and improve visual prognosis.
- Acute glaucoma should be considered as a potential complication after laser panretinal photocoagulation treatment.
- Acute glaucoma can present with vague non ocular symptoms like an acute abdomen or as a viral illness.
- Checking refractive status of patients undergoing panretinal photocoagulation treatment is important as they may be predisposed to acute glaucoma following treatment.