Cardiac failure aggravated by timolol eye drops: preoperative improvement by changing to pilocarpine

The effect of pneumoperitoneum on intraocular pressure in rabbits with alpha-chymotrypsin-induced glaucoma

Increased intraperitoneal pressure is associated with physiological changes including alterations of intraocular pressure (IOP). We have previously shown that IOP is not adversely affected by increased intraperitoneal pressure up to 15 mm Hg in women with no preexisting eye disease. The aim of this study was to measure IOP changes associated with increased intraperitoneal pressure (up to 15 mm Hg) of 2 h duration in 12 rabbits with alpha-chymotrypsin-induced glaucoma. A reliable model of glaucoma was created by injecting alpha-chymotrypsin into the posterior chamber of the right eye in 12 rabbits. Thereafter, 5 of the 12 rabbits with glaucomatous eyes were treated with topical timolol. The left eye was used as a control. During pentobarbital general anesthesia, increased intraperitoneal pressure up to 15 mm Hg was created by intraperitoneal CO2 insufflation. Body temperature and expired CO2 were kept constant throughout the study. IOP measurements were made using an electronic pneumotonometer. IOP, mean arterial pressure, heart rate, and central venous pressure were recorded in head-up and head-down positions before, during, and after increased intraperitoneal pressure. The IOP of both eyes, in both treated and untreated rabbits, increased significantly from baseline only when increased intraperitoneal pressure associated with the head-down position resulted in a significant increase in central venous pressure. However, the IOP increase remained within the diurnal range. The major finding of this study is that, in a reliable model of glaucoma, CO2 pneumoperitoneum was associated with an increase in IOP when a head-down position was combined with pneumoperitoneum.

IMPLICATIONS

In rabbits with alpha-chymotrypsin-induced glaucoma, increased intraperitoneal pressure (up to 15 mm Hg) resulted in a significant intraocular pressure increase when pneumoperitoneum was associated with the head-down position. However, the intraocular pressure increase remained within the diurnal range.

Systemic adverse effects of topical ophthalmic agents. Implications for older patients

Topical ophthalmic medications are widely prescribed by growing numbers of eye-care professionals. Increasingly, these agents are being prescribed by optometrists and ophthalmic-trained nurses in addition to ophthalmologists and general practitioners. As the number and variety of topical agents on the market rises, and as the number of clinicians involved in prescribing those agents increases; the risk of systemic adverse effects will also increase. Thus, professionals involved in the care of these patients must be aware of the risks associated with these drugs in order to minimise the likelihood of complications. Moreover, inadequate training may result in the clinician failing to associate a topical medication with a systemic condition, allowing an adverse effect to pass unrecognised. It is therefore in the interest of the ophthalmic and pharmaceutical communities to improve awareness of the potential dangers intrinsic in the use of topical eye medications. It is the elderly population who are at greatest risk of experiencing systemic adverse effects of topical agents. Chronic ophthalmic diseases, and hence long term ophthalmic drop treatments, are more prevalent among older people. Such individuals are also likely to have other medical conditions (e.g. cardiac, respiratory or neurological disease) that may be induced or exacerbated by topical ophthalmic agents. Moreover, polypharmacy is common in elderly people, and this is associated with an increased risk of drug interactions.