Topical Ocular Drugs Research Articles

Essential topical ocular diagnostic drugs for the family practitioner

may also be used. Always be aware that the minims are preservative free and because fluorescein is a growth medium for bacteria, once opened the container should be discarded within 24 hours. A few blinks spread the now-visible tear film across the cornea. No systemic complications accompany the use of topical fluorescein, but soft contact lenses may be permanently stained because of its porous structure. This may be avoided by first removing contact lenses before instillation of the dye. Fluorescein dye is indispensable for the detection of corneal conditions such as abrations, ulcers, herpetic disease, contact lens overwear and dry eye syndrome. Anaesthetics Among the topical anaesthetics, the most widely used agents are proparacaine hydrochloride 0.5%, benoxinate 0.5% and tetracaine 0.5%. The instillation of 1 drop of these surfaceactive compounds renders the corneal epithelium insensate within 15 seconds. Reapplication will enhance the anaesthetic effect. Such anaesthesia is useful to make surface manipulations painless such as removal of corneal or conjunctival foreign bodies, performing tonometry or giving a subconjunctival injection. Use of an anaesthetic also facilitates the examination of a damaged cornea which otherwise might be difficult because of the pain and accompanying blefarospasm. Patients should be advised not to rub their eyes after receiving such drops to prevent them from inadvertently scratching their corneas. Never prescribe topical anaesthetics for repeated use by patients because they are toxic to the corneal epithelium; they inhibit mitosis and cellular migration and can lead to corneal ulceration and permanent corneal scarring.

Switch to latanoprost monotherapy from combined treatment with beta-antagonist and other antiglaucoma agents in patients with glaucoma or ocular hypertension.

To investigate the effects on intraocular pressure (IOP) and the occurrence of adverse events upon switching directly to latanoprost monotherapy from multiple drug therapy, including a beta-antagonist, for glaucomatous eyes. Patients with primary open-angle glaucoma or ocular hypertension and receiving long-term therapy with two or three topical ocular hypotensive drugs (including one topical beta-antagonist) were switched to latanoprost monotherapy for 12 weeks without any intervening washout period. Observations were performed before switching (baseline) and at weeks 4, 8, and 12 after switching to latanoprost monotherapy. Of the 29 enrolled patients, 26 (90%) completed this protocol. Three patients had excessive IOP elevation, and these patients were withdrawn. The switch to latanoprost monotherapy was followed by a significant ( P < 0.0001) mean reduction of 3.9 mmHg at week 12 in per-protocol cases ( n = 26) and a significant ( P = 0.0016) mean reduction of 2.8 mmHg at last postswitch visit in patients in the intent-to-treat analysis group ( n = 29). Adverse ocular events other than IOP elevation were mild. The switch to latanoprost monotherapy in glaucoma patients receiving multiple drug therapy resulted in an additional, significant IOP reduction.

Optometric therapeutic competency standards 2000

Background:Competency standards for entry‐level to the profession of optometry in Australia were first developed in 1993 and then revised in 1997. The competencies require that optometrists entering the profession have the skills to use ocular diagnostic drugs but did not consider the prescription of topical therapeutic ocular drugs by optometrists. Following the introduction of legislation in the Australian state of Victoria that permitted optometrists to be licensed by the relevant state registration board to prescribe topical therapeutic ocular medication, Optometrists Association Australia (OAA) was asked to develop therapeutic competency standards that could be used in the assessment of the suitability of optometrists for such licensing. Methods:Expert members of the profession and representatives from optometry schools, registration boards in Australia and New Zealand, state divisions of OAA and the New Zealand Association of Optometrists (NZAO) were consulted in the process of developing these standards. Results:Nine new performance criteria with associated indicators, within Units 3 and 5 of the revised entry‐level standards, were developed. Additions were made to the indicators for 25 of the previously developed performance criteria (within all six original units of competency). The modified therapeutic competency standards were adopted on behalf of the profession by the National Council of OAA in March 2000. Discussion:These therapeutic competency standards may be used as a basis for licensing authorities to develop an assessment process to determine suitability of optometrists for licensing to prescribe topical therapeutic ocular medications. At this stage, the therapeutic competencies cannot be regarded as entry‐level competencies in Australia but as second‐tier competencies. However, it is anticipated that the therapeutic competencies will come to be regarded as entry‐level over the coming years.

A survey of ocular therapeutic pharmaceutical agents in optometric practice

Background: In all Australian states optometrists are permitted to use diagnostic topical ocular drugs in the practice of their profession. In addition, legislation has just been passed in Victoria allowing optometrists to prescribe topical S4 medications for ocular conditions. Changing optometric legislation to incorporate S4 ophthalmic agents is a topical issue within optometry. Methods: By postal survey, we asked Queensland optometrists to gauge their level of education, current mode of practice and whether they were in favour of gaining access to prescription‐only therapeutic medications. Their opinions on the education requirements, perceived potential public benefits and the possible barriers to optometrists gaining prescribing rights to therapeutic agents were also investigated. Results: A 45 per cent response rate to the survey (231 responses out of 517) was obtained. The majority of respondents (88 per cent) wanted to be able to prescribe therapeutic agents. Over 50 per cent considered themselves competent and believed they were capable of treating dry eye, blepharitis, allergic conjunctivitis, corneal abrasions and contact lens induced papillary conjunctivitis. Over 90 per cent would be confident recommending topical lubricants and antihistamines, while 65 per cent felt they were adequately prepared to prescribe topical antibiotics. Education level, in particular the completion of a therapeutic drugs course, was the main factor that determined whether the respondents practised or were willing to practise at a higher level. Conclusion: The majority of Queensland optometrists are well aware of the issues surrounding the use of pharmaceutical agents. Many optometrists feel they are well prepared for prescribing ocular therapeutic agents.

