title: Asymmetry in hemifield macular thickness as an early indicator of glaucomatous change.
abstract: OBJECTIVE
  To investigate whether asymmetry in hemifield macular thickness can serve as an early indicator of glaucomatous structural damage using spectral domain optical coherence tomography.
  
  
  METHODS
  Five zones in the macular thickness map were defined. Each zone included reciprocal areas in the superior and inferior hemifield. Differences in average retinal thickness (DRT) between corresponding regional pairs were measured in each of the five zones in 50 healthy eyes. An abnormality was defined as the DRT value lying outside the 95% confidence intervals. An eye was considered to yield an "abnormal macular hemifield test" (MHT) if abnormality was evident in any zone. The sensitivity and specificity for glaucoma detection of MHT and average circumpapillary retinal nerve fiber layer (cRNFL) classification were determined.
  
  
  RESULTS
  A total of 114 healthy, 103 glaucoma-suspect, and 74 glaucomatous eyes were included. Overall, 5.8%, 36.9%, 88.4%, and 77.4% of the eyes of the healthy, glaucoma-suspect (GS), early glaucoma (EG), and advanced glaucoma (AG) groups yielded abnormal MHT results, respectively. In EG eyes, the sensitivity of an abnormal MHT result was significantly greater than that of abnormal average cRNFL classification (P=0.008). In the GS and AG groups, the sensitivity did not significantly differ between an abnormal MHT result and an average cRNFL classification (P=0.880, 0.180). Compared with sectoral cRNFL thickness measurements, MHT showed a similar level of diagnostic performance. Specificity was not different between an abnormal MHT result and an average cRNFL classification (P=0.687).
  
  
  CONCLUSIONS
  Evaluation of asymmetry in hemifield macular thickness may serve as an assessment tool in the early diagnosis of glaucoma.
authors.affiliation: Department of Ophthalmology, University of Ulsan, College of Medicine, Asan Medical Center, Seoul, Republic of Korea.
authors.forename: Tae Woong
authors.initials: TW
authors.lastname: Um
authors.forename: Kyung Rim
authors.initials: KR
authors.lastname: Sung
authors.forename: Gadi
authors.initials: G
authors.lastname: Wollstein
authors.forename: Sung-Cheol
authors.initials: SC
authors.lastname: Yun
authors.forename: Jung Hwa
authors.initials: JH
authors.lastname: Na
authors.forename: Joel S
authors.initials: JS
authors.lastname: Schuman
mesh_terms: D018450:Disease Progression; D042241:Early Diagnosis; D005260:Female; D005500:Follow-Up Studies; D005901:Glaucoma / Q000473:pathology*; D006801:Humans; D008266:Macula Lutea / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013997:Time Factors; D041623:Tomography, Optical Coherence