Deposit buildup on prosthetic eye material (in vitro) and its effect on surface wettability.

BACKGROUND: The aim of this in-vitro study was to investigate the effect of different polishing standards on prosthetic eye material (poly(methyl methacrylate) [PMMA]) on surface wettability and the rate of protein and lipid buildup. METHODS: Sample disks (12 mm diameter × 1 mm thickness) of PMMA were polished to three different standards of surface finish: low, normal, and optical quality contact lens standard. The sample disks were incubated in a protein-rich artificial tear solution (ATS) for the following periods of time: 1 second, 30 minutes, 1 hour, 4 hours, 24 hours, and 14 days. Surface wettability was measured with a goniometer before and after protein deposits were removed. One-way analysis of variance and paired-samples t-test were used for the statistical analysis. RESULTS: Between 13.64 and 62.88 µg of protein adhered to the sample disks immediately upon immersion in ATS. Sample disks with the highest polish attracted less protein deposits. The sample disks polished to optical quality contact lens standard were more wettable than those less highly polished, and wettability significantly decreased following removal of protein deposits. The addition of lipids to protein-only ATS made no difference to the amount of protein deposited on the sample disks for any of the standards of surface polish tested. CONCLUSION: The findings are consistent with the results of the in-vivo investigation reported previously by the authors. Our view that the minimum standard of polish for prosthetic eyes should be optical quality contact lens standard and that deposits on PMMA prosthetic eyes improve the lubricating properties of the socket fluids has been reinforced by the results of this study.

The response of the anophthalmic socket to prosthetic eye wear.

PURPOSE: The aim of this study was to investigate the inflammatory response of the anophthalmic socket to prosthetic eye wear. METHODS: One hundred and two prosthetic eye wearers were recruited for this observational study. Photographic grading scales were used to measure the severity of conjunctival inflammation and the extent and intensity of stained deposits on the prosthetic eyes. Tear volume was measured with the phenol red thread test. For mucoid discharge, visual analogue scales were used to assess frequency of occurrence, colour, volume and viscosity. For the prostheses, assessments were made of weight, shape, wearing time and frequency of cleaning. RESULTS: Anophthalmic sockets had more severe conjunctival inflammation than their companion eyes (p = 0.0001). The difference in inflammation between the companion eye and the anophthalmic socket was associated with discharge volume (p = 0.01) and discharge viscosity (p = 0.007) with greater difference in inflammation being associated with higher levels of discharge volume and viscosity. A greater difference in inflammation was also associated with less surface deposition (p = 0.009). No evidence of associations was found between difference in conjunctival inflammation and the other variables. CONCLUSIONS: Recently developed grading scales for measuring inflammation in anophthalmic sockets and deposits on prosthetic eyes were used for the first time in this study. It is recommended that in clinical practice, inflammation grades for both socket and companion eye conjunctivae be compared, when determining if prosthesis-induced inflammation is present. The finding that more discharge was associated with more conjunctival inflammation is logical but the finding that less inflammation was associated with more deposits is counter-intuitive to those familiar with the contact lens literature. The apparently benign nature of at least some deposits on the prostheses raises questions about the maintenance of prosthetic eyes. We conclude that the simple presence of deposits is unlikely to be linked with inflammation of the conjunctiva in wearers of prostheses, who like those in this study, cleaned their prostheses regularly but not frequently.

The development of measurement tools for prosthetic eye research.

BACKGROUND: The aim was to develop tools to measure the condition of ocular prostheses and the socket's response to prosthetic eyewear. METHODS: A novel staining technique for displaying deposits on prosthetic eyes was developed. Equal interval perceptual grading scales for measuring inferior palpebral conjunctival inflammation, and anterior and posterior stained surface deposits on prosthetic eyes were developed from 800 photographs of 43 volunteers. The photographs for each scale were chosen by the authors. A group of four ophthalmologists, three optometrists and three senior students was consulted about selection criteria and asked to position the photographs along a 1.5 m rule to determine equal intervals. Photographs judged not to represent exactly equal perceptual intervals were exchanged with others from the original pool. The final scales (a five-photograph scale for inflammation and two 11 photograph scales for deposits) were assessed for inter-rater reliability and test-retest reliability by groups of senior optometry students. RESULTS: Standard deviations for inter-rater reliability tests were 0.52 scale units for the inflammation scale, 0.99 for the anterior surface deposits scale and 1.03 for the posterior surface deposits scale. The standard deviation of the test-retest differences for inflammation was 0.6 scale units and for both anterior and posterior surface deposits it was 0.71. CONCLUSIONS: A novel technique for displaying and measuring the intensity and extent of deposit formation on prosthetic eye surfaces has been described. The two equal interval perceptual grading scales that have been developed to quantify the extent of deposit formation together with the equal interval perceptual scale for grading severity of palpebral conjunctival inflammation will for the first time allow the effects of prosthetic eye wear to be evaluated. Further research to validate the scale for palpebral conjunctival inflammation in a clinical setting is recommended. The technique for staining deposits on prosthetic eyes is recommended for clinical practice.

Deposit buildup on prosthetic eyes and implications for conjunctival inflammation and mucoid discharge.

BACKGROUND: The aim of this study was to investigate deposit buildup on prosthetic eyes and the implications for conjunctival inflammation and discharge. METHODS: Forty-three prosthetic eye wearers participated in the study. Twenty-three had their prostheses polished normally before being worn continuously for 2 weeks. After this time, surface deposits were stained, photographed, and graded. The prostheses were then repolished to optical quality contact lens standard and worn for a further 2 weeks, when the deposits were again stained, photographed, and graded. Two participants had deposits on their prostheses stained, photographed, and graded on nine occasions at decreasing intervals ranging from 1 year to 1 day. Eighteen participants had the wetting angles on their prostheses measured with a goniometer before and after cleaning, after polishing normally, after polishing to optical quality contact lens standard, and after 10 minutes of wearing their optical quality contact lens polished prostheses. Concordance correlation, multiple regression, and paired t-tests were used for the statistical analysis. RESULTS: More surface deposits accumulated on prostheses polished normally than on those polished to an optical quality contact lens standard after 2 weeks of wear. The interpalpebral zone of most prostheses (observed without magnification) appeared to be clear of deposits. Removal of deposits significantly decreased surface wettability, but wettability returned after 10 minutes of wear. Optical quality contact lens polishing produced more wettable surfaces and a slower rate of deposit accumulation than normal polishing. CONCLUSION: We recommend that an optical quality contact lens standard be the minimum standard of finish for prosthetic eyes. This standard may assist the smooth action of the lids over the interpalpebral zone of the prosthesis and the cleansing action of tears. The presence of deposits in the retropalpebral zone may improve the lubricating properties of socket fluids which, in turn, may result in less frictional irritation of the conjunctiva and less mucoid discharge.