1. Introuduction

Brain Stroke is a catastrophic event that can damage various organs of the body, including the visual system. Electrophysiology of vision is a diagnostic technique used to assess different pathological conditions of the visual system, primarily the visual pathway and retina. Electroretinography (ERG), Electrooculography (EOG), and visual evoked potential (VEP) are commonly employed electrophysiological techniques in this field. Abdolalizadeh et al. (2022) conducted a study to investigate the potential effects of antiseizure medication on patients using ERG. The study included twenty participants, consisting of ten males and ten females, ranging in age from 15 to 30 years. The findings revealed retinal changes in these patients, which were diagnosed by measuring the amplitude of ERG, specifically b-wave peak [1]. The same research group also examined the retinal pigment epithelium (RPE) of patients undergoing treatment with anti-epileptic medication using EOG. They utilized the same group of patients and observed pathological changes in the RPE, which were identified by assessing the Arden index (AI) of EOG test [2]. Shushtarian et al. (2017) designed a study to investigate the potential effects of vibration on the visual pathway using VEP. They selected 50 workers from a textile factory segment where machinery creating high levels of vibration. The study concluded that occupational vibration had adverse effects on the visual pathway, leading to increased latency of VEP, specifically the P100 peak [3]. Numerous references have been published on this topic [4-37]. In the present work, we utilized flash type VEP to screen the visual pathway of patients who had suffered a brain stroke. Flash type stimulation was chosen due to the reduced visual acuity in most patient, making it difficult for them to discern the fixation point required for recording pattern-type stimulation. Although VEP is a suitable technique for screening the visual pathway in stroke patients [38-40], there exist conflicting findings that will be discussed in the later sections of this manuscript.

2. Patients and Methods:

In this case control study, thirteen patients with brain attack (6 male and 7 female), regardless of the type of stroke, were referred to Basir Eye Clinic for VEP examination to assess possible visual dysfunction. The age range of the patients was 55 to 70 years. Visual acuity was tested and ranged from 1/10  to 4/10 (BCVA). Visual evoked potential (VEP) with flash stimulation method was performed to evaluate the visual pathway of the patients. The latency (msec) and amplitude (µv) of of the P100 peak in VEP were measured for all patients using the Mangoni machine. To connect the machine to the patients three electrodes were used: one attached to the occipital region as the active electrode, one to the vertex as the reference electrode, and one to the forehead as the ground electrode.The same procedure was repeated for 13 healthy individual, matched in terms of age and sex, serving as the control group for comparison with the patient group. These individuals were selected based on their intact visual system, particularly the visual pathway.The obtained results from the two groups were compared to identify any differences between them.

3. Results:

Table1: demographical findings in case and control groups.

Table 2: Measurement of the mean latency and amplitude of the P100 peak in visual evoked potentials (VEP) was conducted in both case and control groups.

There was no statistically significant between the two groups regarding age (P value = 0.88*) and sex (0*), whereas a significant difference was observed in BCVA (P < 0.001).

Table 2 presents the measurement for latency and amplitude of VEP P100 peaks in the control and case groups. There was statistically significant difference in the latency and amplitude of VEP P100 peaks between the healthy and patient groups (P100 < 0.0.1 for both groups).

4. Discussion

Stroke is a heterogenous syndrome and a leading cause of death and disability worldwide.

The visual system, particularly the visual pathway, may be affected during a stroke episode. VEP is a technique used to assess visual pathway disturbances, and it was employed in this study to investigate potential changes in the visual pathway.The findings demonstrated prolonged latency and reduced amplitude of the VEP P100 peak, providing evidence of visual pathway disturbances in these patients. The following references may supports the findings of the present study: Pojda- Wilczek D et al. (2015) conducted a relevant study where they evaluated VEP using flash-type stimulation in various patient with brain circulatory problems, including those with hemianpsia, quadratanpsia and hemiparesis after a stroke. Their result indicated an increase in latency and a decrease in amplitude of the VEP P100 peak in the patients [41]. Gaffat Al-Nasriwy SZ (2018) investigated the utility of VEP in stroke patients with a focus on sensitivity and specificity. The results demonstrated a sensitivity of 25.9% and a specificity of 100% (P value < 0.01, highly significant). Among all patients, 26% exhibited abnormal VEP P100 peak being the most common abnormality [42]. In addition to the above two references, there is a study suggesting that stroke does not produces changes in VEP test [41]. It is worth noting that the authors of that study employed pattern stimulation, whereas the present study used flash-type stimulation.

5. Conclusion

Stroke can affect the visual pathway of patients, as evidenced by alterations in the latency and amplitude of the VEP P100 peak during flash VEP testing.

