Abstract
Purpose: :
To investigate and measure the origins and natural history of the commonly experienced effect of hypersensitivity to glare characterized as "Peripheral-Field Functional Photophobia (PFP)" or "binocular facilitation of aversion to glare" because closing one eye substantially relieves the discomfort even to high luminance values. Also, to measure the time course of changes in measures of binocular fusion and heterophoria as the condition worsens from Stage PFP-1 (discomfort only occasionally to very bright sunlit white walls as on the mornings after long hours of "eye strain" studying for an exam) compared to Stage PFP-4 (chronic discomfort as even to gaining a reputation for keeping home lighting dimmed). Also to compare our findings with the Skeffington et al "Accommodative-Fatigue Deteriorative Syndrome."
Methods: :
All new patients (several hundred) were scored as to stage of functional photophobia when without sunglasses as PFP-0 = no glare hypersensitivity; PFP-1 = infrequent, to highest brightness; PFP-2 = usual on bright sunny days; PFP-3 = chronic to indoors brightness as in supermarkets; PFP-4 = chronic as to home brightness. One hundred consecutive patient records were drawn until each of the five stages was represented by 20 patients. Stages PFP-0 through PFP-4 mean age increased stage-by-stage from 20.2 to 35.5 years. We recorded the "dissociated crossed-cylinder" and the associated heterophoria for each patient as well as the "Positive Relative Accommodation" [PRA] and the "Negative Relative Accommodation" [NRA] at 40 cm and the convergence nearpoint break and recovery among other skills.
Results: :
Significant differences are found between complaint-free PFP-0 and increasing photophobia-complaint stages such that more severe photophobia is associated with increased a) with-the-rule astigmia, b) emmetropization relative to habitual distance Rx, c) exophoria at distance with full correction, d) inversion of the ratio of the {dissociated crossed-cylinder in relation to the expected}/{associated nearpoint phoria}, e) convergence nearpoint break and recovery distances, and decreasing PRA.
Conclusions: :
We find the association of changes in optometric measurements with increasing PFP closely matches the "Skeffington Accommodative-Fatigue Deteriorative Syndrome" described some five decades ago. Subjects with appropriate Habitual Relative Adds--optics otherwise best suited for closework demands--appear less vulnerable to PFP. We were able to time-index a complaint function severity to decrease in vision skills and duration in years of the complaint index.
Keywords: binocular vision/stereopsis • clinical (human) or epidemiologic studies: natural history • refraction