Use Straylight to Plan Cataract Surgery in Retinal Dystrophy Patients
Ophthalmology Retina, November/December 2017
The presence of cataracts often aggravates the visual disability experienced by patients with retinal dystrophies such as retinitis pigmentosa (RP). However, the question of whether to proceed with cataract surgery in these patients has not had a clear answer; evidence has suggested that although they may report improved visual function following cataract surgery, their postoperative visual acuity does not necessarily improve.
As a result, van Bree et al. set out to investigate factors that may predict visual outcomes in patients with RP and other retinal dystrophies who undergo cataract surgery. They found that straylight (disability glare) was the only parameter whose preoperative value could be used to support and thus improve the chance of a beneficial postoperative outcome.
For this prospective study, the researchers evaluated 16 patients (25 eyes) with retinal dystrophy and cataract. The patients’ average age was 50 years (range, 28-71 years), and 10 of the 16 had RP. As for cataract type, posterior subcapsular cataracts dominated, observed in 20 of the 25 eyes.
The patients’ corrected distance visual acuity (CDVA), spatial contrast sensitivity, and straylight were assessed pre- and postoperatively, and straylight values were compared with reference values derived from studies of healthy young eyes. Retinal function was assessed with Goldmann visual field and temporal contrast sensitivity testing, and central retinal structure was assessed with optical coherence tomography and fundus autofluorescence. Patients also completed questionnaires on visual function before and after surgery.
Straylight improvement was found in 72% of eyes postoperatively. The average straylight value was 1.75 preoperatively and 1.45 postoperatively —7.1 and 3.5 times higher than values observed in healthy young eyes, respectively.
In contrast, postoperative CDVA improved in only 20% of eyes. The postoperative CDVA measurements could not be explained by the postoperative presence or progression of maculopathy, as macular structure and function remained stable, the authors reported. They concluded that cataract surgery in patients with retinal dystrophy and early cataract may be beneficial because it significantly reduces glare disability, despite its more limited benefits with regard to CDVA. In addition, they recommended that a cut-off value for straylight of log(s) ≥ 1.66 be used as an indication criterion for cataract surgery.
The original article can be found here.