Question: My elderly mother had an IOP below 5 for several years but now it is 9. Could her ciliary body be producing more fluid, and is this good?
Answer: In and of itself, low pressure is not a problem. If the low pressure is not causing hypotony maculopathy, choroidals, a shallow anterior chamber, or other problems affecting the eye structures or vision, then I am happy to see a low pressure. A rise in pressure could be due to increased fluid production from the ciliary body, or it could be due to decreased outflow (which may not be good).
Answer: Hypotony is either the result of over-filtration through the scleral flap, or a hole that develops in the bleb allowing too much aqueous to escape. The main cause of the former is not enough sutures in the flap, and the main cause of the latter is a breakdown of the conjunctiva from the antimetabolite.
Question: I am four weeks post shunt implantation. My intraocular pressure has been at 0 mm Hg. for 7 days. My eye has moderate pain and seems to be smaller.
Answer: The eye at an intraocular pressure (IOP) of 0 is not inflated to normal size, so the lids will be droopy. Often, this situation will resolve on its own. The fluid that has formed between the layers of the eye can be resorbed, unless that fluid is blood. However, a week is usually not long enough to have the choroidal detachment resolve.
Question: What are the problems associated with hypotony (low intraocular pressure)?
Answer: Some of the problems associated with hypotony are: kissing choroidals (fluid lifting up the retina); hypotony maculopathy (folds in the retina that affect the vision); a shallow anterior chamber that may cause damage to the cornea, etc.
Question: What can be done about hypotony (low intraocular pressure)?
Answer: You need to systematically assess the situation to determine the reason for hypotony. For example, if a trabeculectomy was performed, then perhaps the scleral flap needs revision to decrease outflow, or perhaps a compression suture can be used to decrease the bleb's filtering surface area. If there is a glaucoma drainage implant, then perhaps the tube needs to be tied off. The treatment is complicated and depends on multiple factors. Your ophthalmologist, who knows your complete ocular history, is best to consult for further management because treatment needs to be customized for each patient.
Question: I had a trabeculectomy recently, and now have hypotony. How long will it take for the intraocular pressure (IOP) to settle down? Is the flap ever surgically closed?
Answer: It is O.K. to wait for several months to be sure at which level the IOP will stop, and whether you can tolerate any diminished vision due to low IOP. If the IOP does not increase to acceptable levels after several months, the surgeon can add sutures to the flap to close it down more.
Question: After a recent trabeculectomy, I have hypotony. Is my vision likely to return to my pre-operative level?
Answer: It is moderately likely if the pressure increases to a better range within a couple of months. After two or three months, raising the intraocular pressure (IOP) may not be as effective. A posterior cataract will also form, making vision worse until the cataract is removed.
