June 2013
Volume 54, Issue 15
Free
ARVO Annual Meeting Abstract  |   June 2013
Changes to the Transition Zone with Progression of X-Linked Retinitis Pigmentosa
Author Affiliations & Notes
  • Rebecca Bausell
    College of Physicians & Surgeons, Columbia University, New York, NY
  • Rithambara Ramachandran
    Department of Psychology & Ophthalmology, Columbia University, New York, NY
  • Cindy Cai
    College of Physicians & Surgeons, Columbia University, New York, NY
  • Kirsten Locke
    Rose-Silverthorne Retinal Degenerations Laboratory, Retina Foundation of the Southwest, Dallas, TX
  • David Birch
    Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX
    Rose-Silverthorne Retinal Degenerations Laboratory, Retina Foundation of the Southwest, Dallas, TX
  • Donald Hood
    Department of Psychology & Ophthalmology, Columbia University, New York, NY
  • Footnotes
    Commercial Relationships Rebecca Bausell, None; Rithambara Ramachandran, None; Cindy Cai, None; Kirsten Locke, None; David Birch, Acucela (C), QLT (C), Neurotech, USA (C); Donald Hood, Topcon, In (F)
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 665. doi:https://doi.org/
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      Rebecca Bausell, Rithambara Ramachandran, Cindy Cai, Kirsten Locke, David Birch, Donald Hood; Changes to the Transition Zone with Progression of X-Linked Retinitis Pigmentosa. Invest. Ophthalmol. Vis. Sci. 2013;54(15):665. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

A cross-sectional analysis of the transition zone (TZ), the region between healthy and severely affected retina, is thought to be a model of disease progression in patients with retinitis pigmentosa (RP).[1-4] Here we analyze TZ changes in a group of x-linked (xl)RP patients over time.

 
Methods
 

Two 9mm horizontal line scans, taken with optical coherence tomography, were obtained for one eye of 28 xlRP patients (15.2 ±6.1 yrs) at least 2 years apart (mean 2.4 yrs). Using a computer-aided manual procedure, outer segment (OS) and outer nuclear layer (ONL) thicknesses were measured.[3] As previously described,[3] to quantify changes across the fovea, the TZ was divided into regions A-E based upon the thicknesses of the OS and ONL relative to healthy controls. Region A: OS and ONL normal; B: OS reduced, ONL normal; C: OS and ONL reduced; D: ONL reduced, OS gone; E: ONL reduced to asymptotic thickness. We compared changes in the TZ regions between the first and last visit based upon: 1) location (distance from fovea) and 2) width. Region A was not analyzed as it was absent in 84% of patients. To determine changes in the TZ with eccentricity, patients were also placed in two groups based upon distance of the border between C and D (the point that OS disappears) from the fovea. Nasal and temporal measurements were averaged and paired t-tests were performed.

 
Results
 

As expected, given the central progression of xlRP, the location of regions C (p=.054), D (p<.001) and E (p=.004) shifted towards the fovea (diagonal lines in Fig. 1). Concurrently, the widths of B and C decreased, while D and E expanded (Fig.1). At the final visit, the widths of B and C were narrower, while D and E were wider, in those with C/D borders closer, as compared to farther, from fixation (Fig. 2).

 
Conclusions
 

The TZ exhibits consistent changes with time. All borders move closer to the fovea, and the widths of regions (B & C) with the OS layer present decrease, while regions (D & E) without a detectable OS layer expand. Further, changes in the relative size of these regions with eccentricity are consistent with changes over time and support the TZ as a model of disease progression. 1. Jacobson et al. IOVS, 2009, 2. Jacobson et al. IOVS, 2010, 3. Hood et al. IOVS, 2011, 4. Lazow et al. IOVS, 2011.

 
 
Average change in widths over time
 
Average change in widths over time
 
 
Average change in widths with eccentricity
 
Average change in widths with eccentricity
 
Keywords: 688 retina • 696 retinal degenerations: hereditary • 550 imaging/image analysis: clinical  
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