Eagan S M, Jacobs R J, Demers-Turco P L
Vision Rehabilitation Service, Massachusetts Eye and Ear Infirmary, Boston, USA.
Optom Vis Sci. 1999 Jan;76(1):50-8. doi: 10.1097/00006324-199901000-00028.
The visual acuity of visually impaired patients has been reported to improve after a refraction, despite pinhole test results that show a decline or no change in acuity. Our aim was to investigate whether the pinhole-induced reduction in retinal illuminance accounted for these unreliable predictions of best-corrected acuity.
Participants were 64 adult patients referred for low-vision rehabilitation. Neutral density filters reproduced the pinhole-induced luminance loss, allowing pinhole test and postrefraction acuities to be measured at essentially equivalent levels of retinal illuminance. The following data were collected in random order from each subject's better eye: (1) habitual visual acuity, (2) habitual visual acuity with filter, (3) habitual visual acuity with pinhole, (4) best-corrected/postrefraction visual acuity, (5) postrefraction visual acuity with filter.
On average, the pinhole test under-estimated postrefraction visual acuity by six letters (95% confidence limits = +/- 20). The pinhole test underestimated postrefraction visual acuity with the filter by two letters (95% confidence limits = +/- 16). Among subjects whose acuity improved with the pinhole test (N = 24), 83% experienced better postrefraction visual acuity. Among subjects whose acuity declined or remained unchanged with the pinhole test (N = 40), 50% achieved better postrefraction visual acuity.
The pinhole-induced luminance loss contributed to inadequate predictions of postrefraction visual acuity. Pinhole test results were enormously variable, underestimating and overestimating postrefraction visual acuity. The pinhole test was less reliable when improvements in postrefraction visual acuity were small. Visually impaired patients deserve periodic refractions, and the pinhole test result should not be used as a dichotomizer for clinical decisions regarding the need for a refraction.
据报道，视力受损患者在验光后视力有所提高，尽管针孔测试结果显示视力下降或无变化。我们的目的是研究针孔引起的视网膜照度降低是否导致了这些对最佳矫正视力的不可靠预测。
64名被转诊至低视力康复科的成年患者参与了研究。中性密度滤光片可再现针孔引起的亮度损失，从而能在基本相同的视网膜照度水平下测量针孔测试视力和验光后视力。从每个受试者的较好眼以随机顺序收集以下数据：(1) 习惯视力，(2) 戴滤光片时的习惯视力，(3) 用针孔时的习惯视力，(4) 最佳矫正/验光后视力，(5) 戴滤光片时的验光后视力。
平均而言，针孔测试低估了验光后视力6个字母（95%置信区间=±20）。针孔测试低估了戴滤光片时的验光后视力2个字母（95%置信区间=±16）。在针孔测试视力提高的受试者中（N = 24），83%的人验光后视力更好。在针孔测试视力下降或不变的受试者中（N = 40），50%的人验光后视力更好。
针孔引起的亮度损失导致了对验光后视力的预测不足。针孔测试结果差异极大，既低估也高估了验光后视力。当验光后视力改善较小时，针孔测试的可靠性较低。视力受损患者应定期验光，且针孔测试结果不应作为决定是否需要验光的二分法临床依据。
