@article {397781,
	title = {Margin Reflex Distance: Differences Based on Camera and Flash Positions.},
	journal = {Ophthal Plast Reconstr Surg},
	volume = {32},
	number = {3},
	year = {2016},
	month = {2016 May-Jun},
	pages = {199-203},
	abstract = {PURPOSE: To evaluate the effect of camera flash position on the measurement of photographic margin reflex distances (MRD). METHODS: Subjects without any ophthalmic disease were prospectively enrolled after institutional review board approval. Clinical measurements of MRD1 and interpalpebral fissure were obtained. Photographs were then taken with a digital single lens reflex with built-in pop-up flash (dSLR-pop), a dSLR with lens-mounted ring flash (dSLR-ring), a point-and-shoot camera, and a smartphone, each in 4 positions: with the camera upright, rotated 90{\textdegree}, 180{\textdegree}, and 270{\textdegree}. The images were analyzed using ImageJ software to measure MRD1, interpalpebral fissure, horizontal white-to-white, and distance from nasal limbus to the corneal light reflex. RESULTS: Thirty-two eyes of 16 subjects were included (ages 27-65). When using the dSLR-ring, point-and-shoot, and smartphone, the difference between clinical and photographic MRD1 did not reach statistical significance. There was, however, a statistically significant difference in the upright position with dSLR-pop (mean difference 0.703 mm, σ = 0.984 mm, p = 0.0008). For dSLR-pop, photographic MRD1 in upright versus inverted position differed significantly (mean difference -0.562 mm, σ =0.348 mm, p \&lt; 0.0001). Photographic MRD1 between dSLR-pop and dSLR-ring showed significant difference in upright position (mean difference -0.572 mm, σ = 0.701 mm, p = 0.0002). There were no statistically significant differences between clinical and photographic interpalpebral fissure, and among white-to-white and nasal limbus to light reflex measurements in any position in all 4 cameras. CONCLUSIONS: When using photographs for measurement of MRD1, cameras with a near-coaxial light source and aperture have values that are most similar to clinical measurements.},
	issn = {1537-2677},
	doi = {10.1097/IOP.0000000000000456},
	author = {Choi, Catherine J and Chou, Jonathan C and Lefebvre, Daniel R and Yoon, Michael K}
}
