Cataract is an eye problem that is associated with the clouding of the eye's natural crystalline lens that is located behind the iris. The crystalline lens as well the cornea of the eye are both optical structures that help us see. For one to be able to see, the light must first be focused on the retina. This is what the crystalline lens does. After the image is formed on the retina, light is converted into neurological impulses, which in turn, are conveyed to the brain. It is the interpretation of the impulses by the brain that helps us visualize the world. If the crystalline lens loses its clarity, or becomes cloudy or opaque, the brain would not be able to receive signals and process the signals to form a visual image. This may lead to an impaired vision. It is therefore essential to correct the loss of optical clarity of the eye's natural lens. The surgical process that is used for the same is referred to as a cataract surgery. Under the cataract surgery, the surgeon removes the eye's natural lens and implants an artificial intraocular lens in its place. In this article, we will find what causes dilated pupil after cataract surgery.
What Causes the Pupils to Dilate After a Cataract Surgery?
If cataract is diagnosed at an early stage, a small incision cataract surgery can be performed to remove the cataract. Prior to the surgery, the surgeon puts dilating drops so as to enlarge the pupils. The pupil is an aperture or an opening in the center of the iris of the eye. It is through the pupil that the light enters the retina. The pupil may contract or dilate depending on the amount of light entering the eye. It usually dilates or widens in dim light. Dilating the pupils is an integral part of the eye examination as well as the cataract surgery. The drops that are used for dilating the pupils are referred to as mydriatics. Mydriatics may temporarily paralyze the iris sphincter muscle that contract the pupil or stimulate the iris dilator muscle that cause the pupil to dilate. This helps the doctors examine the inner portion of the eye that lies behind the iris.
Dilating the pupil allows the surgeon to examine the lens, retina and the optic nerve and also makes the removal of the crystalline lens easier. A small incision is made in order to remove the lens, and replace it with an artificial intraocular lens. In certain cases, where small incision surgery may not help, procedures such as phacoemulsification or extracapsular cataract surgery may be used for removing the lens of the eye. The patients may have a blurred vision until the effect of these drops fades away. Studies are also being conducted to find if fixed dilated pupil after this surgery is associated with the use of viscoelastic substances such as hypromellose or methyl cellulose in cataract surgery. The viscoelastic substance is used for protecting corneal endothelium from surgical trauma, while intraocular lens is positioned in the eye.
Effect of Diluting Drops on Pupils
So how long do eye pupils stay dilated after cataract surgery? Well, the effect of the dilating drops may last anywhere from a few hours to several weeks. This is the reason why some people may complain about dilated pupil for a few days after the cataract surgery. The dilating drops that temporarily paralyze the iris sphincter muscle, thereby making the pupil smaller, are referred to as parasympathetic antagonists or parasympatholytics, while the ones that act on the iris dilator muscle are referred to as sympathetic agonists or sympathomimetics. The drops that temporarily paralyze the iris sphincter muscle, which is the muscle that helps in focusing of the crystalline lens, may dilate the pupil for a time ranging anywhere from 24 hours to two weeks. On the other hand, the effect of the drops that stimulate the iris dilator muscle may last for about three to six hours.
The type of intraocular lens that has been implanted is another factor that must be considered while determining the causes of dilated pupils after the surgery. The pupils may stay dilated for a longer time if an accommodating intraocular lens called crystalens is implanted in the eyes. Due to this reason, the patient may be asked to use pupil constricting drops for a week, or until a period of time recommended by the doctor. The success rate of cataract surgery is quite high, and mostly, patients are able to adjust to the lens after some time. If however, one has been experiencing blurry vision or the pupils seem to be dilated for a longer time during the recovery period, one must consult the doctor soon.
Administration of mydriatic drops prior to the surgery is extremely important as it helps the surgeons examine the optical structures that lie behind the iris. Once the effect of these drops lessens, the size of the pupils would become normal and the vision would also get clearer. If the pupils seem to stay dilated for a longer time, let an ophthalmologist examine the eye, and ascertain the underlying cause of dilated pupils.