Biomaterial Database

Assessing the 'cyclodiode G-probe' using a grey scale test: reproducibility and differences between probes. 2003

P Hossain, and G Ghosh, and S A Vernon

Academic Department of Ophthamology, University of Nottingham, Eye, Ear, Nose & Throat Centre, UK. parwex.hossain@nottingham.ac.uk

OBJECTIVE 1. To determine the number of clinicians performing cyclodiode therapy who reuse the 'G-probe' used for the delivery of cyclodiode therapy. 2. To show a simple method to assess the output of the 'G-probe' that can be used in the clinical setting. METHODS A total of 71 questionnaires were sent to ophthalmologists who have an Oculight SLx Iris Medical Diode Laser. Ophthalmologists were asked as to whether they performed cycloablative therapy using the 'G-probe' and whether they reused the G-probe. They were also asked as to the frequency of any reuse of probes. To determine the output of the 'G-probe', paper copies of a custom-made grey scale chart containing graded blocks of increasing shades of grey densities were produced. A special probe holder was made so that the G-probe tip could be held at a fixed distance from the grey scale chart. Laser burns were made on the grey scale using this arrangement and measurements of the burn size were made. After using 'standard settings' of 2000 ms and 2000 mW, 'threshold' burns were defined. Five new probes (with two different operators) were tested to assess the interprobe, interoperator, and intersheet variability of test. Probes were then tested for the burn size produced between 1000 and 3000 mW, and 1000 and 3000 ms. RESULTS Results from the questionnaire showed that of the 44 respondents (62.0% response), 93.2% performed cyclodiode therapy with 58.5% reusing the G-probe. Among them, 56.1% reused probes on more than one occasion. Results from testing a new G-probe on the grey scale chart showed that with 'standard settings', highly reproducible burns at grey density 8 could be produced. No significant interprobe, interoperator, and intersheet variations were noted. Above 3 J of laser energy, the test could detect a 20% increase in energy settings and it was found that at levels of 4 J or above, alterations to the power setting had a greater influence on burn production than alterations to the time setting. CONCLUSIONS This study demonstrates 1. that many clinicians in the UK reuse G-probes, 2. a simple, quick, and highly reproducible method to assess the laser output from the G-probe used for cyclodiode therapy. The method can help the ophthalmic surgeon to test the G-probe prior to commencement of therapy and with a standard treatment protocol, may produce a more predictable intraocular pressure reduction.

UI	MeSH Term	Description	Entries
D009885	Ophthalmology	A surgical specialty concerned with the structure and function of the eye and the medical and surgical treatment of its defects and diseases.	Ocular Surgery,Ocular Surgeries,Surgery, Ocular
D010818	Practice Patterns, Physicians'	Patterns of practice related to diagnosis and treatment as especially influenced by cost of the service requested and provided.	Clinical Practice Patterns,Physician's Practice Patterns,Clinical Practice Pattern,Pattern, Clinical Practice,Patterns, Clinical Practice,Practice Pattern, Clinical,Practice Patterns, Clinical,Practice Patterns, Physician's,Prescribing Patterns, Physician,Physician Practice Patterns,Physician Prescribing Pattern,Physician Prescribing Patterns,Physician's Practice Pattern,Physicians' Practice Pattern,Physicians' Practice Patterns,Practice Pattern, Physician's,Practice Pattern, Physicians',Practice Patterns, Physician,Prescribing Pattern, Physician
D010865	Pilot Projects	Small-scale tests of methods and procedures to be used on a larger scale if the pilot study demonstrates that these methods and procedures can work.	Pilot Studies,Pilot Study,Pilot Project,Project, Pilot,Projects, Pilot,Studies, Pilot,Study, Pilot
D002924	Ciliary Body	A ring of tissue extending from the scleral spur to the ora serrata of the RETINA. It consists of the uveal portion and the epithelial portion. The ciliary muscle is in the uveal portion and the ciliary processes are in the epithelial portion.	Corpus Ciliare,Corpus Ciliaris,Bodies, Ciliary,Body, Ciliary,Ciliare, Corpus,Ciliares, Corpus,Ciliari, Corpus,Ciliaris, Corpus,Ciliary Bodies,Corpus Ciliares,Corpus Ciliari
D002983	Clinical Competence	The capability to perform acceptably those duties directly related to patient care.	Clinical Skills,Competence, Clinical,Clinical Competency,Clinical Skill,Competency, Clinical,Skill, Clinical,Skills, Clinical,Clinical Competencies,Competencies, Clinical
D004868	Equipment Failure	Failure of equipment to perform to standard. The failure may be due to defects or improper use.	Defects, Equipment,Device Failure,Failure, Equipment,Malfunction, Equipment,Medical Device Failure,Misuse, Equipment,Device Failure, Medical,Device Failures, Medical,Failure, Medical Device,Failures, Medical Device,Defect, Equipment,Device Failures,Equipment Defect,Equipment Defects,Equipment Failures,Equipment Malfunction,Equipment Malfunctions,Equipment Misuse,Equipment Misuses,Failure, Device,Failures, Device,Failures, Equipment,Malfunctions, Equipment,Misuses, Equipment
D005901	Glaucoma	An ocular disease, occurring in many forms, having as its primary characteristics an unstable or a sustained increase in the intraocular pressure which the eye cannot withstand without damage to its structure or impairment of its function. The consequences of the increased pressure may be manifested in a variety of symptoms, depending upon type and severity, such as excavation of the optic disk, hardness of the eyeball, corneal anesthesia, reduced visual acuity, seeing of colored halos around lights, disturbed dark adaptation, visual field defects, and headaches. (Dictionary of Visual Science, 4th ed)	Glaucomas
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D017075	Laser Coagulation	The use of green light-producing LASERS to stop bleeding. The green light is selectively absorbed by HEMOGLOBIN, thus triggering BLOOD COAGULATION.	Laser Thermocoagulation,Thermocoagulation, Laser,Coagulation, Laser,Coagulations, Laser,Laser Coagulations,Laser Thermocoagulations,Thermocoagulations, Laser
D017743	Equipment Reuse	Further or repeated use of equipment, instruments, devices, or materials. It includes additional use regardless of the original intent of the producer as to disposability or durability. It does not include the repeated use of fluids or solutions.	Product Recycling,Recycling, Equipment,Equipment Reusability,Equipment Recycling,Recycling, Product,Reusability, Equipment,Reuse, Equipment