A current appreciation of sites for pharmacological intervention in allergic conjunctivitis: effects of new topical ocular drugs.

Two important realizations about pathophysiological mechanisms involved in allergic conjunctivitis have led to novel drug discovery efforts and new topical ocular medications for prevention and treatment of this prevent allergic disease. The first of these, interspecies and intraspecies mast cell heterogeneity, was established in the mid-1980's by investigators working in the field of asthma. It is now appreciated that secretory responses as well as effects of pharmacological agents differ depending upon the mast cell population studied. Two types of human mast cells, the tryptase containing (T) and the tryptase/chymase containing (TC) mast cells, have been characterized in a variety of tissues. Significantly, Irani et al. (1) demonstrated by immunohistochemical staining that the mast cells present in conjunctival tissues from patients with allergic conjunctivitis were 100% TC. Functional responses of human conjunctival mast cells to a variety of secretagogues (2) were consistent with their classification as TC or connective tissue type mast cells. Importantly, the studies by Miller et al. mentioned above allowed the harvesting and preparation of human conjunctival mast cells for use in drug screening studies. Utilization of these cells has led to the identification of Patanol, the most effective human conjunctival mast cell stabilizer available for topical use in allergic conjunctivitis (3). These same studies demonstrated the lack of mast cell stabilizing activity for cromolyn and nedocromil in these connective tissue type, TC containing, human conjunctival mast cells. Similar lack of effect was noted with these drugs on human skin mast cell degranulation (4). The second important discovery in the area of allergic conjunctivitis has been the demonstration that conjunctival epithelial cells may contribute to the perpetuation of the allergic response. A report from Gamache et al. (5) identified cytokines produced by human conjunctival epithelial cells following treatment with a number of stimuli. Significantly, Sharif et al. (6) subsequently identified functional histamine H1 receptors on these same cell types. Recently, Weimer et al. (7) have shown that exposure of human conjunctival epithelial cells to histamine leads to the production of pro-inflammatory cytokines IL-6 and IL-8. Importantly, treatment of the epithelial cells with drugs that possess histamine H1 antagonist properties prevents cytokine production. It is noteworthy that first generation anti-histamines antazoline and pheniramine are not potent inhibitors of histamine-stimulated cytokine synthesis in intact epithelial cells, while newer anti-histamines Emadine and levocabastine are more potent. Surprisingly, Patanol was more potent as an inhibitor of histamine-stimulated cytokine production by the epithelial cells than would be predicted from its histamine H1 antagonist affinity. These inhibitory effects on conjunctival epithelial cell production of pro-inflammatory cytokines may contribute to enhanced clinical activity noted with these recently approved drugs.

Therapeutic Index of Pilocarpine, Carbachol, and Timolol With Nasolacrimal Occlusion

We assessed the effect of nasolacrimal occlusion on the therapeutic index of various antiglaucoma medications in healthy volunteers and patients with glaucoma. Nasolacrimal occlusion used with pilocarpine 2% every 12 hours gave the maximal ocular hypotensive response. Carbachol 1.5% every 12 hours with nasolacrimal occlusion gave the maximal response for this drug. For timolol, nasolacrimal occlusion collapsed the dose-response curve and extended the duration of action. A final trial of carbachol added to timolol with nasolacrimal occlusion showed that timolol 0.25% and carbachol 1.5% every 12 hours gave the maximal response for this combination. Our findings suggest that most of the commercially used ocular hypotensive agents can achieve the same maximal effect with lower concentrations and less frequent administration (never exceeding every 12 hours) than are currently recommended should nasolacrimal occlusion be performed. Furthermore, nasolacrimal occlusion should markedly decrease the systemic absorption of topical ocular drugs and lessen the chance of systemic side effects.

Methods for increasing bioavailability of cycloplegics.

Since it has been shown that (1) fluid instilled in the pouch created by pulling the lower lid away from the eyeball is entrapped, (2) no fluids move into the lacrimal sac when the eyelids are shut and (3) gravity is important in tear-flow dynamics, we reasoned that an instillation technique for topical ocular drugs could be devised which would increase the drug effect for a given amount of drug. To test this hypothesis we administered one drop of 0.5% tropicamide to the right eyes of 12 young adults using an experimental method of instillation and to the left eyes using the conventional technique. The experimental technique produced a significantly greater loss of accommodation than the conventional technique. Wtih this experimental or similar technique, it may be possible to use lower concentrations of a drug to produce the same ocular effects produced by a higher concentration instilled in the conventional manner.