References

1. Abdolalizadeh S, Ghasemi  M, Mohammadzadeh P, et al. Retinal Screening of Patients Treated with Antiseizure Medications Using Electroretinography. Journal of Ophthalmology and Research 5 (2022): 165-167.
2. Abdolalizadeh S, Karami S, Saleh NT,  et al. Retinal Pigment Epithelium Screening of Patients Treated with Anti-Epileptic Medications using Electrooculography. Journal of Ophthalmology and Research 6 (2023): 08-11.
3. Shushtarian SM, Kalantari A S, Tajik F, et al. Effect of occupational vibration on visual pathway measured by visual evoked potentials. Journal of Ophthalmic and Optometric Sciences 1 (2017): 7-11.
4. Keramti S,  Ojani F, Shushtarian SMM,  et al. Early Diagnosis of Pathological Changes in Visual System of Prolactinoma Patients Using Visual Evoked Potential. Journal of Ophthalmology and Research 4 (2021): 289-93.
5. Ojani F, Shushtarian SMM, Shojaei A, et al. Visual Evoked Potential Findings of Bardet-Biedl Syndrome. Journal of Ophthalmology and Research 4(2021): 254-257.
6. Sarzaeim F, Hashemzehi M,  Shushtarian SM M, et al. Flash Visual Evoked Potential as a Suitable Technique to Evaluate the Extent of Injury to Visual Pathway Following Head Trauma. Journal of Ophthalmology and Research 5 (2022): 20-3.
7. Allahdady F, Aghazadeh Amiri M, Shushtarian  M, et al. Comparison of visual evoked potential and electro-oculogram tests in early detection of hydroxychloroquine retinal toxicity. Journal of Ophthalmic and Optometric Sciences 1 (2016).
8. Shushtarian SM, Mirdehghan MS, & Valiollahi P. Retinal damages in turner workers of a factory exposed to intraocular foreign bodies. Indian Journal of Occupational and Environmental Medicine 12 (2008): 136.
9. Shushtarian S MM, Mohammad-Rabei H, & Raki S T B. Effect of Occupational Vibration on Human Retina Measured by Electroretinography. Journal of Ophthalmic and Optometric Sciences 2 (2018): 14-7.
10. Naser M, Shushtarian S MM, Shojaei A, et al. Visual Disturbance in a Patient with Amiodarone Treatment Following Refractive Surgery. Journal of Ophthalmic and Optometric Sciences 1 (2017).
11. Shushtarian SM, Adhami-Moghadam F, Naser M, et al. Electroretinographic Changes in Multiple Sclerosis Patients with Abnormal Visual Evoked Potentials. Journal of Ophthalmic and Optometric Sciences 1 (2017).
12. Shushtarian SMM, Adhami-Moghadam F, Naser M, et al. Severe Headache Initiated by Flash Stimulation during Visual Evoked Potential Recording in a Patient with Monocular Optic Neuritis and History of Migraine Headache. Journal of Ophthalmic and Optometric Sciences 1 (2017).
13. Keramti S, Javanshir S, Tajik F, et al. Retinal Screening of Prolactinoma Patients using Flash Electroretinography. Journal of Ophthalmology and Research 4 (2021): 321-326.
14. Hajibeygi R, Shushtarian SMM, & Abolghasemi S. Visual Evoked Potential Findings of Sjogren's Syndrome. Journal of Ophthalmic and Optometric Sciences 4 (2021): 13-17.
15. Shushtarian SMM, Adhami-Moghadam F, Adhami-Moghadam P, et al. Electrophysiological Eye Examination Changes in a Patient with Sjogren's Syndrome. Journal of Ophthalmic and Optometric Sciences 2 (2018): 40-43.
16. Shushtarian S MM, Tajik F, & Abdolhoseinpour H. Measurement of Visual Evoked Potentials in Patients with Spastic Cerebral Palsy. J. Ophthalmic Optom. Sci 2 (2018): 10-13.
17. Tajik F, & Shushtarian SMM. Electrooculographic and Electroretinographic Changes among Patients Undergoing Treatment with Amiodarone. Journal of Ophthalmic and Optometric Sciences 2 (2018): 7-11.
18. Naser M, & Shushtarian SM. Study the effect of depakine on retina of epileptic patients using electroretinogram. International journal of scientific research 3 (2014): 392-393.
19. Sarzaeim F, Ojani F, Hojati TS, et al. Effect of Hand-Arm Vibration on Retina of Road Drilling Machine Laborers Measured by Electroretinography. Journal of Ophthalmology and Research 5(2022): 81-85.
20. Shushtarian SMM, Naghib SJ, Adhami-Moghadam F, et al. (Diplopia and Blurry Vision Following Refractive Eye Surgery: a Comorbidity Case Report. Journal of Ophthalmic and Optometric Sciences 4 (2020): 40-42
