American Academy of Ophthalmology
There is increasing interest in the value and timing of second-eye cataract surgeries among government and second-party payers. This interest is fueled in part by the increase in the elderly patient population in the United States and around the world. Concurrently, there is an increasing recognition that visual function is a more important guideline to the timing of surgery then is Snellen visual acuity. Binocular visual dysfunction may occur after successful unilateral cataract surgery, even in patients with relatively good acuity in the fellow eye. In a recent study, Cetinkaya et al evaluated using the Pulfrich phenomenon (PP) as a tool to test for binocular motion dysfunction.
The PP is an optical effect of an oscillating target traveling in 2 dimensions seen as traveling an elliptical path in 3 dimensions when 1 eye has a latency induced with a neutral density filter. The magnitude of the PP is determined by the speed of the target, distance from the observer, and illumination of the retina. A similar latency seen in unilateral optic neuritis may cause a more symptomatic PP then in unilateral cataract because the brain can adapt to the latency when linked to an ipsilateral decrease in retinal illumination, as is seen in unilateral cataract.
For this study, 61 patients were examined 6 weeks after uncomplicated cataract surgery to exclude other etiologies of the PP. All patients were on the waiting list for second-eye surgery. The postoperative eye had a logMAR score of 0 VA, and the fellow phakic eye had logMAR 0.2–0.7 VA. Fifteen phakic patients with logMAR 0 VA OU were used as controls.
Patients were interviewed by a masked examiner to determine if they had any new visual complaints postoperatively; if they said “yes,” they were asked if the complaint was represented on a defined list (passing through doors, placing objects on a surface, inserting keys in locks, pouring liquid into a cup, crossing roads, driving or car travel, walking past objects or people). Patients were then tested for the PP with a computerized program (Ophthimus version 3.0, High Tech Vision, Göteborg, Sweden) using a patterned background and constant stimulus to maximize the PP. The magnitude was serially graded with neutral density filters (NDF), and if absent, the PP was induced with those same filters and then retested.
The results showed that 36 (59%) of 61 patients and none (0%) of 15 control subjects were PP+ (P<0.001). The PP+ study patients had worse vision in the fellow eye then the PP– study patients (logMAR 0.44 0.13 vs 0.33 0.15, respectively; P=0.02), and a PP+ was correlated with worse levels of acuity (P=0.01). The magnitude of the PP by NDF was not significantly correlated to the VA, however. Sixteen of 61 study patients answered “yes” when asked about new binocular stereo dysfunction; all had PP+ with statistically greater magnitudes then those study patients without stereodysfunction who were PP+ (P<0.001). These 2 groups had similar VA (P=0.213). This study concludes that the PP may be used to test motion stereopsis in patients complaining of binocular visual dysfunction after unilateral cataract surgery.
REFERENCE
Cetinkaya A, Oto S, Akova YA. Decision-making in second-eye cataract surgery: can presence of Pulfrich phenomenon help? Eye. 2007;21:52–57.