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Jonathan Clarke, Ming-Yueh Lee, Ashkan Khalili, Sumit Dhingra, Catey Bunce, Peng Khaw; The relationship between skin phototype and trabeculectomy outcome. Invest. Ophthalmol. Vis. Sci. 2013;54(15):4795.
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Identification of risk factors for glaucoma drainage surgery (trabeculectomy) failure determines the level of perioperative augmentation with antimetabolites. Spectrophotometers measure the reflectance from skin from a light source giving the individuals phototype. They are non-invasive and acquire information rapidly. 680nm reflectance is reduced in pigmented skin types. They may help quantify the risk of future surgical failure.
Patients who had previously completed a randomized controlled trial of intraoperative 5FU versus placebo were invited to participate in a follow up study. Sun unexposed (constitutional) and sun exposed (facultative) phototypes were measured under standard conditions. Cox regression analysis was performed to assess the association between time to reach trial failure criteria for intraocular pressure control during follow-up and skin reflectance at 680nm wavelength.
Skin photoype of 24 patients was measured. The averages of 5 readings of constitutional and facultative measurements were taken. Examples of the skin phototype curves are shown in figure 1. Mean constitutional value was 40.3% reflectance (range 15.1-50.9), and mean facultative value was 35.5% reflectance (range 7.7-47.7). An association with failure criteria of >17mmHg on 2 consecutive follow up visits was identified with constitutional (HR 0.95 (95% CI 0.90-0.99)) and facultative (HR 0.94 (95% CI 0.90-0.99)) measurements. For failure definition of >21mmHg on 2 consecutive visits also identified associations with failure for both constitutional (HR 0.91 (95% CI 0.86-0.97)) and facultative (HR 0.92 (95% CI 0.87-0.98)) measurement. However, following adjustment for ethnic origin, the effect is not found to be significant.
We have identified an association between lower skin reflectance measurements and surgical outcome. The role of ethnic origin however is complex and requires further investigation. Non-invasive spectrophotometers can measure properties in the skin that are predictive for future outcomes in glaucoma surgery.
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