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Thomas J T P Van Den Berg, Maartje C van Bree, Ingeborgh van den Born; Cataract surgery and Straylight in patients with Retinitis Pigmentosa. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2805.
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© ARVO (1962-2015); The Authors (2016-present)
The importance of straylight derives from the fact that it reduces retinal sensitivity. This may be particularly relevant in conditions with retinal dysfunction, such as Retinitis Pigmentosa (RP). Moreover in RP often early in life PSC cataract develops. The question of this study is whether straylight substantially contributes to visual disability in RP patients, potentially aggravated due to the combination of retinal degradation and increased straylight from cataract formation. In addition, straylight was used to predict possible benefit of (early) cataract surgery.
Eigthteen RP patients (age 51±16, 25 eyes) scheduled for cataract extraction (CE) on the basis of classical criteria (including visual acuity, not including straylight) participated. Before and after CE, best corrected visual acuity (BCVA) in logMAR, contrast sensitivity (CS) in log(CS), temporal contrast sensitivity (TCS) in log(TCS), and straylight (log of the straylight parameter s, log[s]) were tested. TCS, or flicker sensitivity, was tested with a new test, using the C-Quant hardware (ARVO 2011 #1884; JBO 2011;16:085004). TCS measurement was performed to assess foveal function isolated from the eye’s optical quality.
Average pre CE log(s) value was 1.72, corresponding to a factor 6 straylight increase as compared to a healthy, young eye. Functionally significant improvement defined as >0.2 log, was only found for log(s). Only log(s) improvement was related to pre CE values (p<0.001), with a mean improvement of 0.27 log (p<0.001) and a preop break-even point for improvement at log(s)=1.46. logMAR improved on average by 0.12 (p<0.001), without predictability (p=0.85). LogMAR and log(TCS) were correlated (pre CE r=0.57, p<0.01; post CE r=0 .47, p<0.05). Pre and post CE log(TCS) values were similar (p=0.14).
Straylight effects of cataract may substantially aggravate visual disability in RP patients, whereas BCVA may (not yet) be affected. Loss of BCVA may reflect foveal function rather than cataract. Preop straylight lelvel is predictive for the improvement upon surgery. For proper CE referral straylight must be assessed.
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