This is to distinguish the normal elevation of intraocular pressure seen in otherwise normal individuals. Measurement of intraocular pressure is thus one of the first completely new skills that a new ophthalmic nurse practitioner must master. Therefore, knowledge about it is important. Measurement of the intraocular pressure in a large number of normal subjects reveals a normal distribution extending from pressures of 10-12 mmHg to 25-28mmHg (Rossetti et al., 2008, 1053). The pattern of distribution fits a Gaussian curve, so that the majority of subjects have a pressure of about 16mmHg. For clinical purposes, it is necessary to set an arbitrary upper limit of normal. By and large, the eye can stand low pressures remarkably well, but when the pressure is abnormally high, the circulation of blood through the eye becomes jeopardised and serious damage can ensue. For clinical purposes, an upper level of 21 mmHg is often accepted. Above this level, suspicions are raised and further investigations undertaken. Thus measurement of IOP is a significant initial clinical diagnostic step that determines further course of action in such patients (Collaer, Zeyen, and Caprioli, 2005, 196-200). Many nurses need to practice the skill of this measurement since accuracy is a very important parameter leading to the further steps in the ophthalmic care pathway.
Now, the question is, why I have chosen measurement of intraocular pressure to demonstrate my skill as a new specialist nurse. Glaucoma is second only to cataract as a leading cause of global blindness and is the leading cause of irreversible visual loss, largely due to primary open-angle glaucoma (POAG). In 2002, it was estimated that 161 million individuals worldwide had visual impairment and 37 million were blind. Glaucoma accounted for 12.3% of global blindness, Bilateral blindness from glaucoma is projected to affect 8.4 million individuals worldwide by 2010 and greater than 11 million by 2020. Globally, glaucoma is a significant cause of vision loss that disproportionately affects women and Asians (Cedrone et al., 2008, 3-14). While increased IOP is a strong risk factor for the development of glaucoma, it must be remembered that many people with glaucoma have untreated IOPs of 21 mm Hg or less. Elevated intraocular pressure (IOP) is the most important known risk factor for the development of POAG, and its reduction remains the only clearly proven treatment. Several studies have confirmed that reduction of IOP at any point along the spectrum of disease severity reduces progression (Bowling, Chen, and Salmon, 2005, 1102-1104). The Collaborative Normal Tension Glaucoma Study has revealed that IOP reduction reduces the development of POAG in patients with ocular hypertension and reduces progression in patients with glaucoma despite normal IOP (Anderson, and Normal Tension Glaucoma Study, 2003, 86-90). In the UK, as mentioned by Kroese et al. (2002), glaucoma is, indeed, the second most common cause of blindness as estimated from blindness certification. This accounts for 11.7% of all certifications. In the age group of