title: Comparison of recognition and grating acuities in very-low-birth-weight children with and without retinal residua of retinopathy of prematurity. Cryotherapy for Retinopathy of Prematurity Cooperative Group.
abstract: OBJECTIVE
  To compare recognition (letter) and resolution (grating) acuity in eyes with and without retinopathy of prematurity (ROP) residua.
  
  
  METHODS
  Letter acuity measured with the crowded HOTV chart or pocket cards (Good-Lite), and grating acuity measured with the Teller Acuity Card (TAC) procedure, were compared at the 3 1/2- and 4 1/2-year follow-up exams in the CRYO-ROP study. Testers were unaware of the retinal status of individual eyes.
  
  
  RESULTS
  Measurable scores for both letter and grating acuity were obtained from 1694 eyes at 3 1/2 years and 2101 eyes at 4 1/2 years. Correlation analysis showed that the relation between crowded HOTV and grating acuity scores was best described by a quadratic function, with r2 values of 0.57 at 3 1/2 years and 0.68 at 4 1/2 years. Difference scores were calculated for each eye by subtracting the log of the HOTV score (converted to cyc/deg based on the convention that 20/20 = 30 cyc/deg) from the log TAC score. Normal eyes showed HOTV acuity that was higher than TAC acuity by an average of 0.37 octave (SD = 0.46, n = 1150) at 3 1/2 years and 0.27 octave (SD = 0.43, n = 1337) at 4 1/2 years. HOTV and grating acuity scores were similar to each other in eyes with retinal residua of ROP. Overall, eyes with acuity better than 20/150 to 20/300 tended to show better HOTV than grating acuity, whereas those with acuity below 20/150 to 20/300 generally showed better grating than HOTV acuity.
  
  
  CONCLUSIONS
  There is a significant correlation between crowded HOTV letter acuity and TAC grating acuity in young children for normal eyes and eyes with ROP residua. In both groups of eyes, eyes with lower acuity show better grating than letter acuity, whereas eyes with better acuity show slightly higher letter than grating acuity.
authors.affiliation: Department of Ophthalmology, University of Arizona, Tucson.
authors.forename: V
authors.initials: V
authors.lastname: Dobson
authors.forename: G E
authors.initials: GE
authors.lastname: Quinn
authors.forename: B
authors.initials: B
authors.lastname: Tung
authors.forename: E A
authors.initials: EA
authors.lastname: Palmer
authors.forename: J D
authors.initials: JD
authors.lastname: Reynolds
mesh_terms: D002675:Child, Preschool; D003452:Cryosurgery; D005500:Follow-Up Studies; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D012178:Retinopathy of Prematurity / Q000503:physiopathology* / Q000601:surgery; D014787:Vision Tests / Q000379:methods; D014785:Vision, Ocular / Q000502:physiology*; D014792:Visual Acuity / Q000502:physiology*