title: Effect of cataract and its removal on signal strength and peripapillary retinal nerve fiber layer optical coherence tomography measurements.
abstract: OBJECTIVE
  To assess the effect of cataract on optical coherence tomography (OCT), signal strength (SS), and peripapillary retinal nerve fiber layer (RNFL) thickness measurements.
  
  
  METHODS
  Peripapillary RNFL thickness measurements were obtained by Stratus OCT scans using the Fast RNFL thickness (3.4) acquisition protocol before and after cataract extraction in 45 patients with cataract, including 23 glaucoma patients. Cataracts were graded according to the Lens Opacities Classification System III.
  
  
  RESULTS
  The postoperative RNFL thickness and SS were 9.3% (P=0.001) and 24.1% (P<0.001) higher than before surgery, respectively. There was greater postoperative change in RNFL thickness measurements in patients with lower preoperative RNFL measurements (r=-0.63, P<0.001) and SS (r=-0.59, P<0.001). Eyes with preoperative SS more than 6 had no significant difference between precataract and postcataract surgery RNFL thickness (P=0.14). There was no significant difference in RNFL thickness change between eyes with cataract only (10.9±20.8 μm) and those with cataract and glaucoma (7.0±14.7 μm; P=0.81).
  
  
  CONCLUSIONS
  Cataracts may decrease peripapillary RNFL thickness measurements and the SS on OCT scans. Thinning of the peripapillary RNFL suggestive of glaucomatous progression may be the result of artifact from advancing cataract rather than actual structural changes in the peripapillary RNFL. Peripapillary RNFL thickness measurements should be interpreted with caution in glaucomatous eyes with significant cataract, particularly if the SS is attenuated.
authors.affiliation: Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: Jean C
authors.initials: JC
authors.lastname: Mwanza
authors.forename: Anjali M
authors.initials: AM
authors.lastname: Bhorade
authors.forename: Navneet
authors.initials: N
authors.lastname: Sekhon
authors.forename: John J
authors.initials: JJ
authors.lastname: McSoley
authors.forename: Sonia H
authors.initials: SH
authors.lastname: Yoo
authors.forename: William J
authors.initials: WJ
authors.lastname: Feuer
authors.forename: Donald L
authors.initials: DL
authors.lastname: Budenz
mesh_terms: D000368:Aged; D002386:Cataract / Q000145:classification / Q000150:complications / Q000503:physiopathology*; D002387:Cataract Extraction; D005260:Female; D005901:Glaucoma / Q000150:complications / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure; D019654:Lens Implantation, Intraocular; D008297:Male; D009412:Nerve Fibers / Q000473:pathology*; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000150:complications / Q000503:physiopathology*; D011184:Postoperative Period; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence; D014065:Tonometry, Ocular