The Cataract is an ocular pathology characterized by the clouding of the eye’s natural lens; it is usually a condition linked to aging, however, it can occur at any age following an extended use of corticosteroids and, should this be the case, the pathology is referred to as cortisone cataract.
Corticosteroids belong to the large group of chemical compounds referred to as steroid compounds, or simply steroids, present both in animals and plants, where they are vested with biological functions of paramount importance. The most common corticosteroid in nature is the cortisol (or hydrocortisone) from which cortisone and corticosteroid derive. Corticosteroids are powerful anti-inflammatory and immunosuppressive agents; they are the choice drugs for fighting serious inflammations (e.g. in the case of rheumatoid arthritis) and for preventing the repeal reactions in patients who underwent an organ transplant.
Moreover, they represent true real lifesavers in several situations, such as in the case of anaphylactic shock or bronchial asthma.
With regard to the eyes, the most common known side effect given by the use of corticosteroids – in particular cortisone, desametasone and prednisone – is the development of the posterior subcapsular cataract (PSC). The relation between the extended use of corticosteroids and the PSC formation is already known since the ’60s and is valid not only for the steroids administered by systemic way, but also for those taken topically (eye drops and creams) and inhaled (nose sprays, aerosols).
A “dose-time effect” exists between the use of corticosteroids and the onset of the cataract: the higher the dosage and longer the treatment, the more the probability increases of developing the cataract. The induction effect of PSC in children is faster, also with smaller dosages. According to many researchers, in addition to the dose effect, also individual predisposition, probably due to genetic factors must be considered. In any event, the dose effect of corticosteroids gives rise to a problem to which the physicians must pay great attention when they prescribe corticosteroid based therapies to their patients, above all if a long time of treatment is envisaged. Given the existence of individual susceptibility to the same drug and a different susceptibility of the same individual to different drugs, it is not possible to predict whether and when the administration of corticosteroids gives origin to a cataract, therefore, it is always appropriate that a patient being treated with steroids be submitted to regular eye examinations in order to monitor the health condition of the lens.