CORRELATION BETWEEN VISUAL ACUITY AND INNER SEGMENTOUTER SEGMENT

CORRELATION BETWEEN VISUAL ACUITY AND INNER SEGMENT/OUTER SEGMENT JUNCTION AND CONE OUTER SEGMENT TIPS LINE INTEGRITY IN UVEITIC MACULAR EDEMA M. La Cava, P. Tortorella, E. D’Ambrosio, F. De Marco, E. Santoro, L. Iannetti “Sapienza” University of Rome Department of Ophthalmology Ocular Immunovirology Service

INTRODUCTION Optical Coherence Tomography (OCT) findings were used to describe three different morphologic patterns of macular edema (ME): - Diffuse macular edema (DME). - Cystoid macular edema (CME). - Serous retinal detachment (SRD). DME CME SRD Increased macular thickness, small low-reflective areas with spongy appearance of the retinal layers. Low-reflective intraretinal spaces, clearly defined and separated by thin, highreflective retinal tissue. Neuroretinal layer separation from the retinal pigment epithelium (RPE).

On spectral-domain Optical Coherence Tomography (SD-OCT), the outer retina has four distinct hyperreflective lines: 1. external limiting membrane (ELM). 2. inner segments and outer segments of the photoreceptors junction (IS/OS). 3. the cone outer segment tips (COST) or Intermediate Line or Verhoeff’s membrane. 4. RPE. 1. The innermost ELM is formed by the back reflection of the zonulae adherentes that join the inner segment to the Muller cells. 2. The IS/OS junction is thought to represent the boundary between the inner and outer segments of the photoreceptors and is localized between the ELM and the RPE histologically. 3. The COST line represents the outer tip of the cones. 4. The outermost RPE line separates the photoreceptors from the Bruch’s membrane and choriocapillaris. PURPOSE To investigate the correlation between best-corrected visual acuity (BCVA) and foveal IS/OS junction and the COST line integrity in eyes with uveitic ME.

METHODS • 52 eyes of 33 patients. • Retrospective, observational study. • All patients underwent SD-OCT examination with Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany). • The correlation between the BCVA and ME pattern, the integrity of the foveal IS/OS junction and COST line was evaluated with a multivariate correlation. • The correlation between the interruption of the foveal IS/OS junction and COST line was analyzed with a univariate logistic correlation. Demographic and clinical characteristics of the study population Median Age (Q 1 -Q 3) 32 (9 -77) Gender Male/Female 22/23 Median FU mos (Q 1 -Q 3) 25. 5 (1 - 260) Median duration (Q 1 -Q 3) 48 (2 - 204) Laterality Unilateral 38 (84. 4%) Bilateral 7 (15. 6%) Anatomic location of uveitis (eyes) Anterior 12 (23. 07%) Intermediate 20 (38. 46%) Posterior 7 (13. 46%) Panuveitis 13 (25%) Classification of uveitis (patients) Idiopathic 36 (80%) TBC 2 (4. 4%) Behçet 2 (4. 4%) VKH 2 (4. 4%) JIA 5 (11. 1%) Birdshot 1 (2. 2%) B 27+ AAU 2 (4. 4%)

RESULTS Number of patient, mean foveal thickness (CST) and median BCVA according to the different morphological features observed. N of eyes (% on 52 eyes) mean CST ± SD median BCVA (Q 1 -Q 3) DME 39 (75%) 354 ± 124 0. 7 (0. 03 – 1. 0) CME 13 (25%) 430 ± 222 0. 6 (0. 06 – 1. 0) SRD 11 (21. 2%) 432 ± 154 0. 4 (0. 03 – 1. 0) No SRD 41 (78. 8%) 406 ± 216 0. 7 (0. 06 – 1. 0) DME + SRD 3 (5. 8%) 372 ± 176 0. 7 (0. 1 – 1. 0) CME + SRD 8 (15. 4%) 467 ± 257 0. 6 (0. 1 – 1. 0) COST line disruption 13 (25%) 602 ± 303 0. 2 (0. 06 – 0. 8) COST line integrity 39 (75%) 348 ± 99 0. 8 (0. 03 – 1. 0) IS/OS junction disruption 26 (50%) 480 ± 253 0. 35 (0. 06 – 1. 0) IS/OS junction integrity 26 (50%) 342 ± 102 0. 9 (0. 03 – 1. 0) Negative correlation between BCVA and central retinal thickness (p<0. 001), cystoid pattern of edema (p<0. 05) and COST line interruption (p<0. 01). a. Disruption of COST line. b. Disruption of the photoreceptor IS/OS junction. c. Disruption of COST line and IS/OS junction together. Strong correlation between IS/OS segment and COST line integrity (p<0. 05).

CONCLUSIONS • IS/OS segment defect and COST line interruption and central retinal thickness are correlated with poor vision. • BCVA is strongly affected by the cystoid pattern. • The COST line integrity appears to be the most important factor in the visual prognosis of uveitic ME. FINANCIAL DISCLOSURE: This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.