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Dr. Mukesh Patil, P18952, Dr. Shorya Vardhan Azad, Dr. Rohit Saxena

Mukesh Patil, Rohit Saxena , Shorya Vardhan Azad

Title:

 Evaluation of peripapillary choroidal vascular changes in non-arteritic anterior ischemic optic neuropathy using swept source optical coherence tomography

Abstract:

Aim:

To evaluate differences in peripapillary choroidal thickness in eyes with non arteritic anterior ischemic optic neuropathy (NAION), unaffected fellow eyes, and normal age matched controls.

Design:

Cross-sectional observational study

Methods:

Thirty six eyes of 36 patients with unilateral NAION were compared with 36 unaffected fellow eyes and 40 age matched healthy controls. Peripapillary choroidal thickness (PCT) was measured using 12 line radial scanning protocol centered on optic nerve head giving 24 PCT values per eye on either side of the optic disc.

Results:

Mean PCT was 182.18 ± 90.82, 228.22 ± 78.56 (p=0.02) and 200.07 ± 12.85 (p=0.13) in affected, unaffected fellow and control eyes respectively. Difference in mean PCT between upper and lower half of optic nerve head was found to be significant between affected and control eyes (p=0.007). No significant difference (p>0.05) was present when mean PCT between affected and control groups were compared in ST, IT, SN and IN quadrants.

Conclusions:

Our study shows that preexisting difference in choroidal thickness may exist in eyes having NAION and may predispose them to altitudinal defects as seen in such cases. PCT measured with high resolution SS-OCT may help to identify discs at risk, so that aggressive management of risk factors may prevent an ischemic insult.

Keywords: NAION, peripapillary choroidal thickness, SS-OCT

Key Message: PCT measured on  SS-OCT in NAION might help in prophylactic management of disease. 

Introduction :

Nonarteritic anterior ischemic optic neuropathy (NAION) is characterized by the sudden painless loss of vision associated with optic disc edema and peripapillary hemorrhages. NAION is the most common clinical presentation of acute ischemic damage to the optic nerve.

Branches of the short posterior ciliary arteries provide most of the blood supply to the optic nerve head and NAION is associated with occlusion of these arteries. Medial and lateral paraoptic short posterior ciliary arteries form the circle of Zinn-Haller and its anatomical variations possibly make this part of the optic nerve head circulation particularly vulnerable to ischemic attacks. Paraoptic short posterior ciliary arteries also supply the peripapillary choroid as well as peripapillary choroid contributes to the blood supply of the optic nerve head.2 Therefore, choroidal abnormalities might also happen in NAION and measurement of the peripapillary choroidal thickness (PCT) may be highly relevant to this disease.3

Spectral-domain optical coherence tomography (SD-OCT) can quantify the peripapillary choroidal thickness (PCT) using the enhanced depth imaging OCT (EDI-OCT) technique.4

The aim of the current study was to evaluate differences in peripapillary choroidal thickness in eyes with non arteritic anterior ischemic optic neuropathy (NAION), unaffected fellow eyes, and normal age matched controls.

Materials and methods:

Study design:

This was a cross-sectional observational study which was done in the Department of Ophthalmology, Dr. Rajendra Prasad Center for Ophthalmic Sciences, AIIMS, New Delhi, in accordance with the tenets of Declaration of Helsinki and ethical clearance from Institutional Ethics Committee, AIIMS was obtained.

Data collection:

The patients were classified into three groups. First group included the thirty six eyes of 36 patients with unilateral NAION which was compared with second group comprising of 36 unaffected fellow eyes and the third group comprising of 40 eyes of age matched healthy controls.

Peripapillary choroidal thickenss (PCT) was measured using 12 line radial scanning protocol centered on optic nerve head giving 24 PCT values per eye on either side of the optic disc. Primary outcome measure was the mean PCT difference between upper and lower halves of the optic disc compared in all eyes. Secondary outcome measures were comparison of mean PCT changes in superotemporal (ST), inferotemporal (IT), superonasal (SN), inferonasal (IN) quadrants in all eyes.

Statistical analysis:

The data was  analyzed using SPSS version 17 (Statistical Package for Social Sciences)with paired t-test for intragroup comparison and Mann Whitney U value test for intergroup comparisons.A p value less than 0.05 was considered significant.

Results:

Mean PCT was 182.18 ± 90.82, 228.22 ± 78.56 (p=0.02) and 200.07 ± 12.85 (p=0.13) in affected, unaffected fellow and control eyes respectively. Difference in mean PCT between upper and lower half of optic nerve head was found to be significant between affected and control eyes (p=0.007). No significant difference (p>0.05) was present when mean PCT between affected and control groups were compared in ST, IT, SN and IN quadrants.

Discussion:

Our study shows that preexisting difference in choroidal thickness may exist in eyes having NAION and may predispose them to altitudinal defects as seen in such cases. PCT measured with high resolution SS-OCT may help to identify discs at risk, so that aggressive management of risk factors may prevent an ischemic insult.

References:

  1. García-Basterra I, Lahrach I, Morillo Sánchez MJ, et alAnalysis of peripapillary choroidal thickness in non-arteritic anterior ischaemic optic neuropathy British Journal of Ophthalmology 2016;100:891-896.
  2. Jiang L, Chen L, Qiu X, et al. Choroidal thickness in Chinese patients with non-arteritic anterior ischemic optic neuropathy. BMC Ophthalmology. 2016;16(1):153. doi:10.1186/s12886-016-0313-2.
  3. Miller NR, Arnold AC. Current concepts in the diagnosis, pathogenesis and management of nonarteritic anterior ischaemic optic neuropathy. Eye. 2015;29(1):65-79. doi:10.1038/eye.2014.144.
  4. Nagia L, Huisingh C, Johnstone J, Kline LB, Clark M, Girard MJ, Mari JM, Girkin CA. Peripapillary Pachychoroid in Nonarteritic Anterior Ischemic Optic Neuropathy. Invest Ophthalmol Vis Sci. 2016 Sep 1;57(11):4679-85.

Acknowledgement: None

 

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