Currently, there is no evidence stating that constant irrigation with the combination of phenylephrine (1.0%) and ketorolac injection (0.3%) will help to maintain mydriasis in patients with known risk factors such as diabetes, glaucoma, and pseudoexfoliative syndrome. However, Omidria does not provide pupillary dilatation, but rather prevents the pupil from constricting and reduces postoperative ocular pain. The drug is added to the irrigation solution and unlike the substance delivered through the topical route it goes into direct contact with the iris tissue throughout the procedure. Recently, a combination of phenylephrine (1.0%) and ketorolac injection (0.3%) was approved for use in cataract surgery (Omidria Omeros, USA).
Epinephrine alone can be added to irrigation solution for the intracameral administration to achieve sustainable mydriasis during cataract procedure. Constant irrigation is potentially more promising because the concentration of the drug within the eye is not lowering over the course of surgical procedure and the dose of the drug may be lower than that used for single injection at the beginning of the procedure. However, washout by irrigation solution deliberately used in modern cataract procedures may limit the effectiveness and sustainability of the achieved effect. Furthermore, it was shown that intracameral injection of 1.5% intracameral phenylephrine proved to be very effective in relieving the IFIS.Ĭurrently, the drug with the commercial name Mydrane (Thea Pharmaceuticals UK), which is a combination of tropicamide (0.02%), phenylephrine (0.31%), and lidocaine (1%), has been approved for use in some European countries. This approach was pioneered by Sugar in 2006 suggesting mixing buffered lidocaine and epinephrine, the drug combination is known as Epi-Shugarcaine. Combined intracameral use of mydriatic agent and local anesthetic showed to be very helpful to dilate the pupil at the start of the cataract procedure. Intracameral administration of mydriatic drugs has several advantages over topical route including the absence of adverse systemic side effects and direct contact of the drug with the target tissue. Various drugs of that class can be administered preoperatively in multiple daily doses with the aim to inhibit prostaglandin release during and after cataract procedure. The use of nonsteroidal anti-inflammatory drugs (NSAIDs) preoperatively has also been shown to support mydriasis and/or prevent miosis. It is known that even with topical administration, drug absorption may cause some unwanted systemic side effects. The usual topical protocol consists of the combination of cycloplegic (tropicamide 1%) and adrenergic receptor agonist (phenylephrine 2.5%). Various pharmacological agents are used to dilate the pupil. Complication rates in patients having that syndrome can be up to 12.5%.Īdvances in Pharmacological Pupil Expansion The main reason of that is atrophy of iris dilator muscle and decrease of iris tissue rigidity.
Intraoperative floppy iris syndrome (IFIS) was described by Chang and Campbell in 2005 and proved to be associated with systemic administration of alpha-1a receptor antagonist Tamsulosin (Flomax). Furthermore, the pathology of the lens zonular apparatus, loss of lens capsule elasticity, and increase of nucleus hardness should be considered as the factors aggravating cataract surgery through the small pupil. Keeping in mind that, there are numerous factors leading to poor pupil dilation including but not limited to the systemic diseases, intake of some pharmacological agents, local comorbidities (glaucoma, ocular trauma, previous ocular surgery, uveitis, etc.), these eyes are generally more prone to increased permeability of the blood-aqueous barrier, leading to postoperative inflammation. Small pupils are not a purely geometrical issue limiting the access to the surgical field. One of the most significant cataract surgery complications – vitreous loss in patients whose pupils failed to dilate increases by a factor of two, anterior capsular tear, increased inflammation, irregular pupil shape, posterior capsular rupture, and retained lens material. Inadequate preoperative mydriasis and/or intraoperative miosis might result in iris trauma and photophobia.
Small pupil is a well-known risk factor associated with numerous complications during and after cataract surgery.