Despite the known benefits of lighting, people with low vision may not fully appreciate the role of lighting and rate home lighting as adequate when it is suboptimal. Lighting preferences are highly individual, thus, assessment approaches should include objective and subjective evaluations of visual comfort to determine optimum lighting levels1. In low vision practice, practitioners often recommend lighting to their patients. Increases in lighting can be beneficial to reading function, especially for individuals with ring scotoma. Jasper Ridge (San Matteo, CA) has engineered the LuxIQ for adjusting lighting levels over reading material that could be useful for tailoring lighting prescriptions for low vision patients along the dimensions of color and brightness.
AIM 1 – Determine range and variability of preferred (subjective) lighting levels.
Are patient-preferred (subjective) light settings distributed and is this distribution captured by the range of the LuxIQ?
While bright light is important for functional vision, it is challenging to measure and prescribe. To determine if each individual has an optimum light setting and whether settings are distributed, study participants will subjectively set their preferred light level using the LuxIQ Diagnostic Tool (Figure 1) for reading.
To assess optimum near task lighting needs and make lighting recommendations the LuxIQ LightChooser Software will be utilized. Near vision performance will be quantified over a broad range of light levels, color temperatures and colors, based on measurements of study participants optimum light intensity and color.
AIM 2 – Quantify the impact of lighting on reading performance.
Determine whether lighting impacts critical print size or maximum reading rates or both.
To evaluate subjects near acuity as well as reading speed the MN Read test (Minnesota Low vision Reading Test, Optelec, Vista, CA), will be used to determine the critical print size – the minimum size of print that still allows the maximum reading speed. Once near acuity is measured reading speed will be timed using a stop watch and the preferred print size. MN Read cards contain print that is measured on the log scale and are available from -0.5 to 1.3 log when tested at 40 cm. Each card contains 10 words all of the same print size with a total of 60 characters.
Functional reading ability will be measured during the entire reading curve for 4 light settings: ambient, preferred setting (Aim 1), and two set points below and above the preferred setting, to determine whether the patient-preferred (subjective) setting is optimal for reading performance, or whether reading tests are required to find the optimal setting.