21. Shushtarian SMM. Suitable Stimulation Technique to Record Visual Evoked Potential in Migraine Patients. Journal of Ophthalmic and Optometric Sciences 4 (2022): 41-45.
22. Shushtarian SMM, Mazar R P, & Fadaeifard S. (Visual Evoked Potential Recording in a Fatigued and Drowsy Patient under Anti-Seizure Medicine Treatment. Journal of Ophthalmic and Optometric Sciences 5 (2021).
23. Shushtarian SMM, & Dastjerdi MV. Total Blindness Following Anaphylactic Shock due to Co-Amoxiclav Treatment. Journal of Ophthalmic and Optometric Sciences 4 (2020).
24. Shushtarian SMM, Naghitehrani KH, & Aflaki F. Diplopia and Flashes of Light Sensation in a Patient with Fragrance Allergy. Journal of Ophthalmic and Optometric Sciences 4 (2020): 47-49.
25. Naser M, & Shushtarian SMM. Need for Visual Pathway Examination of the Patient Prior to Bone Marrow Transplantation. Journal of Ophthalmology and Research 3(2020): 75-78.
26. Sanaie S, Nematian J, & Shoushtarian SMM. Study of electrooculogram (EOG) abnormalities in patient with ocular toxoplasmosis. Medical Science Journal of Islamic Azad Univesity-Tehran Medical Branch 24 (2014): 33-36.
27. Adhami-Moghadam F, Talebi-Bidhendi S, & Shushtarian SMM. Retinal Screening of Workers Exposed to Mercury Vapor Using Electroretinography. Journal of Ophthalmic and Optometric Sciences 4 (2020): 34-38.
28. Shushtarian S MM. Flash and Pattern Reversal Checkerboard Visual Evoked Potential Recording in Albinism Patients. Journal of Ophthalmic and Optometric Sciences 4 (2020): 42-46
29. Fatemian N, Adhami-Moghadam F, & Shushtarian SMM. Study of Visual Evoked Potentials in Patients Suffering from Exotropia. Journal of Ophthalmic and Optometric Sciences 5 (2021).
30. Shushtarian S MM, & Mazar RP. Far Distance Blurry Vision Following Rhinoplasty. Journal of Ophthalmic and Optometric Sciences 5 (2021): 71-74.
31. Shushtarian SMM, Shojaei A, & Tajik F. Visual Pathway Disturbances in Rosai-Dorfman Diusese: a Case Report. Journal of Ophthalmic and Optometric Sciences 2 (2018): 24-26.
32. Shushtarian SMM. Dermani FS, & Mazar RP. Blurred Vision in a Patient Suffering from Endometriosis and Epilepsy. Journal of Ophthalmic and Optometric Sciences 5 (2021): 57-60.
33. Shushtarian SMM. Dizziness and Nausea Feeling During Pattern Reversal Checkerboard Visual Evoked Potential Recording in A Multiple Sclerosis Patient. Journal of Ophthalmic and Optometric Sciences 5 (2021): 44-47.
34. Shushtarian SMM. Low Vision in a Patient Due to Retinal Dystrophy upon Refractive Surgery. Journal of Ophthalmic and Optometric Sciences 5 (2021).
35. Adhami-Moghadam P, Shushtarian SMM, & Adhami-Moghadam F. Retinal Screening of Coats Disease Using Electroretinography. Journal of Ophthalmic and Optometric Sciences 5 (2021).
36. Shushtarian SM M, & Fatemian N. Large Difference in Latency of Visual Evoked Potential P100 Peak in Case of Pattern and Flash Stimulation in a Multiple Sclerosis Patient. Journal of Ophthalmic and Optometric Sciences 5 (2021).
37. Naser M, & Shushtarian SMM. Amplitude and Latency of Electroretinographical Peaks as a tool to predict the Extent of Retinal Degeneration in Retinitis Pigmentosa Patients. Journal of Ophthalmology and Research 3 (2020): 71-74.
38. Sarzaeim F, Hashemzehi M, Shushtarian S MM, et al. Visual Evoked Potential Findings in Road Drilling Machine laborers. Journal of Ophthalmology and Research 5 (2022): 43-47.
39. Shushtarian S MM, Shojaei A, & Adhami-Moghadam F. Visual Evoked Potentials Changes among Patients with Chronic Mustard Gas Exposure. Journal of Ophthalmic and Optometric Sciences 2 (2018): 6-9.
40. Sarzaeim F, Abdolalizadeh S, Shushtarian SM M, et al. Visual Evoked Potential Findings in Patients using Anti-Seizure Medicine. Journal of Ophthalmology and Research 5 (2022): 123-126.
41. Pojda-Wilczek D. Visual-evoked potentials in patients with brain circulatory problems. International Journal of Neuroscience 125 (2015): 264-269.
42. Jansen BH, & Rit VG. Electroencephalogram and visual evoked potential generation in a mathematical model of coupled cortical columns. Biological cybernetics 73(1995): 357-366.