title: A Novel Method of Quantitative Anterior Chamber Depth Estimation Using Temporal Perpendicular Digital Photography.
abstract: OBJECTIVE
  We hypothesize that: (1) Anterior chamber depth (ACD) is correlated with the relative anteroposterior position of the pupillary image, as viewed from the temporal side. (2) Such a correlation may be used as a simple quantitative tool for estimation of ACD.
  
  
  METHODS
  Two hundred sixty-six phakic eyes had lateral digital photographs taken from the temporal side, perpendicular to the visual axis, and underwent optical biometry (Nidek AL scanner). The relative anteroposterior position of the pupillary image was expressed using the ratio between: (1) lateral photographic temporal limbus to pupil distance ("E") and (2) lateral photographic temporal limbus to cornea distance ("Z"). In the first chronological half of patients (Correlation Series), E:Z ratio (EZR) was correlated with optical biometric ACD. The correlation equation was then used to predict ACD in the second half of patients (Prediction Series) and compared to their biometric ACD for agreement analysis.
  
  
  RESULTS
  A strong linear correlation was found between EZR and ACD,R= -0.91,R2= 0.81. Bland-Altman analysis showed good agreement between predicted ACD using this method and the optical biometric ACD. The mean error was -0.013 mm (range -0.377 to 0.336 mm), standard deviation 0.166 mm. The 95% limits of agreement were ±0.33 mm.
  
  
  CONCLUSIONS
  Lateral digital photography and EZR calculation is a novel method to quantitatively estimate ACD, requiring minimal equipment and training.
  
  
  CONCLUSIONS
  EZ ratio may be employed in screening for angle closure glaucoma. It may also be helpful in outpatient medical clinic settings, where doctors need to judge the safety of topical or systemic pupil-dilating medications versus their risk of triggering acute angle closure glaucoma. Similarly, non ophthalmologists may use it to estimate the likelihood of acute angle closure glaucoma in emergency presentations.
authors.affiliation: Centre for Eye Research, Victoria, Australia ; The Royal Victorian Eye and Ear Hospital, Victoria, Australia ; Melbourne Eye Specialists, Victoria, Australia.
authors.forename: Ehud
authors.initials: E
authors.lastname: Zamir
authors.affiliation: Centre for Eye Research, Victoria, Australia ; The Royal Victorian Eye and Ear Hospital, Victoria, Australia.
authors.forename: George Y X
authors.initials: GY
authors.lastname: Kong
authors.affiliation: Centre for Eye Research, Victoria, Australia.
authors.forename: Tanya
authors.initials: T
authors.lastname: Kowalski
authors.affiliation: Centre for Eye Research, Victoria, Australia ; The Royal Victorian Eye and Ear Hospital, Victoria, Australia ; Melbourne Eye Specialists, Victoria, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Coote
authors.affiliation: Centre for Eye Research, Victoria, Australia ; The Royal Victorian Eye and Ear Hospital, Victoria, Australia ; Melbourne Eye Specialists, Victoria, Australia.
authors.forename: Ghee Soon
authors.initials: GS
authors.lastname: Ang
keywords: angle closure glaucoma; anterior chamber depth; digital photography; photogrammetry